The safe hold is a pre-programmed, automatic response by the spacecraft to an unplanned event which requires immediate corrective action. In this case, the spacecraft stopped all routine operations, pointed its medium gain antenna at Earth, and awaited further instructions.

Recovery from the safe hold and return to normal operations occurred on the afternoon of February 2, and the spacecraft successfully executed a revised engine burn on February 3 at noon EST (17:00 UT).

The cause of the safe hold was incorrect data input to the spacecraft attitude control system as onboard accelerometers were powered up, which resulted in a small autonomous engine firing. Fuel expenditure was insignificant.

Helen Worth, NEAR mission spokesperson at John Hopkins' said that an electical spike occured that exceeded operational parameters as the accelerometers were powered on. The reason why this is happening is not yet known, but as a precaution the accelerometers will be left on until the cause of the problem is determined. At this stage of the mission leaving them on is not a problem. With the successful engine burn today, the NEAR spacecraft is back on course for arrival at Eros as planned on February 14.

NEAR managers in their latest science report confirmed that there was some lose of science observations that were scheduled to take place during the time that the spacecraft was in safe hold.

After another heroic effort on the part of our sequencing team and operations team, a new set of commands has been loaded on the spacecraft to recover the most critical of these observations, which include image sequences of Eros and an infrared spectrometer mirror geometry test.

The image sequences will be used for optical navigation to pin down the trajectory of the spacecraft now that the engine burn has been completed.

The infrared spectrometer test was needed to determine accurately the look direction of the instrument, which uses a scan mirror.

This mirror functions like a periscope - we turn the mirror to scan the instrument field of view through a 140 degree arc.

The test will use Eros as a source of light to calibrate the viewing direction versus the scan mirror position.

For the test to work, Eros cannot be too close or too far - hence the need to perform the test this week.

Both the recovery image sequences and mirror geometry test are scheduled to occur over the next few days.

Spacecraft Operations

Feb 4   Eros Satellite Search C
Feb 8   Rendezvous Maneuver and Momentum Bias
Feb 9   Eros Satellite Search D
Feb 14  Eros Orbit Insertion

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