Space Missions: Chasing Comets and Asteroids


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	Space Missions: Chasing Comets and Asteroids By Michael Paine Special to SPACE.com posted: 08:17 pm ET 08 February 2000

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Several researchers are using supercomputers to predict the effects of asteroid-deflection techniques. One day these simulations may be needed to plan a mission to save Earth from a collision.

But the physical properties of asteroids and comets are poorly understood, and so the information gathered from space missions to these objects is crucial for these simulations.

Several challenging missions to asteroids and comets are underway or are planned.

Space Missions to Asteroids and Comets

Deep Space 1: NASA. Launched in 1998. DEEP SPACE 1 flew within 10 miles (16 kilometers) of Asteroid 1992 KD Braille on July 28, 1999. The mission is mainly a test of new propulsion and navigation technology. The extended mission was to include flybys of two comets, Wilson-Harrington and Borrelly, but a problem with the tracking system meant that priority is now being given to Comet Borrelly.

NEAR: NASA. Launched in 1996. NEAR flew within 753 miles (1,212 kilometers) of Asteroid Mathilde in June 1997. Earth swing-by January 1998. Planned Eros rendezvous in January 1999 failed. Next attempt February 14, 2000 when NEAR will go into orbit around Eros.

MUSES C: Japanese Space Agency. Launch planned for 2002. MUSES C is a mission to the asteroid, Nereus. This mission will return fragments of Nereus' surface to the Earth for detailed analysis.

CONTOUR: ASA/JPL Launch planned for 2002. The CONTOUR spacecraft will study three: Encke, Schwassmann-Wachmann 3 SW3 and d'Arrest.

Rosetta: European Space Agency (ESA). Launch planned for 2003. ROSETTA is designed to land and remain on comet Wirtanen as it tours the inner solar system.

Stardust: NASA. Launched 1999. STARDUST will fly past comet Wild 2 and capture dust grains blown from the comet's surface. These will be returned to Earth for analysis.

NEAP: Spacedev Corp. SpaceDev is a publicly owned company. With the assistance of the science community, SpaceDev has selected 4660 Nereus, possibly a carbonaceous near-earth asteroid, as its NEAP mission target. To reach Nereus, NEAP is currently scheduled to launch on April 3, 2001 (possibly put back nine months to simplify the mission). It will land a payload on the surface of the asteroid and will be a demonstration of the potential for commercial mining of asteroids.

Deep Impact: NASA/University of Maryland. Launch planned for 2005. A University of Maryland proposed space mission to penetrate deep into the nucleus of a comet. The launch of the DEEP IMPACT mission is planned for January 2004. The schedule calls for the mission to reach its target, Comet Tempel 1, at the beginning of July 2005, with impact on July 4.

Although knowledge about asteroids is important for protecting Earth from collisions, it is more likely to be used, ultimately, for commercial purposes.

Over the next few decades an impact by a large asteroid is highly unlikely (but cannot be ruled out). During that time commercial mining of asteroids may become commonplace.

Many asteroids are rich in the raw materials needed for manufacturing in space, and some are easier to reach than the moon. Of course, one way to deal with an Earth-threatening object is to mine it away to nothing.