Editing CONTOUR

{{Short description|Failed NASA cometary flyby mission (2002)}}
{{DISPLAYTITLE: ''CONTOUR''}}
{{Infobox spaceflight
| name                  = ''CONTOUR''
| names_list            = Comet Nucleus Tour
| image                 = Contour comet.jpg
| image_caption         = Artist impression of ''CONTOUR'' approaching a comet.
| image_alt             = The ''CONTOUR'' spacecraft approaches the coma of a comet, while another comet is visible in the background.
| image_size            = 300px

| mission_type          = [[Comet|Cometary]] flyby
| operator              = [[NASA]] / [[Applied Physics Laboratory|APL]]
| COSPAR_ID             = 2002-034A
| SATCAT                = 27457
| website               = [https://science.nasa.gov/mission/contour/ science.nasa.gov]
| mission_duration      = {{time interval|3 Jul 2002|15 Aug 2002|sep=,}}

| manufacturer          = [[Applied Physics Laboratory]]
| launch_mass           = {{cvt|398|kg|lb}}
| dimensions            = {{cvt|2.1|xx|1.8|xx|1.8|m|ft}}
| power                 = 670&nbsp;watts

| launch_date           = 3 July 2002, 06:47:41 [[Coordinated Universal Time|UTC]]
| launch_rocket         = [[Delta II]] 7425–9.5<br>D-292
| launch_site           = [[Cape Canaveral Space Force Station|Cape Canaveral]] [[Cape Canaveral Air Force Station Space Launch Complex 17|SLC-17]]
| launch_contractor     = [[Boeing]]

| disposal_type         = Destroyed
| last_contact          = 15 August 2002

| instruments_list       = <!-- start collapsible list of instruments -->
 {{Infobox spaceflight/Instruments
  |acronym1  = CIDA  | name1  = Comet Impact Dust Analyzer
  |acronym2  = CRISP | name2  = CONTOUR Remote Imager/Spectrograph
  |acronym3  = CAI   | name3  = CONTOUR Aft Imager
  |acronym4  = NGIMS | name4  = Neutral Gas Ion Mass Spectrometer
 }}

| programme             = '''[[Discovery Program]]'''
| previous_mission      = [[Genesis (spacecraft)|Genesis]]
| next_mission          = [[MESSENGER]]
}}

The '''Comet Nucleus Tour''' ('''CONTOUR''') was a [[NASA]] [[Discovery Program|''Discovery''-class]] space probe that failed shortly after its July 2002 launch. It was the only Discovery mission to fail.

The two comets scheduled to be visited were [[Comet Encke|Encke]] and [[Schwassmann-Wachmann-3]], and the third target was [[6P/d'Arrest|d'Arrest]]. It was hoped that a new comet would have been discovered in the [[inner Solar System]] between 2006 and 2008, in which case the spacecraft trajectory would have been changed if possible to rendezvous with the new comet. Scientific objectives included imaging the nuclei at resolutions of up to {{convert|4|m|ft|sp=us}}, performing spectral mapping of the nuclei at resolutions of up to {{convert|100|m|ft|sp=us}}, and obtaining detailed [[compositional data]] on gas and dust in the near-nucleus environment, with the goal of improving knowledge of the characteristics of comet nuclei.

After the [[solid rocket motor]] intended to inject the spacecraft into [[solar orbit]] was ignited on August 15, 2002, contact with the probe could not be re-established. Ground-based telescopes later found three objects along the course of the satellite, leading to the speculation that it had disintegrated. Attempts to contact the probe were ended on December 20, 2002. The probe thus accomplished none of its primary scientific objectives, but did prove some spaceflight technologies, such as the APL-developed non-coherent [[Doppler tracking]] spacecraft navigation technique, which was later used on the [[New Horizons]] spacecraft.<ref name=DeBoy_2004/>

==Spacecraft==
[[File:CONTOUR pre-launch.jpg|thumb|right|The ''CONTOUR'' spacecraft at the [[Kennedy Space Center]] in May 2002, being prepared for launch.]]

