View source for Discovery Program

{{Short description|Solar system exploration program by NASA}}
{{distinguish|Space Shuttle Discovery|CORONA (satellite)#Discoverer}}
{{Use mdy dates|date=June 2019}}
[[File:Discovery program website header, 2016.png|thumb|500px|right|Header of the Discovery Program website (January 2016)<ref>{{cite web |title=Discovery Program Official Website (January 2016) |url=http://discovery.nasa.gov/index.cfml |publisher=[[NASA|National Aeronautics and Space Administration (NASA)]] |date=January 15, 2016 |access-date=January 15, 2016 |archive-url=https://web.archive.org/web/20160115105036/http://discovery.nasa.gov/index.cfml |archive-date=January 15, 2016 |url-status=dead  }}</ref>]]
[[File:Lucy and Psyche discovery-missions 13 and 14-v3.jpg|thumb|Depictions of the ''Lucy'' and ''Psyche'' missions]]
[[File:Properties of regolith on Eros.jpg|thumb|Asteroid [[433 Eros|Eros]] regolith, as viewed by Discovery's NEAR Shoemaker mission]]
The '''Discovery Program''' is a series of [[Solar System exploration]] missions funded by the U.S. [[National Aeronautics and Space Administration]] (NASA) through its [[Planetary Missions Program Office]]. The cost of each mission is capped at a lower level than missions from NASA's [[New Frontiers program|New Frontiers]] or [[Flagship Program|Flagship]] Programs. As a result, Discovery missions tend to be more focused on a specific scientific goal rather than serving a general purpose.

The Discovery Program was founded in 1990. Existing NASA programs had specified mission targets and objectives in advance, then sought bidders to construct and operate them. In contrast, Discovery missions are solicited through a [[call for proposals]] on any science topic and assessed through [[peer review]]. Selected missions are led by a scientist called the [[principal investigator]] (PI) and may include contributions from industry, universities or government laboratories.

The Discovery Program also includes Missions of Opportunity, which fund U.S. participation in spacecraft operated by other space agencies, for example by contributing a single [[scientific instrument]]. It can also be used to re-purpose an existing NASA spacecraft for a new mission.

As of June 2021, the most recently selected Discovery missions were [[VERITAS (spacecraft)|VERITAS]] and [[DAVINCI]], the fifteenth and sixteenth missions in the program.<ref name=nasataps>{{Cite news|url=http://www.sciencemag.org/news/2017/01/breaking-nasa-taps-missions-tiny-metal-world-and-jupiter-trojans|title=Updated: NASA taps missions to tiny metal world and Jupiter Trojans|date=2017-01-04|newspaper=[[Science (journal)|Science]]|publisher=AAAS|access-date=2017-01-04}}</ref>

==History==
In 1989, NASA's Solar System Exploration Division began to define a new strategy for Solar System exploration up to the year 2000. This included a Small Mission Program Group that investigated missions that would be low cost and allow focused scientific questions to be addressed in shorter time than existing programs. The result was a request for rapid studies of potential missions and NASA committed funding in 1990. The new program was called "Discovery".<ref name="History">{{cite news |title=A Look Back at the Beginning: How the Discovery Program Came to Be |year=2010 |url=http://discovery.nasa.gov/lib/pdf/HistoricalDiscoveryProgramInformation.pdf |publisher=NASA |archive-url=https://web.archive.org/web/20110301135255/http://discovery.nasa.gov/lib/pdf/HistoricalDiscoveryProgramInformation.pdf |archive-date=March 1, 2011 |url-status=dead  }}</ref>

The panel assessed several concepts that could be implemented as low-cost programs, selecting [[NEAR Shoemaker]] which became the first launch in the Discovery Program on February 17, 1996. The second mission, [[Mars Pathfinder]], launched on December 4, 1996, carried the [[Sojourner rover|''Sojourner'' rover]] to Mars.<ref name="History" />

==Missions==
<gallery mode="packed" heights="140">
File:(253) mathilde crop.jpg|alt=An image of a rocky asteroid|Asteroid [[253 Mathilde]]
File:PIA02406.jpg|alt=A view of the rocky Martian surface|''Mars Pathfinder''{{'}}s view of [[Ares Vallis]]
File:Eros rotation Dec. 3-4 2000.gif|alt=An animation of the rotation of an asteroid|Animation of the rotation of 433 Eros.
File:Hollows in Sholem Aleichem.jpg|alt=The surface of Mercury|''MESSENGER'' imaging Mercury's surface hollows at [[Sholem Aleichem (crater)|Sholem Aleichem]].<ref>{{cite web|url=http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1349 |title=High-resolution Hollows |work=MESSENGER Featured Images |date=March 12, 2014 |publisher=JHU – APL |archive-url=https://web.archive.org/web/20140314010953/http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1349 |archive-date=March 14, 2014 |url-status=dead  }}</ref>
File:PIA19664-MarsInSightLander-Assembly-20150430.jpg|alt=InSight being built|InSight lander in assembly (April 2015, NASA)
</gallery>

===Standalone missions===
{| class="wikitable sortable" style="margin:1em auto;"
|+ Standalone Discovery Program missions
! scope="col" | No.
! scope="col" | Name
! scope="col" | Targets<!-- 
! scope="col" | Primary investigator -->
! scope="col" | Launch date
! scope="col" | Rocket
! scope="col" | Launch mass
! scope="col" | First science
! scope="col" | Status
! scope="col" | Principal investigator
! scope="col" | Cost <br>(million USD)

|-
! scope="row" rowspan=2 style="text-align:center;" | 1
! [[NEAR Shoemaker]]
| '''[[433 Eros]]''' (lander), [[253 Mathilde]]
| February 17, 1996
| [[Delta II]]<br> 7925-8
| {{convert| 800|kg|disp=br()|abbr=on}}
| June 1997
| {{success|Completed in 2001}}
| Andrew Cheng <br>([[Applied Physics Laboratory|APL]])<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-008A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
| 224<br>(2000)<ref>{{cite web|url=https://near.jhuapl.edu/intro/faq.html |title=Frequently Asked Questions |publisher=Near.jhuapl.edu |access-date=2018-05-02}}</ref>
|-
| colspan="9" | ''Near Earth Asteroid Rendezvous – Shoemaker'' (named after [[Eugene Shoemaker]]) was the first man-made object to both orbit and land on an asteroid. It carried many scientific instruments designed to study both [[253 Mathilde]] and [[433 Eros]], such as a magnetometer, multi spectral imager, and an x-ray/gamma ray spectrometer. After a February 17, 1996, launch, it performed a flyby of [[253 Mathilde]] on June 27, 1997, and an Earth flyby in 1998. It flew by [[433 Eros]] once in 1998, before a second approach allowed it to enter orbit around Eros of February 14, 2000. After nearly a year of orbital observations, the spacecraft was landed on the asteroid on February 12, 2001, and  continued to function successfully after touching down softly at under 2&nbsp;m/s, becoming the first probe to soft-land on an asteroid. The probe continued to emit signals until February 28, 2001, and the final attempt to communicate with the spacecraft was on December 10, 2002.<ref name=":2">{{Cite web|title=In Depth {{!}} NEAR Shoemaker|url=https://solarsystem.nasa.gov/missions/near-shoemaker/in-depth/|access-date=20 February 2021|website=[[NASA]]|date=December 20, 2017 }}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 2
! [[Mars Pathfinder]]
| '''[[Mars]]''' (rover)
| December 4, 1996 
| [[Delta II]]<br> 7925
| {{convert| 890 |kg|disp=br()|abbr=on}}
| July 4, 1997
| {{success|Completed in 1998}}
| Joseph Boyce<br> ([[Jet Propulsion Laboratory|JPL]])
| 265<br>(1998)<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-068A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
|-
| colspan="9" | [[Mars Pathfinder]] was a lander and rover designed to study [[Mars]]'s geology and climate, as well as to demonstrate rover technology on another planet. It launched about a month after the [[Mars Global Surveyor]], on December 4, 1996. After entering the Martian atmosphere, the hypersonic capsule deployed a complex landing system including a parachute and an airbag to hit the surface at 14&nbsp;m/s. The lander deployed the [[Sojourner rover|''Sojourner'' rover]], weighing (10.5&nbsp;kg), on the Martian surface on July 5, 1997, on Mars's [[Ares Vallis]], thus becoming the first rover to operate outside the Earth-Moon system. It carried a series of scientific instruments to analyze the Martian atmosphere, climate, geology and the composition of its rocks and soil. It completed its primary and extended mission and after over 80 days, the last signal was sent on September 27, 1997. The mission was terminated on March 10, 1998.<ref>{{Cite web|title=In Depth {{!}} Mars Pathfinder|url=https://solarsystem.nasa.gov/missions/mars-pathfinder/in-depth/|access-date=20 February 2021|website=[[NASA]]|date=December 20, 2017 }}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 3
! [[Lunar Prospector]]
| '''[[Moon]]'''
| January 7, 1998
| [[Athena II]] <br>{{nowrap|[Star-3700S]}}
| {{convert| 296 |kg|disp=br()|abbr=on}}
| January 16, 1998
| {{success|Completed in 1999}}
| Alan Binder<ref name="autogenerated4">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1998-001A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
| 63<br>(1998)<ref>{{cite news|url=https://www.cnn.com/TECH/9801/11/space.probe/index.html |title=U.S. space probe moving into lunar orbit – January 11, 1998 |publisher=CNN |access-date=2018-04-28}}</ref>

|-
| colspan="9" | [[Lunar Prospector]] was a lunar orbiter to characterize the lunar mineralogy, including polar ice deposits, measure magnetic and gravitational fields, and study lunar outgassing events. After preliminary mappings, it achieved the targeted primary Lunar orbit on January 16. The primary mission in this orbit lasted one year until January 28, 1999, followed up by a half-year extended mission in a lower orbit for higher resolution. On July 31, 1999, it deliberately impacted into the [[Shoemaker (lunar crater)|Shoemaker]] crater near the Lunar South pole in an attempt to produce water vapor plumes that would be observable from Earth.<ref>{{Cite web|title=Prospector Mission Overview|url=https://www.lpi.usra.edu/lunar/missions/prospector/overview/index.shtml|access-date=20 February 2021|website=[[Lunar and Planetary Institute]]}}</ref><ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/planetary/lunarprosp.html |title=Lunar Prospector Information |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-04-28}}</ref><ref name="autogenerated4"/>

|-
! scope="row" rowspan=2 style="text-align:center;" | 4
! ''[[Stardust (spacecraft)|Stardust]]''
| '''[[81P/Wild]]''' (sample collect), [[5535 Annefrank]], [[Tempel 1]]
| February 7, 1999
| [[Delta II]]<br> 7426-9.5
| {{convert| 391 |kg|disp=br()|abbr=on}}
| November 2, 2002
| {{success|Completed in 2011}}
| [[Donald Brownlee]] <br>([[University of Washington|UW]])
| 200<br>(2011)<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1999-003A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
|-
| colspan="9" | [[Stardust (spacecraft)|Stardust]] was a mission to collect interstellar dust and dust particles from the nucleus of comet [[81P/Wild]] for study on [[Earth]]. After a flyby of Earth and then of asteroid [[5535 Annefrank]] in November 2002, it performed a flyby of comet Wild 2 in January 2004, during which the Sample Collection plate collected dust grain samples from the [[coma (cometary)|coma]]. Samples were stored in a return capsule which landed on Earth on January 15, 2006. Scientists worldwide are currently studying the comet dust samples while citizen scientists are attempting to find interstellar dust bits through the [[Stardust@home]] project, and in 2014, scientists announced the identification of possible [[interstellar dust]] particles. Meanwhile, the spacecraft  was diverted for a flyby of [[Tempel 1]] comet, as part of [[Stardust (spacecraft)#New Exploration of Tempel 1 (NExT)|Stardust-NExT]] extension, to observe the crater left by ''Deep Impact''. Stardust did a final burn to deplete its remaining fuel on March 21, 2011''.<ref>{{cite web |title=NASA's Stardust: Good to the Last Drop |url=http://www.nasa.gov/mission_pages/stardust/news/stardust20110323.html |website=NASA.gov |publisher=NASA |access-date=April 17, 2016 |language=en |date=April 20, 2015 |archive-date=June 9, 2021 |archive-url=https://web.archive.org/web/20210609011904/http://www.nasa.gov/mission_pages/stardust/news/stardust20110323.html |url-status=dead }}</ref>''

|-
! scope="row" rowspan=2 style="text-align:center;" | 5
! ''[[Genesis (spacecraft)|Genesis]]''
| '''[[Solar wind]]''' (collect at Sun–Earth L<sub>1</sub>)
| August 8, 2001
| [[Delta II]]<br> 7326
| {{convert| 494 |kg|disp=br()|abbr=on}}(dry)
| December 3, 2001
| {{success|Completed in 2004}}
| Donald Burnett <br>([[California Institute of Technology|Caltech]])<ref name="autogenerated5">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2001-034A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
| 209<br>(2004)<ref name="autogenerated5"/>
|-
| colspan="9" | [[Genesis (spacecraft)|Genesis]] was a mission to collect [[solar wind]] charged particles for analysis on Earth. After reaching L<sub>1</sub> orbit on November 16, 2001,<ref>{{Cite web|title=Genesis - Sun Missions|url=https://www.jpl.nasa.gov/missions/genesis|access-date=20 February 2021|website=[[NASA]]}}</ref> it collected solar wind for 850 days between 2001 and 2004. It left [[Lissajous orbit]] and began its return to Earth on April 22, 2004,<ref>{{Cite web|title=Genesis : Search for Origins.|url=https://genesismission.jpl.nasa.gov/gm2/mission/history.htm|access-date=20 February 2021|website=[[Jet Propulsion Laboratory]]}}</ref> but on September 8, 2004, the sample-return capsule's parachute failed to deploy, and the capsule crashed into the Utah desert. However, solar wind samples were salvaged and are available for study. Despite the hard landing, ''Genesis'' has met or anticipates meeting all of its baseline science objectives.<ref>{{Cite web|title=Genesis Mishap Investigation Board Report Volume I|url=https://www.nasa.gov/pdf/149414main_Genesis_MIB.pdf|access-date=20 February 2021|website=[[NASA]]}}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 6
! [[CONTOUR]]
| [[Comet Encke|Encke]], [[Schwassmann-Wachmann-3]]
| July 3, 2002
| [[Delta II]] 7425 <br>[Star-30BP]
| {{convert| 398 |kg|disp=br()|abbr=on}}
| —
| {{failure|Disintegrated <br>after launch}}
| [[Joseph Veverka]] <br>([[Cornell University|Cornell]])<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2002-034A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
| 154<br> (1997)<ref>{{Cite web|last=Isbell|first=Douglas|date=20 October 1997|title=MISSIONS TO GATHER SOLAR WIND SAMPLES AND TOUR THREE COMETS SELECTED AS NEXT DISCOVERY PROGRAM FLIGHTS|url=https://nssdc.gsfc.nasa.gov/planetary/text/discovery_pr_971020.txt|access-date=20 February 2021|website=[[NASA]]}}</ref>
|-
| colspan="9" | ''Comet Nucleus Tour'' was a mission to visit and study at least 2 comets. On August 15, 2002, the spacecraft disintegrated during a planned maneuver that was intended to propel it out of Earth orbit and into its comet-chasing solar orbit. The investigation board concluded the probable cause was structural failure of the spacecraft due to plume heating during the Star-30 solid-rocket motor burn.<ref name="History" /><ref name=":1">{{cite web |url=http://discovery.nasa.gov/lib/presentations/pdf/mishap_board_report_503.pdf |title=CONTOUR Mishap Investigation Board Report |publisher=NASA |date=May 21, 2003 |archive-url=https://web.archive.org/web/20060103182107/http://discovery.nasa.gov/lib/presentations/pdf/mishap_board_report_503.pdf |archive-date=January 3, 2006 |url-status=dead  }}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 7
! ''[[MESSENGER]]''
| '''[[Mercury (planet)|Mercury]]''', [[Venus]]
| August 3, 2004
| [[Delta II]]<br> 7925H-9.5
| {{convert| 1,108 |kg|disp=br()|abbr=on}}
| August 2005
| {{success|Completed in 2015}}
| [[Sean Solomon]]<br>([[Applied Physics Laboratory|APL]])<ref name="autogenerated2004">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2004-030A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
| 450<br>(2015)<ref>{{cite web|author=Mike Wall |url=https://spacenews.com/nasas-long-lived-messenger-probe-slams-into-mercury/ |title=NASA's Long-lived MESSENGER Probe Slams into Mercury |publisher=Spacenews.com |date= April 30, 2015|access-date=2018-05-02}}</ref>
|-
| colspan="9" | ''Mercury Surface, Space Environment, Geochemistry and Ranging'' was an orbiter which conducted the first orbital study of Mercury. Its science goals were to provide the first images of the entire planet and collect detailed information on the composition and structure of Mercury's crust, its geologic history, the nature of its thin atmosphere and active magnetosphere, and the makeup of its core and polar materials. It was only the second spacecraft to flyby Mercury, after [[Mariner 10]] in 1975. After one Earth flyby, two of Venus and three of Mercury, it finally entered orbit around Mercury on March 18, 2011. The primary science mission began on April 4, 2011, and lasted until March 17, 2012. It achieved 100% mapping of Mercury on March 6, 2013, and completed its first year-long extended mission on March 17, 2013. After another mission extension, the spacecraft ran out of propellant and was deorbited on April 30, 2015.<ref>[https://www.space.com/29281-messenger-spacecraft-mercury-crash.html Farewell, MESSENGER! NASA Probe Crashes Into Mercury]. Mike Wall. ''Space News'' April 30, 2015.</ref><ref name="autogenerated2004"/>

