View source for Deep Impact (spacecraft)

{{Short description|NASA space probe launched in 2005}}
{{italic title}}
{{Infobox spaceflight
| auto               = all
| name               = ''Deep Impact''
| image              = Deep Impact.jpg
| image_caption      = Artist's impression of the ''Deep Impact'' space probe after deployment of the impactor
| image_alt          = A spacecraft deploys an impactor towards a comet, visible in the background
| image_size         = 
| mission_type       = Flyby/impactor ([[Tempel 1|9P/Tempel]])
| operator           = [[NASA]]{{dot}}[[Jet Propulsion Laboratory|JPL]]
| COSPAR_ID          = 2005-001A
| SATCAT             = 28517
| website            = {{url|http://www.jpl.nasa.gov/missions/deep-impact/}}
| mission_duration   = Final: {{time interval|12 January 2005 18:47:08|8 August 2013|show=ymd|sep=,}}
| manufacturer       = [[Ball Aerospace & Technologies|Ball Aerospace]]{{dot}}[[University of Maryland, College Park|University of Maryland]]
| launch_mass        = Total: 973 kg <br /> Spacecraft: {{convert|601|kg|lb|abbr=on}}<ref name="presskit">{{cite web |url=https://www.nasa.gov/pdf/103744main_presskit_121404.pdf |title=Deep Impact Launch: Press Kit |publisher=NASA |date=January 2005 |access-date=July 3, 2018 |archive-date=June 26, 2021 |archive-url=https://web.archive.org/web/20210626233333/https://www.nasa.gov/pdf/103744main_presskit_121404.pdf |url-status=dead }}</ref> <br /> Impactor: {{convert|372|kg|lb|abbr=on}}<ref name="presskit" />
| dimensions         = {{convert|3.3|xx|1.7|xx|2.3|m|ft|1|abbr=on}}<ref name="presskit" />
| power              = 92 [[Watt|W]] ([[photovoltaic system|solar array]]{{\}}[[nickel–hydrogen battery|{{chem2|NiH2}} battery]])<ref name="presskit" />
| launch_date        = {{start-date|January 12, 2005, 18:47:08}}&nbsp;[[UTC]]
| launch_rocket      = [[Delta II]] 7925 /[[PAM-D]]
| launch_site        = [[Cape Canaveral Air Force Station|Cape Canaveral]] [[Cape Canaveral Air Force Station Space Launch Complex 17|SLC-17B]]
| launch_contractor  = [[Boeing]]
| disposal_type      = Contact lost
| last_contact       = {{end-date|August 8, 2013}}
| interplanetary     = {{Infobox spaceflight/IP
  |type                 = flyby
  |object               = [[Tempel 1]]
  |arrival_date         = July 4, 2005, 06:05&nbsp;UTC
  |distance             = {{convert|575|km|mi|abbr=on}}
 }}
 {{Infobox spaceflight/IP
  |type                 = impactor
  |object               = [[Tempel 1]]
  |arrival_date         = July 4, 2005, 05:52&nbsp;UTC
 }}

 {{Infobox spaceflight/IP
  |type                 = flyby
  |object               = [[Earth]]
  |arrival_date         = December 31, 2007, 19:29:20&nbsp;UTC
  |distance             = {{convert|15567|km|mi|abbr= on}}
 }}

 {{Infobox spaceflight/IP
  |type                 = flyby
  |object               = [[Earth]]
  |arrival_date         = December 29, 2008
  |distance             = {{convert|43450|km|mi|abbr= on}}
 }}

 {{Infobox spaceflight/IP
  |type                 = flyby
  |object               = [[Earth]]
  |arrival_date         = June 28, 2010, 22:25:13 &nbsp;UTC
  |distance             = {{convert|30496|km|mi|abbr= on}}
 }}

 {{Infobox spaceflight/IP
  |type                 = flyby
  |object               = [[Hartley 2]]
  |arrival_date         = November 4, 2010, 13:50:57&nbsp;UTC
  |distance             = {{convert|694|km|mi|abbr= on}}
 }}
| programme          = [[Discovery Program]]
| previous_mission   = ''[[MESSENGER]]''
| next_mission       = ''[[Dawn (spacecraft)|Dawn]]''
| insignia           = Deep Impact Mission Patch.png
| insignia_caption   = Official insignia of the ''Deep Impact'' mission
| insignia_alt       = An oval with a red and black border encloses an image of a spacecraft and it's trajectory from Earth, depicting a deployed impactor before and after its impact with a comet.
| insignia_size      = 180px
}}

'''''Deep Impact''''' was a [[NASA]] [[space probe]] launched from [[Cape Canaveral Air Force Station]] on January 12, 2005.<ref name="SFN Over"/> It was designed to study the interior composition of the [[comet]] [[Tempel 1]] (9P/Tempel), by releasing an [[Deliberate crash landings on extraterrestrial bodies|impactor]] into the comet. At 05:52 UTC on July 4, 2005, the Impactor successfully collided with the comet's [[comet nucleus|nucleus]]. The impact excavated debris from the interior of the nucleus, forming an [[impact crater]]. Photographs taken by the spacecraft showed the comet to be more dusty and less icy than had been expected. The impact generated an unexpectedly large and bright dust cloud, obscuring the view of the impact crater.

Previous space missions to comets, such as ''[[Giotto mission|Giotto]]'', ''[[Deep Space 1]]'', and ''[[Stardust (spacecraft)|Stardust]]'', were [[Flyby (spaceflight)|fly-by missions]]. These missions were able to photograph and examine only the surfaces of cometary nuclei, and even then from considerable distances. The ''Deep Impact'' mission was the first to eject material from a comet's surface, and the mission garnered considerable publicity from the media, international scientists, and amateur astronomers alike.

Upon the completion of its primary mission, proposals were made to further utilize the spacecraft. Consequently, ''Deep Impact'' flew by Earth on December 31, 2007, on its way to an extended mission, designated [[EPOXI]], with a dual purpose to study [[extrasolar planet]]s and comet [[103P/Hartley|Hartley 2]] (103P/Hartley).<ref name="NASASSE">{{cite news |last1=Tune |first1=Lee |first2=Bill |last2=Steigerwald |first3=Grey |last3=Hautaluoma |first4=D.C. |last4=Agle |title=Deep Impact Extended Mission Heads for Comet Hartley 2 |publisher=[[University of Maryland, College Park]] |url=http://www.newsdesk.umd.edu/scitech/release.cfm?ArticleID=1564 |date=December 13, 2007 |access-date=August 7, 2009 |archive-url=https://web.archive.org/web/20090620043143/http://www.newsdesk.umd.edu/scitech/release.cfm?ArticleID=1564 |archive-date=June 20, 2009 |url-status=dead }}</ref> Communication was unexpectedly lost in August 2013 while the craft was heading for another asteroid flyby.

==Scientific goals==
The ''Deep Impact'' mission was planned to help answer fundamental questions about comets, which included what makes up the composition of the comet's nucleus, what depth the crater would reach from the impact, and where the comet originated in its formation.<ref name="Milems">{{cite news |last=Lamie |first=William E. |title=Case study: NASA's "Deep Impact" employs embedded systems to score bullseye 80 million miles away |publisher=Military Embedded Systems |date=January 13, 2006 |url=http://mil-embedded.com/article-id/?400= |access-date=March 30, 2015 |archive-url=https://web.archive.org/web/20150404014428/http://mil-embedded.com/article-id/?400= |archive-date=April 4, 2015 |url-status=dead}}</ref><ref name="NASAQ&A">{{cite web |title=Deep Impact: Mission Science Q&A |publisher=NASA |url=http://www.nasa.gov/mission_pages/deepimpact/launch/event_transcript5.html |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050911114930/http://www.nasa.gov/mission_pages/deepimpact/launch/event_transcript5.html |archive-date=September 11, 2005}}</ref> By observing the composition of the comet, astronomers hoped to determine how comets form based on the differences between the interior and exterior makeup of the comet.<ref name="NSSDC">{{cite web |title=Deep Impact/EPOXI |publisher=National Space Science Data Center |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2005-001A |access-date=May 11, 2009 }}</ref>

The mission's Principal Investigator was [[Michael A'Hearn]], an astronomer at the [[University of Maryland, College Park|University of Maryland]]. He led the science team, which included members from [[Cornell University]], University of Maryland, [[University of Arizona]], [[Brown University]], Belton Space Exploration Initiatives, [[JPL]], [[University of Hawaii]], [[Science Applications International Corporation|SAIC]], [[Ball Aerospace]], and [[Max-Planck-Institut für extraterrestrische Physik]].<ref>{{cite web|url=https://deepimpact.astro.umd.edu/science/bios/team.html|title=Deep Impact Science Team|publisher=University of Maryland|access-date=December 10, 2022}}</ref>