===Design and construction===
The ''CONTOUR'' spacecraft was constructed in-house at the [[Johns Hopkins University]] [[Applied Physics Laboratory]]. ''CONTOUR'' was shaped as an [[octagonal prism]], measuring at {{convert|2.1|m|ft}} tall and {{convert|1.8|m|ft}} long, had a total fueled mass of {{cvt|398|kg|lb}} at launch, not including the {{cvt|377|kg|lb}} mass of the [[Star 30]] [[Booster (rocketry)|booster]] it was attached to, during the launch phase of the mission.<ref name=nssdc/> The spacecraft was fitted with a {{cvt|25|cm|in}} [[whipple shield]], similar to the one used on ''[[Stardust (spacecraft)|Stardust]]'', on its leading face, designed with four layers of nextel fabric and seven layers of [[kevlar]].{{r|sfn-spacecraft|Ulivi_2012}} The shield was built to allow the spacecraft to withstand the respective 28.2 and 14&nbsp;km/s velocity flybys of comets Encke and Schwassmann-Wachmann-3, where the spacecraft would be subjected to numerous particles ejecting from the [[comet nucleus|nuclei]] of the comets.<ref name=Osegueda_2001/> Although mission scientists predicted that the spacecraft would take no significant damage during the Encke and Schwassmann-Wachmann-3 encounters, the shield and its [[prototype]]s were tested vigorously during the construction of the spacecraft, including one where a shield prototype was shot at with surrogate [[nylon]] particles from a two stage [[light-gas gun]]. The results of the earlier tests allowed mission planners to determine a safe distance from which the ''CONTOUR'' would pass by comets targeted on the mission.<ref name=Osegueda_2001/> Three of the four [[scientific instrument]]s aboard the spacecraft were embedded within this shield.<ref name=sfn-spacecraft/>

===Spacecraft subsystems===

====Power====
Power for ''CONTOUR'' derives from [[solar cell]]s, which are mounted onto the spacecraft, decorating the sides and rear and generating up to 670 [[watt]]s of power. A [[nickel–cadmium battery]] designed to last up to nine [[ampere hour]]s was also installed aboard the spacecraft in the event that the solar cell system fails, or does not provide enough power for the spacecraft or its instruments to function.<ref name=sfn-spacecraft/>

====Communications and data====

====Propulsion and guidance====
Unlike many interplanetary missions, CONTOUR was not designed to be propelled beyond Earth orbit by the rocket that launched it, instead it exited Earth orbit using a STAR-30 solid rocket booster built into the spacecraft. This STAR-30 engine provided 1,922 meters per second of delta-v.<ref name="Osegueda_2001" /> The firing of this engine is the reason the CONTOUR spacecraft was destroyed. In addition, there were 16 hydrazine thrusters for normal propulsion and course corrections. These thrusters were divided into four clusters of four.<ref name="Osegueda_2001" />

===Scientific payload===
* '''CIDA'''
:The Comet Impact Dust Analyzer (CIDA)

* '''CRISP'''
:The CONTOUR Remote Imager/Spectrograph (CRISP)

* '''CAI'''
:The CONTOUR Aft Imager (CAI), also known as the CONTOUR Forward Imager (CFI)

* '''NGIMS'''
:Neutral Gas Ion Mass Spectrometer (NGIMS)

==Mission==
[[File:CONTOUR Launch (19083178100).jpg|thumb|left|Long-exposure photograph of the launch of ''CONTOUR'' from [[Cape Canaveral Air Force Station|Cape Canaveral]] on July 3, 2002.]]
CONTOUR launched on a Delta 7425 (a [[Delta II rocket|Delta II]] Lite launch vehicle with four strap-on solid-rocket boosters and a Star 27 third stage) on July 3, 2002, at 6:47:41 UT (2:47:41&nbsp;a.m. EDT) from [[Cape Canaveral Air Force Station]]. It was launched into a high-[[apogee]] Earth orbit with a period of 5.5 days. Following a series of phasing orbits, the Star 30 solid rocket motor was used to perform an injection maneuver on August 15, 2002, to put CONTOUR in the proper trajectory for an Earth flyby on August 15, 2003, followed by an encounter with comet Encke on November 12, 2003, at a distance of 100 to 160&nbsp;km and a flyby speed of 28.2&nbsp;km/s, 1.07 AU from the Sun and 0.27 AU from Earth. During the August 2002 injection maneuver, the probe was lost.

Three more Earth flybys would have followed, on August 14, 2004, February 10, 2005, and February 10, 2006. On June 18, 2006, CONTOUR would have encountered comet Schwassmann-Wachmann-3 at 14&nbsp;km/s, 0.95 AU from the Sun and 0.33 AU from Earth. Two more Earth flybys were scheduled in February 2007 and 2008, and a flyby of comet d'Arrest might have occurred on 16 August 2008 at a relative velocity of 11.8&nbsp;km/s, 1.35 AU from the Sun and 0.36 AU from Earth. All flybys would have had a closest encounter distance of about 100&nbsp;km and would have occurred near the period of maximum activity for each comet. After the comet Encke encounter, CONTOUR might have been retargeted towards a new comet if one was discovered with the desired characteristics (e.g. active, brighter than [[absolute magnitude]] 10, perihelion within 1.5 AU).
{{clear}}

==Investigation into failure==
According to NASA: "An investigation board concluded that the most likely cause of the mishap was structural failure of the spacecraft due to plume heating during the solid-rocket motor burn. Alternate possible but less likely causes determined were catastrophic failure of the solid rocket motor, collision with space debris, and loss of dynamic control of the spacecraft."{{r|nasa1|nasa2|nasa3}}