|-
! scope="row" rowspan=2 style="text-align:center;" | 8
! ''[[Deep Impact (spacecraft)|Deep Impact]]''
| '''[[Tempel 1]]''' (impactor), [[103P/Hartley]]
| January 12, 2005
| [[Delta II]]<br> 7925
| {{convert| 650 |kg|disp=br()|abbr=on}}
| April 25, 2005
| {{success|Completed in 2013}}
| [[Michael A'Hearn]] <br>([[University of Maryland, College Park|UMD]])<ref name="autogenerated2005">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2005-001A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
| 330<br>(2005)<ref>{{cite web|url=http://www.cnn.com/2005/TECH/space/07/04/deep.impact/ |title=Deep Impact probe hits comet – Jul 4, 2005 |publisher=CNN.com |date=2005-07-04 |access-date=2018-05-02}}</ref>
|-
| colspan="9" | [[Deep Impact (spacecraft)|Deep Impact]] was a space probe launched with the goal to both flyby and impact the comet [[Tempel 1]]. It was launched from [[Cape Canaveral Air Force Station]] on January 12, 2005. The spacecraft released a 350&nbsp;kg impactor into the path of comet [[Tempel 1]] on July 3, 2005, and the impact occurred on July 4, 2005, releasing an energy equivalent of 4.7 tons of [[TNT]]. The resulting impact plume was observed by the spacecraft and other space-based observatories. The 2007 Stardust spacecraft NExT mission determined the resulting crater's diameter to be 150 meters (490&nbsp;ft). After the successful completion of its mission, the main spacecraft was put in hibernation before being reactivated for a new mission designated [[EPOXI]]. On November 4, 2010, it performed a flyby of comet [[103P/Hartley|Hartley 2]].<ref name="autogenerated2005"/> In 2012 it performed long-distance observations of comet Garradd [[Gordon J. Garradd|C/2009 P1]],<ref>{{Cite journal|last1=Farnham|first1=Tony|last2=Bodewits|first2=D.|last3=A'Hearn|first3=M.F|last4=Feaga|first4=L.M|title=Deep Impact MRI Observations Of Comet Garradd (C/2009 P1)|url=https://ui.adsabs.harvard.edu/abs/2012DPS....4450605F/abstract|access-date=20 February 2021|journal=[[Astrophysics Data System]]|year=2012|volume=44|pages=506.05|bibcode=2012DPS....4450605F}}</ref> and in 2013 of [[Comet ISON]].<ref>{{Cite web|title=Deep Impact Images Spectacular incoming Comet ISON – Curiosity & NASA Armada Will Try|url=https://www.universetoday.com/99777/deep-impact-images-spectacular-incoming-comet-ison-curiosity-nasa-armada-will-try/#more-99777|access-date=20 February 2021|website=[[Universe Today]]|date=February 6, 2013}}</ref> Contact was abruptly lost in August 2013, later attributed to a [[Year 2000 problem|Y2K]]-like integer overflow software bug.<ref>{{Cite news|last=Vergano|first=Dan|date=20 September 2013|title=NASA Declares End to Deep Impact Comet Mission|work=[[National Geographic]]|url=https://www.nationalgeographic.com/science/article/130920-deep-impact-ends-comet-mission-nasa-jpl#:~:text=After%20a%20month%20of%20attempts,%2C%22%20said%20A%27Hearn.|archive-url=https://web.archive.org/web/20210305013113/https://www.nationalgeographic.com/science/article/130920-deep-impact-ends-comet-mission-nasa-jpl#:~:text=After%20a%20month%20of%20attempts,%2C%22%20said%20A%27Hearn.|url-status=dead|archive-date=March 5, 2021|access-date=20 February 2021}}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 9
! ''[[Dawn (spacecraft)|Dawn]]''
| [[4 Vesta]], '''[[Ceres (dwarf planet)|Ceres]]'''
| September 27, 2007 
| [[Delta II]]<br> 7925H
| {{convert| 1,218 |kg|disp=br()|abbr=on}}
| May 3, 2011
| {{success|Completed in 2018}}
| [[Christopher T. Russell]] ([[University of California, Los Angeles|UCLA]])<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2007-043A |title=NASA – NSSDCA – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |access-date=2018-05-02}}</ref>
| 472<br> (2015)<ref>{{Cite news|last=Hotz|first=Robert|date=6 March 2015|title=NASA's Dawn Spacecraft Orbits Dwarf Planet Ceres|work=[[The Wall Street Journal]]|url=https://www.wsj.com/articles/nasas-dawn-spacecraft-orbits-dwarf-planet-ceres-1425654292|access-date=20 February 2021}}</ref>
|-
| colspan="9" | ''[[Dawn (spacecraft)|Dawn]]'' was the first spacecraft to orbit two extraterrestrial bodies, the two most massive objects of the [[asteroid belt]]: the [[protoplanet]] [[4 Vesta|Vesta]] and the [[dwarf planet]] [[Ceres (dwarf planet)|Ceres]]. The spacecraft employed highly efficient [[ion thrusters]], with just 425&nbsp;kg of [[xenon]] for the entire mission after escaping Earth. After a 2009 Mars flyby, it entered orbit around Vesta on July 16, 2011. It entered its lowest Vesta orbit on December 8, 2011, and after a year-long Vesta mission of observing surface terrain and mineral composition, left its orbit on September 5, 2012. It entered Ceres's orbit on March 6, 2015, becoming the first spacecraft to visit a [[dwarf planet]], and began its lowest orbit on December 16. In June 2016 it was approved for an extended mission at Ceres.<ref name="NewSci2012">{{cite web |url=https://www.newscientist.com/blogs/shortsharpscience/2012/09/asteroid-hopping-spacecraft-ma.html |title=Dawn departs Vesta to become first asteroid hopper |first=Jacob |last=Aron |work=[[New Scientist]] |date=September 6, 2012 |archive-url=https://web.archive.org/web/20120907134311/http://www.newscientist.com/blogs/shortsharpscience/2012/09/asteroid-hopping-spacecraft-ma.html |archive-date=September 7, 2012 |url-status=live}}</ref><ref name="dawn_timetable">{{cite web|title=DAWN – A Journey to the Beginning of the Solar System |work=Dawn Mission Timeline |publisher=[[Jet Propulsion Laboratory]] |url=http://dawn.jpl.nasa.gov/mission/timeline.asp |archive-url=https://web.archive.org/web/20131019233834/http://dawn.jpl.nasa.gov/mission/timeline.asp |archive-date=October 19, 2013 |url-status=dead  }}</ref> On October 19, 2017, NASA announced that the mission would be extended until its hydrazine fuel ran out,<ref name=":3">{{Cite web|last=Landau|first=Elizabeth|date=19 October 2017|title=Dawn Mission Extended at Ceres|url=https://www.jpl.nasa.gov/news/dawn-mission-extended-at-ceres|access-date=20 February 2021|website=[[Jet Propulsion Laboratory]]}}</ref> which occurred on October 31, 2018.<ref>{{Cite web|last1=Brown|first1=Dwayne|last2=Wendel|first2=Joanna|last3=McCartney|first3=Gretchen|date=1 November 2018|title=NASA's Dawn Mission to Asteroid Belt Comes to End|url=https://www.jpl.nasa.gov/news/nasas-dawn-mission-to-asteroid-belt-comes-to-end|access-date=20 February 2021|website=[[Jet Propulsion Laboratory]]}}</ref> The spacecraft is currently in an uncontrolled orbit around Ceres.<ref>{{Cite web|date=4 August 2019|title=A mountain on dwarf planet Ceres|url=https://earthsky.org/space/mountain-ceres-ahuna-mon-image#:~:text=Dawn%20%E2%80%93%20the%20first%20spacecraft%20ever,around%20Ceres%20to%20this%20day.|access-date=20 February 2021|website=EarthSky}}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 10
! [[Kepler space telescope]]
| transiting [[exoplanet]] survey
| March 7, 2009
| [[Delta II]]<br> 7925-10L
| {{convert| 1,052 |kg|disp=br()|abbr=on}}
| May 12, 2009
| {{success|Completed in 2018}}
| [[William Borucki]] <br>([[Ames Research Center|NASA Ames]])
| 640<br>(2009)<ref>{{cite web|url=https://www.popularmechanics.com/space/telescopes/a9565/all-about-tess-nasas-next-planet-finder-16097391/ |title=All About TESS, NASA's Next Planet Finder |publisher=Popularmechanics.com |date=2013-10-30 |access-date=2018-05-02}}</ref>
|-
| colspan="9" | [[Kepler space telescope|Kepler]] was a [[space observatory]] named after [[Johannes Kepler]] in a heliocentric, Earth-trailing orbit tasked to explore the structure and diversity of [[exoplanet]] systems, with a special emphasis on the detection of Earth-size planets in orbit around stars outside the Solar System.<ref>{{cite web |last1=Koch |first1=David |last2=Gould |first2=Alan |title=Kepler Mission |url=http://www.kepler.arc.nasa.gov/ |publisher=[[NASA]] |date=March 2009 |archive-url=https://web.archive.org/web/20140306190326/http://kepler.arc.nasa.gov/ |archive-date=March 6, 2014 |url-status=dead}}</ref> Initially planned for 3.5 years, the spacecraft functioned for about 10 years, including a ''K2'' "Second Light" mission extension with reduced precision owing to failing [[Reaction wheel|reaction wheels]]. By 2015, the spacecraft had detected over 2,300 confirmed planets,<ref name="NASA-20150106">{{cite web|last1=Clavin|first1=Whitney|last2=Chou|first2=Felicia|last3=Johnson|first3=Michele|title=NASA's Kepler Marks 1,000th Exoplanet Discovery, Uncovers More Small Worlds in Habitable Zones|url=http://www.jpl.nasa.gov/news/news.php?release=2015-003|date=January 6, 2015|work=[[NASA]]|access-date=January 6, 2015}}</ref><ref>{{cite web|title='Alien Earth' is among eight new far-off planets|url=https://www.bbc.co.uk/news/science-environment-30705517|date=January 7, 2015|work=BBC|access-date=January 7, 2015}}</ref> including [[hot Jupiter]]s, [[super-Earth]]s, [[circumbinary planet]]s, and planets located in the [[circumstellar habitable zone]]s of their host stars. In addition, ''Kepler'' detected over 3,600 unconfirmed planet candidates<ref name="wall-2013">{{cite news|url=http://exoplanetarchive.ipac.caltech.edu/index.html|title=NASA Exoplanet archive|date=September 5, 2013|agency=TechMediaNetwork|access-date=June 15, 2013|author=Wall, Mike}}</ref><ref name="keplersite">{{cite web|title=NASA – Kepler|url=http://www.nasa.gov/mission_pages/kepler/main/index.html|access-date=February 26, 2014|url-status=dead|archive-url=https://web.archive.org/web/20131105082102/http://www.nasa.gov/mission_pages/kepler/main/index.html|archive-date=November 5, 2013}}</ref> and over 2,000 [[eclipsing binary star]]s.<ref name=keplersite/> The telescope was retired on October 30, 2018, after depleting its fuel.<ref>{{Cite web|url=https://www.nasaspaceflight.com/2018/10/kepler-retired-after-running-out-of-fuel/|title=Kepler – NASA's planet-hunting spacecraft – retired after running out of fuel|date=October 30, 2018|website=NASASpaceflight.com|language=en-US|access-date=2018-10-31}}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 11
! [[Gravity Recovery and Interior Laboratory|GRAIL]]
| '''[[Moon]]''' 
| September 10, 2011
| [[Delta II]]<br> 7920H-10C
| {{convert| 307 |kg|disp=br()|abbr=on}}
| March 7, 2012
| {{success|Completed in 2012}}
| [[Maria Zuber]] <br>([[Massachusetts Institute of Technology|MIT]])
| 496 <br>(2011)<ref>{{Cite web|title=Gravity Recovery and Interior Laboratory (GRAIL) Launch|url=https://www.nasa.gov/pdf/582116main_GRAIL_launch_press_kit.pdf|access-date=20 February 2021|website=[[NASA]]|archive-date=January 26, 2022|archive-url=https://web.archive.org/web/20220126152202/https://www.nasa.gov/pdf/582116main_GRAIL_launch_press_kit.pdf|url-status=dead}}</ref>
|-
| colspan="9" | ''Gravity Recovery and Interior Laboratory'' was a Moon orbiter that provided higher-quality [[gravitational field]] mapping of the Moon to determine its interior structure.<ref name="LaunchCBS">{{cite web |last=Harwood |first=William |title=NASA launches GRAIL lunar probes |url=https://www.cbsnews.com/news/nasa-launches-grail-lunar-probes/ |work=CBS News |date=September 10, 2011 |archive-url=https://web.archive.org/web/20110911193237/http://www.cbsnews.com/stories/2011/09/10/scitech/main20104282.shtml |archive-date=September 11, 2011 |url-status=live}}</ref> The two small spacecraft ''GRAIL A (Ebb)'' and ''GRAIL B (Flow)'' separated soon after the launch and entered Lunar orbits on December 31, 2011, and January 1, 2012, respectively. The primary scientific phase was achieved in May 2012. After the extended mission phase, the two spacecraft impacted the Moon on December 17, 2012. MoonKAM (Moon Knowledge Acquired by Middle school students) was an education related sub-program and instrument of this mission.<ref>{{cite web |title=About GRAIL MoonKAM |url=http://www.grailmoonkam.com/about |publisher=Sally Ride Science |date=2010 |access-date=April 15, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100427105214/http://www.grailmoonkam.com/about |archive-date=April 27, 2010  }}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 12
! ''[[InSight]]''
| '''[[Mars]]''' (lander)
| May 5, 2018
| [[Atlas V]]<br> (401)
| {{convert| 721 |kg|disp=br()|abbr=on}}
| November 2018
| {{success|Completed in 2022}}
| [[W. Bruce Banerdt]] <br>([[Jet Propulsion Laboratory|JPL]])
| 830<br>(2016)<ref>{{cite web |url=https://www.nasa.gov/feature/jpl/nasa-approves-2018-launch-of-mars-insight-mission |title=NASA Approves 2018 Launch of Mars InSight Mission &#124; NASA |date=September 2, 2016 |publisher=Nasa.gov |access-date=2018-05-02 |archive-date=December 30, 2019 |archive-url=https://web.archive.org/web/20191230195231/https://www.nasa.gov/feature/jpl/nasa-approves-2018-launch-of-mars-insight-mission/ |url-status=dead }}</ref>
|-
| colspan="9" | ''Interior Exploration using Seismic Investigations, Geodesy and Heat Transport'' is a 358&nbsp;kg lander reusing technology from the Mars [[Phoenix lander]]. It was intended to study the interior structure and composition of Mars as well as to detect [[Marsquake]]s and other seismic activity, advancing understanding of the formation and evolution of terrestrial planets.<ref>{{cite news |publisher=NASA |date=August 20, 2012 |title=New NASA Mission to Take First Look Deep Inside Mars |url=http://www.nasa.gov/mission_pages/mars/news/mars20120820.html |archive-url=https://web.archive.org/web/20120822070713/http://www.nasa.gov/mission_pages/mars/news/mars20120820.html |archive-date=August 22, 2012 |url-status=live}}</ref><ref>{{Cite web|title=Measuring the Pulse of Mars|url=https://mars.nasa.gov/insight/spacecraft/instruments/seis/|access-date=6 March 2021|website=mars.nasa.gov|publisher=[[NASA]]}}</ref> Its launch was delayed from 2016 to May 2018.<ref name=delay>{{cite web |url=http://www.nasa.gov/press-release/nasa-suspends-2016-launch-of-insight-mission-to-mars |title=NASA Suspends 2016 Launch of InSight Mission to Mars |date=December 22, 2015}}</ref> The lander touched down successfully on November 26, 2018, at a site about 600&nbsp;km (370&nbsp;mi) from the [[Curiosity rover]].<ref>{{cite news|last=Amos|first=Jonathan|date=November 26, 2018|title=Mars: Nasa lands InSight robot to study planet's interior|publisher=BBC|url=https://www.bbc.com/news/science-environment-46351114|access-date=5 March 2021}}</ref> It detected its first possible quake on April 6, 2019.<ref>{{Cite news|last=Alexandra|first=Witze|date=24 April 2019|title=First "Marsquake" Detected on Red Planet|work=[[Scientific American]]|url=https://www.scientificamerican.com/article/first-marsquake-detected-on-red-planet1/|access-date=6 March 2021}}</ref> Dust accumulating on the lander's solar arrays gradually reduced available power over the course of the mission, and contact was lost on December 15, 2022.<ref>{{Cite web |title=NASA InSight – Dec. 19, 2022 – Mars InSight |url=https://blogs.nasa.gov/insight/2022/12/19/nasa-insight-dec-19-2022/ |access-date=2022-12-20 |website=blogs.nasa.gov |date=December 19, 2022 |language=en-US}}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 13
! ''[[Lucy (spacecraft)|Lucy]]''
| '''[[Jupiter trojan]]s'''
| October 16, 2021
| [[Atlas V]] <br> 401<ref name="Lucy_launch">{{cite web |title=NASA Awards Launch Services Contract for Lucy Mission |url=https://www.nasa.gov/press-release/nasa-awards-launch-services-contract-for-lucy-mission |publisher=NASA |access-date=23 January 2020|date=January 31, 2019 }}</ref>
|1,550&nbsp;kg (3,417 lb)<ref>{{Cite web|last=Dunbar|first=Brian|date=3 December 2020|editor-last=Hille|editor-first=Karl|title=The Lucy Spacecraft and Payload|url=https://www.nasa.gov/content/lucy-spacecraft-and-payload|access-date=6 March 2021|website=nasa.gov|publisher=[[NASA]]|archive-date=April 23, 2022|archive-url=https://web.archive.org/web/20220423081253/https://www.nasa.gov/content/lucy-spacecraft-and-payload/|url-status=dead}}</ref>
| 2025 
| {{success|'''En route'''}}
| [[Harold F. Levison]] <br>([[Southwest Research Institute|SwRI]])
| 450<ref name="spaceflightnow1">{{cite web|author=Stephen Clark |url=https://spaceflightnow.com/2017/05/26/earlier-launch-of-nasas-psyche-mission-touted-as-cost-saving-measure/ |title=Earlier launch of NASA's Psyche mission touted as cost-saving measure – Spaceflight Now |publisher=Spaceflightnow.com |access-date=2018-05-02}}</ref>+ 148<ref name="psyche">{{Cite news|last=Foust|first=Jeff|date=28 February 2020|title=Falcon Heavy to launch NASA Psyche asteroid mission|work=[[SpaceNews]]|url=https://spacenews.com/falcon-heavy-to-launch-nasa-psyche-asteroid-mission/|access-date=20 February 2021}}</ref>
|-
| colspan="9" | [[Lucy (spacecraft)|Lucy]] is a space probe that will study multiple [[Jupiter trojan]] asteroids. Named after the hominin [[Lucy (Australopithecus)|Lucy]], it will tour six [[Trojan asteroids]] in order to better understand the [[formation and evolution of the Solar System]].<ref name="jobs">{{cite journal |author=jobs |title=Five Solar System sights NASA should visit: Nature News & Comment |issue=7543 |pages=274–5 |journal=Nature News |volume=519 |date=March 16, 2015 |doi=10.1038/519274a |pmid=25788076 |s2cid=4468466 |doi-access=free }}</ref> It was launched in October 2021.<ref>{{cite web| url=https://www.lpi.usra.edu/sbag/meetings/jan2016/presentations/Levison.pdf| title=Lucy: Surveying the Diversity of Trojan Asteroids| last=Levison| first=Hal| date=January 2017|access-date=February 1, 2017}}</ref> Lucy will make two Earth flybys before arriving at Jupiter's L4 Trojan cloud in 2027 to visit [[3548 Eurybates]] (with its satellite), [[15094 Polymele]], [[11351 Leucus]], and [[21900 Orus]]. After an Earth flyby, ''Lucy'' will arrive at the L5 Trojan cloud (trails behind Jupiter) to visit the [[617 Patroclus]]−Menoetius binary in 2033. It will also fly by the inner main-belt asteroid [[52246 Donaldjohanson]] in 2025.<ref>{{Cite web|last=Garner|first=Rob|date=3 December 2020|title=Lucy: The First Mission to the Trojan Asteroids|url=https://www.nasa.gov/mission_pages/lucy/overview/index|access-date=20 February 2021|website=[[NASA]]|archive-date=December 6, 2020|archive-url=https://web.archive.org/web/20201206213030/https://www.nasa.gov/mission_pages/lucy/overview/index|url-status=dead}}</ref>