==Spacecraft design and instrumentation==
The [[spacecraft]] consists of two main sections, the {{convert|372|kg|lb|sp=us|adj=on}} copper-core "Smart Impactor" that impacted the comet, and the {{convert|601|kg|lb|abbr=on}} "Flyby" section, which imaged the comet from a safe distance during the encounter with Tempel 1.<ref name="presskit" /><ref name="NASADeepImpactOverview">{{cite web |publisher=NASA |url=http://www.nasa.gov/mission_pages/deepimpact/spacecraft/index.html |title=NASA – The Deep Impact Spacecraft |date=May 11, 2005 |access-date=November 4, 2014 |archive-date=October 26, 2013 |archive-url=https://web.archive.org/web/20131026011604/http://www.nasa.gov/mission_pages/deepimpact/spacecraft/index.html |url-status=dead }}</ref><ref name="NASAimpactor">{{cite news |last=Lovgren |first=Stefan |title=NASA Launches "Deep Impact" Craft for Comet Smash |work=[[National Geographic Society|National Geographic News]] |url=http://news.nationalgeographic.com/news/2005/01/0111_050111_deepimpact.html |archive-url=https://web.archive.org/web/20050115094300/http://news.nationalgeographic.com/news/2005/01/0111_050111_deepimpact.html |url-status=dead |archive-date=January 15, 2005 |date=January 12, 2005 |access-date=May 11, 2009}}</ref>

The Flyby spacecraft is about {{convert|3.3|m|ft|1|sp=us}} long, {{convert|1.7|m|ft|1|sp=us}} wide and {{convert|2.3|m|ft|1|sp=us}} high.<ref name="presskit" /><ref name="Milems"/> It includes a solar panel, a [[Whipple shield|Whipple debris shield]], and several science instruments for [[speckle imaging|imaging]], [[infrared spectroscopy]], and optical navigation to its destination near the comet.<ref>{{cite web |title=Deep Impact/EPOXI |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2005-001A |publisher=NASA |access-date=18 July 2025}}</ref> The spacecraft also carried two cameras, the High Resolution Imager (HRI), and the Medium Resolution Imager (MRI). The HRI is an imaging device that combines a visible-light camera with a filter wheel, and an imaging [[infrared]] [[spectrometer]] called the "Spectral Imaging Module" or SIM that operates on a spectral band from 1.05 to 4.8 micrometres. It has been optimized for observing the comet's nucleus. The MRI is the backup device, and was used primarily for navigation during the final 10-day approach. It also has a filter wheel, with a slightly different set of filters.<ref>{{cite web |title=Deep Impact: Technology: Instruments |url=https://deepimpact.astro.umd.edu/tech/instruments.html |website=deepimpact.astro.umd.edu |access-date=18 July 2025}}</ref><ref>{{cite web |title=Deep Impact: Technology: Instruments: MRI |url=https://deepimpact.astro.umd.edu/tech/mri.html |website=deepimpact.astro.umd.edu |access-date=18 July 2025}}</ref><ref>{{cite web |title=Deep Impact: Technology: Instruments: HRI |url=https://deepimpact.astro.umd.edu/tech/hri.html |website=deepimpact.astro.umd.edu |access-date=18 July 2025}}</ref>

The Impactor section of the spacecraft contains an instrument that is optically identical to the MRI, called the Impactor Targeting Sensor (ITS), but without the filter wheel. Its dual purpose was to sense the Impactor's trajectory, which could then be adjusted up to four times between release and impact, and to image the comet from close range. As the Impactor neared the comet's surface, this camera took high-resolution pictures of the nucleus (as good as {{convert|0.2|m|in|sp=us|disp=x| per [[pixel]] [|/px]}}) that were transmitted in real-time to the Flyby spacecraft before it and the Impactor were destroyed. The final image taken by the Impactor was snapped only 3.7 seconds before impact.<ref name="NASA2">{{cite web |title=Deep Impact: Technology: Instruments |publisher=Solar System Exploration |url=http://deepimpact.jpl.nasa.gov/tech/instruments.html |access-date=May 11, 2009}}</ref>

The Impactor's payload, dubbed the "Cratering Mass", was 100% copper, with a weight of 113&nbsp;kg.<ref>{{cite web |title=The Deep Impact Mission |url=https://www.eso.org/public/events/astro-evt/deepimpact/background/mission/ |website=www.eso.org |access-date=18 July 2025 |language=en}}</ref><ref name="NASA20">{{cite web |title=First Look Inside a Comet |publisher=NASA |url=http://www.nasa.gov/mission_pages/deepimpact/mission/index.html |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050907090910/http://www.nasa.gov/mission_pages/deepimpact/mission/index.html |archive-date=September 7, 2005}}</ref> Including this cratering mass, copper formed 49% of total mass of the Impactor (with aluminium at 24% of the total mass);<ref name="NASAImpactor">{{cite web |title=Deep Impact's Impactor |publisher=NASA |url=http://www.nasa.gov/mission_pages/deepimpact/spacecraft/impactor.html |access-date=November 4, 2014 |archive-date=June 23, 2016 |archive-url=https://web.archive.org/web/20160623220100/http://www.nasa.gov/mission_pages/deepimpact/spacecraft/impactor.html |url-status=dead }}</ref> this was to minimize interference with scientific measurements. Since copper was not expected to be found on a comet, scientists could ignore copper's signature in any spectrometer readings.<ref name="NASA20"/> Instead of using explosives, it was also cheaper to use copper as the payload.<ref name="NASAQ&A"/>

Explosives would also have been superfluous. At its closing velocity of 10.2&nbsp;km/s, the Impactor's kinetic energy was equivalent to 4.8 tonnes of TNT, considerably more than its actual mass of only 372&nbsp;kg.<ref name="NASAtelcom">{{cite web |title=Deep Impact Flyby and Impactor Telecommunications |publisher=NASA |url=http://descanso.jpl.nasa.gov/DPSummary/di_article_cmp20050922.pdf |access-date=June 16, 2014}}</ref>

<gallery mode=packed heights=200px>
Deep Impact diagram.png|Deep Impact diagram
Deep impact clean room.jpg|Deep Impact in a clean room
File:PIA02110.jpg|The Impactor
File:Deep Impact HRI tests.jpg|Cameras of the Flyby spacecraft, HRI at right, MRI at left
File:PIA07923_modest.jpg|Artist's concept of the impact on Tempel 1
</gallery>
{{Clear}}

==Mission profile==
[[File:Delta II 7925 (2925) rocket with Deep Impact.jpg|thumb|upright|''Deep Impact'' prior to launch on a [[Delta II]] rocket]]
Following its launch from [[Cape Canaveral Air Force Station]] pad [[Cape Canaveral Air Force Station Space Launch Complex 17|SLC-17B]] at 18:47 UTC on January 12, 2005,<ref name="SFN Over">{{cite web |author=Ray, Justin |title=Probe launched to smack heart of wandering comet |url=http://spaceflightnow.com/delta/d311 |publisher=Spaceflight Now |date=January 12, 2005 |access-date=June 9, 2014 |location=[[Cape Canaveral]], FL |archive-date=April 22, 2014 |archive-url=https://web.archive.org/web/20140422131644/http://spaceflightnow.com/delta/d311/ |url-status=dead }}</ref> the ''Deep Impact'' spacecraft traveled {{convert|429|e6km|e6mi|abbr=unit}} in 174 days to reach comet Tempel 1 at a cruising speed of {{convert|28.6|km/s|km/h mph|abbr=on}}.<ref name="Milems"/> Once the spacecraft reached the vicinity of the comet on July 3, 2005, it separated into the Impactor and Flyby sections. The Impactor used its thrusters to move into the path of the comet, impacting 24 hours later at a relative speed of {{convert|10.3|km/s|km/h mph|abbr=on}}.<ref name="Milems"/> The Impactor delivered {{Val|1.96|e=10|ul=joule}}s of [[kinetic energy]]—the equivalent of 4.7 [[ton]]s of [[Trinitrotoluene|TNT]]. Scientists believed that the energy of the high-velocity collision would be sufficient to excavate a crater up to {{convert|100|m|ft|abbr=on}} wide, larger than the bowl of the Roman [[Colosseum]].<ref name="Milems"/> The size of the crater was still not known one year after the impact.<ref name="NYTimes30"/>  The [[Stardust (spacecraft)|Stardust]] spacecraft [[Tempel 1#NExT mission|observed the impact site]] in 2011; it was determined that the crater's diameter is around {{convert|150|m|ft|sp=us}}.<ref>{{cite web |title=Stardust probe finds 'subdued' comet crater |work=BBC News |date=February 14, 2011 |url=https://www.bbc.com/news/science-environment-12433138 |publisher=BBC |access-date=18 July 2025}}</ref><ref>{{cite journal |last1=Schultz |first1=Peter H. |last2=Hermalyn |first2=Brendan |last3=Veverka |first3=Joe |title=The Deep Impact crater on 9P/Tempel-1 from Stardust-NExT |journal=Icarus |date=1 February 2013 |volume=222 |issue=2 |pages=502–515 |doi=10.1016/j.icarus.2012.06.018 |bibcode=2013Icar..222..502S |url=https://www.sciencedirect.com/science/article/abs/pii/S0019103512002473 |issn=0019-1035|url-access=subscription }}</ref>

