NEAR Shoemaker Weekly Report 2 Mar 2001

MISSION OPERATIONS:

NEAR Shoemaker Mission Operations was extremely busy during the final weeks
of the program. End of Mission activities began in late January with a
series of asteroid close flybys beginning January 24th and culminating on
January 28th. These flybys were immediately followed by two targeting
maneuvers, Orbit Correction Maneuver 24 (OCM 24) on February 2nd and Orbit
Correction Maneuver 25 (OCM 25) on February 6th. On February 12th, the
spacecraft performed a spectacular descent and soft landing on the surface
of 433 Eros. The precision of this propulsive maneuver sequence enabled an
extension to the mission, allowing the XGRS Gamma Ray Spectrometer and
Magnetometer to perform in situ measurements. Finally, during the last
track, on February 28th, the spacecraft was configured for hibernation mode.

The controlled descent and landing sequence, executed on February 28th,
consisted of a series of five propulsive maneuvers, End of Mission Maneuver
1 (EMM 1) through End of Mission Maneuver 5 (EMM 5). Entry into this
descent sequence began from a 35 km orbit with the execution of EMM 1 @
15:13:56 UTC and terminated on the surface of Eros with EMM 5. The final
four EMMs began at 18:58:35 UTC with EMM 2, after which subsequent maneuvers
were performed approximately every 15 minutes until EMM 5 terminated having
successfully soft landed NEAR Shoemaker on the surface of 433 Eros. Landing
velocity was approximately 1.5 m/sec and a telemetry beacon from the surface
was immediately received. Later that evening, realtime telemetry was
received from the spacecraft confirming its excellent state of health. All
subsystems were nominal and the Power Subsystem’s solar arrays were
generating 5 times more power than spacecraft loads required.

Success of the landing sequence precipitated an extension to the mission.
The landing orientation of the spacecraft pointed the instrument suite
directly at the asteroids surface. Exploiting this opportunity, the XGRS
science team requested, and was granted, two weeks to perform in situ Gamma
Ray measurements. Gamma Ray science records and Magnetometer science
packets were collected and retrieved during the mission extension.

On February 28th, Mission Operations conducted the final Deep Space Network
(DSN) contact with the NEAR Shoemaker spacecraft. Like every extended
mission track, this contact was performed with the 70 meter antenna at
Goldstone, DSS 14. As usual, XGRS Gamma Ray science records were recovered
during this contact. Additionally, final commands to initiate spacecraft
hibernation were transmitted to the spacecraft. To prevent interruption to
XGRS data recovery, these commands were loaded into timetag memory bins.
When executed, they will disable the remainder of the instrument suite and
Guidance and Control Subsystem components. Just before the end of track,
spacecraft telemetry was disabled and the active transponder’s exciter was
turned off. Loss of symbol stream and carrier lock were silent witnesses to
the end of the NEAR Shoemaker mission.