|-
! scope="row" rowspan=2 style="text-align:center;" | 14
! ''[[Psyche (spacecraft)|Psyche]]''
| '''[[16 Psyche]]'''
| October 13, 2023
| [[Falcon Heavy]]
|2,608&nbsp;kg
| 2029
| {{success|'''En route'''}}
| [[Lindy Elkins-Tanton]] <br>([[Arizona State University|ASU]])
| 450<ref name="spaceflightnow1"/>+ 117<ref name=psyche/>
|-
| colspan="9" |''[[Psyche (spacecraft)|Psyche]]'' is an orbiter that will travel to and study the asteroid [[16 Psyche]], the most massive metallic asteroid in the [[asteroid belt]], thought to be the exposed iron core of a protoplanet.<ref name="hou.usra.edu">[https://www.hou.usra.edu/meetings/lpsc2014/pdf/1253.pdf Journey to a Metal World: Concept for a Discovery Mission to Psyche]. (PDF) 45th Lunar and Planetary Science Conference (2014).</ref> Launched on 13 October 2023, it will arrive in 2029.<ref name="jpl-20221028">{{cite web |url=https://edition.cnn.com/2023/10/13/world/psyche-metal-asteroid-nasa-launch-scn/index.html |title=Psyche mission launches as NASA's first trip to a metal world |work=[[JPL]] |publisher=[[CNN]] |date=13 October 2023 |access-date=13 October 2023}}</ref> It carries an imager, a magnetometer, and a gamma-ray spectrometer.<ref>{{Cite web|title=Psyche Spacecraft Instruments & Science Investigations|url=https://psyche.asu.edu/mission/instruments-science-investigations/|access-date=20 February 2021|website=[[Arizona State University|ASU]]}}</ref>
|-
! rowspan="2" |15
![[DAVINCI]]
|'''[[Venus]]'''
|2031–2032
|
|
||
| {{planned|In development}}
|
|500<ref name=":4" />
|-
| colspan="9" |''Deep Atmosphere Venus Investigation of Noble Gases, Chemistry, and Imaging'' is an atmospheric probe that will study the chemical composition of Venus's atmosphere during descent. These measurements are important to understanding the origin of the Venusian atmosphere, how it has evolved, and how and why it is different from Earth and Mars. ''DAVINCI''<nowiki/>'s measurements will reveal the history of [[water on Venus]] and the chemical processes at work in the unexplored lower atmosphere. Before it reaches the surface, the ''DAVINCI'' probe will take the first ever photos of the planet's intriguing, ridged terrain (“[[Tessera (Venus)|tesserae]]”) to explore its origin and tectonic, volcanic, and weathering history.<ref>{{cite web |last=Neal Jones |first=Nancy |url=https://www.nasa.gov/feature/goddard/2022/nasa-s-davinci-mission-to-take-the-plunge-through-massive-atmosphere-of-venus |title=NASA's DAVINCI Mission To Take the Plunge Through Massive Atmosphere of Venus |work=[[NASA]] |date=June 2, 2022 |access-date=July 15, 2022}}</ref><ref name="verge-20210602" /> The launch is planned for 2031–2032.<ref name="aas-20240325">{{cite web |last=Devarakonda |first=Yaswant |url=https://aas.org/posts/advocacy/2024/03/fy25-presidential-budget-request-nasa |title=The FY25 Presidential Budget Request for NASA |work=[[American Astronomical Society]] |date=25 March 2024 |access-date=29 July 2024}}</ref>
|-
! rowspan="2" |16
![[VERITAS (spacecraft)|VERITAS]]
|'''[[Venus]]'''
|2031
|
|
||
| {{planned|In development}}
|
|500<ref name=":4" />
|-
| colspan="9" |''Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy'' is an orbiter mission that will map the surface of Venus with high resolution. A combination of topography, near-infrared [[spectroscopy]], and radar image measurements would provide knowledge of Venus's tectonic and impact history, gravity, geochemistry, the timing and mechanisms of [[Volcanism on Venus|volcanic resurfacing]], and the mantle processes responsible for them. The launch is planned for 2031.<ref>{{cite tweet |author=Jeff Foust |user=jeff_foust |number=1641078389963366401 |title=In a presentation at Space Science Week, Sue Smrekar says the earliest VERITAS can now launch is late 2029, which she argues is preferable over 2031 to deconflict with DAVINCI and EnVision and lower overall cost. Need "modest" bridge funding in FY23 and 24 to do so. |date=30 March 2023}}</ref><ref name="space-20221104">{{cite web |last=Howell |first=Elizabeth |url=https://www.space.com/nasa-problems-psyche-venus-probe-veritas-launch-delay |title=Problems with NASA asteroid mission Psyche delay Venus probe's launch to 2031 |work=[[Space.com]] |date=4 November 2022 |access-date=5 November 2022}}</ref><ref name="verge-20210602">{{cite web |last=Roulette |first=Joey |url=https://www.theverge.com/2021/6/2/22465588/nasa-mission-to-venus-davinci-veritas-discovery-program |title=NASA will send two missions to Venus for the first time in over 30 years |work=[[The Verge]] |date=June 2, 2021 |access-date=June 2, 2021}}</ref>
|}

===Missions of opportunity===
These provide opportunities to participate in non-NASA missions by providing funding for a science instrument or hardware components of an instrument, or for an extended mission for a spacecraft that may differ from its original purpose.<ref>{{Cite web|title=Discovery Program|url=https://www.nasa.gov/planetarymissions/discovery.html|access-date=25 February 2021|website=[[NASA]]|date=June 18, 2019 }}</ref>

* '''[[Mars Express#Scientific instruments|ASPERA-3]]''', an instrument designed to study the interaction between the solar wind and the [[atmosphere of Mars]], is flying on board the [[European Space Agency]]'s [[Mars Express]] orbiter. Launched on 2 June 2003, it has been orbiting Mars since 30 December 2003.<ref>{{Cite web|title=Mars Express operations|url=https://www.esa.int/Enabling_Support/Operations/Mars_Express_operations|access-date=21 February 2021|website=[[European Space Agency|ESA]]}}</ref> The Principal Investigator is [[David Winningham]] of [[Southwest Research Institute]].<ref>{{Cite web|date=18 December 2003|title=ASPERA-3: Next Stop Mars|url=https://www.nasa.gov/audience/forstudents/postsecondary/features/F_ASPERA_3.html|access-date=21 February 2021|website=[[NASA]]}}</ref>
*A NASA contribution to the joint [[European Space Agency|ESA]] - [[CNES]] '''[[NetLander]]''' Mars meteorological mission was planned, consisting of meteorological, seismic, and geodetic instruments; however, the mission was terminated prior to its 2007 launch.<ref>{{Cite web|last=Heil|first=Martha|date=4 January 2001|title=NASA CONSIDERS DISCOVERY MISSION PROPOSALS|url=https://www2.jpl.nasa.gov/releases/2001/discovery.html|access-date=8 May 2021|website=[[Jet Propulsion Laboratory]]|publisher=[[NASA]]}}</ref><ref>{{Cite web|date=3 January 2006|title=Announcement of Opportunity Discovery Program 2006 and Missions of Opportunity|url=https://spacese.spacegrant.org/uploads/Design%20Module/Discovery_AO_2006.pdf|access-date=8 May 2021|website=Space Systems Engineering|publisher=[[National Space Grant College and Fellowship Program]]}}</ref>
* '''[[Moon Mineralogy Mapper]]''' (M3) is a NASA-designed instrument placed on board the [[Indian Space Research Organisation|ISRO]]'s [[Chandrayaan-1|Chandrayaan]] orbiter selected in February 2005.<ref>{{Cite web|url=https://www.nasa.gov/home/hqnews/2005/feb/HQ_05037_moon_mapper.html|title=NASA – NASA Selects Moon Mapper for Mission of Opportunity|website=www.nasa.gov|language=en|first1=Dolores |last1=Beasley|first2=Gretchen |last2=Cook-Anderson|access-date=2023-01-17}}</ref> Launched in 2008, it was designed to explore the Moon's mineral composition at high resolution. M3's detection of water on the Moon was announced in late September 2009, one month after the mission ended.<ref>{{Cite web|last1=Nemiroff|first1=Robert|last2=Bonnell|first2=Jerry|date=28 September 2009|title=Astronomy Picture of the Day 2009 - September 28|url=https://apod.nasa.gov/apod/ap090928.html|access-date=21 February 2021|website=[[NASA]]}}</ref> The Principal Investigator was [[Carle Pieters]] of [[Brown University]].<ref>{{Cite web|title=Carle M. Pieters|url=http://www.planetary.brown.edu/html_pages/pieters.htm|access-date=21 February 2021|website=Brown University Planetary Geosciences Group|archive-date=April 23, 2011|archive-url=https://web.archive.org/web/20110423105339/http://www.planetary.brown.edu/html_pages/pieters.htm|url-status=dead}}</ref>
* '''[[EPOXI|Extrasolar Planet Observation and Deep Impact Extended Investigation]]''' (EPOXI) was selected in July 2007.<ref>{{cite news |url=http://www.space.com/missionlaunches/061031_ap_deep_impact.html |title=Deep Impact Heads to New Comet |work=[[Space.com]] |date=October 31, 2006 |archive-url=https://web.archive.org/web/20061102042130/http://www.space.com/missionlaunches/061031_ap_deep_impact.html |archive-date=November 2, 2006 |url-status=dead  }}</ref><ref name=":0">{{Cite web|url=https://www.nasa.gov/home/hqnews/2007/jul/HQ_07147_Discovery_missions.html|title=NASA – NASA Gives Two Successful Spacecraft New Assignments|website=www.nasa.gov|language=en|first1=Grey |last1=Hautaluoma|first2=Tabatha |last2=Thompson|access-date=2023-01-17}}</ref> It was a series of two new missions for the existing ''[[Deep Impact (spacecraft)|Deep Impact]]'' probe following its success at Tempel 1:<ref>{{Cite web|title=Deep Impact - EPOXI|url=https://www.jpl.nasa.gov/missions/deep-impact-epoxi|access-date=21 February 2021|website=[[Jet Propulsion Laboratory]]}}</ref>
** The '''Extrasolar Planet Observations and Characterization''' (EPOCh) mission used the Deep Impact high-resolution camera in 2008<ref>{{Cite web|title=EPOXI Mission|url=https://pdssbn.astro.umd.edu/data_sb/missions/epoxi/index.shtml|access-date=21 February 2021|website=NASA PDS: Small Bodies Node}}</ref> to better characterize known giant [[extrasolar planets]] orbiting other stars and to search for additional planets in the same system, as well as to investigate possible moons and ring systems of said exoplanets. A secondary science goal was to better observe the earth in both infrared and visible light, in order to create better computer models of exoplanets.<ref>{{Cite web|title=EPOXI Mission Overview|url=https://epoxi.astro.umd.edu/1mission/#:~:text=The%20main%20objective%20of%20EPOXI's,planets%20of%20the%20targeted%20stars.|access-date=21 February 2021|website=[[EPOXI]]}}</ref> The Principal Investigator was [[L. Drake Deming]] of NASA's [[Goddard Space Flight Center]].<ref>{{Cite web|last1=Neal-Jones|first1=Nancy|last2=Zubritsky|first2=Liz|date=13 January 2010|title=NASA Goddard's Drake Deming Wins Astrophysics Award|url=https://www.nasa.gov/centers/goddard/news/topstory/2009/deming-award.html#:~:text=Tinsley.-,Dr.,Flight%20Center%2C%20Greenbelt%2C%20Md.|access-date=21 February 2021|website=[[NASA]]}}</ref> [[File:Comet Hartley 2.jpg|thumb|Nucleus of Comet Hartley 2 imaged by [[Deep Impact (spacecraft)|Deep Impact]]]]
** The '''Deep Impact eXtended Investigation of Comets''' (DIXI) mission used the Deep Impact spacecraft for a flyby mission to a second comet, [[103P/Hartley|Hartley 2]]. The goal was to take pictures of its nucleus to increase our understanding of the diversity of comets. The flyby of Hartley 2 was successful with closest approach occurring on November 4, 2010.<ref>{{Cite web|title=Deep Impact Extended Investigation (DIXI) and Extrasolar Planet Observation and Characterization (EPOCh)|url=https://astrobiology.nasa.gov/missions/epoxi/|access-date=21 February 2021|website=[[NASA]]}}</ref> [[Michael A'Hearn]] of the [[University of Maryland]] was the Principal Investigator.<ref>{{Cite web|date=1 November 2006|title=University of Maryland Proposal for Deep Impact Extended Mission Clears Major Hurdle|url=http://spaceref.com/news/viewpr.html?pid=21191|access-date=21 February 2021|website=SpaceRef}}</ref>
* '''[[Stardust (spacecraft)#New Exploration of Tempel 1 (NExT)|New Exploration of Tempel 1]]''' (NExT) was selected in July 2007 together with the EPOXI extension.<ref name=":0" /> It was a new mission for the ''[[Stardust (spacecraft)|Stardust]]'' spacecraft to fly by comet [[9P/Tempel|Tempel 1]] in 2011 and observe changes since the Deep Impact mission visited it in July 2005. Later in 2005, Tempel 1 made its closest approach to the [[Sun]], possibly changing the surface of the comet. The flyby was completed successfully on February 15, 2011. [[Joseph Veverka]] of [[Cornell University]] is the Principal Investigator.<ref>{{Cite news|last=Wall|first=Mike|date=10 February 2011|title=FAQ: Inside NASA's Valentine's Day Visit to Comet Tempel 1|work=[[Space.com]]|url=https://www.space.com/10813-nasa-stardust-comet-tempel1-flyby-faq.html|access-date=21 February 2021}}</ref><ref>{{Cite news|date=9 February 2011|title=Stardust NExT set to meet its second comet|work=[[ScienceDaily]]|url=https://www.sciencedaily.com/releases/2011/02/110209131953.htm|access-date=21 February 2021}}</ref>
* '''[[BepiColombo#Mercury Planetary Orbiter|Strofio]]''' is a [[Mass spectrometry|mass spectrometer]] that is a part of the SERENA instrument package on board the [[BepiColombo#Mercury Planetary Orbiter|Mercury Planetary Orbiter]] component of the [[European Space Agency|ESA's]] [[BepiColombo]] mission. Strofio will study the atoms and molecules that compose [[Mercury's atmosphere]] to reveal the composition of the planet's surface. [[Stefano Livi]] of Southwest Research Institute is the Principal Investigator.<ref>{{cite web|title=Discovery Program – Strofio|url=http://discovery.nasa.gov/strofio.cfml|url-status=dead|archive-url=https://web.archive.org/web/20110301014547/http://discovery.nasa.gov/strofio.cfml|archive-date=March 1, 2011|access-date=21 February 2021|website=[[NASA]]|publisher=}}</ref>
* '''[[Martian Moons Exploration#Scientific payload|MEGANE]]''' (Mars-moon Exploration with GAmma rays and NEutrons) is an instrument planned to fly aboard the [[Martian Moons Exploration]] (MMX), a [[Japanese Aerospace Exploration Agency]] (JAXA) probe to [[Phobos (moon)|Phobos]] and [[Deimos (moon)|Deimos]] launching in 2026. MEGANE includes a [[Gamma spectroscopy|gamma-ray spectrometer]] and a [[Neutron spectroscopy|neutron spectrometer]]. [[David J. Lawrence]] of [[Johns Hopkins University]] is the Principal Investigator.<ref>{{cite web|title=MEGANE Mars-moon Exploration with GAmma rays and Neutrons|url=https://megane.jhuapl.edu/|access-date=21 February 2021|website=MEGANE|publisher=JHU APL}}</ref><ref>{{Cite web|title=MEGANE:Team|url=https://megane.jhuapl.edu/Team/|access-date=21 February 2021|website=MEGANE|publisher=JHU APL}}</ref>
* '''[[EnVision#Instruments|VenSAR]]''' (Venus Synthetic Aperture Radar), is an instrument planned to fly aboard ESA's [[EnVision]] Venus orbiter. The principal investigator is [[Scott Hensley]], [[Jet Propulsion Laboratory]] NASA/California Institute of Technology.<ref>{{cite web|title=Then There Were 3: NASA to Collaborate on ESA’s New Venus Mission|url=https://www.jpl.nasa.gov/news/then-there-were-3-nasa-to-collaborate-on-esas-new-venus-mission/|publisher=Jet Propulsion Laboratory}}</ref>
* In addition, the '''[[Lunar Reconnaissance Orbiter]]''' was temporarily managed under the Discovery Program from the termination of the [[Lunar Precursor Robotic Program]]<ref>{{Cite web|title=LRO (Lunar Reconnaissance Orbiter) + LCROSS|url=https://directory.eoportal.org/web/eoportal/satellite-missions/l/lro|access-date=25 February 2021|website=eoPortal}}</ref> until the creation of the [[Lunar Discovery and Exploration Program]].<ref name=NASABudget19Estimates>{{cite web|url=https://www.nasa.gov/sites/default/files/atoms/files/fy19_nasa_budget_estimates.pdf#page=369|title=NASA FY 2019 Budget Estimates}}</ref><ref name=ClarkePres>{{cite web|url=https://www.lpi.usra.edu/pac/presentations/0919/Day1/Clark.pdf|title=Lunar Discovery & Exploration Program Status|author=Clarke, Steve}}</ref>