Just minutes after the impact, the Flyby probe passed by the nucleus at a close distance of {{convert|500|km|mi|abbr=on}}, taking pictures of the crater position, the [[Ejecta|ejecta plume]], and the entire cometary nucleus. The entire event was also photographed by Earth-based telescopes and [[Space observatory|orbital observatories]], including ''[[Hubble Space Telescope|Hubble]]'', ''[[Chandra X-ray Observatory|Chandra]]'', ''[[Spitzer Space Telescope|Spitzer]]'', and ''[[XMM-Newton]]''. The impact was also observed by cameras and [[spectroscope]]s on board Europe's [[Rosetta spacecraft|''Rosetta'' spacecraft]], which was about {{convert|80|e6km|e6mi|abbr=unit}} from the comet at the time of impact. ''Rosetta'' determined the composition of the gas and [[cosmic dust|dust]] cloud that was kicked up by the impact.<ref name="ESA portal">{{cite web |publisher=ESA Portal |url=http://www.esa.int/esaCP/SEMCOZ1DU8E_index_0.html |title=Rosetta monitors Deep Impact |date=June 20, 2005 |access-date=May 11, 2009}}</ref>

==Mission events==
[[File:Animation of Deep Impact trajectory.gif|thumb|250px|Animation of ''Deep Impact''{{'s}} trajectory from January 12, 2005, to August 8, 2013<br /> {{legend2|magenta|''Deep Impact''}}{{·}}{{legend2|lime|[[Tempel 1]]}}{{·}}{{legend2|royalblue|[[Earth]]}}{{·}}{{legend2|cyan|[[103P/Hartley]]}}]]

===Before launch===
A comet-impact mission was first proposed to NASA in 1996, but at the time, NASA engineers were skeptical that the target could be hit.<ref name="NASA3">{{cite news |last=Delamere |first=Alan |title=Deep Impact: Mission: How Deep Impact got its name |publisher=Solar System Exploration |url=http://solarsystem.nasa.gov/deepimpact/mission/di-name.cfm |access-date=May 11, 2009}}</ref> In 1999, a revised and technologically upgraded mission proposal, dubbed ''Deep Impact'', was accepted and funded as part of NASA's [[Discovery Program]] of low-cost spacecraft. The two spacecraft (Impactor and Flyby) and the three main instruments were built and integrated by [[Ball Aerospace & Technologies]]<ref name="Ball">{{cite web |title=Deep Impact |publisher=Ball Aerospace & Technologies Corp. |url=http://www.ballaerospace.com/page.jsp?page=60 |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090301053550/http://www.ballaerospace.com/page.jsp?page=60 |archive-date=March 1, 2009 }}</ref> in [[Boulder, Colorado]]. Developing the software for the spacecraft took 18 months and the application code consisted of 20,000 lines and 19 different application threads.<ref name="Milems"/> The total cost of developing the spacecraft and completing its mission reached {{US$|330 million}}.<ref name="CNNDI"/>

===Launch and commissioning phase===
The probe was originally scheduled for launch on December 30, 2004, but NASA officials delayed its launch, in order to allow more time for testing the software.<ref name="SpaceFlightNow">{{cite news |last=Ray |first=Justin |title=Rocket trouble stalls launch of Deep Impact mission |publisher=Spaceflight Now |url=http://spaceflightnow.com/delta/d311/041214delay.html |date=December 14, 2004 |access-date=May 11, 2009 |archive-date=February 7, 2009 |archive-url=https://web.archive.org/web/20090207094504/http://spaceflightnow.com/delta/d311/041214delay.html |url-status=dead }}</ref> It was successfully launched from [[Cape Canaveral]] on January 12, 2005, at 1:47&nbsp;pm EST (1847 UTC) by a [[Delta II]] rocket.<ref name="Boeing">{{cite web |title=Boeing Launches NASA Deep Impact Spacecraft to Intercept Comet Tempel 1 |publisher=Boeing Image Gallery |url=http://www.boeing.com/companyoffices/gallery/images/space/delta_ii/delta2_impact.htm |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090302013706/http://www.boeing.com/companyoffices/gallery/images/space/delta_ii/delta2_impact.htm |archive-date=March 2, 2009 }}</ref>

''Deep Impact''{{'s}} state of health was uncertain during the first day after launch. Shortly after entering orbit around the Sun and deploying its solar panels, the probe switched itself to [[Safe mode (spacecraft)|safe mode]]. The cause of the problem was simply an incorrect temperature limit in the fault protection logic for the spacecraft's [[reaction control system|RCS thruster]] catalyst beds. The spacecraft's thrusters were used to detumble the spacecraft following third stage separation. On January 13, 2005, NASA announced that the probe was out of safe mode and healthy.<ref name="NASA4">{{cite news |last=Agle |first=D.C. |title=Deep Impact Status Report |publisher=Jet Propulsion Laboratory |url=http://www.nasa.gov/mission_pages/deepimpact/media/2005-016.html |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050911112241/http://www.nasa.gov/mission_pages/deepimpact/media/2005-016.html |archive-date=September 11, 2005}}</ref>

On February 11, 2005, ''Deep Impact''{{'s}} rockets were fired as planned to correct the spacecraft's course. This correction was so precise that the next planned correction maneuver on March 31, 2005, was unnecessary and canceled. The "commissioning phase" verified that all instruments were activated and checked out. During these tests it was found that the HRI images were not in focus after it underwent a [[bake-out]] period.<ref name="Spaceflight Now">{{cite news |last=Ray |first=Justin |title=Deep Impact's comet-watching telescope is blurred |publisher=Spaceflight Now |url=http://www.spaceflightnow.com/news/n0503/25deepimpact/ |date=March 25, 2005 |access-date=May 11, 2009}}</ref> After mission members investigated the problem, on June 9, 2005, it was announced that by using image processing software and the mathematical technique of [[Deconvolution#Optics and other imaging|deconvolution]], the HRI images could be corrected to restore much of the resolution anticipated.<ref name="Space">{{cite news |last=Than |first=Ker |title=Deep Impact Team Solves Blurry Photo Problem |work=Space.com |url=http://www.space.com/missionlaunches/050609_impact_camera.html |date=June 9, 2005 |access-date=May 11, 2009}}</ref>

===Cruise phase===
[[File:Deep Impact Animation JPL-540-MASTER high.webm|thumb|A conceptualized view of the impact, beginning with the Deep Impact spacecraft releasing a probe into the path of comet Tempel 1.]]

