by Dr. Tony Phillips
|Comet Tempel 1, as seen by the Deep Impact impactors camera. Three last-minute AutoNav-controlled impact correction maneuvers enabled the Impactor to hit the bulls-eye.|
The system was developed and tested on another "Deep" spacecraft: Deep Space 1, which flew to asteroid Braille in 1999 and Comet Borrelly in 2001. The mission of Deep Space 1 was to try out a dozen new technologies, among them an ion propulsion drive, advanced solar panels and AutoNav. AutoNav worked so well it was eventually installed on Deep Impact.
"Without AutoNav, the impactor would have completely missed the nucleus," says JPL's Ed Riedel, who led the development of AutoNav on Deep Space 1 and helped colleague Dan Kubitschek implement it on Deep Impact.
En route to the nucleus, AutoNav "executed three maneuvers to keep the impactor on course: 90, 35, and 12.5 minutes before impact," says Riedel. The nearest human navigators were 14 light-minutes away (round trip) on Earth, too far and too slow to make those critical last-minute changes.
Having proved itself with comets, AutoNav is ready for new challenges: moons, planets, asteroids wherever NASA needs an improbable bulls-eye.
Dr. Marc Rayman, project manager for Deep Space 1, describes the validation performance of AutoNav in his mission log at http://nmp.nasa.gov/ds1/arch/mrlog13.html (also check mrlog24.html and the two following). Also, for junior astronomers, the Deep Impact mission is described at http://spaceplace.nasa.gov/en/kids/deepimpact/deepimpact.shtml
This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.