View source for SNAP-10A

{{short description|Experimental nuclear-powered US Air Force satellite}}
{{Use dmy dates|date=April 2017}}

{{Infobox spaceflight
| name                  = SNAP-10A (SNAPSHOT)
| image                 = SNAP 10A Space Nuclear Power Plant.jpg
| image_size            = 180px
| image_caption         = Image of SNAP 10A Space Nuclear Power Plant
| mission_type          = [[Engineering]]
| operator              = [[USAF]]
| COSPAR_ID             = 1965-027A
| SATCAT                = 
| mission_duration      = 43 days (achieved) <br/> {{time interval|3 April 1965, 21:25|sep=,}} (in orbit)

| spacecraft_bus        = 
| manufacturer          = [[Atomics International]]
| dry_mass              = 
| launch_mass           = {{convert|440|kg|lb|abbr=on}}
| power                 =

| launch_date           = {{start-date|3 April 1965, 21:25}}
| launch_rocket         = [[Atlas SLV-3|Atlas-Agena D]] 
| launch_site           = [[Vandenberg Air Force Base Space Launch Complex 4|Vandenberg AFB, PALC2-4]]<ref name=log>{{Cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=9 April 2020}}</ref>

| last_contact          = May 16, 1965
| decay_date            = 2965

| orbit_epoch           = 3 April 1965
| orbit_reference       = [[geocentric orbit|Geocentric]]
| orbit_regime          = [[Low Earth orbit|Low Earth]]
| orbit_periapsis       = {{convert|1268|km|abbr=on}}
| orbit_apoapsis        = {{convert|1317|km|abbr=on}}
| orbit_inclination     = 90.2°
| orbit_semimajor       = 
| orbit_eccentricity    = 0.00319
| orbit_period          = 111.4 minutes<ref name = NSSDC>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1965-027A|title=Snapshot|publisher=NASA Space Science Data Coordinated Archive|access-date=9 April 2020}}</ref>
| orbit_RAAN            = 
| orbit_arg_periapsis   = 
| orbit_mean_anomaly    = 
| orbit_mean_motion     = 
| orbit_rev_number      = 
| apsis                 = gee

| programme             = ''Systems for Nuclear Auxiliary Power''
| previous_mission      = [[Systems for Nuclear Auxiliary Power|SNAP-9A]]
| next_mission          = [[Systems for Nuclear Auxiliary Power|SNAP-11]]
}}