The "cruise phase" began on March 25, 2005, immediately after the commissioning phase was completed. This phase continued until about 60 days before the encounter with comet Tempel 1. On April 25, 2005, the probe acquired the first image of its target at a distance of {{convert|64|e6km|e6mi|abbr=unit}}.<ref name="JPL1">{{cite news |last1=Beasley |first1=Dolores |first2=Erica |last2=Hupp |first3=D.C. |last3=Agle |title=NASA's Deep Impact Spacecraft Spots Its Quarry, Stalking Begins |publisher=Jet Propulsion Laboratory |url=http://nssdc.gsfc.nasa.gov/planetary/text/di_pr_20050427.txt |date=April 27, 2005 |access-date=May 11, 2009}}</ref>

On May 4, 2005, the spacecraft executed its second trajectory correction maneuver. Burning its rocket engine for 95 seconds, the spacecraft speed was changed by {{convert|18.2|km/h|mph|abbr=on}}.<ref name="Spaceref">{{cite press release |title=Deep Impact Mission Status Report |url=https://deepimpact.astro.umd.edu/press/050513jpl.html |publisher=[[JPL]] and [[University of Maryland]] |access-date=23 October 2023 |archive-url=https://web.archive.org/web/20210228163136/https://deepimpact.astro.umd.edu/press/050513jpl.html |archive-date=28 February 2021 |date=13 May 2005 |url-status=live |id=2005-074 }}</ref> Rick Grammier, the project manager for the mission at NASA's Jet Propulsion Laboratory, reacted to the maneuver stating that "spacecraft performance has been excellent, and this burn was no different... it was a textbook maneuver that placed us right on the money."<ref name="Spaceref"/>

===Approach phase===
The approach phase extended from 60 days before encounter (May 5, 2005) until five days before encounter. Sixty days out was the earliest time that the ''Deep Impact'' spacecraft was expected to detect the comet with its MRI camera.<ref name="presskit"/> In fact, the comet was spotted ahead of schedule, 69 days before impact (see [[#Cruise phase|Cruise phase]] above). On June 14 and 22, 2005, ''Deep Impact'' observed two outbursts of activity from the comet, the latter being six times larger than the former.<ref name="JPL2">{{cite web |title=NASA's Deep Impact Craft Observes Major Comet "Outburst" |publisher=Jet Propulsion Laboratory |url=http://deepimpact.jpl.nasa.gov/press/050628jpl.html |date=June 28, 2005 |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20060207083425/http://deepimpact.jpl.nasa.gov/press/050628jpl.html |archive-date=February 7, 2006}}</ref> The spacecraft studied the images of various distant stars to determine its current trajectory and position.<ref name="Milems"/> {{ill|Donald Yeomans|nl|Donald K. Yeomans|lt=Don Yeomans}}, a mission co-investigator for JPL pointed out that "it takes 7½ minutes for the signal to get back to Earth, so you cannot joystick this thing. You have to rely on the fact that the Impactor is a smart spacecraft as is the Flyby spacecraft. So you have to build in the intelligence ahead of time and let it do its thing."<ref name="SpaceBull">{{cite news |last=Duignan-Cabrera |first=Anthony |title=Bullseye: Deep Impact Slams Into Comet |work=Space.com |url=http://www.space.com/missionlaunches/050704_deepimpact_success.html |date=July 4, 2005 |access-date=May 11, 2009}}</ref> On June 23, 2005, the first of the two final trajectory correction maneuvers (targeting maneuver) was successfully executed. A {{convert|13|mi/h|m/s|abbr=on}} velocity change was needed to adjust the flight path towards the comet and target the Impactor at a window in space about {{convert|100|km|mi|sp=us}} wide.<ref>{{cite web |title=Deep Impact: Press: Press Release: 2005-07-01: NASA's Deep Impact Spacecraft Preps for July 4 Fireworks |url=https://deepimpact.astro.umd.edu/press/050701nasa.html |website=deepimpact.astro.umd.edu |access-date=26 August 2025}}</ref><ref>{{cite web |title=Deep Impact: Press: Press Release: 2005-07-03: Deep Impact Status Report |url=https://deepimpact.astro.umd.edu/press/050703jpl.html |website=deepimpact.astro.umd.edu |access-date=26 August 2025}}</ref>

<gallery class="center">
File:PIA07879.jpg|Tempel 1 imaged on April 25, 2005
File:DI_MRI_T1_doy150.jpg|May 30, 2005, 35 days from impact
File:PIA03297.jpg|June 15, 19 days from impact
File:PIA02101.jpg|June 21, 13 days from impact
File:DI_MRI_log_T1_doy178.jpg|June 27, 7 days from impact, near end of approach phase
</gallery>

===Impact phase===
[[File:Deep Impact encounter sequence.png|thumb|''Deep Impact'' comet encounter sequence]]
Impact phase began nominally on June 29, 2005, five days before impact. The Impactor successfully separated from the Flyby spacecraft on July 3 at 6:00 UTC (6:07 UTC [[Earth-received time|ERT]]).<ref name="Deep Impact Home">{{cite web |title=Deep Impact: A Smashing Success |publisher=Deep Impact homepage |url=http://www.nasa.gov/mission_pages/deepimpact/main/index.html |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050713055939/http://www.nasa.gov/mission_pages/deepimpact/main/index.html |archive-date=July 13, 2005}}</ref><ref name="Bloomberg">{{cite news |last=Dolmetsch |first=Chris |title=Deep Impact Launches Projectile to Blow Hole in Comet (Update1) |publisher=Bloomberg |url=https://www.bloomberg.com/apps/news?pid=10000103&sid=a7aFRLrijlBM&refer=us |date=July 3, 2005 |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20050911024350/http://www.bloomberg.com/apps/news?pid=10000103&sid=a7aFRLrijlBM&refer=us |archive-date=September 11, 2005 }}</ref> The first images from the instrumented Impactor were seen two hours after separation.<ref name="DICE">{{cite web |title=Design, Development, and Operations of the Big Event at Tempel 1 |publisher=Deep Impact Comet Encounter |url=http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38045/1/05-3268.pdf |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090326020647/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38045/1/05-3268.pdf |archive-date=March 26, 2009 }}</ref>

The Flyby spacecraft performed one of two divert maneuvers to avoid damage. A 14-minute burn was executed which slowed down the spacecraft. It was also reported that the communication link between the Flyby and the Impactor was functioning as expected.<ref name="NASA4"/> The Impactor executed three correction maneuvers in the final two hours before impact.<ref name="NASA5">{{cite web |title=A Cyber-Astronaut's Final Moves |publisher=NASA |url=http://www.nasa.gov/mission_pages/deepimpact/multimedia/SHYAM.html |date=July 4, 2005 |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050911023113/http://www.nasa.gov/mission_pages/deepimpact/multimedia/SHYAM.html |archive-date=September 11, 2005}}</ref>

The Impactor was maneuvered to plant itself in front of the comet, so that Tempel 1 would collide with it.<ref name="NASAQ&A"/> Impact occurred at 05:45 UTC (05:52 UTC [[Earth-received time|ERT]], +/− up to three minutes, one-way light time = 7m 26s) on the morning of July 4, 2005.<ref>{{cite web |title=Impact Phase Timeline |url=http://www.nasa.gov/mission_pages/deepimpact/timeline/index.html |archive-url=https://web.archive.org/web/20150602052326/http://www.nasa.gov/mission_pages/deepimpact/timeline/index.html |archive-date=June 2, 2015 |publisher=NASA}}</ref>

The impactor returned images as late as three seconds before impact. Most of the data captured was stored on board the Flyby spacecraft, which radioed approximately 4,500 images from the HRI, MRI, and ITS cameras to Earth over the next few days.<ref name="BBC1">{{cite news |title=NASA probe strikes Comet 9P/Tempel |work=BBC News |url=http://news.bbc.co.uk/1/hi/sci/tech/4647673.stm |date=July 4, 2005 |access-date=May 11, 2009}}</ref><ref name="NASA6">{{cite web |title=NASA's Deep Impact Tells a Tale of the Comet |publisher=NASA |url=http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact-070805.html |date=July 8, 2005 |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050911024426/http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact-070805.html |archive-date=September 11, 2005}}</ref> The energy from the collision was similar in size to exploding five tons of [[dynamite]] and the comet shone six times brighter than normal.<ref name="Wired">{{cite news |agency=Associated Press |title=Deep Impact Scores Bull's-Eye |magazine=[[Wired (magazine)|Wired]] |url=https://www.wired.com/science/space/news/2005/07/68085 |date=July 4, 2005 |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090207151728/http://www.wired.com/science/space/news/2005/07/68085 |archive-date=February 7, 2009 }}</ref>

<gallery class="center">
File:PIA02112.jpg|Comet [[Tempel 1]], imaged from 4.2&nbsp;million km at the start of Impact phase
File:DI_MRI_Impactor_-24hr.jpg|Impactor imaged by Flyby spacecraft shortly after separation
File:Tempel_Impactor_150Km.jpg|Image from Impactor
File:Deep_Impact_Impactor_3.jpg|Impactor close-up image, taken shortly before impact
File:Deep Impact approach 2.jpg|The moment of impact, as shown on [[NASA TV]]
File:Impact of comet Tempel 1 into Deep Impact's probe (HRI film of resulting flash).gif|HRI movie of impact
File:HRIV Impact.gif|High Resolution Instrument, Visual CCD (HRIV) during encounter (video)
File:ITS Impact.gif|Impactor Targeting Sensor, Visual CCD (ITS) during encounter (video)
</gallery>

==Results==
[[File:Deep Impact celebration.jpg|thumb|left|Mission team members celebrate after the impact with the comet.]]