===Mission timeline===
{{NASA Planetary Missions Program}}

==Proposals and concepts==
[[File:Lunar Sample.jpg|thumb|Possible configuration of a lunar sample return spacecraft]]
[[File:Mercury in color - Prockter07 (cropped).jpg|thumb|Mercury by Discovery's ''MESSENGER'']]
However often the funding comes in, there is a selection process with perhaps two dozen concepts. These sometimes get further matured and re-proposed in another selection or program.<ref name="nasa">{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/discovery3.html |title=3 Proposed Discovery Missions |publisher=National Space Science Data Center, NASA |archive-url=https://web.archive.org/web/20140301113019/http://nssdc.gsfc.nasa.gov/planetary/discovery3.html |archive-date=March 1, 2014 |url-status=live}}</ref> An example of this is ''Suess-Urey Mission'', which was passed over in favor of the successful ''[[Stardust (spacecraft)|Stardust]]'' mission, but was eventually flown as [[Genesis (spacecraft)|Genesis]],<ref name="nasa" /> while a more extensive mission similar to INSIDE was flown as ''[[Juno (spacecraft)|Juno]]'' in the [[New Frontiers program]]. Some of these concepts went on to become actual missions, or similar concepts were eventually realized in another mission class. This list is a mix of previous and current proposals.

Additional examples of Discovery-class mission proposals include:
* [[Whipple (spacecraft)|Whipple]], a space-observatory to detect objects in the [[Oort cloud]] by transit method.<ref name="whipple">{{cite web|last1=Alcock|first1=Charles|last2=Brown|first2=Michael|last3=Tom|first3=Gauron|last4=Cate|first4=Heneghan|title=The Whipple Mission Exploring the Oort cloud and the Kuiper Belt|url=http://whipple.cfa.harvard.edu/inc/documents/Alcock_AGUPoster_2014dec.pdf|url-status=live|archive-url=https://web.archive.org/web/20151117031224/http://whipple.cfa.harvard.edu/inc/documents/Alcock_AGUPoster_2014dec.pdf|archive-date=November 17, 2015|access-date=21 February 2021}}</ref>
* [[Io Volcano Observer]], was proposed for missions 15 or 16, a Jupiter orbiter designed to make 10 flybys of the volcanically active moon [[Io (moon)|Io]].<ref name="McEwen2021LPSC">{{cite conference|last=McEwen|first=A. S.|date=2021|title=The Io Volcano Observer (IVO)|url=https://www.hou.usra.edu/meetings/lpsc2021/pdf/1352.pdf|conference=[[Lunar and Planetary Science Conference]]|id=Abstract #1352|access-date=9 February 2021}}</ref>
* [[Comet Hopper]] (CHopper), a mission to comet [[46P/Wirtanen]] that would've utilised multiple short flights to repeatedly land on the comet's nucleus in order to map various geological processes such as [[outgassing]].<ref name="AdamsBrief">{{cite web|title=Planetary Science Division Update|url=http://solarsystem.nasa.gov/docs/Adams%20PPS%2005102011.pdf|url-status=dead|archive-url=https://web.archive.org/web/20111114141842/http://solarsystem.nasa.gov/docs/Adams%20PPS%2005102011.pdf|archive-date=14 November 2011|access-date=May 23, 2011|publisher=[[NASA]]}}</ref>
* [[Titan Mare Explorer]] (TiME), a lander mission to explore one of the [[Lakes of Titan|methane lakes]] found in the north polar region of [[Titan (moon)|Titan]], a moon of [[Saturn]].<ref>{{Cite news|last=Taylor Redd|first=Nola|date=14 April 2017|title=Lander Designed for Titan's Methane Seas Tests Tech on Chilean Lake|work=[[Space.com]]|url=https://www.space.com/36476-titan-lander-design-test-chilean-lake.html|access-date=21 February 2021}}</ref>
* '''Suess-Urey''', similar to the later [[Genesis (spacecraft)|Genesis]] mission.<ref name="nasa" />
* '''Hermes''', a Mercury orbiter.<ref>{{cite journal |title=1994LPI 25..985N Page 985 |journal=Astrophysics Data System |pages = 985|publisher=Harvard-Smithsonian Centre for Astrophysics |bibcode = 1994LPI....25..985N|last1 = Nelson|first1 = R. M.|last2 = Horn|first2 = L. J.|last3 = Weiss|first3 = J. R.|last4 = Smythe|first4 = W. D.|year = 1994}}</ref> (similar to the [[MESSENGER]] Mercury orbiter)
* '''INSIDE Jupiter''', an orbiter that would map Jupiter's magnetic and gravity fields in an effort to study the giant planet's interior structure.<ref name="finalists01">{{cite web |url=http://www.spacetoday.net/Summary/7 |title=NASA announces Discovery mission finalists |publisher=Space Today |date=January 4, 2001 |archive-url=https://web.archive.org/web/20030916192235/http://www.spacetoday.net/Summary/7 |archive-date=September 16, 2003 |url-status=live}}</ref> The concept was further matured and implemented as [[Juno (spacecraft)|Juno]] in the [[New Frontiers program]].<ref name="Space Missions Roster 2012">{{cite web |url=http://www.lpl.arizona.edu/research/missions |title=Space Missions Roster |work=Lunar and Planetary Laboratory |publisher=The University of Arizona |url-status=live |archive-date=March 13, 2014 |archive-url=https://web.archive.org/web/20140313171936/http://www.lpl.arizona.edu/research/missions}}</ref>
* The '''Dust Telescope''', a space observatory that would measure various properties of incoming [[cosmic dust]].<ref name="dust">{{cite web |url=http://www.irs.uni-stuttgart.de/cosmicdust/documents/CDB_Dustgroup.pdf |title=Cosmic Dust – Messenger from Distant Worlds |publisher=University Stuttgart |archive-url=https://web.archive.org/web/20140224180419/http://www.irs.uni-stuttgart.de/cosmicdust/documents/CDB_Dustgroup.pdf |archive-date=February 24, 2014 |url-status=live}}</ref> The dust telescope would combine a trajectory sensor and a [[mass spectrometer]], to allow the elemental and even isotopic composition to be analyzed.<ref name="dust" />
* '''OSIRIS''' (Origins Spectral Interpretation, Resource Identification and Security), an asteroid observation and sample return mission concept selected in 2006 for further concept studies.<ref name="select">{{cite web |url=http://www.nasa.gov/home/hqnews/2006/oct/HQ_06342_Discovery_AO.html |title=NASA Announces Discovery Program Selections |work=News Release |publisher=NASA |date=October 30, 2006 |archive-url=https://web.archive.org/web/20090629094310/http://www.nasa.gov/home/hqnews/2006/oct/HQ_06342_Discovery_AO.html |archive-date=June 29, 2009 |url-status=live}}</ref> It further matured and launched September 8, 2016, as [[OSIRIS-REx]] in the [[New Frontiers Program]].<ref name="factsheet">{{cite web |title=OSIRIS-REx Factsheet |url=http://osiris-rex.lpl.arizona.edu/sites/osiris-rex.lpl.arizona.edu/files/pdfs/Technical%20Fact%20Sheet%202013-05-01.pdf |publisher=University of Arizona |archive-url=https://web.archive.org/web/20130722204427/http://osiris-rex.lpl.arizona.edu/sites/osiris-rex.lpl.arizona.edu/files/pdfs/Technical%20Fact%20Sheet%202013-05-01.pdf |archive-date=July 22, 2013 |url-status=dead  }}</ref>
* '''Small Body Grand Tour''', an asteroid rendezvous mission.<ref name=bodies>{{cite journal |bibcode=1993STIA...9581370F |title=Extended-mission opportunities for a Discovery-class asteroid rendezvous mission |last1=Farquhar |first1=Robert |last2=Jen |first2=Shao-Chiang |last3=McAdams |first3=Jim V. |journal=Astrophysics Data System |volume=95 |pages=435 |publisher=Harvard-Smithsonian Centre for Astrophysics |date=September 12, 2000}}</ref> This 1993 concept reviews possible targets for what became NEAR{{mdash}} [[4660 Nereus]] and [[2019 Van Albada]].<ref name=bodies/> Other targets considered for an extended mission included [[Encke's comet]] (2P), [[433 Eros]], [[1036 Ganymed]], [[4 Vesta]], and [[4015 Wilson–Harrington]] (1979 VA).<ref name=bodies/> ([[NEAR Shoemaker]] visited 433 Eros and [[Dawn (spacecraft)|Dawn]] visited 4 Vesta)<ref name=":2" /><ref name=":3" />
* '''Comet Coma Rendezvous Sample Return''', a spacecraft designed to rendezvous with a comet, make extended observations within the cometary coma (but not land on the comet), gently collect multiple coma samples, and return them to Earth for study.<ref name="lpi_SaS">{{cite web |url=http://www.lpi.usra.edu/decadal/sbag/topical_wp/ScottASandford.pdf |title=The Comet Coma Rendezvous Sample Return |first1=Scott A. |last1=Sandford |first2=Michael |last2=A'Hearn |first3=Louis J. |last3=Allamandola |first4=Daniel |last4=Britt |first5=Benton |last5=Clark |first6=Jason P. |last6=Dworkin |first7=George |last7=Flynn |first8=Danny |last8=Glavin |first9=Robert |last9=Hanel | first10=Martha | last10=Hanner |first11=Fred |last11=Hörz |first12=Lindsay |last12=Keller |first13=Scott |last13=Messenger |first14=Nicholas |last14=Smith |first15=Frank |last15=Stadermann |first16=Darren |last16=Wade |first17=Ernst |last17=Zinner |first18=Michael E. |last18=Zolensky |publisher=Lunar and Planetary Institute |archive-url=https://web.archive.org/web/20100628104309/http://www.lpi.usra.edu/decadal/sbag/topical_wp/ScottASandford.pdf |archive-date=June 28, 2010 |url-status=live}}</ref> (Similar to [[Stardust (spacecraft)|''Stardust'']])
* '''Micro Exo Explorer''', a spacecraft that would've utilised a new form of micro-electric propulsion, called 'Micro Electro-fluidic-spray Propulsion' to travel to a near Earth object and gather important data.<ref>{{cite web |url=http://lcpm10.caltech.edu/pdf/session-5/9_NEO_Hunter_Seeker13.pdf |title=A Low-Cost NEO Micro Hunter-Seeker Mission Concept |work=Low-Cost Planetary Missions Conference, LCPM-10 |first1=Joseph E. |last1=Riedel |first2=Colleen |last2=Marrese-Reading |first3=Young H. |last3=Lee |publisher=California Institute of Technology |date=June 19, 2013 |archive-url=https://web.archive.org/web/20140301115330/http://lcpm10.caltech.edu/pdf/session-5/9_NEO_Hunter_Seeker13.pdf |archive-date=March 1, 2014 |url-status=dead |access-date=February 25, 2014 }}</ref>

