NEAR Mission Status Report 12 May 2000

MISSION OPERATIONS:
 
NEAR Shoemaker continued to operate nominally this past week in orbit around the asteroid 433 Eros.  NEAR Shoemaker remained in Operational Mode with Flight Computer #1 and Attitude Interface Unit #2 in control of spacecraft attitude.  The spacecraft instrument suite remained "ON" and operational this week.
 
NEAR Shoemaker is presently in a nominal 50 km circular orbit around Eros. The spacecraft entered this orbit April 30, 2000 at 16:15 UTC when Orbit Correction Maneuver 6 (OCM 6) was executed.  According to the current long term trajectory plan, NEAR Shoemaker will remain in this orbit conducting Science observations until July 7, 2000 at 18:00 UTC when Orbit Correction Maneuver 7 (OCM 7) will initiate the 50 km x 35 km transfer orbit.
 
Since the next planned OCM is not scheduled until July 7, weekly Momentum Correction Maneuvers (MCM) are required to manage spacecraft system momentum.  Beginning May 10, these maneuvers are scheduled every Wednesday until June 28.  The first MCM during this period, MCM 3, was successfully executed this past Wednesday, May 10, at 14:00 UTC.  The achieved momentum was well within operational tolerances, and the imparted delta V was insignificant.
 
Revised XGRS PIN Diode autonomy rules and macros were loaded this past week. The modified autonomy rules trigger at a lower threshold voltage (2.995 volts) and disable the PIN diode for a shorter interval (2 hours) before attempting to reinitiate PIN diode solar detection.  Additionally, XGRS autonomy macros no longer effect the solar sensor toggle mode.  The revised XGRS rules and macros are performing as expected.
 
Science activities conducted this week included Eros observations by the full instrument suite: MSI, NIS, MAG, NLR and XGRS.  Please consult science timelines for more details.
 
Upcoming Spacecraft Activities:
 
In addition to regular Eros Science and Optical Navigation, the following are operationally significant activities planned for the NEAR Shoemaker mission operation:
 
May 17  Momentum Correction Maneuver 4
 
July 7  Eros Orbit Correction Maneuver 7  (50x35km transfer orbit)
 
July 14 Eros Orbit Correction Maneuver 8  (35km orbit circularization)
 
July 23 Eros Orbit Correction Maneuver 9  (35×50 km transfer orbit)
 
July 30 Eros Orbit Correction Maneuver 10 (50 km orbit circularization)