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JPL has critical role on NEAR asteroid orbit mission

JPL Universe
February 18, 2000

Several teams from JPL are contributing to the first-ever spacecraft mission to orbit an asteroid.

On Feb. 14, the Near Earth Asteroid Rendezvous (NEAR) mission, managed by Johns Hopkins University's Applied Physics Laboratory, went into orbit around asteroid 433 Eros, a potato-shaped, 34-kilometer-long (21-mile) body about 256 million kilometers (160 million miles) from Earth.

JPL teams are providing critical support to the mission in these areas:

  • Navigation
  • Radio science (including gravity science)
  • Deep Space Network tracking
  • Multispectral imager and near-infrared spectrometer
  • Shape modeling working group
  • Mission design (in conjunction with APL)

Dr. Don Yeomans, manager of JPL's Near-Earth Objects Program Office, is radio science team chief for NEAR, which will study Eros for a year, gradually dropping its elliptical orbit to as low as 1 kilometer above the surface by mission end. Another member of the team, Jon Giorgini of the Navigation and Mission Design Section 312, said the team is involved in tracking the asteroid's rotation state and gravity field, as well as the trajectory of the spacecraft in its orbit around Eros.

The navigation team has been involved with NEAR since its inception, including determining requirements for the spacecraft and selecting the target asteroid. The team, headed by JPL's Dr. Bobby Williams, processes radiometric data through the Deep Space Network and optical data through NEAR's onboard camera.

"This mission is not only the first to orbit an asteroid, it's also the first to use landmark tracking for deep-space navigation," Williams said, noting that craters on the rock are identified and then used for points of reference.

Williams said the spacecraft's current transfer orbit will continue through about March 10, at which point it will be lowered to about 200 kilometers (125 miles).

He said NASA is considering a crash landing on Eros at the end of the mission next February, when the spacecraft will be out of fuel.

Images of Eros and other information about the mission are available online at".

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