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Aqua Daily Report May 17, 2002 1130 GMT - May 20, 2002 1130 GMT

Status Report From: Goddard Space Flight Center
Posted: Monday, May 20, 2002

(DOY 137:1130z – 140:1130z)

The following activities were completed:

  1. On Friday (May 17), spin-up of the AMSR-E instrument commenced with an increase, in steps, from 4 to 21 rpm and their “spin-down” telemetry monitors (TMONs) were enabled. Daily uplink of the Master Command Loads and Ephemeris were also completed.
  2. Overnight Friday, the HSB and AMSU-A1 and A2 instruments performed their Cold Soak tests.
  3. On Saturday, as part of the continuation of the spin-up to the 40 rpm operational rate, the AMSR-E OBM was statically balanced followed by an increase in spin rate to 24 rpm. Daily uplink of the Master Command Loads and Ephemeris were also completed.
  4. The AMSR-E spin-up continued on Sunday (May 19). While at the 34 rpm spin rate “step” and while out-of-contact, the spacecraft transitioned to Survival state (inducing a spacecraft 911 to the Ground System). As part of the Survival state transition, the AMSR-E instrument was automatically de-spun to 4 rpm. As a result of the anomaly (see Anomaly #1), instrument statuses are now:
    1. AIRS, AMSU, CERES, HSB, and MODIS are in Survival mode
    2. AMSR-E is in Modified Sleep, rotating at 4 rpm.
  5. Science data processing status: HSB Level 0 science data has been received by the JPL DAAC and is being analyzed.

The following activities are scheduled for the next 24 hours:

  1. Activities will be performed to transition back to Earth Point Mode.
  2. Uplink the daily Master Command Loads and Ephemeris (tentative).

Aqua Spacecraft Status:

  1. Spacecraft State is currently Survival.
  2. GNC Mode is Sun Point Mode, HiFi Ephemeris.

Aqua Instrument Status:

  1. AIRS is in Survival state, Quiet bus is OFF, Noisy bus is OFF, Cryocooler is OFF, Scan mirror rotating is OFF and earth shield is CLOSED.
  2. AMSR-E is in Modified Sleep mode, rotating at 4 RPM.
  3. AMSU A1 is in Survival mode and the antenna is in the Target position.
  4. AMSU A2 is in Survival mode and the antenna is in the Target position.
  5. CERES Aft is in Survival mode and the covers are CLOSED.
  6. CERES Fore is in Survival mode and the covers are CLOSED.
  7. HSB is in Survival mode and the antenna is in the Target position.
  8. MODIS is in Survival mode, Nadir Door is Unlatched and CLOSED, Solar Diffuser Door is Unlatched and CLOSED, and the Space View Door is Unlatched and CLOSED.

Activities Deferred:

  1. All instrument activation activities have been postponed until Spacecraft recovery to Earth Point Mode.

Anomalies:

  1. At 16:15z on Sunday (May 19) while the spacecraft was in a planned out-of-view period, the EOC received notification from TDRSS that the Aqua spacecraft declared an emergency and began broadcasting the ‘911’ 1k telemetry format. With telemetry data immediately routed to the consoles in the launch support room, the flight support team quickly assessed that the spacecraft was in Survival Mode and had begun to reconfigure itself for sun pointing. An immediate concern was the AMSR-E instrument, which had been in the process of spin-up and balancing. However, the spacecraft momentum appeared to be low and the AMSR-E sensor unit was still spinning, but slowing down considerably from its initial speed of 34 rpm. The FST found that a level 3 fault was triggered from the power controller. As the spacecraft re-oriented its –X axis (propulsion module) toward the sun, the solar array began to generate power and recharge the battery. As the spacecraft acquired the sun and began to settle down, and as electrical power became steadily positive, the team switched the telemetry format to 4k Nominal in order to access instrument state of health. All instruments reported successful transition to their respective survival modes and were in excellent shape based upon limited telemetry from this mode. Loss of Signal (LOS) occurred before the spacecraft attitude settled completely, but enough telemetry had been received to convince the FST that the spacecraft was properly taking care of the business of going to Survival. Support personnel worked to schedule TDRSS contacts, but were hampered due to the spacecraft having been commanded to a higher 4k rate for 911. The EOC performed blind acquisition, commanded the spacecraft to the 1k format and acquired the return link signal. Telemetry showed the spacecraft in a stable condition and in safe mode. All Stored Command Sequences (SCSs) and control modes worked to bring the spacecraft to a safe sun pointed orientation. After establishing the state of health of the spacecraft, the EOC dumped the fault and activity logs from the power and GNC controllers. Evidence indicates that at 16:09:42 the power controller recorded a flag denoting excessive depth of discharge upon entering eclipse. Data indicated that the spacecraft entered sunlight at 16:09:43, one second after the flag was set. No other faults were recorded. Activity logs indicate the fault management SCSs activated as expected and demonstrated in I&T. Other data showed that the power subsystem was very healthy immediately after the event considering that it had just exited eclipse and would have begun charging the battery. Charging was interrupted by the transition to Sun Point Mode, but once sun pointed, the battery charged normally, consistent with Survival mode.
  2. During the AMSR-E run up from 4 to 12 rpm and 12 to 18 rpm, GNC detected disturbances in roll and yaw rates. The yaw amplitude remains constant from the 12 rpm run up which is consistent with a static imbalance. The increasing peak to peak amplitude in roll may be due to a solar array excitation mode. As an attempt to avoid the current SA excitation mode (at 18 rpm), AMSR-E was run up to an intermediate speed of 21 rpm. The AMSR-E OBM positions were re-verified, and a demonstration of OBM movement (OBM-XH) was performed. GNC analyzed the data and performed the necessary OBM balancing prior to continuance of spin-up activities.
  3. AMSR-E was unable to reset their SPC error flag 1 and SPS error flag 4. Resolution is under investigation.

// end //

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