'''SNAP-10A''' ('''Systems for Nuclear Auxiliary Power''',<ref>{{cite news |url=http://nla.gov.au/nla.news-article104304731 |title=News In Brief: Nuclear Reactor For Space |newspaper=[[The Canberra Times]] |volume=36 |issue=10,203 |location=Australian Capital Territory, Australia |date=18 April 1962 |access-date=12 August 2017 |page=3 |via=National Library of Australia}}, ''...the reactor would "be known as "Snaps 10a" for "Systems for Nuclear Auxiliary Power"...''</ref> aka '''Snapshot''' for '''Space Nuclear Auxiliary Power Shot''', also known as '''OPS 4682'''<ref name="Gunther"/>) was a US experimental [[Nuclear power in space|nuclear powered satellite]] launched into space in 1965<ref>{{cite news |url=http://nla.gov.au/nla.news-article131765167 |title=Reactor goes into space |newspaper=[[The Canberra Times]] |volume=39 |issue=11,122 |location=Australian Capital Territory, Australia |date=5 April 1965 |access-date=12 August 2017 |page=1 |via=National Library of Australia}}</ref> as part of the SNAPSHOT program.<ref name="GRC">[https://web.archive.org/web/20030111163512/http://www.grc.nasa.gov/WWW/ion/past/60s/snapshot.htm SNAPSHOT], NASA Glenn Research Center, March 20, 2007.  Retrieved 3 April 2019.</ref><ref name="Gunther">[https://space.skyrocket.de/doc_sdat/snapshot.htm Snapshot], Gunther's Space Page.  Retrieved 3 April 2019.</ref> The test marked both the world's first operation of a nuclear reactor in orbit,<ref name="beyondNERVA2019">"[https://beyondnerva.com/2018/11/26/history-of-us-astronuclear-reactors-part-1-snap-2-and-10a/ History of US Astronuclear Reactors part 1: SNAP-2 and 10A]", ''Beyond NERVA'', April 3, 2019.  Retrieved 3 April 2019.</ref><ref>Andrew LePage, "[https://www.drewexmachina.com/2015/04/03/first-nuclear-reactor-in-orbit/ The First Nuclear Reactor in Orbit]", ''Drew Ex Machina,'' April 3, 2015.  Retrieved 3 April 2019.</ref> and the first operation of an [[ion thruster]] system in orbit.  It is the only [[fission power system|fission reactor]] power system launched into space by the United States.<ref>{{cite report|title=NASA Utilization of Space Nuclear Systems for Robotic and Human Exploration Missions|date=July 2022|page=4|url=https://www.nasa.gov/sites/default/files/atoms/files/50777_nasa_eo_13972_report_rev_11b_final1_tagged.pdf|publisher=NASA|access-date=March 19, 2023|archive-date=20 March 2023|archive-url=https://web.archive.org/web/20230320034107/https://www.nasa.gov/sites/default/files/atoms/files/50777_nasa_eo_13972_report_rev_11b_final1_tagged.pdf|url-status=dead}}</ref> The reactor stopped working after just 43 days due to a non-nuclear electrical component failure.<ref>[https://webarchive.nla.gov.au/awa/20060305130000/http://pandora.nla.gov.au/pan/11193/20060306-0000/www.uic.com.au/nip82.htm Nuclear Reactors for Space]{{cbignore|bot=medic}}, Briefing Paper # 82, January 2004</ref> The [[Systems Nuclear Auxiliary Power Program]] reactor was specifically developed for satellite use in the 1950s and early 1960s under the supervision of the [[U.S. Atomic Energy Commission]].<ref name="nasa/doe2010"/><ref>
{{Citation
 | last= Lords
 | first= R. E.
 | title= SNAP and AI Fuel Summary Report
 | publisher= Westinghouse Idaho Nuclear Company, Inc.
 | date= August 1994
 | id= WINCO-1222, UC-510
 | doi= 10.2172/10182034
 | osti= 10182034
 | url= https://digital.library.unt.edu/ark:/67531/metadc1402334/
 | doi-access= free
 }}
</ref>

==History==

The [[Systems for Nuclear Auxiliary Power]] (SNAP) program developed as a result of Project Feedback, a Rand Corporation study of reconnaissance satellites completed in 1954.<ref name="feedback">{{cite web|url=https://www.rand.org/pubs/reports/R262z1.html|title=Project Feedback Summary Report Volume I|author1=J. E. Lipp|author2=Robert M. Salter|date=March 1954|publisher=RAND|access-date=11 April 2020}}</ref> As some of the proposed satellites had high power demands, some as high as a few kilowatts, the U.S. Atomic Energy Commission (AEC) requested  a series of nuclear power-plant studies from industry in 1951. Completed in 1952, these studies determined that nuclear power plants were technically feasible for use on satellites.<ref name="SNAP">{{cite book|author=William R. Corliss|title=SNAP NUCLEAR POWER REACTORS|date=1966|publisher=U.S. Atomic Energy Commission/Division of Technical Information}}</ref>{{rp|5}}

In 1955, the AEC began two parallel SNAP nuclear power projects. One, contracted with The Martin Company, used radio-isotopic decay as the power source for its generators. These plants were given odd-numbered SNAP designations beginning with SNAP-1. The other project used nuclear reactors to generate energy, and was developed by the [[Atomics International|Atomics International Division]] of [[North American Aviation]]. Their systems were given even-numbered SNAP designations, the first being SNAP-2.<ref name="SNAP"/>{{rp|5}}

