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The Comet Nucleus Tour (CONTOUR) spacecraft was presumed lost after numerous attempts at contact. The spacecraft was scheduled to ignite its STAR 30 solid rocket engine on 15 August 2003 at 08:49 UT (4:49 a.m. EDT). This firing was to take CONTOUR out of Earth orbit and put it on a heliocentric trajectory. However, following the scheduled firing time, no further contact was made with the craft. Telescopic surveys were made under the assumption that the firing took place on schedule, and three objects were identified near the expected position of CONTOUR, leading investigators to believe that the firing took place and that these objects were parts of the spacecraft and rocket engine. 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.

The Comet Nucleus Tour (CONTOUR) Discovery class mission had as its primary objective close fly-bys of two comet nuclei with the possibility of a fly-by of a third known comet or an as-yet-undiscovered comet. The two comets to be visited were Encke and Schwassmann-Wachmann-3, and the third target was d'Arrest. It was hoped that a new comet would be discovered that would be 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 4 m, performing spectral mapping of the nuclei at resolutions of 100-200 m, and obtaining detailed compositional data on gas and dust in the near-nucleus environment, with the goal of improving our knowledge of the characteristics of comet nuclei.

Spacecraft and Subsystems

The CONTOUR spacecraft has a total fueled mass of 775 kg, including a Star 30 SRM booster with a mass of 377 kg and 70 kg of hydrazine fuel. Power is provided by a body-mounted solar array designed for operation at distances between 0.75 and 1.5 AU from the Sun. It is three-axis stabilized for encounters and spin-stabilized during cruise mode between encounters. Communications are through a fixed 0.45 m diameter high-gain antenna which will support data rates greater than 100 kbit/sec at encounters. Data and images are stored on two 3.3 Gbit solid-state recorders with a capacity of 600 images. The spacecraft is equipped with four primary science instruments, the Contour Remote Imager/Spectrograph (CRISP), the Contour Aft Imager (CAI), the Dust Analyzer (CIDA), and the Neutral Gas Ion Mass Spectrometer (NGIMS).

Mission Profile

CONTOUR launched on a Delta 7425 (a Delta II Lite launch vehicle with four strap-on solid-rocket boosters and a Star 30 third stage) on 3 July 2002 at 6:47:41 UT (2:47:41 a.m. EDT) into a high-apogee Earth orbit with a period of 5.5 days from Cape Canaveral Air Force Station. Following a series of phasing orbits, the command was given to fire the Star 30BP solid rocket motor on 15 August 2002 at 08:49 UT to perform an injection maneuver to eject CONTOUR from Earth orbit and put it in a heliocentric trajectory.

Contact was not regained 46 minutes after the scheduled firing as planned. It was assumed the firing was at least partially completed, on 16 August three objects were observed on the approximate trajectory CONTOUR would have entered if the firing had ended 3 seconds early. When no contact was made by 20 December, the mission was declared lost. A mishap investigation board concluded the most likely cause of the failure was structural failure due to plume heating by the embedded solid rocket motor burn.

A successful firing would have put CONTOUR in the proper trajectory for an Earth fly-by in August 2003 followed by an encounter with comet Encke on 12 November 2003 at a distance of 100 to 160 km and a fly-by speed of 28.2 km/sec, 1.07 AU from the Sun and 0.27 AU from Earth. Three more Earth fly-bys were to follow, in August 2004, February 2005, and February 2006. On 18 June 2006 CONTOUR would encounter comet Schwassmann-Wachmann-3 at 14 km/sec, 0.95 AU from the Sun and 0.33 AU from Earth. Two more Earth fly-bys were scheduled in February of 2007 and 2008, and a fly-by of comet d'Arrest was possible on 16 August 2008 at a relative velocity of 11.8 km/sec, 1.35 AU from the Sun and 0.36 AU from Earth.

All fly-bys had a planned closest encounter distance of about 100 km and would have occurred near the period of maximum activity for each comet. After the comet Encke encounter, CONTOUR could 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).

Alternate Names

  • 27457
  • Comet Nucleus Tour
  • urn:nasa:pds:context:instrument_host:spacecraft.con

Facts in Brief

Launch Date: 2002-07-03
Launch Vehicle: Delta II 7425
Launch Site: Cape Canaveral, United States
Mass: 328 kg

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Joseph F. VeverkaMission Principal InvestigatorCornell
Dr. Robert W. FarquharMission DirectorApplied Physics Laboratory

Selected References

  • CONTOUR Mishap Invest. Board, Comet nucleus tour CONTOUR - Mishap investigation board report May 31, 2003, NASA, Unnumbered, Wash., DC, Undated.
  • Cochran, A., et al., The comet nucleus tour (CONTOUR): A NASA Discovery mission, Earth, Moon and Planets, 89, No. 1-4, 289-300, 2002.
[CONTOUR diagram]

Full CONTOUR Mishap Board Investigation Report (PDF file)

CONTOUR Mishap Board Completes Investigation - Press Release (15 October 2003)
CONTOUR Team Ends Contact Attempts - Press Release (20 December 2002)
Team readies for final attempts to contact CONTOUR - Press Release (13 December 2002)
NASA Appoints CONTOUR Mission Investigation Team - NASA Press Release (26 August 2002)
Team scales back CONTOUR monitoring - Press Releases (21-23 August 2002)
Contact lost with CONTOUR spacecraft - Press Releases (15 - 19 August 2002)
CONTOUR Spacecraft Launches from Cape Canaveral - NASA Press Release (3 July 2002)
Prelaunch Press Briefing - NASA Press Release (12 June 2002)
CONTOUR Approved for Construction - NASA Press Release (15 Feb 2000)

Comet Page
Comet Fact Sheet
NASA's Discovery Program
Press Release on selection of CONTOUR mission - 20 October 1997
Stardust Comet Sample Return Mission

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