ACE Weekly 10/24/2007 - 10/30/2007 All ACE spacecraft subsystems are performing nominally. ============================================================================ Orbit/Attitude: Type Attitude Date 10/29/2007 DOY 302 2007 Thrusters 2R 4R+ 4R- Duration 14:19 min Start 15:27:49z Stop 15:42:08z HGAStart -6.90deg HGAStop +7.25deg SunStart 12.70deg SunStop 5.85deg Nutation 0.44deg Firing 73 pulses FuelUsed 0.2381lbs FuelRemain 153.7592lbs FinalSCMass 1388.019lbs The next attitude maneuver is scheduled for Thursday, 11/15/2007. ============================================================================ OCRs: DOY 303 (10/30/2007) OCR GND-189 Recalculate Clock Calibration Over the years, several problems have been corrected in the clock calibration calculation (leap seconds, bad ground receipt time, numerical error, incorrect epoch, etc.) ASC had adjusted several solutions while the problems were being resolved. This OCR uses the updated clock calibration software delivered 12/05/2006 (OCR GND-174) to recalculate the clock calibration for the entire life of the mission. These updated values are not expected to deviate from the ASC adjusted values by more than 1 second. Note that this recalculation does not incorporate the range delay as decided by the instrument teams at the Science Working Team meeting (October 2007). All timestamps (maneuvers, limit violations, etc) correspond to the Ground Receive Time (aka Earth Receive Time). The actual spacecraft events occur approximately 5 seconds before the time given due to the light travel time (aka range delay). ============================================================================ Activities: Space Link Extension (SLE) Testing status (F-CLTU) Wed 10/24 297 DSS-46 DSS-46 was RED due to X Axis brake failure Thu 10/25 298 DSS-34 Success with CMD and receiving low and medium TLM Mon 10/29 302 DSS-46 Several problems were encountered with this test * Unable to bind and no telemetry available due to problems with the Monitor Control Processor (MCP1). Station rebooted MCP, reloaded the desktop and reconfigured for the SLE test support. The MOC finally received telemetry. * The MOC was still unable to bind. The station reset the Telemetry Control Processor (TCP) system clock which was running 5 seconds fast. The MOC was finally able to bind. * The MOC was still unable to command. The station halted the command state and returned to Operate mode which then allowed successful commanding. * The MOC commanded to high-rate, but did not receive VC2 data. The station had to unload the desktop and reconfigure. DSN will continue to reconfigure the ACE 26m desktops. The desktops had already been updated to resolve a previous problem of not discarding uncorrectable data. DSN will review their procedures concerning resetting the TCP clock and/or widening the command time constraint. The following tests have been scheduled for upcoming weeks Day Date DOY Station Thu 11/01 305 DSS-66 with DSS-27 Thu 11/01 305 DSS-27 Mon 11/05 309 DSS-24 Wed 11/07 311 DSS-46 DSS-45 (34m HEF, Canberra) has had an S-Band Transmitter installed. After testing DSS-45, ACE will start using it along with the currently used DSN stations (24, 27, 34, 46, 54, 66). The DSS-45 tests have been scheduled for Monday 11/12/2007 and Thursday 11/15/2007. DSS-65 (34m HEF, Madrid) will also have a new S-Band Transmitter and will be tested in December. ============================================================================ Anomalies: DOY 297 10/24/2007 S-ACE-0240 G07-0093 DSS-66 TLM/CMD Outage DSS-66 uplink and downlink signal strength started decreasing at 150900z. Signal strength returned to nominal at 151030z. A command transmitted at 150930z was retransmitted. IMPACT: Minimal. Brief 1 minute telemetry outage and the spacecraft's RCVR B lost lock on the uplink. DOY 298 10/24/2007 S-ACE-0241 G07-0094 ROBOTT/C&C Start 2 Procs ROBOTT/C&C started 2 procedures without waiting for the other to complete; G_END_DAY (19:10:01) and S_OPS_PLBK_COMPLETE (19:10:11). The spacecraft was commanded to BinDump format when SSR redumps were started. IMPACT: The automation software sent commands to the spacecraft in an unexpected order. Fortunately, the STOL procedures successfully handled the unexpected spacecraft configuration. Several contingency situations have been incorporated into procedures.