SNAP-10A was the first Atomics International, nuclear-reactor power system built for use in space. Evolved from the SNAP-10 300 watt design, SNAP-10A fulfilled a 1961 Department of Defense requirement for a 500 watt system.<ref name="SNAP"/>{{rp|5,7}}

Most of the systems development and reactor testing was conducted at the [[Santa Susana Field Laboratory]], Ventura County, California using a number of specialized facilities.<ref name="etec">{{cite web|url=https://www.etec.energy.gov/Operations/Major_Operations/SNAP_Overview.php|title=SNAP Overview|publisher=U.S. Department of Energy|access-date=9 April 2020}}</ref>

==Construction==
{{CSS image crop|Image=HD.6D.539 (10967393854).jpg|cWidth=300|cHeight=200|oTop=50|oLeft=50|bSize=400|Description=Production line of SNAP-10A reactors|Align=left}}
The SNAP-10A has three major components&nbsp;– (1) a compact fission reactor that generates heat, (2) an energy converter that transforms some of the heat into electricity, and (3) a radiator that radiates away heat that cannot be used.<ref name="SNAP"/>

The reactor measures 39.62&nbsp;cm (15.6&nbsp;in) long, 22.4&nbsp;cm (8.8&nbsp;in) diameter and holds 37 fuel rods containing [[Uranium-235|<sup>235</sup>U]] as [[Uranium zirconium hydride|uranium-zirconium-hydride]] fuel.<ref name="ans"/> The SNAP-10A reactor was designed for a thermal power output of 30&nbsp;kW and unshielded weighs {{convert|650|lb|abbr=on}}. The reactor can be identified at the top of the SNAP-10A unit.<ref>{{cite book | last = Voss | first = Susan | title = SNAP Reactor Overview | publisher = U.S. Air Force Weapons Laboratory |place= Kirtland AFB, New Mexico | date = August 1984 | url = http://apps.dtic.mil/dtic/tr/fulltext/u2/a146831.pdf | archive-url = https://web.archive.org/web/20170215062826/http://www.dtic.mil/dtic/tr/fulltext/u2/a146831.pdf | url-status = live | archive-date = 15 February 2017 | id = AFWL-TN-84-14 | access-date = 2018-09-19}}</ref>

Reflectors were arranged around the outside of the reactor to provide the means to control the reactor. The reflectors were composed of a layer of beryllium, which would reflect neutrons, thus allowing the reactor to begin and maintain the fission process. The reflectors were held in place by a retaining band anchored by an [[Pyrotechnic fastener|explosive bolt]]. When the reflector was ejected from the unit, the reactor could not sustain the nuclear fission reaction and the reactor permanently shut down.{{citation_needed|date=July 2019}}

The [[eutectic]] sodium-potassium ([[NaK]]) alloy was used as a coolant in the SNAP-10A. The NaK was circulated through the core and thermoelectric converters by a [[Electromagnetic pump|liquid metal direct current conduction-type]] pump. The thermoelectric converters (identified as the long white "apron") are doped silicon germanium materials, thermally coupled, but electrically isolated from the NaK heat transfer medium. The temperature difference between the NaK on one side of the thermoelectric converter and the cold of space on the other created an electric potential and usable electricity.<ref>{{cite book | last = Schmidt | first = G.L. | title = SNAP 10A Test Program | publisher = Rockwell International, Canoga Park, California | date = September 1988 | id = DCN: SP-100-XT-0002 }}</ref>

== SNAPSHOT mission==
[[File:SNAPSHOT 1965-027A.jpg|left|thumb|April 3, 1965 launch of the SNAP-10A using an [[Atlas-Agena|Atlas-Agena D]] SLV-3 launch vehicle. Launched from [[Vandenberg Space Force Base|Vandenberg AFB]], California.]]