===Mars focused===
[[File:PIA11858 Starburst Spider.jpg|thumb|Mars Geyser Hopper would investigate 'spider' features on Mars, as imaged by an orbiter. Image size: {{convert|1|km|mi|abbr=on}} across.]]
* '''Pascal''', a Mars climate network mission.<ref>{{cite journal |bibcode=2000came.work..135H |last1=Haberle |first1=R. M. |last2=Catling |first2=D. C. |last3=Chassefiere |first3=E. |last4=Forget |first4=F. |last5=Hourdin |first5=F. |last6=Leovy |first6=C. B. |last7=Magalhaes |first7=J. |last8=Mihalov |first8=J. |last9=Pommereau |first9=J. P. | last10=Murphy | first10=J. R. |title=The Pascal Discovery Mission: A Mars Climate Network Mission |journal=Astrophysics Data System |pages=135 |publisher=Harvard-Smithsonian Centre for Astrophysics |year=2000 }}</ref>
* '''MUADEE''' (Mars Upper Atmosphere Dynamics, Energetics, and Evolution), an orbiter mission designed to study Mars's upper atmosphere.<ref name="delft">{{cite web |url=https://discover.tudelft.nl/recordview/view?recordId=Elsevier%3Aelsevier%3ACXT0348A%3A00945765%3A003500S1%3A9400203X |title=MUADEE: A Discovery-class mission for exploration of the upper atmosphere of Mars |publisher=Delft University of Technology |location=Netherlands |access-date=February 28, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20150204180416/https://discover.tudelft.nl/recordview/view?recordId=Elsevier:elsevier:CXT0348A:00945765:003500S1:9400203X |archive-date=February 4, 2015}}</ref> (similar to [[MAVEN]] of the Mars Scout program)
* '''PCROSS''', similar to [[LCROSS]], but directed towards Mars's moon [[Phobos (moon)|Phobos]].<ref>{{cite journal |bibcode=2012LPICo1679.4180C |title=PCROSS – Phobos Close Rendezvous Observation Sensing Satellite |last1=Colaprete |first1=A. |last2=Bellerose |first2=J. |last3=Andrews |first3=D. |journal=Astrophysics Data System |volume=1679 |pages=4180 |publisher=Harvard-Smithsonian Centre for Astrophysics |year=2012 }}</ref>
* '''Merlin''', a mission that would place a lander on Mars's moon [[Deimos (moon)|Deimos]].<ref>{{cite web |url=http://multimedia.seti.org/PhD2011/abstracts/PhD2-11-014.pdf |title=Merlin : Mars-Moon Exploration, Reconnaissance and Landed Investigation |first1=A. S. |last1=Rivkin |first2=N. L. |last2=Chabot |first3=S. L. |last3=Murchie |first4=D. |last4=Eng |first5=Y. |last5=Guo |first6=R. E. |last6=Arvidson |first7=A. |last7=Trebi-Ollennu |first8=F. P. |last8=Seelos |publisher=SETI |archive-url=https://web.archive.org/web/20140228132654/http://multimedia.seti.org/PhD2011/abstracts/PhD2-11-014.pdf |archive-date=February 28, 2014 |url-status=dead}}</ref>
* '''Mars Moons Multiple Landings Mission''' (M4), would conduct multiple landings on Phobos and Deimos.<ref name="lpi_4363">{{cite web |url=http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4363.pdf |title=Phobos and Deimos: Robotic Exploration in Advance of Humans to mars Orbit |first1=Pascal |last1=Lee |first2=Christopher |last2=Hoftun |first3=Kira |last3=Lorbe |work=Concepts and Approaches for Mars Exploration (2012) |publisher=Lunar and Planetary Institute |archive-url=https://web.archive.org/web/20140301114741/http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4363.pdf |archive-date=March 1, 2014 |url-status=live}}</ref>
* '''Hall''', a Phobos and Deimos sample return mission.<ref name="lpi_1633">{{cite web |url=http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1633.pdf |title=HALL: A Phobos and Deimos Sample and Return Mission |first1=Pascal |last1=Lee |first2=Joseph |last2=Veverka |first3=Julie |last3=Bellerose |first4=Marc |last4=Boucher |first5=John |last5=Boynton |first6=Stephen |last6=Braham |first7=Ralf |last7=Gellert |first8=Alan |last8=Hildebrand |first9=David |last9=Manzella | first10=Greg | last10=Mungas |first11=Steven |last11=Oleson |first12=Robert |last12=Richards |first13=Peter C. |last13=Thomas |first14=Michael D. |last14=West |work=41st Lunar and Planetary Science Conference (2010) |publisher=Lunar and Planetary Institute |archive-url=https://web.archive.org/web/20140227183425/http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1633.pdf |archive-date=February 27, 2014 |url-status=live}}</ref>
* '''Aladdin''', a Phobos and Deimos sample return mission.<ref>{{cite journal |bibcode=1997LPI....28.1111P |title=ALADDIN – Phobos-Deimos sample return |last1=Pieters |first1=C. |last2=Murchie |first2=S. |last3=Cheng |first3=A. |last4=Zolensky |first4=M. |last5=Schultz |first5=P. |last6=Clark |first6=B. |last7=Thomas |first7=P. |last8=Calvin |first8=W. |last9=McSween |first9=H. | last10=Yeomans | first10=D. |last11=McKay |first11=D. |last12=Clemett |first12=S. |last13=Gold |first13=R. |journal=Astrophysics Data System |pages=1111 |publisher=Harvard-Smithsonian Centre for Astrophysics |year=1997 }}</ref> It was a finalist in the 1999 Discovery selection, with a planned launch in 2001 and return of the samples by 2006.<ref name="sr">{{cite web |url=http://www.lpi.usra.edu/meetings/LPSC99/pdf/1155.pdf |title=ALADDIN: Exploration and Sample Return of Phobos and Deimos |first1=C. |last1=Pieters |first2=W. |last2=Calvin |first3=A. |last3=Cheng |first4=B. |last4=Clark |first5=S. |last5=Clemett |first6=R. |last6=Gold |first7=D. |last7=McKay |first8=S. |last8=Murchie |first9=J. |last9=Mustard | first10=J. | last10=Papike |first11=P. |last11=Schultz |first12=P. |last12=Thomas |first13=A. |last13=Tuzzolino |first14=D. |last14=Yeomans |first15=C. |last15=Yoder |first16=M. |last16=Zolensky |first17=O. |last17=Barnouin-Jha |first18=D. |last18=Domingue |work=Lunar and Planetary Science |publisher=Lunar and Planetary Institute |archive-url=https://web.archive.org/web/20040905173338/http://www.lpi.usra.edu/meetings/LPSC99/pdf/1155.pdf |archive-date=September 5, 2004 |url-status=live}}</ref> Sample collection was intended to work by sending projectiles into the moons, then collecting the ejecta by means of a collector spacecraft flyby.<ref name="sr" />
* [[Mars Geyser Hopper]], a lander that would investigate the springtime [[carbon dioxide]] [[Martian geyser]]s found in regions around the [[Planum Australe|Martian south pole]].<ref name="Geyser Hopper">{{citation |first1=Geoffrey A. |last1=Landis |first2=Steven J. |last2=Oleson |first3=Melissa |last3=McGuire |contribution=Design Study for a Mars Geyser Hopper |title=50th AIAA Aerospace Sciences Conference |publisher=Glenn Research Center, NASA |date=January 9, 2012 |contribution-url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120004036_2012004260.pdf |contribution-format=PDF |access-date=July 1, 2012}}</ref><ref>{{cite web |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120004036_2012004260.pdf |title=Mars Geyser-Hopper (AIAA2012) |work=NASA Technical Reports |publisher=NASA |access-date=February 28, 2014}}</ref>
* '''MAGIC''' (Mars Geoscience Imaging at Centimeter-scale), an orbiter that would provide images of the Martian surface at 5–10&nbsp;cm/pixel, permitting resolution of features as small as 20–40&nbsp;cm.<ref name="lpi_4325">{{cite web |url=http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4325.pdf |title=Mars Geoscience Imaging at Centimetre-Scale (MAGIC) from Orbit |first1=M. A. |last1=Ravine |first2=M. C. |last2=Malin |first3=M. A. |last3=Caplinger |work=Concepts and Approaches for Mars Exploration (2012) |publisher=Lunar and Planetary Institute |archive-url=https://web.archive.org/web/20131029185914/http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4325.pdf |archive-date=October 29, 2013 |url-status=live}}</ref>
* ''[[Red Dragon (spacecraft)|Red Dragon]]'', a Mars lander and sample return.<ref name="8m">{{citation |contribution=Red Dragon |title=Feasibility of a Dragon-derived Mars lander for scientific and human-precursor investigations |url=http://digitalvideo.8m.net/SpaceX/RedDragon/karcz-red_dragon-nac-2011-10-29-1.pdf |publisher=SpaceX |date=October 31, 2011 |archive-url=https://web.archive.org/web/20120616154043/http://digitalvideo.8m.net/SpaceX/RedDragon/karcz-red_dragon-nac-2011-10-29-1.pdf |archive-date=June 16, 2012 |url-status=live}}</ref>

===Lunar focused===
* Lunar sample return from the [[South Pole–Aitken basin]], current geological models don't adequately describe the area and this mission would have attempted to solve this issue.<ref name="lpi_8017">{{cite web |url=http://www.lpi.usra.edu/meetings/moon99/pdf/8017.pdf |title=Sample Return Mission to the South Pole Aitken Basin |first1=M. B. |last1=Duke |first2=B. C. |last2=Clark |first3=T. |last3=Gamber |first4=P. G. |last4=Lucey |first5=G. |last5=Ryder |first6=G. J. |last6=Taylor |work=Workshop on New Views of the Moon II |publisher=Lunar and Planetary Institute |archive-url=https://web.archive.org/web/20041109233513/http://www.lpi.usra.edu/meetings/moon99/pdf/8017.pdf |archive-date=November 9, 2004 |url-status=live}}</ref>
* '''EXOMOON''', ''in situ'' investigation on Earth's Moon.<ref>{{cite web |url=http://www.ri.cmu.edu/publication_view.html?pub_id=6129 |title=Robotics Institute: EXOMOON – A Discovery and Scout Mission Capabilities Expansion Concept |publisher=Robotics Institute, Carnegie Mellon University |date=June 15, 2011 |archive-url=https://web.archive.org/web/20140228020156/http://www.ri.cmu.edu/publication_view.html?pub_id=6129 |archive-date=February 28, 2014 |url-status=dead}}</ref>
* '''PSOLHO''', would use the Moon as an occulter to look for exoplanets.<ref>{{cite journal |bibcode=2003AAS...203.0305C |title=Planetary System Occultation from Lunar Halo Orbit (PSOLHO): A Discovery Mission |last=Clarke |first=T. L. |journal=Astrophysics Data System |volume=203 |pages=03.05 |publisher=Harvard-Smithsonian Centre for Astrophysics |year=2003 }}</ref>
* '''Lunette''', a lunar lander.<ref name="lpi_klaus">{{cite web |url=http://www.lpi.usra.edu/meetings/leag2012/presentations/Klaus.pdf |title=Concepts Leading to a Sustainable Architecture for Cislunar Development |first=K |last=Klaus |work=LEAG |publisher=Lunar and Planetary Institute |date=October 24, 2012 |archive-url=https://web.archive.org/web/20140301113544/http://www.lpi.usra.edu/meetings/leag2012/presentations/Klaus.pdf |archive-date=March 1, 2014 |url-status=live}}</ref>
* '''Twin Lunar Lander''', a double lander mission to better understand the Moon's evolution and geology.<ref name="lpi_2832">{{cite web |url=http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2832.pdf |title=Lunette: A Two-Lander Discovery-Class Geophysics Mission to the Moon |first1=C. R. |last1=Neal |first2=W. B. |last2=Banerdt |first3=L. |last3=Alkalai |work=42nd Lunar and Planetary Science Conference (2011) |publisher=Lunar and Planetary Institute |archive-url=https://web.archive.org/web/20140301115247/http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2832.pdf |archive-date=March 1, 2014 |url-status=live}}</ref>

[[File:Vmpmvenus.gif|thumb|The Venus Multiprobe Mission involved sending 16 atmospheric probes into Venus in 1999.<ref>{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/discovery3.html |title=Discovery Missions Under Consideration |publisher=Goddard Space Flight Centre, NASA |archive-url=https://web.archive.org/web/20140301113019/http://nssdc.gsfc.nasa.gov/planetary/discovery3.html |archive-date=March 1, 2014 |url-status=live}}</ref>]]

===Venus focused===
* '''Venus Multiprobe''', proposed for a 1999 launch, would have dropped 16 atmospheric probes into Venus, which would fall slowly to the surface, taking pressure and temperature measurements.<ref name="nasa" />
* '''Vesper''', a concept for a Venus orbiter focused on studying the planet's atmosphere.<ref name="finalists">{{cite web |url=http://deepimpact.umd.edu/press/98-203.html |series=Press Releases |title=Deep Impact: Five Discovery Mission Proposals Selected for Feasibility Studies |work=Deep Impact |publisher=University of Maryland |date=November 12, 1998 |archive-url=https://web.archive.org/web/20020620083019/http://deepimpact.umd.edu/press/98-203.html |archive-date=June 20, 2002 |url-status=live}}</ref><ref name="vesper">{{cite web |url=http://www.nasa.gov/centers/goddard/news/topstory/2006/vesper.html |title=NASA – Vesper Could Explore Earth's Fiery Twin |publisher=NASA |archive-url=https://web.archive.org/web/20070823131906/http://www.nasa.gov/centers/goddard/news/topstory/2006/vesper.html |archive-date=August 23, 2007 |url-status=live}}</ref><ref>{{cite journal |title=The VESPER Mission to Venus |volume = 30|pages = 1106|journal=Astrophysics Data System |publisher=Harvard-Smithsonian Centre for Astrophysics |bibcode = 1998BAAS...30.1106A|last1 = Allen|first1 = M.|last2 = Chin|first2 = G.|author3 = VESPER Science Team|year = 1998}}</ref> It was one of three concepts to receive funds for further study in the 2006 Discovery selection.<ref name="vesper" /> Osiris and GRAIL were the other two, and eventually GRAIL was chosen and went on to be launched.<ref name="select" /> 
* '''V-STAR''' (Venus Sample Targeting, Attainment and Return), a Venus sample return mission with a goal of understanding Venus's evolution.<ref name="vsr">{{cite web |url=http://henry.pha.jhu.edu/2007_Academy_Group_Project.pdf |title=Venus Sample Targeting, Attainment, and Return (V-STAR) |work=2007 NASA Academy at the Goddard Space Flight Center |publisher=The Henry Foundation |archive-url=https://web.archive.org/web/20120315021449/http://henry.pha.jhu.edu/2007_Academy_Group_Project.pdf |archive-date=March 15, 2012 |url-status=dead  }}</ref><ref name="trs_0542">{{cite web |url=http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/14139/1/00-0542.pdf |title=Venus Sample Return Missions – A Range of Science, A Range of Costs |first1=Ted |last1=Sweetser |first2=Craig |last2=Peterson |first3=Erik |last3=Nilsen |first4=Bob |last4=Gershman |publisher=California Institute of Technology |archive-url=https://web.archive.org/web/20100526220032/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/14139/1/00-0542.pdf |archive-date=May 26, 2010 |url-status=dead  }}</ref> The mission would have consisted of a [[Venus]] orbiter with an attached lander. The lander would fall through the Venusian atmosphere, collecting samples along the way, as well as after landing through the use of a "mole". Said lander would launch those samples into a low orbit, where they would rendezvous with the orbiter, returning the samples to Earth.<ref name="vsr" />
* '''VEVA''' (Venus Exploration of Volcanoes and Atmosphere), an atmospheric probe for Venus.<ref name="veva">{{cite journal  |title=VEVA Discovery mission to Venus: exploration of volcanoes and atmosphere |first1=Kenneth |last1=Klaasen |first2=Ronald |last2=Greeley |date=March 31, 2003| doi=10.1016/s0094-5765(02)00151-0 |volume=52 |issue=2–6 |journal=Acta Astronautica |pages=151–158|bibcode=2003AcAau..52..151K }}</ref> The main component is a 7-day balloon flight through the atmosphere accompanied by various small probes dropped deeper into the planet's thick gases.<ref name="veva" />
* '''Venus Pathfinder''', a long-duration Venus lander.<ref>{{cite web |url=http://www.planetaryprobe.org/sessionfiles/session2/papers/lorenz_venus_lander-paper.pdf |title=Venus Pathfinder: A Stand-Alone Long-Lived Venus Lander Mission Concept |first1=Ralph D. |last1=Lorenz |first2=Doug |last2=Mehoke |first3=Stuart |last3=Hill |work=8th International Planetary Probe Workshop (IPPW-8) |publisher=National Institute of Aerospace |archive-url=https://web.archive.org/web/20140227204705/http://www.planetaryprobe.org/sessionfiles/session2/papers/lorenz_venus_lander-paper.pdf |archive-date=February 27, 2014 |url-status=dead  }}</ref> 
* '''RAVEN''', a Venus orbiter radar mapping mission.<ref>{{cite journal |bibcode=2009AGUFM.P31D..04S |title=RAVEN – High-resolution Mapping of Venus within a Discovery Mission Budget |last1=Sharpton |first1=V. L. |last2=Herrick |first2=R. R. |last3=Rogers |first3=F. |last4=Waterman |first4=S. |journal=Astrophysics Data System |volume=2009 |pages=P31D–04 |publisher=Harvard-Smithsonian Centre for Astrophysics |year=2009 }}</ref>
* '''VALOR''', a Venus mission to study its atmosphere with a balloon.<ref name="val">{{cite web |url=https://smartech.gatech.edu/bitstream/handle/1853/26401/65-172-1-PB.pdf |title=Exploring Venus with Balloons: Science Objectives and Mission Architectures for small and Medium-Class Missions |first1=Kevin H. |last1=Baines |first2=Jeffery L. |last2=Hall |first3=Tibor |last3=Balint |first4=Viktor |last4=Kerzhanovich |first5=Gary |last5=Hunter |first6=Sushil K. |last6=Atreya |first7=Sanjay S. |last7=Limaye |first8=Kevin |last8=Zahnle |publisher=Georgia Tech Library |archive-url=https://web.archive.org/web/20140227192352/https://smartech.gatech.edu/bitstream/handle/1853/26401/65-172-1-PB.pdf |archive-date=February 27, 2014 |url-status=live}}</ref> Twin balloons would circumnavigate the planet over 8 Earth-days.<ref name="val" /> 
* '''Venus Aircraft''', a robotic atmospheric flight on Venus's atmosphere using a long-duration solar-powered aircraft system.<ref name="VenusAirplane">{{cite conference |conference=40th AIAA Aerospace Sciences Meeting & Exhibit |citeseerx=10.1.1.195.172 |title=NASA TM-2002-0819 : Atmospheric Flight on Venus |first1=Geoffrey A. |last1=Landis |first2=Christopher |last2=LaMarre |first3=Anthony |last3=Colozza |publisher=American Institute of Aeronautics and Astronautics, The Pennsylvania State University |date=January 14, 2002 |doi=10.2514/6.2002-819 }}</ref> It would carry 1.5&nbsp;kg of scientific payload and would contend with violent wind, heat and a corrosive atmosphere.<ref name="VenusAirplane" />
* [[Venus Landsailing Rover|Zephyr]], a rover concept that would be propelled by the wind force on its vertical wingsail. Conceived in 2012, the project has since made progress in developing electronic components that would allow the vehicle to operate for 50 days on the surface of Venus without a cooling system.<ref name='Zephyr 2015 Report'>[https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150000879.pdf Zephyr: A Landsailing Rover For Venus]. (PDF) Geoffrey A. Landis, Steven R. Oleson, David Grantier, and the COMPASS team. NASA John Glenn Research Center. 65th International Astronautical Congress, Toronto, Canada. February 24, 2015.  Report: IAC-14,A3,P,31x26111</ref>