Mission control did not become aware of the Impactor's success until five minutes later at 05:57 [[UTC]].<ref name="CNNDI">{{cite news |last=Mihelich |first=Cindy |title=Deep Impact probe hits comet |publisher=CNN |url=http://www.cnn.com/2005/TECH/space/07/04/deep.impact/index.html |date=July 4, 2005 |access-date=May 11, 2009}}</ref> Don Yeomans confirmed the results for the press, "We hit it just exactly where we wanted to"<ref name="NewRussia">{{cite news |title=NASA is sued for Deep Impact probe |publisher=NewsFromRussia |url=http://newsfromrussia.com/society/2005/07/04/60510.html |date=July 4, 2005 |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20080516100511/http://newsfromrussia.com/society/2005/07/04/60510.html |archive-date=May 16, 2008 |url-status=dead}}</ref> and JPL Director [[Charles Elachi]] stated "The success exceeded our expectations."<ref name="CriEnglish">{{cite news |last=Kridler |first=Chris |title=NASA Hails a Direct Hit on Comet |work=CriEnglish.com |url=http://english.cri.cn/2239/2005-7-8/88@254989.htm |archive-url=https://archive.today/20130115233439/http://english.cri.cn/2239/2005-7-8/88@254989.htm |url-status=dead |archive-date=January 15, 2013 |date=July 8, 2005 |access-date=May 11, 2009}}</ref>

In the post-impact briefing on July 4, 2005, at 08:00 UTC, the first processed images revealed existing [[Impact crater|craters]] on the comet. NASA scientists stated they could not see the new crater that had formed from the Impactor, but it was later discovered to be about 100&nbsp;meters wide and up to {{convert|30|m|ft|sp=us}} deep.<ref name="NewScientist"/> Lucy McFadden, one of the co-investigators of the impact, stated "We didn't expect the success of one part of the mission [bright dust cloud] to affect a second part [seeing the resultant crater]. But that is part of the fun of science, to meet with the unexpected."<ref name="MissResults">{{cite web |title=Mission Results: Excavating Comet 9P/Tempel |publisher=NASA |url=http://solarsystem.nasa.gov/deepimpact/results/excavating.cfm |access-date=May 11, 2009}}</ref> Analysis of data from the [[Swift Gamma-Ray Burst Mission|''Swift'' X-ray telescope]] showed that the comet continued outgassing from the impact for 13 days, with a peak five days after impact. A total of {{convert|5|e6kg|e6lb|abbr=unit}} of water<ref name="BBC News">{{cite news |last=Amos |first=Jonathan |title=Impactor ejects mighty water mass |work=BBC News |url=http://news.bbc.co.uk/2/hi/science/nature/4871934.stm |date=April 4, 2006 |access-date=May 11, 2009}}</ref> and between {{convert|10|and|25|e6kg|e6lb|abbr=unit}} of dust were lost from the impact.<ref name="NewScientist">{{cite news |last=McKee |first=Maggie |title=Deep Impact collision ejected the stuff of life |publisher=NewScientist.com |url=https://www.newscientist.com/article.ns?id=dn7961 |date=September 7, 2005 |access-date=May 11, 2009}}</ref>

Initial results were surprising as the material excavated by the impact contained more dust and less ice than had been expected. The only models of cometary structure astronomers could positively rule out were the very porous ones which had comets as loose aggregates of material. In addition, the material was finer than expected; scientists compared it to [[talcum powder]] rather than [[sand]].<ref name="VPNews">{{cite web |title=A Deep Cometary Impact |publisher=vigyanprasar |url=http://www.vigyanprasar.gov.in/dream/jan2006/English.pdf |page=5 |date=January 2006 |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090326020648/http://www.vigyanprasar.gov.in/dream/jan2006/English.pdf |archive-date=March 26, 2009 }}</ref> Other materials found while studying the impact included [[clay]]s, [[carbonate]]s, [[sodium]], and crystalline [[silicate]]s which were found by studying the spectroscopy of the impact.<ref name="NYTimes30">{{cite news |last=Chang |first=Kenneth |work=The New York Times |title=Composition of a Comet Poses a Puzzle for Scientists |url=https://www.nytimes.com/2005/09/07/science/07comet.html?ex=1183867200&en=0a4d2e3f70107d4f&ei=5070 |date=September 7, 2005 |access-date=May 11, 2009}}</ref> Clays and carbonates usually require liquid water to form and sodium is rare in space.<ref name="AstroBiology.com">{{cite news |title=Astrobiology.com |publisher=Scientists Gaining Clearer Picture of Comet Makeup and Origin |url=http://www.astrobiology.com/news/viewpr.html?pid=20339 |archive-url=https://archive.today/20130102020614/http://www.astrobiology.com/news/viewpr.html?pid=20339 |url-status=dead |archive-date=January 2, 2013 |date=July 14, 2006 |access-date=May 11, 2009}}</ref> Observations also revealed that the comet was about 75% empty space, and one astronomer compared the outer layers of the comet to the same makeup of a snow bank.<ref name="NYTimes30"/> Astronomers have expressed interest in more missions to different comets to determine if they share similar compositions or if there are different materials found deeper within comets that were produced at the time of the Solar System's formation.<ref name="C&EN">{{cite news |last=Jacoby |first=Mitch |title=A Comet's Chemical Composition |publisher=C&EN |url=http://pubs.acs.org/cen/news/84/i29/8429notw1.html |date=July 17, 2006 |access-date=May 11, 2009}}</ref>

[[File:DeepImpactTempelCrater.jpg|thumb|'Before and after' comparison images from ''Deep Impact'' and ''Stardust'', showing the crater formed by ''Deep Impact'' on the right hand image]]

Astronomers hypothesized, based on its interior chemistry, that the comet formed in the [[Uranus]] and [[Neptune]] [[Oort cloud]] region of the Solar System. A comet which forms farther from the Sun is expected to have greater amounts of ices with low freezing temperatures, such as [[ethane]], which was present in Tempel 1. Astronomers believe that other comets with compositions similar to Tempel 1 are likely to have formed in the same region.<ref>{{cite news |title=Comet Tempel-1 May Have Formed in Giant Planets Region |publisher=SpaceRef.com |url=http://www.spaceref.com/news/viewpr.html?pid=17842 |date=September 19, 2005 |access-date=May 11, 2009 |archive-date=June 6, 2020 |archive-url=https://web.archive.org/web/20200606002833/http://www.spaceref.com/news/viewpr.html?pid=17842 |url-status=dead }}</ref>

===Crater===
Because the quality of the images of the crater formed during the ''Deep Impact'' collision was not satisfactory, on July 3, 2007, NASA approved the New Exploration of Tempel 1 (or NExT) mission. The mission utilized the already existing [[Stardust (spacecraft)|''Stardust'' spacecraft]], which had studied [[Comet Wild 2]] in 2004. ''Stardust'' was placed into a new orbit so that it passed by Tempel 1 at a distance of approximately {{convert|200|km|mi|abbr=on}} on February 15, 2011, at 04:42 UTC.<ref>{{cite web |title=Stardust NExT: Status Report 2009 |url=http://stardustnext.jpl.nasa.gov/mission/mission_status10_q1.html |access-date=February 26, 2010 |archive-date=February 9, 2010 |archive-url=https://web.archive.org/web/20100209003011/http://stardustnext.jpl.nasa.gov/mission/mission_status10_q1.html |url-status=dead }}</ref> This was the first time that a comet was visited by two probes on separate occasions ([[1P/Halley]] had been visited by several probes within a few weeks in 1986), and it provided an opportunity to better observe the crater that was created by ''Deep Impact'' as well as observing the changes caused by the comet's latest close approach to the Sun.<ref>{{cite web |url=https://www.jpl.nasa.gov/missions/stardust/ |title=Stardust |publisher=JPL |quote=The Stardust spacecraft, which had been recycled for a second mission called Stardust-NExT, flew by comet Tempel 1, marking the first time a comet had been visited twice by any spacecraft.}}</ref>

On February 15, NASA scientists identified the crater formed by ''Deep Impact'' in images from ''Stardust''. The crater is estimated to be {{convert|150|m|ft|sp=us}} in diameter, and has a bright mound in the center likely created when material from the impact fell back into the crater.<ref>{{cite web |url=http://www.nasa.gov/mission_pages/stardust/multimedia/Schultz4.html |title=Tempel 1 Impact Site |publisher=NASA |date=February 18, 2011 |access-date=April 5, 2012 |archive-url=https://web.archive.org/web/20110629031530/http://www.nasa.gov/mission_pages/stardust/multimedia/Schultz4.html |archive-date=June 29, 2011}}</ref>