===Launch and orbital operation ===

SNAP-10A was launched from [[Vandenberg Air Force Base]] by an [[Atlas-Agena|ATLAS Agena D rocket]] on 3 April 1965 into a [[low Earth orbit]] altitude of approx. 1,300&nbsp;km. It is in a slightly [[retrograde orbit|retrograde]] [[polar orbit]]<ref>{{Cite web|url=http://www.heavens-above.com/orbit.aspx?satid=1314|title=Snapshot – Orbit|website=www.heavens-above.com|access-date=15 June 2016|quote=Inclination: 90,3084°}} – an object with an [[Retrograde and prograde motion#Inclination|inclination]] between 90 and 180 degrees is in a retrograde orbit.</ref>
— this ensured that the spent rocket stages landed in the ocean. Its nuclear electrical source, made up of thermoelectric elements, was intended to produce over 500 watts of electrical power for one year.<ref>{{cite web|url=https://www.etec.energy.gov/Operations/Major_Operations/SNAP_Overview.html|title=SNAP Overview|publisher=USDOE ETEC|access-date=14 April 2012|archive-url=https://web.archive.org/web/20130215134831/https://www.etec.energy.gov/Operations/Major_Operations/SNAP_Overview.html|archive-date=15 February 2013|df=dmy-all}}</ref><ref>{{cite web|url=http://www.fas.org/nuke/space/bennett0706.pdf|title=Space Nuclear Power: Opening the Final Frontier|last=Bennett|first=Gary L.|date=2006|publisher=[[American Institute of Aeronautics and Astronautics]]|pages=17|access-date=3 April 2010}}</ref> After 43 days, an onboard [[voltage regulator]] within the spacecraft&nbsp;– unrelated to the SNAP reactor&nbsp;– failed, causing the [[reactor core]] to be shut down, after reaching a maximum output of 590 watts.<ref name="ans">{{cite web|last=Schmidt|first=Glen|title=SNAP Overview – general background |url=http://anstd.ans.org/NETS2011/Documents/Presentations/Opening%20Dinner%20SNAP%2010A%20Schmidt.pdf|publisher=[[American Nuclear Society]]|access-date=27 August 2012|date=February 2011}}</ref><ref name="portr">{{cite journal |last1=Portree |first1=David S. F |last2=Loftus, Jr. |first2=Joseph P. |date=January 1999 |title=Orbital Debris: A Chronology |journal=NASA Sti/Recon Technical Report N |volume=99 |id=TP-1999-208856 |publisher=[[NASA]] |pages=29–31 |bibcode=1999STIN...9941786P |url=http://ston.jsc.nasa.gov/collections/trs/_techrep/TP-1999-208856.pdf <!-- alternate URL: http://www.spacelaw.olemiss.edu/library/space/US/Executive/NASA/TechReports/TP-1999-208856%20-%20Orbiting%20Debris.pdf --> |url-status=dead|archive-url=https://web.archive.org/web/20000901071135/http://ston.jsc.nasa.gov/collections/TRS/_techrep/TP-1999-208856.pdf |archive-date=1 September 2000 |df=dmy-all }}</ref>

After the 1965 system failure, the reactor was left in a {{convert|700|nmi|km||disp=flip|adj=on}} Earth orbit for an expected duration of 1,000 years.<ref name="nasa/doe2010"/><ref>{{cite book | last = Staub | first = D.W. | title = SNAP 10 Summary Report | publisher = Atomics International Division of North American Aviation, Inc., Canoga Park, California | date = 25 March 1967 | id = NAA-SR-12073}}</ref><ref>{{cite news |url=http://nla.gov.au/nla.news-article110889894 |title=U.S. ADMISSION : Satellite mishap released rays |newspaper=[[The Canberra Times]] |volume=52 |issue=15,547 |location=Australian Capital Territory, Australia |date=30 March 1978 |access-date=12 August 2017 |page=5 |via=National Library of Australia}}, ''...Launched in 1965 and carrying about 4.5 kilograms of uranium 235, Snap 10A is in a 1,000-year orbit....''</ref>

