[meteorite-list] Rosetta Update - March 8, 2004
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:47 2004 Message-ID: <200403092028.MAA03178_at_zagami.jpl.nasa.gov> http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=34822 Activating Rosetta European Space Agency March 8, 2004 Summary The spacecraft and ground segment continue to operate well. All activities planned for the initial, critical phase after launch have been successfully completed ahead of schedule. In the early morning of 5 March the Mission Control Team at ESOC has moved from the Main Control Room to the Rosetta Dedicated Control Room to commence the spacecraft and payload commissioning. This early relocation of the team, just 3 days after launch, is a record at ESOC and it is seen as remarkable, considering the complexity of the Rosetta spacecraft. The 5-day launch delay, from 26 February to 2 March, has been largely recovered and the early commissioning activities are now scheduled to within 1 or 2 days of the original plan. The New Norcia ground station in Australia (35 m antenna) will support the daily operations, while the support from the ESA Kourou and NASA Deep Space Network Madrid and Goldstone ground stations has been released with the termination of the critical phase. By midday on 8 March Rosetta is already 2 million km from the Earth. The signal round-trip light-time is almost 14 seconds. Ground Stations Location Latitude Longitude Type Size Kourou French Guiana 05.25° N 52.80° W Beam Wave Guide 15 m New Norcia Australia 31.03° S 116.11° E Beam Wave Guide 35 m DSS 24 Goldstone, USA 36.69° N 116.87° W Beam Wave Guide 34 m DSS 54 Madrid, Spain 41.15° N 04.25° W Beam Wave Guide 34 m Spacecraft Activities Initial activation of S-band transmission, using the 2.2 m large dish antenna, commenced at 23:16 on 3 March. Successful commissioning of the S-band up and downlinks on the low and high gain antennas took place throughout the night. Following on from this, configuration of the X-band, also using the high gain antenna, took place with a downlink signal received at both the Kourou and Madrid ground stations at 13:07 UT. Termination of the S-band uplink occurred at 13:20 and X-band uplink established at 13:35. The X-band uplink was then terminated at 14:30 and uplink communications were re-established via the High Gain Antenna at S-band. By 7 March, tests of the X-band communications had been completed. These activities successfully demonstrated the nominal performance of the major communication systems, which will be critical for the mission. Due to the rapidly increasing distance between the spacecraft and the Earth, the possible data rate using the low gain antenna is already limited to 7.8 bits per second and this link will soon vanish. Using the High Gain Antenna the maximum data rate of 22 kbits per second is sustainable. The attitude control system has undergone several characterization tests, such as gyroscope calibrations and determination of the friction in the reaction wheel system. This included, for the first time, switching on all four reaction wheels simultaneously. Substantial disturbance torques acted on the spacecraft during its first few days in orbit. Over the following days these torques gradually decreased to nominal levels. The phenomenon, attributed to the outgassing of the spacecraft, diminishes with time because the spacecraft is in the high vacuum of space. Full configuration of the 25 Gbit solid-state mass memory took place on 4 March in order to support routine operations: creating data stores for all instruments and storing redundant files of application software. Activation of all memory modules for the mission is now complete. Commissioning of the power subsystem took place at the end of the Madrid pass on 4 March. All checks were successful and the power subsystem behaved as expected. The drive mechanisms of the solar array are being exercised during the early days of the flight in order to keep the solar cells perpendicular to the Sun as the spacecraft rotates. The azimuth and