==Public interest==
The mission coincidentally shared its name with the 1998 film, ''[[Deep Impact (film)|Deep Impact]]'', in which a comet strikes the Earth.<ref name="ABCNews2">{{cite news |agency=[[Associated Press]] |work=[[ABC News (United States)|ABC News]] |title=NASA's Deep Impact Spacecraft Blasts Off |url=https://abcnews.go.com/US/wireStory?id=410785&CMP=OTC-RSSFeeds0312 |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050426170803/https://abcnews.go.com/US/wireStory?id=410785&CMP=OTC-RSSFeeds0312 |archive-date=April 26, 2005}}</ref>

===Media coverage===
[[File:Deep Impact HRI.jpeg|thumb|The image of the impact which was widely circulated in the media]]
The impact was a substantial news event reported and discussed online, in print, and on television. There was a genuine suspense because experts held widely differing opinions over the result of the impact. Various experts debated whether the Impactor would go straight through the comet and out the other side, would create an impact crater, would open up a hole in the interior of the comet, and other theories. However, twenty-four hours before impact, the flight team at JPL began privately expressing a high level of confidence that, barring any unforeseen technical glitches, the spacecraft would intercept Tempel 1. One senior personnel member stated "All we can do now is sit back and wait. Everything we can technically do to ensure impact has been done." In the final minutes as the Impactor hit the comet, more than 10,000 people watched the collision on a giant movie screen at Hawaii's [[Waikīkī Beach]].<ref name="Wired"/>

Experts came up with a range of soundbites to summarize the mission to the public. Iwan Williams of [[Queen Mary University of London]], said "It was like a mosquito hitting a [[Boeing 747|747]]. What we've found is that the mosquito didn't splat on the surface; it's actually gone through the windscreen."<ref name="BBCNews3">{{cite news |title=Nasa probe strikes Comet Tempel 1 |work=BBC News |url=http://news.bbc.co.uk/2/hi/science/nature/4647673.stm |date=July 4, 2005 |access-date=May 11, 2009}}</ref>

One day after the impact, Marina Bay, a Russian [[astrologer]], sued NASA for {{US$|300 million}} for having "ruin[ed] the natural balance of forces in the universe."<ref name="MSNBCRussia">{{cite news |agency=Associated Press |title=Astrologer's comet lawsuit lingers |work=[[NBC News]] |url=https://www.nbcnews.com/id/wbna8474735 |date=July 5, 2005 |access-date=May 11, 2009}}</ref> Her lawyer asked the public to volunteer to help in the claim by declaring "The impact changed the magnetic properties of the comet, and this could have affected mobile telephony here on Earth. If your phone went down this morning, ask yourself Why? and then get in touch with us."<ref name="BBCNews17">{{cite news |last=Liss |first=Artyom |title=Russian sues Nasa for comet upset |work=BBC News |url=http://news.bbc.co.uk/2/hi/europe/4649987.stm |date=July 4, 2005 |access-date=May 11, 2009}}</ref> On August 9, 2005, the Presnensky Court of Moscow ruled against Bay, although she did attempt to appeal the result. One Russian physicist said that the impact had no effect on Earth and "the change to the orbit of the comet after the collision was only about 10&nbsp;cm (3.9&nbsp;in)."<ref name="MosNews">{{cite news |title=Court Rejects Russian Astrologer's Lawsuit Against NASA |publisher=MosNews.com |url=http://www.mosnews.com/news/2005/11/08/marinabai.shtml |date=August 11, 2005 |access-date=May 11, 2009 |archive-url=https://archive.today/20070521082005/http://www.mosnews.com/news/2005/11/08/marinabai.shtml |archive-date=May 21, 2007 |url-status=usurped }}</ref>

===Send Your Name To A Comet campaign===
[[File:Send Your Name to a Comet CD on Deep Impact.jpg|thumb|left|The CD containing the 625,000 names is added to the Impactor]]
[[File:Deep Impact Discovery Mission to Comet Tempel 1.PNG|thumb|right|''Deep Impact'' participation certificate of Mathias Rex]]
The mission was notable for one of its promotional campaigns, "Send Your Name To A Comet!". Visitors to the [[Jet Propulsion Laboratory]]'s website were invited to submit their name between May 2003 and January 2004, and the names gathered—some 625,000 in all—were then burnt onto a mini-CD, which was attached to the Impactor.<ref name="NASA7">{{cite web |title=Send Your Name To A Comet |publisher=NASA |url=http://deepimpact.umd.edu/sendyourname/ |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20080724203405/http://deepimpact.umd.edu/sendyourname/ |archive-date=July 24, 2008 }}</ref> Dr. Don Yeomans, a member of the spacecraft's scientific team, stated "this is an opportunity to become part of an extraordinary space mission&nbsp;... when the craft is launched in December 2004, yours and the names of your loved-ones can hitch along for the ride and be part of what may be the best space fireworks show in history."<ref name="NASA8">{{cite news |title=Your Name Could Make a 'Deep Impact' on a Comet |publisher=NASA |url=http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact-050904.html |date=May 9, 2003 |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20061004215357/http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact-050904.html |archive-date=October 4, 2006}}</ref> The idea was credited with driving interest in the mission.<ref name="Space.com2">{{cite news |last=Carey |first=Bjorn |title=625,000 names to be vaporised in Deep Impact |work=Space.com |url=http://www.space.com/businesstechnology/050630_deep_impact_CDs.html |date=June 30, 2005 |access-date=May 11, 2009}}</ref>

===Reaction from China===
Chinese researchers used the ''Deep Impact'' mission as an opportunity to highlight the efficiency of American science because public support ensured the possibility of funding long-term research. By contrast, "in China, the public usually has no idea what our scientists are doing, and limited funding for the promotion of science weakens people's enthusiasm for research."<ref name="xinhuanet">{{cite news|date=July 5, 2005|title=Deep impact for Chinese scientists|publisher=China.org.cn|url=http://www.china.org.cn/english/2005/Jul/134075.htm|url-status=live|access-date=September 15, 2021|archive-url=https://web.archive.org/web/20050708012803/http://www.china.org.cn/english/2005/Jul/134075.htm|archive-date=July 8, 2005}}</ref>

Two days after the US mission succeeded in having a probe collide with a comet, China revealed a plan: landing a probe on a small comet or [[asteroid]] to push it off course.  China said it would begin the mission after sending a probe to the [[Moon]].<ref name="EconTimes">{{cite web |agency=[[Reuters]] |title=After US, China plans "Deep Impact" mission |work=The Economic Times |url=http://economictimes.indiatimes.com/articleshow/1163067.cms |date=July 7, 2005 |access-date=May 11, 2009 |archive-url=https://web.archive.org/web/20050830003558/http://economictimes.indiatimes.com/articleshow/1163067.cms |archive-date=August 30, 2005}}</ref>

===Contributions from amateur astronomers===
Since observing time on large, professional [[telescopes]] such as [[W. M. Keck Observatory|Keck]] or ''Hubble'' is always scarce, the ''Deep&nbsp;Impact'' scientists called upon "advanced amateur, student, and professional [[astronomer]]s" to use small telescopes to make long-term observations of the target comet before and after impact. The purpose of these observations was to look for "volatile outgassing, dust coma development and dust production rates, dust tail development, and jet activity and outbursts."<ref name="AOP">{{cite web |title=Advanced Guide |publisher=Amateur Observers' Program |url=http://dawn-aop.astro.umd.edu/advanced/sec4.shtml |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090515104316/http://dawn-aop.astro.umd.edu/advanced/sec4.shtml |archive-date=May 15, 2009 }}</ref> By mid-2007, amateur astronomers had submitted over a thousand [[Charge-coupled device|CCD]] images of the comet.<ref name="STSP">{{cite web |title=Welcome to the Deep Impact Mission's Small Telescope Science Program |publisher=Small Science Telescope Program |url=http://stsp.astro.umd.edu/ |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090516044616/http://stsp.astro.umd.edu/ |archive-date=May 16, 2009 }}</ref>