In November 1979 the vehicle began shedding, eventually losing 50 pieces of traceable [[space debris|debris]]. The reasons were unknown, but the cause could have been a collision. Although the main body remains in place, radioactive material may have been released. Later research, published in 2008 and based on [[Haystack Observatory#Haystack Radar operations|Haystack]] data, suggests that there are another 60 or more pieces of debris of size <10&nbsp;cm.<ref name="portr"/><ref>
{{Citation
 | last1 = Stokely
 | first1 = C.
 | last2 = Stansbury
 | first2 = E.
 | date = 2008
 | title = Identification of a debris cloud from the nuclear powered SNAPSHOT satellite with Haystack radar measurements
 | periodical = Advances in Space Research
 | volume = 41
 | issue = 7
 | pages = 1004–1009
 | bibcode = 2008AdSpR..41.1004S
 | doi = 10.1016/j.asr.2007.03.046
| hdl = 2060/20060028182
 | url = https://zenodo.org/record/1258764
 | hdl-access = free
 }}
</ref>

===Ion propulsion===

The SNAPSHOT test included a cesium [[ion thruster]] as a secondary payload, the first test of an [[electrically powered spacecraft propulsion]] system to operate in orbit (following the [[SERT-1]] suborbital test in 1964). The ion-beam power supply was operated at 4500 V and 80 mA to produce a thrust of about 8.5&nbsp;mN.<ref name= "GRC" /> The ion engine was to be operated off batteries for about one hour, and then the batteries were to be charged for approximately 15 hours using 0.1&nbsp;kW of the nominal 0.5&nbsp;kW SNAP system as the power supply. The ion engine operated for a period of less than 1 hour before being commanded off permanently. Analysis of flight data indicated a significant number of high-voltage breakdowns, and this apparently caused electromagnetic interference (EMI), causing attitude perturbations of the spacecraft. Ground tests indicated that the engine arcing produced conducted and radiated EMI significantly above design levels.{{citation_needed|date=July 2019}}

==Safety==
The SNAP reactor program necessitated a safety program and led to the inception of the Aerospace Nuclear Safety Program. The program was established to evaluate the nuclear hazards associated with the construction, launch, operation and disposal of SNAP systems and to develop designs to assure their radiological safety.{{citation_needed|date=July 2019}}

[[Atomics International]] had primary responsibility for safety, while [[Sandia National Laboratories]] was responsible for the Aerospace Safety Independent Review and conducted many of the safety tests. Before launch was permitted, proof had to be obtained that under all circumstances the launch of the reactor would not pose a serious threat.{{citation_needed|date=July 2019}}

A variety of tests were successfully completed and several videos of the development and tests are available for viewing.<ref>{{cite web |title=ETEC - Videos |url=https://www.etec.energy.gov/Library/Video/Video_index.php |access-date= 12 January 2018 |archive-url=https://web.archive.org/web/20170204230330/http://www.etec.energy.gov/Library/Video/Video_index.html |archive-date=4 February 2017}}</ref> The [[Idaho National Laboratory]] conducted three destructive tests of SNAP nuclear reactors at [[Test Area North]] prior to the launch of SNAP-10A.<ref name=ProvePrinciple17>{{cite book
| last =Stacy
| first =Susan M.
| title =Proving the Principle: A History of The Idaho National Engineering and Environmental Laboratory, 1949–1999
| publisher = U.S. Department of Energy, Idaho Operations Office
| date = 2000
| url = http://ia410331.us.archive.org/peth04/20041031005051/http://www.inel.gov/proving-the-principle/chapter_17.pdf 
| isbn = 978-0-16-059185-3}} Chapter 17: Science in the Desert.</ref> The SNAPTRAN-3 destructive experiment, on 1 April 1964, simulated a rocket crash into the ocean, purposely sending [[radioactive]] debris across the Idaho desert.

