The Comet Nucleus Tour (CONTOUR) was a Discovery-class space mission. It 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 scheduled to be visited were Encke and Schwassmann-Wachmann-3, and the third target was d'Arrest. It was hoped that a new comet would have been discovered that would have been 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. Comet Hale-Bopp, showing a white dust tail and blue gas tail (February 1997) A comet is a small astronomical object similar to an asteroid but composed largely of ice. ... Comet Encke (officially designated 2P/Encke) is a periodic comet, named after Johann Franz Encke, who through laborious study of its orbit and many calculations was able to link multiple observations in 1786 (2P/1786 B1), 1795 (2P/1795 V1), 1805 (2P/1805 U1) and 1818 (2P/1818 W1) to... 2006 is a common year starting on Sunday of the Gregorian calendar. ... 2008 is a leap year starting on Tuesday of the Gregorian calendar. ... In statistics, compositional data is data in which each data point is an n-tuple of nonnegative numbers whose sum is 1. ...

After booster ignition for solar orbit injection on 15 August 2003, 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 been destroyed. Attempts to contact the probe were ended on 20 December 2003. The probe accomplished none of its objectives. August 15 is the 227th day of the year in the Gregorian Calendar (228th in leap years), with 138 days remaining. ... 2003 is a common year starting on Wednesday of the Gregorian calendar. ... December 20 is the 354th day of the year (355th in leap years) in the Gregorian calendar. ... 2003 is a common year starting on Wednesday of the Gregorian calendar. ...

Spacecraft design

The CONTOUR spacecraft had a total fueled mass of 775 kg, including 70 kg of hydrazine fuel and a Star 27 SRM booster with a mass of 377 kg. Power was provided by a body-mounted solar array designed for operation at distances between 0.75 and 1.5 AU from the Sun. It was three-axis stabilized for encounters and spin-stabilized during cruise mode between encounters. Communications were through a fixed 0.45 m diameter high-gain antenna to support data rates greater than 100 kbit/s at encounters. Data and images were stored on two 3.3 Gbit solid-state recorders with a capacity of 600 images. The spacecraft was 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

CONTOUR launched on a Delta 7325 (a Delta II Lite launch vehicle with three strap-on solid-rocket boosters and a Star 27 third stage) on July 3, 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 Star 27 solid rocket motor was used to perform an injection maneuver on August 15, 2002 to 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/s, 1.07 AU from the Sun and 0.27 AU from Earth. During the maneuver the probe was lost. Three more Earth fly-bys would have followed, in August 2004, February 2005, and February 2006. On 18 June 2006 CONTOUR would have encountered comet Schwassmann-Wachmann-3 at 14 km/s, 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 might have occurred on 16 August 2008 at a relative velocity of 11.8 km/s, 1.35 AU from the Sun and 0.36 AU from Earth. All fly-bys would have had a 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 might have been retargeted towards a new comet if one is discovered with the desired characteristics (e.g. active, brighter than absolute magnitude 10, perihelion within 1.5 AU). July 3 is the 184th day of the year (185th in leap years) in the Gregorian calendar, with 181 days remaining. ... 2002 is a common year starting on Tuesday of the Gregorian calendar. ... August 15 is the 227th day of the year in the Gregorian Calendar (228th in leap years), with 138 days remaining. ... 2002 is a common year starting on Tuesday of the Gregorian calendar. ... November 12 is the 316th day of the year (317th in leap years) in the Gregorian Calendar, with 49 days remaining. ... 2003 is a common year starting on Wednesday of the Gregorian calendar. ... June 18 is the 169th day of the year in the Gregorian Calendar (170th in leap years), with 196 days remaining. ... 2006 is a common year starting on Sunday of the Gregorian calendar. ... August 16 is the 228th day of the year (229th in leap years) in the Gregorian Calendar. ... 2008 is a leap year starting on Tuesday of the Gregorian calendar. ...

External links

CONTOUR homepage Report of the NASA Mishap Investigation Board on the loss of the spacecraft