[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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