The upcoming burn will last 24 minutes and will increase the spacecraft's speed by 2,100 mph (939 meters per second), putting it at close to the same speed as Eros. The burn will be divided into an initial three-minute "settling burn" with the spacecraft's small hydrazine thrusters that will change its velocity by only 11 mph (five meters per second), and a 21-minute firing of the bipropellant main engine that will provide the rest of the velocity change.

The burn will lessen the distance between NEAR and Eros as they orbit the sun. For the next year NEAR will travel behind Eros in a slightly closer orbit to the sun, which will enable it to pick up speed. By mid-February 2000, NEAR will catch up to Eros. The spacecraft will then enter orbit around Eros and begin its planned year long study of the asteroid.

The spacecraft's first attempted rendezvous burn was aborted on Dec. 20, 1998, just seconds after the settling burn was completed. An investigation by mission personnel revealed that the brief engine burn exceeded certain safety limits associated with the onboard system that autonomously controls the spacecraft. This resulted in the engine abort. Reprogramming of these values is now being completed and the spacecraft will be ready for the Jan. 3 burn.

"We're very confident that we've found the problems associated with the Dec. 20 abort," says Thomas B. Coughlin, NEAR Project Manager at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, MD, which manages the mission for NASA. "The abort lost us time but the flyby gave us valuable information about Eros' shape and mass that we wouldn't have had -- information that will help us during our orbital phase a little more than a year from now."

Because the spacecraft did not complete the Dec. 20 burn, the opportunity to orbit Eros next month as originally planned was lost. The setback presented mission planners with a huge challenge but also an unexpected opportunity. Within days of the abort, the NEAR team developed a complicated command sequence for a Dec. 23 flyby of Eros to obtain multicolor images, near-infrared spectra, and magnetic field measurements. The commands were uploaded swiftly to the spacecraft and executed as planned, producing images of the asteroid and valuable data that is now being processed.

Due to the rescheduling of mission events, the previously announced Jan. 10 and Jan. 14 press briefings have been canceled.

Near Earth Asteroid Opportunities

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