CONTOUR: NASA's failed comet explorer

Artist's Illustration of CONTOUR at a comet. Credit: NASA

• Launch Date: July 3 2002
• Launch Site: Space Launch Complex 17A, Cape Canaveral Florida, United States
• Launch Vehicle: Delta 7425-9.5 (no. D292)
• Mission Type: Flyby
• Targets: Encke, Schwassmann-Wachmann-3, and possibly d'Arrest.
• Dimensions: 1.8 Meters across, and 2.1 Meters long
• Mass: 328 Kilograms

You can build your own CONTOUR spacecraft out of LEGO here.

The COmet Nucleus TOUR (CONTOUR) spacecraft was part of a NASA mission to study two, possibly three comets. The spacecraft never made it out of Earth orbit.

The Mission

CONTOUR was conceived as NASA's sixth Discovery class mission. While most Discovery missions have ended up making great discoveries, as intended, CONTOUR would never get to fulfill its full potential.

The mission was planned to take high resolution images of up to 4 meters, and mapping the surface of its primary targets. While it was expected that the spacecraft could visit comet d'Arrest after its primary mission, the hope was to send it to an as yet undiscovered comet, similar to ESA's upcoming Comet Interceptor plan. However, this would be an inner solar system comet, instead of an Oort cloud comet.

CONTOUR specifications. Credit: NASA/JHAPL

After launch in Summer of 2002, the spacecraft would make a flyby of Encke on November 12 next year. Three years later CONTOUR would fly by Schwassmann-Wachmann-3 on June 19, 2006. If all went well, and no other suitable comets could be found, CONTOUR would fly by d'Arrest on August 16, 2008.

After launch, CONTOUR was placed in an orbit with a period of around five-and-a-half days. Almost two dozen orbital maneuvers were implimented to prepare the spacecraft for its exit of the Earth/Moon system, and to start its cometary journey.

On August 15, 2002, CONTOUR was sent the command to perform the burn that would send the spacecraft into heliocentric orbit. Communication ceased, and the spacecraft was never heard from again.

Fragments of CONTOUR, circled in green. Credit: Spacewatch/Lunar and Planetary Laboratory/University of Arizona

An investigation of the incident showed that the spacecraft had broken up during the burn. The cause was determined to be a fault in the solid rocket motor that caused "plume heating," which ripped apart the spacecraft.

The Targets

Encke imaged by the Spacewatch Kitt Peak teliscope. Credit: Jim Scotti/Spacewatch

• Date Discovered: January 17, 1786
• Designation: 2P/Encke
• Class: Encke-Type Comet [NEO]
• Radius: 2.4 Kilometres
• Rotational Period: 11.08 Hours
• Orbital Period: 1204.01 Days (3.3 Years)

  
  

Breakup of Schwassmann-Wachmann-3 as seen by Hubble. Credit: NASA/ESA/H. Weaver (APL/JHU)/M. Mutchler and Z. Levay (STScI)

• Date Discovered: May 2, 1930
• Designation: 73/sChwassmann-Wachmann-3 (Fragment C)
• Class: Jupiter Family Comet [NEO]
• Radius: N/A
• Rotational Period: N/A
• Orbital Period: 1958.48 Days (5.36 Years)

This data is for Schwassmann-Wachmann-3's primary body (fragment C). The comet broke up into multiple pieces in 1995.

Comet d'Arrest can be seen in the center of this image from the Steward Observatory. Credit: Steward Observatory/Elizabeth Romer

• Date Discovered: June 28, 1851
• Designation: 6P/d'Arrest
• Class: Jupiter Family Comet
• Radius: 1.6 Kilometres
• Rotational Period: N/A
• Orbital Period: 2388.84 Days (6.54 Years)