elevation drives, enabling the High Gain Antenna to track the Earth, have been extensively characterized. These mechanical functions are critical to the mission and they are working nominally. Overview of Activities Note all times are in Universal Time (UT) LOS = Loss of Signal AOS = Acquisition of Signal EOT = End of Transmission 3 March 2004 15:50 Bit rate changed to 52428.8 sps 16:14 AOS DSS24 16:27 Stop Uplink DSS54 16:31 Start Uplink DSS24 21:33 LOS Kourou 22:23 AOS New Norcia 23:01 Ranging stopped at DSS24 23:06 Stop Uplink DSS24 23:10 Start Uplink New Norcia 23:16 Ranging started from New Norcia 23:19 Ranging stopped at New Norcia 23:21 Stop Uplink New Norcia 23:31 Start Uplink New Norcia with reduced power before HGA activation (100 W) 23:53 HGA antenna on Transponder#1 activated. New Norcia and DSS24 have an increased input level of 32 dB 4 March 2004 00:50 EOT DSS24 07:06 AOS DSS54 07:29 Telecommunication link out 07:30 Carrier Down New Norcia 08:00 Start S-Band commissioning procedure 08:00 Switch HGA to LGA Rear 09:00 TC bitrate change to 1000 bits per second (bps) 09:58 AOS Kourou 10:08 LOS New Norcia 10:22 TC bitrate change to 250 bps on Transponder 2 10:40 TC bitrate change to 1000 bps on Transponder 1 10:50 TC bitrate change to 250 bps on Transponder 1 10:56 TC bitrate change to 7.8125 bps on Transponder 1 11:05 TC bitrate change to 2000 bps on Transponder 2 11:14 Change over to the on board Ultra Stable Oscillator 12:40 Kourou configured for X-band 13:07 X-band AOS in Kourou and DSS54 13:27 X-Band Telemetry processed from Kourou 13:34 X-Band Carrier up from Kourou 13:34-14:20 Several re-sweeps were conducted at different uplink levels (300W, 12W, 6W) in order to check the onboard AGC readings 14:20 First X-Band Command sent from Kourou 15:44 TMm Symbol rate change to 5461 sps 15:55 Switch HGA to LGA Rear 16:52 TC bitrate change to 7.8125 bits per second 21:30 LOS Kourou 22:21 AOS New Norcia 23:37 Carrier down New Norcia 23:50 Carrier up New Norcia with reduced power (100 W) after HGA Earth pointing and activation 5 March 2004 00:15 Downlink switched off Transponder 1 on LGA Downlink switched on Transponder 2 on HGA 00:18 Transmitter 2 on-board switched on: HGA radiating in S-Band 00:24 TLM symbol rate change to 52428.88 sps. Ranging Modulation index change to 0.2 rad 08:36 Switch over from Transponder 1 to Transponder 2 08:40:00 Transponder switch: downlink drop Transponder 1 08:40:19 Transponder switch: downlink back on Transponder 2 10:05 LOS New Norcia 11:00 End of Launch and Early Orbit Phase Planned Instrument Activities COSIMA 08 Mar First payload commissioning CONSERT 11 Mar Payload commissioning, including antenna deployment OSIRIS 12 Mar Payload commissioning Lander 12-17 Mar Payload commissioning RPC 17-21 Mar Payload commissioning Planned Spacecraft Activities 09 Mar Change attitude to +X axis Sun pointing, test of the star trackers in the new attitude and Sun sensor alignment calibration 10 Mar Solar array flexible modes calibration 18 Mar RPC boom deployment Orbit Trajectory At 12:00 on 8 March 2004 Rosetta was 1.988 million km from Earth. This placed it more than one million km outside its sphere of influence. Orbital elements are, therefore, quoted with respect to the Sun as Earth centric information is not so relevant at such a distance. The signal round-trip time was 13.26 seconds. EPOCH (UTC) 2004/03/08 11:58:55.8 UTC Heliocentric state and elements (reference plane is Earth mean equator of J2000.0) Position (km) X -143442749.489284 Y 27368977.567599 Z 12005574.989980 Velocity (kms-1) Xdot -3.027967 Ydot -27.696812 Zdot -11.774408 Semi Major Axis km 148022446.315397 AU 0.9895 Eccentricity 0.105414 Inclination (°) 23.044997 Ascending Node (°) 0.340809 Argument of Pericentre (°) 258.457557 True Anomaly (°) 269.460347 Pericentre Distance km 132418878.617842 AU 0.8852 Apocentre Distance km 163626014.012952 AU 1.0938 Osc. Orbit Period Hours 8628.055233 Days 359.5 Received on Tue 09 Mar 2004 03:28:35 PM PST |
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