==Selection process==
=== Discovery 1 and 2 ===
[[File:Pathfinder01.jpg|thumb|Mars Pathfinder's ''Sojourner'' rover taking its Alpha Particle X-ray Spectrometer measurement of the [[Yogi Rock]] (1997)]]
The first two Discovery missions were [[NEAR Shoemaker|Near Earth Asteroid Rendezvous (NEAR)]] (later called Shoemaker NEAR) and ''[[Mars Pathfinder]]''. These initial missions did not follow the same selection process that started once the program was under-way.<ref name="mars.nasa.gov">{{Cite web|last=|first=|title=Mars Pathfinder Frequently Asked Questions|url=https://mars.nasa.gov/MPF/mpf/faqs_general.html#discovery|access-date=20 February 2021|website=[[NASA]]|date=December 20, 2017}}</ref> ''Mars Pathfinder'' was salvaged from the idea for a technology and EDL demonstrator from the [[Mars Environmental Survey]] program.<ref name="mars.nasa.gov"/> One of the goals of ''Pathfinder'' was to support the Mars Surveyor program.<ref name="mars.nasa.gov"/> Later missions would be selected by a more sequential process involving Announcements of Opportunity.<ref name="mars.nasa.gov"/>

In the case of NEAR, a working group for the program recommended that the first mission should be to a [[near-Earth asteroid]].<ref name="techdigest.jhuapl.edu">{{cite web |url=http://techdigest.jhuapl.edu/TD/td2301/farquhar.pdf |title=02-0483D Farquhar.Indd |access-date=2018-04-28 |archive-date=February 26, 2018 |archive-url=https://web.archive.org/web/20180226155236/http://techdigest.jhuapl.edu/TD/td2301/farquhar.pdf |url-status=dead }}</ref> A series of proposals limited to missions to a near-Earth asteroid missions were reviewed in 1991.<ref name="techdigest.jhuapl.edu"/> What would be the NEAR spacecraft mission was formally selected in December 1993, after which began a 2-year development period prior to launch.<ref name="techdigest.jhuapl.edu"/> NEAR was launched on February 15, 1996, and arrived to orbit [[433 Eros|asteroid Eros]] on February 14, 2000.<ref name="techdigest.jhuapl.edu"/> ''[[Mars Pathfinder]]'' launched on December 4, 1996, and landed on Mars on July 4, 1997, bringing along with it the first NASA Mars rover, ''Sojourner''.<ref>{{cite web|url=https://www.nasa.gov/centers/glenn/about/history/marspath.html |title=NASA Glenn Participation in Mars Pathfinder Mission &#124; NASA |publisher=Nasa.gov |date=1996-12-04 |access-date=2018-04-28}}</ref>

=== Discovery 3 and 4 ===
[[File:Lunar Thorium concentrations.jpg|thumb|Thorium concentrations on the Moon, as mapped by ''Lunar Prospector'']]
In August 1994, NASA made an Announcement of Opportunity for the next proposed Discovery missions.<ref name=d95>{{cite web|url=http://nssdc.gsfc.nasa.gov/planetary/discover95.txt |title=Discover 95: Mission to the Moon, Sun, Venus and a Comet Picked for Discovery – NASA |access-date=2018-04-28}}</ref> There were 28 proposals submitted to NASA in October 1994:<ref name=d95/> 
{{div col|colwidth=30em}}
# ASTER - Asteroid Earth Return
# Comet Nucleus Penetrator
# Comet Nucleus Tour (CONTOUR)
# Cometary Coma Chemical Composition (C4)
# Diana  (Lunar and Cometary Mission)
# FRESIP-A mission to Find the Frequency of Earth-sized Inner Planets
# Hermes Global Orbiter (Mercury Orbiter)
# Icy Moon Mission (Lunar Orbiter)
# Interlune-One (Lunar Rovers)<ref>{{cite web |url=https://www.researchgate.net/publication/234389634 |title=Interlune-One: A Scientific Mission Across the Surface of the Moon (PDF Download Available) |website=Researchgate.net |access-date=January 11, 2016}}</ref>
# Jovian Integrated Synoptic Telescope (IO Torus investigation)
# Lunar Discovery Orbiter<ref>{{cite web |url=https://tucsoncitizen.com/morgue2/1995/01/27/97568-ua-scientist-seeking-big-bucks-from-nasa/ |title=UA scientist seeking big bucks from NASA – Tucson Citizen Morgue, Part 2 (1993–2009) |website=Tucsoncitizen.com |date=January 27, 1995 |access-date=January 11, 2016}}</ref>
#  {{Background color|#EEE|'''[[Lunar Prospector]]''' (Lunar Orbiter) – chosen in February 1995 for Discovery 3.}}
# Mainbelt Asteroid Exploration/Rendezvous
# Mars Aerial Platform (Atmospheric)
# Mars Polar Pathfinder (Polar Lander)
# Mars Upper Atmosphere Dynamics, Energetics and Evolution
# Mercury Polar Flyby
# Near Earth Asteroid Returned Sample
# Origin of Asteroids, Comets and Life on Earth
# PELE: A Lunar Mission to Study Planetary Volcanism
# Planetary Research Telescope
# Rendezvous with a Comet Nucleus (RECON)
#  {{Background color|#EEE|'''Suess-Urey''' (Solar Wind Sample Return) – Discovery 4 finalist.}}
# Small Missions to Asteroids and Comets
#  {{Background color|#EEE|'''[[Stardust (spacecraft)|Stardust]]''' (Cometary/Interstellar Dust Return) – Discovery 4 finalist.}}
# Venus Composition Probe (Atmospheric)
# Venus Environmental Satellite (Atmospheric)
#  {{Background color|#EEE|'''Venus Multi-Probe Mission''' (Atmospheric)<ref>{{cite web |url=https://ntrs.nasa.gov/search.jsp?R=20020038535 |title=NASA Technical Reports Server (NTRS) – Venus Multiprobe Mission |website=Ntrs.nasa.gov |date=January 2001 |access-date=January 11, 2016}}</ref> – Discovery 4 finalist.}}
{{div col end}}
In February 1995, ''[[Lunar Prospector]]'', a lunar orbiter mission, was selected for launch. Three other missions were left to undergo a further selection later in 1995 for the fourth Discovery mission: ''Stardust'', ''Suess-Urey'', and ''Venus Multiprobe''.<ref name=d95/> [[Stardust (spacecraft)|''Stardust'']], a comet sample-return mission, was selected in November 1995 over the two other finalists.<ref name="autogenerated1">{{cite web |url=http://stardust.jpl.nasa.gov/news/sd-selected.html |title=STARDUST Selected as Discovery Flight |website=Stardust.jpl.nasa.gov |access-date=January 11, 2016}}</ref>

=== Discovery 5 and 6 ===
In October 1997, NASA selected ''[[Genesis (spacecraft)|Genesis]]'' and ''[[CONTOUR]]'' as the next Discovery missions, out of 34 proposals that were submitted in December 1996.<ref>{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/text/discovery_pr_971020.txt |format=TXT |title=Missions to Gather Solar Wind Samples and Tour Three Comets Selected as Next Discovery Program Flights |website=Nssdc.gsfc.nasa.gov |access-date=January 11, 2016}}</ref>

The five finalists were:<ref>{{cite web |url=http://www.lpi.usra.edu/publications/newsletters/lpib/lpib82/nspace82.html |title=News from Space – LPIB 82 |website=Lpi.usra.edu |date=September 30, 2002 |access-date=January 11, 2016}}</ref>
* Aladdin (Mars moon sample return)
* Comet Nucleus Tour ([[CONTOUR]])
* ''[[Genesis (spacecraft)|Genesis]]'' (Solar wind sample return)
* Mercury Surface, Space Environment, Geochemistry and Ranging mission ([[MESSENGER]])
* Venus Environmental Satellite (VESAT)

=== Discovery 7 and 8 ===
[[File:Deep Impact HRI.jpeg|thumb|''Deep Impact'' impacted a comet nucleus]]
In July 1999, NASA selected ''[[MESSENGER]]'' and [[Deep Impact (spacecraft)|''Deep Impact'']] as the next Discovery Program missions.<ref name="nssdc.gsfc.nasa.gov"/> ''MESSENGER'' was the first [[Mercury (planet)|Mercury]] orbiter and mission to that planet since [[Mariner 10]].<ref name="nssdc.gsfc.nasa.gov">{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/news/discovery_pr_19990707.html |title=NASA Selects Missions to Mercury and a Comet's Interior as Next Discovery Flights |website=Nssdc.gsfc.nasa.gov |access-date=January 11, 2016}}</ref> Both missions targeted a launch in late 2004 and the cost was constrained at about US$300 million each.<ref name="nssdc.gsfc.nasa.gov"/>

In 1998 five finalists had been selected to receive US$375,000 to further mature their design concept.<ref name="autogenerated1998">{{cite web |url=http://www.nasa.gov/home/hqnews/1998/98-203.txt |format=TXT |title=Five Discovery Mission Proposals Selected For Feasibility Studies |website=Nasa.gov |access-date=January 11, 2016 |archive-date=November 26, 2020 |archive-url=https://web.archive.org/web/20201126075335/https://www.nasa.gov/home/hqnews/1998/98-203.txt |url-status=dead }}</ref> The five proposals were selected out of about 30 with the goal of achieving the best science.<ref name="autogenerated1998"/> Those missions were:<ref name="autogenerated1998"/>
* ''Aladdin''
* ''[[Deep Impact (spacecraft)|Deep Impact]]''
* [[MErcury Surface, Space ENvironment, GEochemistry and Ranging|''MESSENGER'']]
* ''INSIDE Jupiter''
* ''Vesper''

''Aladdin'' and ''MESSENGER'' were also finalists in the 1997 selection.<ref name="autogenerated1998"/>

=== Discovery 9 and 10 ===
[[File:Ceres and Vesta, Moon size comparison.jpg|alt=|thumb|Scale comparison of Vesta, Ceres, and the Moon]]
[[File:Kepler spacecraft artist render (crop).jpg|thumb|[[Kepler space telescope]], artist's impression]]
26 proposals were submitted to the 2000 Discovery solicitation, with budget initially targeted at US$300 million.<ref name="autogenerated3"/> Three candidates were shortlisted in January 2001 for a phase-A design study: [[Dawn (spacecraft)|''Dawn'']], [[Kepler space telescope]], and ''INSIDE Jupiter''.<ref>{{cite web |url=http://www.spacetoday.net/Summary/7 |title=NASA announces Discovery mission finalists |website=Spacetoday.net |date=January 4, 2001 |access-date=January 11, 2016}}</ref> ''INSIDE Jupiter'' was similar to a later New Frontiers mission called ''[[Juno (spacecraft)|Juno]]''; ''Dawn'' was a mission to asteroids [[4 Vesta|Vesta]] and [[Ceres (dwarf planet)|Ceres]], and ''Kepler'' was a space telescope mission aimed to discover [[extrasolar planet]]s. The three finalists received US$450,000 to further mature the mission concept.<ref>{{cite news |first1=Richard |last1=Stenger |url=https://www.cnn.com/2001/TECH/space/01/05/discovery.missions/ |title=Space – NASA selects finalists for next Discovery mission – January 5, 2001 |website=CNN.com |access-date=January 17, 2023}}</ref>

In December 2001, Kepler and ''Dawn'' were selected for flight.<ref name="autogenerated2001">{{cite web |url=http://www.nasa.gov/centers/ames/news/releases/2001/01_107AR.html |title=NASA |website=Nasa.gov |access-date=January 11, 2016 |archive-date=November 26, 2020 |archive-url=https://web.archive.org/web/20201126075755/https://www.nasa.gov/centers/ames/news/releases/2001/01_107AR.html |url-status=dead }}</ref> At this time, only 80 exoplanets had been detected, and the main mission of Kepler to look for more exoplanets, especially Earth-sized.<ref name="autogenerated2001"/><ref>{{cite web |url=http://www.seti.org/seti-institute/project/science-analysis-support-nasa-discovery-programs-kepler-extended-mission |title=Science Analysis Support for NASA Discovery Program's Kepler Extended Mission &#124; SETI Institute |website=Seti.org |access-date=January 11, 2016 |archive-url=https://web.archive.org/web/20151215105444/http://www.seti.org/seti-institute/project/science-analysis-support-nasa-discovery-programs-kepler-extended-mission |archive-date=December 15, 2015 |url-status=dead }}</ref> Both ''Kepler'' and ''Dawn'' were initially projected for launch in 2006.<ref name="autogenerated3">{{cite web |author=Susan Reichley |url=http://www.jpl.nasa.gov/releases/2001/release_2001_245.html |title=2001 News Releases – JPL Asteroid Mission Gets Thumbs Up from NASA |website=Jpl.nasa.gov |date=December 21, 2001 |access-date=January 11, 2016 |archive-date=May 1, 2017 |archive-url=https://web.archive.org/web/20170501104328/https://www.jpl.nasa.gov/releases/2001/release_2001_245.html |url-status=dead }}</ref>