One notable amateur observation was by students from schools in Hawaii, working with US and UK scientists, who during the press conference took live images using the [[Faulkes Telescope North|Faulkes Automatic Telescope]] in Hawaii (the students operated the telescope over the Internet) and were one of the first groups to get images of the impact. One amateur astronomer reported seeing a structureless bright cloud around the comet, and an estimated 2&nbsp;[[Apparent magnitude|magnitude]] increase in brightness after the impact.<ref name="Google Groups">{{cite web |title=Deep Impact/Tempel 1 Observation |publisher=Google Groups |url=http://groups.google.com.au/group/sci.astro.amateur/browse_thread/thread/e62afbef29b10d9e/49eb86190c68f9c1?hl=en#49eb86190c68f9c1 |access-date=May 11, 2009 |archive-date=February 7, 2009 |archive-url=https://web.archive.org/web/20090207100024/http://groups.google.com.au/group/sci.astro.amateur/browse_thread/thread/e62afbef29b10d9e/49eb86190c68f9c1?hl=en#49eb86190c68f9c1 |url-status=dead }}</ref> Amateur astronomer Jost Jahn published a map of the crash area from NASA images.<ref name="Jost Jahn">{{cite web |title=My Deep Impact |publisher=Jost Jahn |url=http://www.jostjahn.de/di.html |access-date=May 11, 2009}}</ref>

===Musical tribute===
The ''Deep Impact'' mission coincided with celebrations in the Los Angeles area marking the 50th&nbsp;anniversary of "[[Rock Around the Clock]]" by [[Bill Haley & His Comets]] becoming the first [[rock and roll]] single to reach No.&nbsp;1 on the recording sales charts. Within 24&nbsp;hours of the mission's success, a 2-minute music video produced by [[Martin Lewis (humorist)|Martin Lewis]] had been created using images of the impact itself combined with computer animation of the ''Deep Impact'' probe in flight, interspersed with footage of Bill Haley & His Comets performing in 1955 and the surviving original members of The Comets performing in March 2005.<ref name="Extra">{{cite web |title=Clockathon rocks Hollywood, NASA |publisher=Reviews & News about Bill Haley and The Comets |url=http://www.rockabillyhall.com/Extra3.html#clockathon2 |access-date=July 5, 2013 |archive-date=February 18, 2021 |archive-url=https://web.archive.org/web/20210218131000/http://www.rockabillyhall.com/Extra3.html#clockathon2 |url-status=dead }}</ref>

On July 5, 2005, the surviving original members of The Comets (ranging in age from 71&ndash;84) performed a free concert for hundreds of employees of the Jet Propulsion Laboratory to help them celebrate the mission's success. This event received worldwide press attention.<ref name="USAToday">{{cite news |agency=Associated Press |title=The Comets rock for NASA scientists |work=USA Today |url=https://www.usatoday.com/life/music/news/2005-07-06-comets-rock-nasa_x.htm?csp=34 |access-date=May 11, 2009 |date=July 6, 2005}}</ref> In February 2006, the [[International Astronomical Union]] citation that officially named asteroid [[79896 Billhaley]] included a reference to the JPL concert.<ref name="Klet Observatory">{{cite web |title=Comet Billhaley |work=Klet Observatory |url=http://www.klet.org/names/view.php3?astnum=79896 |access-date=May 11, 2009 |archive-date=February 2, 2021 |archive-url=https://web.archive.org/web/20210202203101/http://www.klet.org/names/view.php3?astnum=79896 |url-status=dead }}</ref>

==Extended mission==
{{main|EPOXI}}
''Deep Impact'' embarked on an extended mission designated EPOXI (Extrasolar Planet Observation and ''Deep Impact'' Extended Investigation) to visit other comets, after being put to sleep in 2005 upon completion of the Tempel 1 mission.<ref name="snhartley">{{cite news|url=https://spacenews.com/deep-impacts-latest-comet-flyby-yields-plenty-surprises/ |title=Deep Impact's Latest Comet Flyby Yields Plenty of Surprises|first=Mike |last=Wall|date=November 8, 2010|publisher=[[Space News]]|access-date=December 10, 2022}}</ref>

===Comet Boethin plan===
Its first extended visit was to do a flyby of [[85D/Boethin|Comet Boethin]], but with some complications. On July 21, 2005, ''Deep Impact'' executed a trajectory correction maneuver that allows the spacecraft to use Earth's gravity to begin a new mission in a path towards another comet.<ref name="SDaily3">{{cite web |title=Deep Impact Mission: Aiming For Close-ups Of Extrasolar Planets |website=Science Daily |url=https://www.sciencedaily.com/releases/2007/04/070410120957.htm |date=April 11, 2007 |access-date=May 11, 2009}}</ref>

The original plan was for a December 5, 2008, flyby of Comet Boethin, coming within {{convert|700|km|mi|sp=us}} of the comet. Michael A'Hearn, the ''Deep Impact'' team leader, explained "We propose to direct the spacecraft for a flyby of Comet Boethin to investigate whether the results found at Comet Tempel 1 are unique or are also found on other comets."<ref name="Skymania News">{{cite news |last=Sutherland |first=Paul |title=Deep Impact will fly to new comet |publisher=Skymania News |url=http://skymania.com/wp/2006/11/deep-impact-will-fly-to-new-comet.html |date=November 3, 2006 |access-date=May 11, 2009 |archive-date=December 14, 2014 |archive-url=https://web.archive.org/web/20141214171554/http://www.skymania.com/wp/2006/11/deep-impact-will-fly-to-new-comet.html/ |url-status=dead }}</ref> The $40&nbsp;million mission would provide about half of the information as the collision of Tempel 1 but at a fraction of the cost.<ref name="Skymania News"/><ref name="40Fox">{{cite news |agency=Associated Press |title=Space Probe Slingshots Around Earth On Way to Comet |publisher=Fox News |url=https://www.foxnews.com/story/space-probe-slingshots-around-earth-on-way-to-comet |date=January 2, 2008 |access-date=November 3, 2009 |archive-url=https://web.archive.org/web/20091128153539/http://www.foxnews.com/story/0,2933,319431,00.html |archive-date=November 28, 2009 |url-status=live |df=mdy-all }}</ref> ''Deep Impact'' would use its spectrometer to study the comet's surface composition and its telescope for viewing the surface features.<ref name="SDaily3"/>

However, as the December 2007 Earth [[gravity assist]] approached, astronomers were unable to locate Comet Boethin, which may have broken up into pieces too faint to be observed. Consequently, its orbit could not be calculated with sufficient precision to permit a flyby.<ref name="EPOXIMissionStatus"/>

===Flyby of Comet Hartley 2===
[[File:Tempel 1 and Hartley 2.jpg|thumb|upright=1.6|Comets Tempel 1 and Hartley 2]]
In November 2007 the JPL team targeted ''Deep Impact'' toward Comet [[103P/Hartley|Hartley 2]]. However, this would require an extra two years of travel for ''Deep Impact'' (including earth gravity assists in December 2007 and December 2008).<ref name="EPOXIMissionStatus">{{cite web |title=Mission Status Reports |publisher=NASA |url=http://epoxi.umd.edu/1mission/status.shtml |access-date=May 11, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20101115215854/http://epoxi.umd.edu/1mission/status.shtml |archive-date=November 15, 2010 }}</ref> On May 28, 2010, a burn of 11.3 seconds was conducted, to enable the June 27 Earth fly-by to be optimized for the transit to Hartley 2 and fly-by on November 4. The velocity change was {{Convert|0.1|m/s|ft/s|sp=us|abbr=on}}.<ref>[http://www.nasa.gov/mission_pages/epoxi/epoxi20100528.html NASA Spacecraft Burns For Home, Then Comet] {{Webarchive|url=https://web.archive.org/web/20210408085117/https://www.nasa.gov/mission_pages/epoxi/epoxi20100528.html |date=April 8, 2021 }}, media release 2010-185, NASA, May 28, 2010, accessed June 1, 2010</ref>

On November 4, 2010, the ''Deep Impact'' extended mission (EPOXI) returned images from comet Hartley 2.<ref name="snhartley"/> EPOXI came within {{convert|700|km|sp=us}} of the comet, returning detailed photographs of the "peanut" shaped cometary nucleus and several bright jets. The probe's medium-resolution instrument captured the photographs.<ref name="snhartley"/>