==Proposed reflight==
After the loss of CONTOUR, a replacement spacecraft &ndash; CONTOUR 2 &ndash; was proposed, scheduled for launch in 2006. However, the replacement did not ultimately materialize.{{Citation needed|date=August 2020}}

==See also==
* [[List of missions to comets]]

==References==
{{Reflist|refs=

<ref name="DeBoy_2004">{{cite conference
| author1= C. C. DeBoy
| author2= C. B. Haskins
| author3= T. A. Brown
| author4= R. C. Schulze
| author5= M. A. Bernacik
| author6= J. R. Jensen
| author7= W. Millard
| author8= D. Duven
| author9= S. Hill
| display-authors=5
| conference= 2004 IEEE Aerospace Conference Proceedings
| id= IEEE Cat. No.04TH8720
| title= The RF telecommunications system for the New Horizons mission to Pluto
| pages= 1463–1478
| volume= 3
| location= Big Sky, Montana, USA
| doi= 10.1109/AERO.2004.1367922
| isbn= 978-0-780-38155-1
| year= 2004
| s2cid= 1979067 }}
</ref>

<ref name="nasa1">{{cite web
| title= CONTOUR – NASA Science
| url= https://science.nasa.gov/mission/contour/
| website= science.nasa.gov
| publisher= [[NASA]]
| access-date= 19 January 2012 }}
</ref>

<ref name="nasa2">{{cite report
| author1= T. Bradley, Jr
| author2= C. Gay
| author3= P. Martin
| author4= D. Stepheson
| author5= C. Tooley
| url= https://spacese.spacegrant.org/Failure%20Reports/ContourFailureReport.pdf 
| title= Comet Nucleus Tour (CONTOUR) Mishap Investigation
| publisher= [[NASA]]
| date= 31 May 2003
| access-date= 19 January 2012 }}
</ref>

<ref name="nasa3">{{cite web
| title= Lessons Learned #1385
| url= https://llis.nasa.gov/lesson/1385
| website= llis.nasa.gov
| publisher= [[NASA]]
| access-date= 19 January 2012 }}
</ref>

<ref name="nssdc">{{cite web
| author1= David R. Williams
| title= CONTOUR
| url= https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2002-034A
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| date= 2002
| access-date= 23 January 2016 }}
</ref>

<ref name="Osegueda_2001">{{cite journal
| author1= R. Osegueda
| author2= C. Carrasco
| author3= M. Orozco
| author4= J. Eftis
| author5= E. Reynolds
| author6= T. Sholar
| title= CONTOUR Dust Shield Performance
| journal= [[Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering|Journal of Aerospace Engineering]]
| date= 1 October 2001
| volume= 14
| issue= 4
| pages= 147–157
| doi= 10.1061/(ASCE)0893-1321(2001)14:4(147)
| issn= 0893-1321 }}
</ref>

<ref name="sfn-spacecraft">{{cite web
| title= The CONTOUR spacecraft
| url= https://spaceflightnow.com/delta/d292/020628contour.html
| website= Spaceflight Now
| date= 28 June 2002
| access-date= 24 January 2016 }}
</ref>

<ref name="Ulivi_2012">{{cite book
| author1= P. Ulivi
| author2= D. Harland
| title= Robotic Exploration of the Solar System (Part III): Wows and Woes, 1997-2003
| date= 14 August 2012
| publisher= [[Springer Nature|Springer]]
| isbn= 978-0-387-09627-8
| pages= 250–254
| url= https://books.google.com/books?id=Ndjt1DkCFvoC&pg=PR1
| access-date= 23 January 2016 }}
</ref>

}}

==External links==
{{Portal|Spaceflight}}
* {{cite web
 |url         = http://discovery.nasa.gov/contour.html
 |title       = CONTOUR
 |work        = NASA Discovery Program
 |access-date  = December 27, 2007
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20100425080955/http://discovery.nasa.gov/contour.html
 |archive-date = April 25, 2010
}}
* [https://web.archive.org/web/20070610161342/http://solarsystem.nasa.gov/missions/profile.cfm?MCode=CONTOUR CONTOUR Mission Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]

{{Planetary Missions Program Office|Discovery=y}}
{{Comet spacecraft}}
{{Orbital launches in 2002}}

{{Use American English|date=January 2014}}

{{DEFAULTSORT:Contour}}
[[Category:Missions to comets]]
[[Category:NASA space probes]]
[[Category:Discovery Program]]
[[Category:Satellite launch failures]]
[[Category:Space probes launched in 2002]]
[[Category:Derelict satellites in heliocentric orbit]]
[[Category:Spacecraft launched by Delta II rockets]]
[[Category:Destroyed space probes]]
[[Category:Spacecraft launched in 2002]]
[[Category:Space accidents and incidents in the United States]]