=== Discovery 11 ===
The original Announcement of Opportunity for a Discovery mission released on April 16, 2004.<ref>{{Cite web|date=16 April 2004|title=Announcement of Opportunity Discovery Program 2004 and Missions of Opportunity|url=https://nspires.nasaprs.com/external/viewrepositorydocument/cmdocumentid=71453/solicitationId=%7BA9BD7790-3480-5577-1572-EB65D9985FD2%7D/viewSolicitationDocument=1/NNH04ZSS002O.pdf|access-date=20 February 2021|website=[[NASA]]}}</ref> The only candidate for selection for a concept Phase A study was JASSI, which was a Jupiter flyby mission based on the New Frontiers Mission Juno that was already under consideration for final selection (eventually Juno was selected as the 2nd New Frontiers mission in 2005 and launched in 2011). No other discovery mission proposed in response to the Announcement of Opportunity was considered for concept study and therefore no Discovery mission was selected for this opportunity (although a mission of opportunity was selected (Moon Mineralogy Mapper) as part of the AO in 2004<ref>{{Cite web|last1=Dolores|first1=Beasley|last2=Cook-Anderson|first2=Gretchen|date=2 February 2021|title=NASA Selects Moon Mapper for Mission of Opportunity|url=https://nspires.nasaprs.com/external/viewrepositorydocument/cmdocumentid=71454/solicitationId=%7BA9BD7790-3480-5577-1572-EB65D9985FD2%7D/viewSolicitationDocument=1/DISC04%20selections.pdf|access-date=20 February 2021|website=[[NASA]]}}</ref>). The next Announcement of Opportunity for a Discovery mission was released on January 3, 2006.<ref>{{cite news |last=Cain |first=Fraser |url=http://www.universetoday.com/966/back-to-venus-with-vesper/ |title=Back to Venus with Vesper |work=Universe Today |access-date=January 11, 2016}}</ref> There were three finalists for this Discovery selection including [[GRAIL]] (the eventual winner), OSIRIS, and VESPER.<ref name="google1">{{cite book |url=https://books.google.com/books?id=CJWLBAAAQBAJ&pg=PA349|title=Robotic Exploration of the Solar System: Part 4: The Modern Era 2004–2013 |author1=Paolo Ulivi |author2=David M. Harland |page=349|date=September 16, 2014|publisher=Springer|isbn=978-1-4614-4812-9}}</ref> OSIRIS was very similar to the later [[OSIRIS-REx]] mission, an asteroid sample-return mission to [[101955 Bennu]], and ''Vesper'', a Venus orbiter mission.<ref name="google1"/> A previous proposal of ''Vesper'' had also been a finalist in the 1998 round of selection.<ref name="google1"/> The three finalists were announced in October 2006 and awarded US$1.2 million to further develop their proposals for the final round.<ref name="autogenerated2006">{{cite web |url=http://www.nasa.gov/home/hqnews/2006/oct/HQ_06342_Discovery_AO.html |title=NASA – NASA Announces Discovery Program Selections |website=Nasa.gov |date=November 2, 2008 |access-date=January 11, 2016 |archive-date=June 29, 2009 |archive-url=https://web.archive.org/web/20090629094310/http://www.nasa.gov/home/hqnews/2006/oct/HQ_06342_Discovery_AO.html |url-status=dead }}</ref>

In November 2007 NASA selected the GRAIL mission as the next Discovery mission, with a goal of mapping lunar gravity and a 2011 launch.<ref name="nbcnews1">{{cite web |url=http://www.nbcnews.com/id/22202797/ns/technology_and_science-space/t/nasa-aiming-look-inside-moon/ |archive-url=https://web.archive.org/web/20160306114716/http://www.nbcnews.com/id/22202797/ns/technology_and_science-space/t/nasa-aiming-look-inside-moon/ |url-status=dead |archive-date=March 6, 2016 |title=NASA aiming to look inside the moon - Technology & science - Space - Space.com |work=[[NBC News]] |date=September 6, 2011 |access-date=January 11, 2016}}</ref> There were 23 other proposals that were also under consideration.<ref name="nbcnews1"/> The mission had a budget of US$375 million (then-year dollars) which included construction and launch.<ref name="nbcnews1"/>

=== Discovery 12 ===
[[File:TSSM-TandEM-Lander.jpg|thumb|Artist's impression of proposed TiME lake lander for Saturn's moon Titan]]

The Announcement of Opportunity for a Discovery mission released on June 7, 2010. For this cycle, 28 proposals were received; 3 were for the Moon, 4 for Mars, 7 for Venus, 1 for Jupiter, 1 to a Jupiter Trojan, 2 to Saturn, 7 to asteroids, and 3 to comets.<ref>{{cite journal |first=Eric |last=Hand |title=Venus scientists fear neglect |journal=Nature |volume=477 |issue=7363 |pages=145 |date=September 2, 2011 |pmid=21900987 |bibcode=2011Natur.477..145H |doi=10.1038/477145a |s2cid=4410972 |doi-access=free }}</ref><ref>{{cite web |author=Jpl, Nasa |url=http://marsmobile.jpl.nasa.gov/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1316 |title=Mars Mobile |website=Marsmobile.jpl.nasa.gov |date=August 20, 2012 |access-date=January 11, 2016 |archive-url=https://web.archive.org/web/20160604121730/http://marsmobile.jpl.nasa.gov/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1316 |archive-date=June 4, 2016 |url-status=dead }}</ref> Out of the 28 proposals, three finalists received US$3 million in May 2011 to develop a detailed concept study:<ref>{{cite web |title=NASA Selects Investigations For Future Key Planetary Mission |url=http://www.nasa.gov/home/hqnews/2011/may/HQ_11-132_Future_Plantary.html |publisher=NASA |access-date=May 6, 2011 |archive-date=May 7, 2011 |archive-url=https://web.archive.org/web/20110507065258/http://www.nasa.gov/home/hqnews/2011/may/HQ_11-132_Future_Plantary.html |url-status=dead }}</ref> 
* ''[[InSight]]'', a Mars lander.
* [[Titan Mare Explorer]] (TiME), a lake lander for [[Saturn]]'s moon [[Titan (moon)|Titan]] with methane-ethane lakes.
* [[Comet Hopper]] (CHopper) to study cometary evolution by landing on a comet multiple times and observing its changes as it interacts with the Sun.

In August 2012, '''''[[InSight]]''''' was selected for development and launch.<ref name="washington">{{cite news |url=https://www.washingtonpost.com/national/health-science/nasa-will-send-robot-drill-to-mars-in-2016/2012/08/20/43bf1980-eaef-11e1-9ddc-340d5efb1e9c_story.html |title=NASA will send robot drill to Mars in 2016 |newspaper=The Washington Post |first=Brian |last=Vastag |date=August 20, 2012}}</ref> The mission launched on May 5, 2018, and successfully landed on Mars on November 26.<ref>{{Cite web|title=InSight Mission Timeline Overview|url=https://mars.nasa.gov/insight/timeline/overview/|access-date=24 February 2021|website=mars.nasa.gov|publisher=[[NASA]]}}</ref>

=== Discovery 13 and 14 ===
[[File:NASA NEXT Ion thruster.712983main NEXT LDT Thrusterhi-res full.jpg|thumb|NASA made ion thruster technology available for proposals for the thirteenth Discovery Program mission.<ref name="fp">{{cite web |first=Van |last=Kane |url=https://futureplanets.blogspot.com/2014/02/boundaries-for-next-discovery-mission.html |title=Boundaries for the Next Discovery Mission Selection |publisher=Future Planets |date=February 20, 2014 |url-status=live |archive-url=https://web.archive.org/web/20140307163947/http://futureplanets.blogspot.co.uk/2014/02/boundaries-for-next-discovery-mission.html |archive-date=March 7, 2014}}</ref>]]
{{main|Selection of Discovery Mission 13 and 14}}

In February 2014, NASA released a Discovery Program 'Draft Announcement of Opportunity' for launch readiness date of December 31, 2021.<ref>{{cite news |title=NASA Discovery Program Draft Announcement of Opportunity |date=February 19, 2014 |publisher=SpaceRef |url=http://www.spaceref.com/news/viewsr.html?pid=45337 |work=[[Science Mission Directorate|NASA Science Mission Directorate]] |access-date=February 22, 2014 |archive-date=February 22, 2014 |archive-url=https://archive.today/20140222205001/http://www.spaceref.com/news/viewsr.html?pid=45337 |url-status=dead }}</ref> The final AO was released on November 5, 2014, and on September 30, 2015, NASA selected five mission concepts as finalists,<ref>{{cite web |author=Stephen Clark |url=https://spaceflightnow.com/2015/10/05/nasa-might-pick-two-discovery-missions-but-at-a-price/ |title=NASA might pick two Discovery missions, but at a price |publisher=Spaceflight Now |access-date=January 11, 2016}}</ref><ref name="selection 1st round">{{cite news |last1=Brown |first1=Dwayne C. |last2=Cantillo |first2=Laurie |url=http://www.nasa.gov/press-release/nasa-selects-investigations-for-future-key-planetary-mission |title=NASA Selects Investigations for Future Key Planetary Mission |work=NASA News |location=Washington, D.C. |date=September 30, 2015 |access-date=October 1, 2015}}</ref> each received $3 million for one-year of further study and concept refinement.<ref name="laser2015">{{cite news |last=Clark |first=Stephen |url=https://spaceflightnow.com/2015/02/24/nasa-receives-proposals-for-new-planetary-science-mission/ |title=NASA receives proposals for new planetary science mission |work=Space Flight Now |date=February 24, 2014 |access-date=February 25, 2015}}</ref><ref>{{cite news |last=Kane |first=Van |url=http://www.planetary.org/blogs/guest-blogs/van-kane/20141201-selecting-the-next-creative-discovery-mission.html |title=Selecting the Next Creative Idea for Exploring the Solar System |work=Planetary Society |date=December 2, 2014 |access-date=February 10, 2015}}</ref>

*[[DAVINCI (spacecraft)|Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging]] (DAVINCI)
*[[VERITAS (spacecraft)|Venus Emissivity, Radio Science, InSAR Topography and Spectroscopy]] (VERITAS)
*[[Near-Earth Object Camera]] (NEOCam)
*[[Lucy (spacecraft)|''Lucy'']]
*[[Psyche (spacecraft)|''Psyche'']]

On January 4, 2017, '''''[[Lucy (spacecraft)|Lucy]]''''' and '''''[[Psyche (spacecraft)|Psyche]]''''' were selected for the 13th and 14th Discovery missions, respectively and launched on 16 October 2021 and 13 October 2023, respectively.<ref name=nasataps /><ref name="nasaselectslucypsyche">{{cite news |url=https://www.nasa.gov/press-release/nasa-selects-two-missions-to-explore-the-early-solar-system/|title=NASA Selects Two Missions to Explore the Early Solar System|date=January 4, 2017 |access-date=January 4, 2017}}</ref> ''Lucy'' will fly by five [[Jupiter trojan]]s, [[asteroid]]s which share Jupiter's [[orbit]] around the [[Sun]], orbiting either ahead of or behind the planet.<ref name="NYT-20170106">{{cite news |url=https://www.nytimes.com/2017/01/06/science/nasa-psyche-asteroid.html |title=A Metal Ball the Size of Massachusetts That NASA Wants to Explore |work=[[The New York Times]] |last=Chang |first=Kenneth |date=January 6, 2017 |access-date=January 7, 2017}}</ref><ref name="nasaselectslucypsyche" /> ''Psyche'' will explore the origin of [[planetary core]]s by orbiting and studying the metallic asteroid [[16 Psyche]].<ref name="NYT-20170106" />

===Discovery 15 and 16===
On December 22, 2018, NASA released a draft of its Discovery 2019 Announcement of Opportunity, which outlined its intent to select up to two missions with launch readiness dates of July 1, 2025 – December 31, 2026, and/or July 1, 2028 – December 31, 2029, as Discovery 15 and 16, respectively.<ref name="NASA 19AO">{{cite web|title=NASA SOMA: Discovery 2019 AO Homepage|publisher=[[NASA]]|url=https://discovery.larc.nasa.gov/|access-date=16 February 2020}}</ref><ref>{{cite web|title=NSPIRES: DRAFT Discovery AO (Solicitation: NNH19ZDA009J)|publisher=[[NASA]]|url=https://nspires.nasaprs.com/external/solicitations/summary!init.do?solId={858E0901-4A66-3391-60AE-3EF0779AE750}&path=open|access-date=16 February 2020}}</ref> The final Announcement of Opportunity was released on April 1, 2019, and proposal submissions were accepted between then and July 1, 2019.<ref>{{cite web |title=NASA Announcement: Release of the 2019 Announcement of Opportunity for Discovery Program |url=https://www.fbo.gov/index.php?s=opportunity&mode=form&id=544eb5d82b65bcddaf467e61c668f179&tab=core&_cview=0 |publisher=NASA |access-date=23 July 2019|archive-url=https://web.archive.org/web/20190510195634/https://www.fbo.gov/index.php?s=opportunity&mode=form&id=544eb5d82b65bcddaf467e61c668f179&tab=core&_cview=0|archive-date=10 May 2019}}</ref>

Finalists, announced on February 13, 2020, were:<ref>{{cite web|title=NASA Selects Four Possible Missions to Study the Secrets of the Solar System|publisher=[[NASA]]|date=13 February 2020|url=https://www.nasa.gov/press-release/nasa-selects-four-possible-missions-to-study-the-secrets-of-the-solar-system|access-date=13 February 2020}}</ref>

*[[DAVINCI]] (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging), a Venus atmospheric probe.<ref>[https://www.scientificamerican.com/article/venus-earths-evil-twin-beckons-space-agencies/ Venus, Earth's Evil Twin, Beckons Space Agencies]. By Shannon Hall, ''Scientific American''. 12 June 2019.</ref>
*[[Io Volcano Observer]], an orbiter to Jupiter to perform at least nine flybys of Jupiter's volcanically active moon [[Io (moon)|Io]].<ref>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-996-1.pdf "Follow the Heat: Io Volcano Observer".] A.S. McEwen, E. Turtle, L. Kestay, K. Khurana, J. Westlake, etal. EPSC Abstracts Vol. 13, EPSC-DPS2019-996-1, 2019 EPSC-DPS Joint Meeting 2019.</ref>
*[[Trident (spacecraft)|''Trident'']], a probe that would conduct a flyby of [[Neptune]] and its moon [[Triton (moon)|Triton]].<ref name="Trident_Description">{{cite web |url=https://www.hou.usra.edu/meetings/lpsc2019/pdf/3188.pdf |title=Exploring Triton With Trident: A Discovery-Class Mission |date=2019-03-23|website=Universities Space Research Association |access-date=2019-03-26}}</ref>
*[[VERITAS (spacecraft)|VERITAS]] (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy), a Venus orbiter to map the surface of Venus in high resolution.<ref>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1124-1.pdf VERITAS (Venus Emissivity, Radio Science, InSAR, Topography And Spectroscopy): A Proposed Discovery Mission.] Suzanne Smrekar, Scott Hensley, Darby Dyar, Jörn Helbert, and the VERITAS Science Team. EPSC Abstracts Vol. 13, EPSC-DPS2019-1124-1, 2019 EPSC-DPS Joint Meeting 2019.</ref>
On June 2, 2021, NASA administrator [[Bill Nelson]] announced in his "State of NASA" address that the two Venus missions, '''[[VERITAS (spacecraft)|VERITAS]]''' and '''[[DAVINCI]]''', had been selected for development.<ref name="space-20221104" /><ref name=":4">{{cite press release |last=Potter |first=Sean |url=https://www.nasa.gov/press-release/nasa-selects-2-missions-to-study-lost-habitable-world-of-venus |title=NASA Selects 2 Missions to Study 'Lost Habitable' World of Venus |publisher=[[NASA]] |date=June 2, 2021 |access-date=June 2, 2021}}</ref> The two missions will launch between 2031 and 2032.<ref name="aas-20240325" />

Other proposal submissions for Discovery 15 and 16 missions included:

;Asteroids, comets, Centaurs, interplanetary dust
*''[[Centaurus (spacecraft mission)|Centaurus]]'', a reconnaissance mission to explore multiple [[Centaur (small Solar System body)|Centaurs]] via flybys as a way to learn about Solar System and planet formation.<ref>{{Citation|last1=Singer|first1=Kelsi|title=Centaurus: A Spacecraft Discovery Mission Proposal to Explore Centaurs and More, Messengers from the Era of Planet Formation|date=2019|url=https://figshare.com/articles/Centaurus_A_Spacecraft_Discovery_Mission_Proposal_to_Explore_Centaurs_and_More_Messengers_from_the_Era_of_Planet_Formation/9956210|doi=10.6084/m9.figshare.9956210|access-date=2019-10-08|last2=S. Alan Stern|publisher=Figshare }}</ref><ref>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-2025.pdf Centaurus: Exploring Centaurs and More, Messengers from the Era of Planet Formation]. Kelsi N. Singer, S. Alan Stern, Daniel Stern, Anne Verbiscer, Cathy Olkin, and the Centaurus Science Team. (. EPSC Abstracts Vol. 13, EPSC-DPS2019-2025-1, 2019 EPSC-DPS Joint Meeting 2019</ref>
*''[[Chimera (spacecraft)|Chimera]]'', a mission concept to orbit the highly active [[Centaur (small Solar System body)|Centaur]] 29P/[[29P/Schwassmann–Wachmann|Schwassmann-Wachmann 1]], to study the evolutionary middle ground between the [[Trans Neptunian Object]]s (TNOs) and Jupiter Family Comets.<ref>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1094-1.pdf "Chimera: A Mission of Discovery to the First Centaur".] Walter Harris, Laura Woodney, Geronimo Villanueva and the Chimera Science team. EPSC Abstracts Vol. 13, EPSC-DPS2019-1094-1, 2019 EPSC-DPS Joint Meeting 2019.</ref>
*FOSSIL (Fragments from the Origins of the Solar System and our Interstellar Locale), a spacecraft to be placed in an Earth-trailing orbit to determine the composition of the local and [[interplanetary dust cloud]].<ref>"[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1202-6.pdf Fragments from the Origins of the Solar System and our Interstellar Locale (FOSSIL): A Discovery Mission Concept."] Mihaly Horányi, Neal J. Turner, Conel Alexander, Nikolas Altobelli, Tibor Balint, Julie Castillo-Rogez, Bruce Draine, Cecile Engrand, Jon Hillier, Hope Ishii, Sascha Kempf, Tobin Munsat, David Nesvorný, Larry Nittler, Peter Pokorný, Frank Postberg, Ralf Srama, Thomas Stephan, Zoltan Sternovsky, Jamey Szalay, Andrew Westphal, Diane Wooden. EPSC Abstracts Vol. 13, EPSC-DPS2019-1202-6, 2019 EPSC-DPS Joint Meeting. 2019</ref>
*[[MANTIS (spacecraft)|MANTIS]] (Main-belt Asteroid and NEO Tour with Imaging and Spectroscopy), a mission that would flyby 14 asteroids covering a wide range of types and masses.<ref>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1277-1.pdf The Main-belt Asteroid and NEO Tour with Imaging and Spectroscopy (MANTIS)]. Andrew S. Rivkin, Barbara A. Cohen, Olivier Barnouin, Carolyn M. Ernst, Nancy L. Chabot, Brett W. Denevi, Benjamin T. Greenhagen, Rachel L. Klima, Mark Perry, Zoltan Sternovsky, and the MANTIS Science Team. EPSC Abstracts Vol. 13, EPSC-DPS2019-1277-1, 2019 EPSC-DPS Joint Meeting 2019</ref>