===Comet Garradd (C/2009 P1)===

''Deep Impact'' observed [[Gordon J. Garradd|Comet Garradd (C/2009 P1)]] from February 20 to April 8, 2012, using its Medium Resolution Instrument, through a variety of filters. The comet was {{convert|1.75|-|2.11|AU|e6km|abbr=unit|lk=in}} from the Sun and {{convert|1.87|-|1.30|AU|e6km|abbr=unit|lk=in}} from the spacecraft. It was found that the outgassing from the comet varies with a period of 10.4 hours, which is presumed to be due to the rotation of its nucleus. The dry ice content of the comet was measured and found to be about ten percent of its water ice content by number of molecules.<ref>[http://adsabs.harvard.edu/abs/2012DPS....4450605F Deep Impact MRI Observations Of Comet Garradd (C/2009 P1)] Smithsonian/NASA Astrophysics Data System, October 2012.</ref><ref name="EPOXI Mission Status Reports">[http://epoxi.umd.edu/1mission/status.shtml EPOXI Mission Status Reports] {{webarchive|url=https://web.archive.org/web/20101115215854/http://epoxi.umd.edu/1mission/status.shtml |date=November 15, 2010 }} NASA/University of Maryland, July 12, 2012.</ref>

===Possible mission to asteroid (163249) 2002 GT===
At the end of 2011, ''Deep Impact'' was re-targeted towards asteroid [[(163249) 2002 GT]] which it would reach on January 4, 2020. At the time of re-targeting, whether or not a related science mission would be carried out in 2020 was yet to be determined, based on NASA's budget and the health of the probe.<ref name="2002GT">[http://spaceflightnow.com/news/n1112/17deepimpact/ Deep Impact sets path for asteroid encounter in 2020] – spaceflightnow.com – Stephen Clark – December 17, 2011</ref> A 71-second engine burn on October 4, 2012, changed the probe's velocity by {{Convert|2|m/s|ft/s|sp=us|abbr=on}} to keep the mission on track.<ref name="2002GT2012">[http://www.jpl.nasa.gov/news/news.php?release=2012-313 Deep Impact Spacecraft Completes Rocket Burn] – JPL News – October 4, 2012</ref> Also, there was a 140-second burn on November 24, 2011.<ref>{{Cite web|url=https://www.sciencedaily.com/releases/2011/12/111201220648.htm|title=NASA's Deep Impact spacecraft eyes the future|website=ScienceDaily}}</ref> Distance of a flyby was estimated to be around 200 kilometers.<ref>{{cite web |first=Emily |last=Lakdawalla |url=http://www.planetary.org/blogs/emily-lakdawalla/2012/10051022-deep-impact-asteroid-flyby.html |title=Deep Impact targets possible 2020 asteroid flyby |date=5 October 2012 |quote=Deep Impact's possible January 4, 2020 flyby would be a nice one, at a close-approach distance of around 200 kilometers and a relative velocity of 7 kilometers per second. That's both closer and slower than the Hartley 2 flyby (which was at 700 kilometers and 12 kilometers per second).}}</ref>

===Comet C/2012 S1 (ISON)===
In February 2013, ''Deep Impact'' observed [[Comet ISON]]. The comet remained observable until March 2013.<ref name="ISON-UT">{{cite news |last=Kremer |first=Ken |title=Deep Impact Images Spectacular Incoming Comet ISON – Curiosity & NASA Armada Will Try |work=[[Universe Today]] |date=February 6, 2013 |url=http://www.universetoday.com/99777/deep-impact-images-spectacular-incoming-comet-ison-curiosity-nasa-armada-will-try/#more-99777 |access-date=February 7, 2013}}</ref><ref name="ARXIV-20140508">{{cite report|last1=Sekanina |first1=Zdenek |last2=Kracht |first2=Rainer |title=Disintegration of Comet C/2012 S1 (ISON) Shortly Before Perihelion: Evidence From Independent Data Sets |id=Earth and Planetary Astrophysics (astro-ph.EP) |page=(49 pages) |arxiv=1404.5968 |date=May 8, 2014 |bibcode=2014arXiv1404.5968S}}</ref>

===Contact lost and end of mission===
On September 3, 2013, a mission update was posted to the EPOXI mission status website, stating "Communication with the spacecraft was lost some time between August 11 and August 14 ... The last communication was on August 8. ... the team on August 30 determined the cause of the problem. The team is now trying to determine how best to try to recover communication."<ref name="EPOXI Mission Status Reports"/>

On September 10, 2013, a ''Deep Impact'' mission status report explained that mission controllers believed the computers on the spacecraft were continuously rebooting themselves and so were unable to issue any commands to the vehicle's thrusters. This was believed to make communication with the spacecraft more difficult because the orientation of the antennas was unknown. Additionally, the solar panels on the vehicle were unlikely to be positioned correctly for generating power.<ref>{{cite web |url=https://www.jpl.nasa.gov/news/news.php?release=2013-275 |title=Team Attempts to Restore Communications |publisher=NASA{{\}}Jet Propulsion Laboratory |first1=D. C. |last1=Agle |first2=Dwayne |last2=Brown |date=September 10, 2013 |access-date=March 18, 2017}}</ref>

On September 20, 2013, NASA abandoned further attempts to contact the spacecraft.<ref>{{cite news |url=http://www.abc.net.au/news/2013-09-21/nasa-calls-off-search-for-deep-impact-comet-probe/4972930 |title=NASA calls off search for lost Deep Impact comet probe |work=[[ABC News (Australia)|ABC News]] |date=September 20, 2013 |access-date=March 18, 2017}}</ref> According to chief scientist A'Hearn,<ref>{{cite magazine |url=http://news.nationalgeographic.com/news/2013/09/130920-deep-impact-ends-comet-mission-nasa-jpl/ |archive-url=https://web.archive.org/web/20130923193357/http://news.nationalgeographic.com/news/2013/09/130920-deep-impact-ends-comet-mission-nasa-jpl/ |url-status=dead |archive-date=September 23, 2013 |title=NASA Declares End to Deep Impact Comet Mission |magazine=National Geographic |first=Dan |last=Vergano |date=September 20, 2013 |access-date=March 18, 2017}}</ref> the reason for the software malfunction was a [[Year 2000 problem|Y2K]]-like problem. August 11, 2013, 00:38:49.6, was 2<sup>32</sup> tenth-seconds (deciseconds) from January 1, 2000, suggesting that a system on the craft tracked time in one-tenth second increments since January 1, 2000, and stored it in an [[integer (computer science)|unsigned 32-bit integer]], which then [[integer overflow|overflowed]] at this time, similar to the [[Year 2038 problem]].<ref name=y2k>{{cite web |url=http://permalink.gmane.org/gmane.comp.time.tz/7588 |title=Re: [tz] Deep Impact: wrong time zone? |work=Time Zone Database |first=Malcolm |last=Wallace |date=September 23, 2013 |archive-url=https://web.archive.org/web/20131002233200/http://permalink.gmane.org/gmane.comp.time.tz/7588 |archive-date=October 2, 2013}}</ref>

==See also==
* [[Double Asteroid Redirection Test]]&nbsp;– Similar mission that impacted the asteroid [[Dimorphos]] to study the effect of impact on asteroid trajectory
* [[LCROSS|Lunar Crater Observation and Sensing Satellite]] (LCROSS)&nbsp;– Satellite that impacted Earth's Moon in 2009 in an attempt to eject water
* [[Hayabusa2]]
* [[Timeline of Solar System exploration]]
* [[List of minor planets and comets visited by spacecraft]]
* [[List of missions to minor planets]]
* [[List of missions to comets]]

==References==
{{reflist|colwidth=25em}}

==External links==
{{commons category|Deep Impact}}
* [http://webarchive.loc.gov/all/20090420200048/http://www.nasa.gov/deepimpact ''Deep Impact'' website] at NASA.gov
* [http://www.nasa.gov/epoxi ''EPOXI'' website] {{Webarchive|url=https://web.archive.org/web/20160213232953/http://www.nasa.gov/epoxi |date=February 13, 2016 }} at NASA.gov
* [https://pdssbn.astro.umd.edu/data_sb/missions/epoxi/index.shtml ''EPOXI Mission Archive''] at the NASA Planetary Data System, Small Bodies Node
* [https://web.archive.org/web/20161006223154/http://solarsystem.nasa.gov/missions/deepimpact ''Deep Impact'' website] by NASA's Solar System Exploration
* [http://solarsystem.nasa.gov/deepimpact/ ''Deep Impact'' legacy site] by NASA's Solar System Exploration
* [http://www.ball.com/aerospace/programs/epoxi-deep-impact ''Deep Impact'' website] by Ball Aerospace
* [https://pdssbn.astro.umd.edu/data_sb/missions/deepimpact/index.shtml ''Deep Impact Mission Archive''] at the NASA Planetary Data System, Small Bodies Node

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