The testing and development involving radioactive materials caused environmental contamination at the former Atomics International Santa Susana Field Laboratory (SSFL) facilities. The [[United States Department of Energy]] is responsible for the identification and cleanup of the radioactive contamination. (The SSFL was also used for the unrelated testing and development of rocket engines by [[Pratt & Whitney Rocketdyne|Rocketdyne]] primarily for [[NASA]].) The DOE website supporting the site cleanup<ref>{{cite web |title=U.S. DOE Nuclear Energy Development at SSFL |url= http://etec.energy.gov/Operations/Rad_Timeline.html |access-date= 12 January 2018 |archive-url=https://web.archive.org/web/20170804053306/http://www.etec.energy.gov/Operations/Rad_Timeline.html |archive-date=4 August 2017}}</ref>  details the historical development of nuclear energy at SSFL including additional SNAP testing and development information.

==Related work and follow-on programs==
Atomics International also developed and tested other compact nuclear reactors including the SNAP Experimental Reactor (SER), SNAP-2, SNAP-8 Developmental Reactor (SNAP8-DR) and SNAP-8 Experimental Reactor (SNAP-8ER) units at the Santa Susana Field Laboratory (see [[Systems for Nuclear Auxiliary Power]] article). Atomics International also built and operated the [[Sodium Reactor Experiment]], the first U.S. nuclear power plant to supply electricity to a public power system.<ref>{{Cite web|title=ETEC - Department of Energy ETEC Closure Project|url=https://www.etec.energy.gov/Operations/Major_Operations/SRE.php|access-date=2021-11-19|website=www.etec.energy.gov}}</ref><ref>{{Cite journal|date=September 1956|url=https://pubs.acs.org/doi/pdf/10.1021/i651400a779|journal=Industrial & Engineering Chemistry|volume=48|issue=9|pages=100A|doi=10.1021/i651400a779|issn=0019-7866|title=Atomics International|url-access=subscription}}</ref>

{{asof|2010}}, more than 30 small fission power system nuclear reactors have been sent into space in Soviet [[RORSAT]] satellites; also, over 40 [[radioisotope thermoelectric generator]]s have been used globally (principally US and USSR) on space missions.<ref name="nasa/doe2010">
{{cite news | vauthors=Mason L, Bailey S, Bechtel R, Elliott J, Fleurial JP, Houts M, Kapernick R, Lipinski R, MacPherson D, Moreno T, Nesmith B, Poston D, Qualls L, Radel R, Weitzberg A, Werner J |title=Small Fission Power System Feasibility Study – Final Report |url=http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=32899.0;attach=543853 |access-date=3 October 2015 |agency=[[NASA]]/[[US DOE|DOE]] |date=18 November 2010 |quote=Space Nuclear Power: Since 1961 the U.S. has flown more than 40 Radioisotope Thermoelectric Generators (RTGs) with an essentially perfect operational record. The specifics of these RTGs and the missions they have powered have been thoroughly reviewed in the open literature. The U.S. has flown only one reactor, which is described below. The Soviet Union has flown only 2 RTGs and had shown a preference to use small fission power systems instead of RTGs. The USSR had a more aggressive space fission power program than the U.S. and flew more than 30 reactors. Although these were designed for short lifetime, the program demonstrated the successful use of common designs and technology.}}</ref>

==See also==
{{Portal|Spaceflight}}
*[[Nuclear power in space]]
*[[RORSAT]], the Soviet Union nuclear reactor powered satellites.
*[[Safe Affordable Fission Engine]], NASA experimental series

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

==External links==
* [[International Designator]]: [https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-027A 1965-027A]
* [http://www.heavens-above.com/orbit.aspx?satid=1314 Snapshot – Orbit]
* {{YouTube|vFk6A-IdTV8|"First Reactor in Space...SNAP-10A"}}

{{Nukesats}}
{{Orbital launches in 1965}}

{{DEFAULTSORT:Snap-10A}}
[[Category:Nuclear power in space]]
[[Category:Nuclear power reactor types]]
[[Category:Atomics International]]
[[Category:Satellites orbiting Earth]]
[[Category:Derelict satellites orbiting Earth]]
[[Category:Spacecraft launched in 1965]]
[[Category:United States Atomic Energy Commission]]
[[Category:Satellite nuclear reactors]]

[[ru:Ядерные реакторы на космических аппаратах#SNAP]]