;Venus:
*HOVER (Hyperspectral Observer for Venus Reconnaissance), a Venus orbiter that would perform spectral studies from the top of the atmosphere to the surface. Its main goal is understanding the mechanics of the Venus climate and atmospheric super-rotation.<ref name='HOVER EPSC 2019'>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-340-2.pdf Hyperspectral Observer for Venus Reconnaissance (HOVER)]. Larry W. Esposito, and the HOVER Team. EPSC Abstracts Vol. 13, EPSC-DPS2019-340-2, 2019 EPSC-DPS Joint Meeting 2019.</ref>

;Moon:
*[[Moon Diver (spacecraft)|''Moon Diver'']], a lunar lander which would deploy a rover to rappel down a deep pit, analyzing the exposed geological layers and investigate if the pit connects to a [[lunar lava tube|lava tube]].<ref name='Issa 2019'>[https://ieeexplore.ieee.org/abstract/document/8741788 Moon Diver: A Discovery Mission Concept for Understanding the History of Secondary Crusts through the Exploration of a Lunar Mare Pit.] Issa A. Nesnas, Laura Kerber, Aaron Parness, Richard Kornfeld, Glenn Sellar, etal. 2019 IEEE Aerospace Conference. 2–9 March 2019. Big Sky, MT, USA. {{doi|10.1109/AERO.2019.8741788}}</ref>
*''Lunar Compass Rover,'' a rover designed to explore a nearside magnetic region and [[Lunar swirls|swirl]], and would answer some questions in planetary science, including planetary magnetism, [[Plasma (physics)|space plasma]] physics, space weathering, planetary geology, and the [[lunar water]] cycle. A proposal for Lunar Compass was not submitted to this Discovery round.<ref>[https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/347040 Key Questions in Planetary Science to be Addressed by Exploration of a Lunar Magnetic Anomaly: The Lunar Compass Rover Discovery Mission Concept.] David T. Blewett, Jasper S. Halekas, Benjamin T. Greenhagen, etal. AGU Fall Meeting, Washington DC, 14 December 2018.</ref>
*[[ISOCHRON (spacecraft)|ISOCHRON]] (Inner SOlar system CHRONology), a mission that would perform a robotic lunar sample-return of the youngest [[Lunar mare|mare basalts]].<ref>[https://www.hou.usra.edu/meetings/lpsc2019/pdf/1110.pdf The Inner Solar System Chronology (ISOCHRON) Discovery Mission: Returning Samples of the Youngest Lunar Mare Basalts.] D. S. Draper, R. L. Klima, S. J. Lawrence, B. W. Denevi, and the ISOCHRON Team. 50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132).</ref>
*NanoSWARM, a lunar orbiter to investigate [[lunar swirls]], space weathering, [[lunar water]], lunar magnetism, and small-scale magnetospheres.<ref>[https://www.hou.usra.edu/meetings/lpsc2019/pdf/2786.pdf NanoSWARM: A Proposed Discovery Mission to Study Space Weathering, Lunar Water, lunar magnetism, and small-scale magnetospheres.] 50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132).</ref>

;Mars
*COMPASS (Climate Orbiter for Mars Polar Atmospheric and Subsurface Science) is a mission concept for a Mars orbiter to research the Martian climate record through the study of its ice deposits and their interaction with current climate.<ref name='Byrne EPSC 2019'>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-912-1.pdf Climate Orbiter for Mars Polar Atmospheric and Subsurface Science (COMPASS): Deciphering the Martian Climate Record.] S. Byrne, P. O. Hayne, P. Becerra, The COMPASS Team. EPSC Abstracts Vol. 13, EPSC-DPS2019-912-1, 2019 EPSC-DPS Joint Meeting 2019.</ref> This mission is led by the Lunar and Planetary Laboratory at the University of Arizona and the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder.<ref name="Byrne EPSC 2019" />
*[[Icebreaker Life]], a mission concept led by the [[Ames Research Center]] for a lander to search for direct signs of life on Mars via biomarker detection, with a focus on sampling ice-cemented ground for its potential to preserve and protect biomolecules or biosignatures.<ref name="LPI 2012">{{Cite journal|author=McKay, C. P.|author2=Carol R. Stoker|author3=Brian J. Glass|author4=Arwen I. Davé|author5=Alfonso F. Davila|author6=Jennifer L. Heldmann|author7=Margarita M. Marinova|author8=Alberto G. Fairen|author9=Richard C. Quinn|author10=Kris A. Zacny|author11=Gale Paulsen|date=2012|title=THE ICEBREAKER LIFE MISSION TO MARS: A SEARCH FOR BIOCHEMICAL EVIDENCE FOR LIFE|url=https://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4091.pdf|journal=Concepts and Approaches for Mars Exploration|publisher=[[Lunar and Planetary Institute]]|author17=Wayne H. Pollard|name-list-style=amp|author16=Denis Lacelle|author15=Michael H. Hecht|author14=Dale T. Andersen|author13=Victor Parro|author12=Peter H. Smith}}</ref>

;Jupiter

*MAGIC (Magnetics, Altimetry, Gravity and Imaging of Callisto) is an orbiter reconnaissance concept to Jupiter's moon [[Callisto (moon)|Callisto]].<ref name='Smith EPSC MAGIC 2019'>[https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-363-1.pdf MAGIC, A Proposed Geophysical Mission to Jupiter's Icy Moon, Callisto.] David E. Smith, Terry Hurford, Maria T. Zuber, Robin Canup, Francis Nimmo, Mark Wieczorek, Edward Bierhaus, Antonio Genova, Erwan Mazarico and the MAGIC Team. EPSC Abstracts Vol. 13, EPSC-DPS2019-363-1, 2019 EPSC-DPS Joint Meeting 2019.</ref>

===Discovery 17 and beyond===
On August 24, 2023, NASA announced that due to budgetary constraints enacted through the [[Fiscal Responsibility Act of 2023]], the official release of the Announcement of Opportunity for the [[New Frontiers program#New Frontiers 5|fifth mission]] in the Discovery Program's "big sibling" program, New Frontiers, would be delayed to no earlier than 2026.<ref>{{cite web |last=Foust |first=Jeff |url=https://spacenews.com/nasa-confirms-multi-year-delay-in-next-new-frontiers-competition/ |title=NASA confirms multi-year delay in next New Frontiers competition |work=[[SpaceNews]] |date=August 28, 2023 |access-date=August 31, 2023}}</ref> In October 2023, Planetary Science Division Director [[Lori Glaze]] presented to the National Academies' Committee on Astrobiology and Planetary Science on the implications of these resource constraints, noting that there were unlikely to be solicitations for further Discovery missions until at least 2026 either.<ref>{{cite conference|title=Presentation to Committee on Astrobiology and Planetary Sciences Autumn 2023 Meeting|contribution=Planetary Science Division Update|date=24 October 2023|place=Irvine CA|url=https://www.nationalacademies.org/documents/embed/link/LF2255DA3DD1C41C0A42D3BEF0989ACAECE3053A6A9B/file/DB5A7F1704EF6D9AA343457C70C7D0477572C5D6EEA0?noSaveAs=1|last1=Glaze|first1=Lori|publisher=National Academies of Science, Engineering and Medicine|access-date=1 March 2025}}</ref>

==Gallery==
===Artists' impressions===
{| class="wikitable" style="margin: 1em auto 1em auto; width:90%"
|-
!colspan=6| Discovery Program
|- style="background:white;"
| [[File:Near Shoemaker.jpg|center|100x100px]]
| [[File:Lander and rover drawing.gif|center|100x100px]]
| [[File:LPnosunm.jpeg|center|100x100px]]
| [[File:Stardust - Concepcao artistica.jpg|center|100x100px]]
| [[File:Genesis in collection mode.jpg|center|100x100px]]
| [[File:Contour comet.jpg|center|100x100px]]
|-
| '''[[NEAR Shoemaker]]'''<br />1996
| '''[[Mars Pathfinder]]'''<br />1996
| '''[[Lunar Prospector]]'''<br />1998
| '''''[[Stardust (spacecraft)|Stardust]]'''''<br />1999
| '''''[[Genesis (spacecraft)|Genesis]]'''''<br />2001
| '''''[[CONTOUR]]'''''<br />2002
|- style="background:white;"
| [[File:MESSENGER - spacecraft at mercury - atmercury lg.jpg|center|100x100px]]
| [[File:Deep Impact.jpg|center|100x100px]]
| [[File:Dawn Flight Configuration 2.jpg|center|100x100px]]
| [[File:Kepler bkgd.sm.jpg|center|100x100px]]
| [[File:GRAIL Artwork cropped.jpg|center|100x100px]]
| [[File:InSight Lander.jpg|center|100x100px]]
|-
| '''''[[MESSENGER]]'''''<br />2004
| '''''[[Deep Impact (spacecraft)|Deep Impact]]'''''<br />2005
| '''''[[Dawn (spacecraft)|Dawn]]'''''<br />2007
| '''[[Kepler space telescope|Kepler]]'''<br />2009
| '''[[Gravity Recovery and Interior Laboratory|GRAIL]]'''<br />2011
| '''''[[InSight]]'''''<br />2018
|- style="background:white;"
| [[File:Lucy--mission-13--v3.png|center|100x100px]]
| [[File:PIA21275 - Psyche Artist's Concept.jpg|center|100x100px]]
| [[File:DAVINCI Venus mission descent.jpg|center|100x100px]]
| [[File:Veritas20150930.jpg|center|100x100px]]
|-
| '''''[[Lucy (spacecraft)|Lucy]]'''''<br />2021
| '''''[[Psyche (spacecraft)|Psyche]]'''''<br />2023
| '''''[[DAVINCI]]'''''<br/ >2031–2032
| '''''[[VERITAS (spacecraft)|VERITAS]]'''''<br />2031
|}

===Mission insignias===
''This section includes an image of the Discovery missions' patches or logos, as well as the launch year''.

{| class="wikitable" style="margin: 1em auto 1em auto; width:90%"
|-
!colspan=6| Discovery Program
|- style="background: white;"
| [[File:NEAR Shoemaker insignia.png|center|100x100px]]
| [[File:Mars Pathfinder Insignia.png|center|100x100px]]
| [[File:Lunar Prospector insignia.png|center|100x100px]]
| [[File:Stardust - starlogo.png|center|100x100px]]
| [[File:Genesis Sample Return Sticker.jpg|center|100x100px]]
|
|-
| '''[[NEAR Shoemaker]]'''<br />1996
| '''[[Mars Pathfinder]]''' <br />1996
| '''[[Lunar Prospector]]'''<br />1998
| '''''[[Stardust (spacecraft)|Stardust]]'''''<br />1999
| '''''[[Genesis (spacecraft)|Genesis]]'''''<br />2001
| '''''[[CONTOUR]]'''''<br />2002
|- style="background: white;"
| [[File:MESSENGER mission emblem.png|center|100x100px]]
| [[File:Deep Impact Mission Patch.png|center|100x100px]]
| [[File:Dawn logo.png|center|100x100px]]
| [[File:Kepler logo.svg|center|100x100px]]
| [[File:GRAIL - GRAIL-logo-sm.png|center|100x100px]]
| [[File:InSight Mission Logo.svg|center|100x100px]]
|-
| '''''[[MESSENGER]]'''''<br />2004
| '''''[[Deep Impact (spacecraft)|Deep Impact]]'''''<br />2005
| '''''[[Dawn (spacecraft)|Dawn]]'''''<br />2007
| '''''[[Kepler (spacecraft)|Kepler]]'''''<br />2009
| '''[[Gravity Recovery and Interior Laboratory|GRAIL]]'''<br />2011
| '''''[[InSight]]'''''<br />2018
|- style="background: white;"
| [[File:Lucy insignia.svg|center|100x100px]]
| [[File:Psyche insignia.svg|center|100x100px]]
| <!-- [[  |center|100x100px]] -->
| <!-- [[  |center|100x100px]] -->&nbsp;
|-
| '''''[[Lucy (spacecraft)|Lucy]]'''''<br />2021
| '''''[[Psyche (spacecraft)|Psyche]]'''''<br />2023
| '''''[[DAVINCI]]'''''<br/ >2031–2032
| '''''[[VERITAS (spacecraft)|VERITAS]]'''''<br />2031
|}

===Launches===
This section includes an image of the Discovery missions' rockets, as well as the launch year.

{| class="wikitable" style="margin: 1em auto 1em auto; width:90%"
|-
!colspan=6| Discovery Program
|- style="background: white;"
| [[File:Launch of NEAR on a Delta II 7925-8.jpg|center|100x100px]]
| [[File:Mars Pathfinder launch.jpg|center|100x100px]]
| [[File:Athena-2 - Lunar Prospector 2.jpg|center|100x100px]]
| [[File:Stardust - launch photo - ksc9902074.jpg|center|100x100px]]
| [[File:Delta II Genesis Launch.jpg|center|100x100px]]
| [[File:CONTOUR Launch (19083178100).jpg|center|100x100px]]

|-
| '''[[NEAR Shoemaker]]'''<br />1996
| '''[[Mars Pathfinder]]''' <br />1996
| '''[[Lunar Prospector]]'''<br />1998
| '''''[[Stardust (spacecraft)|Stardust]]'''''<br />1999
| '''''[[Genesis (spacecraft)|Genesis]]'''''<br />2001
| '''''[[CONTOUR]]'''''<br />2002
|- style="background: white;"
| [[File:Delta 7925H MESSENGER ignition.jpg|center|100x100px]]
| [[File:Delta II 7925 (2925) rocket with Deep Impact.jpg|center|100x100px]]
| [[File:Dawn ignition.jpg|center|100x100px]]
| [[File:Ignition of Kepler's Delta II 7925-10L.jpg|center|100x100px]]
| [[File:GRAIL on the Pad.jpg|center|100x100px]]
| [[File:InSight Prelaunch (NHQ201805050009).jpg|center|100x100px]]
|-
| '''''[[MESSENGER]]'''''<br />2004
| '''''[[Deep Impact (spacecraft)|Deep Impact]]'''''<br />2005
| '''''[[Dawn (spacecraft)|Dawn]]'''''<br />2007
| '''[[Kepler space telescope|Kepler]]'''<br />2009
| '''[[Gravity Recovery and Interior Laboratory|GRAIL]]'''<br />2011
| '''''[[InSight]]'''''<br />2018
|- style="background: white;"
| [[File:NHQ202110160012 - Lucy Spacecraft Launch.jpg|center|100x100px]]
|[[File:Psyche Liftoff (KSC-20231013-PH-KLS01 0067).jpg|center|100x100px]]
<!-- |[[  |center|100x100px]] -->
<!-- |[[  |center|100x100px]] -->&nbsp;
|-
| '''''[[Lucy (spacecraft)|Lucy]]'''''<br />2021
|'''''[[Psyche (spacecraft)|Psyche]]'''''<br />2023
<!--| '''''[[DAVINCI]]'''''<br/ >2031–2032
| '''''[[VERITAS (spacecraft)|VERITAS]]'''''<br />2031-->
|}

==References==
{{Reflist|30em}}

==External links==
{{Portal |Spaceflight}}
* [https://www.nasa.gov/planetarymissions/discovery.html Official NASA website for Discovery Program]

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[[Category:Discovery Program| ]]
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