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No. 158 - Spin-up and entry into deep-space hibernation

No. 158 - Spin-up and entry into deep-space hibernation

Report for the period 6 to 14 June 2011This report covers nine days of Rosetta mission operations. The main activities were the spin-up of the spacecraft and entry into deep-space hibernation mode. The spacecraft will remain in this state until 20 January 2014 when the hibernation exit sequence will be initiated. The next Rosetta status report will be issued towards the end of January 2014.

During the reporting period Rosetta was successfully spun-up and commanded into Deep Space Hibernation Mode. The manoeuvre was executed as planned on 8 June without problems. The signal was lost on-ground at about 08:00:35 UTC when the spin-up manoeuvre was triggered on board the spacecraft. After the initial transient, the NASA Deep Space Network (DSN) DSS-43 70-metre antenna in Canberra detected an extremely weak strobing signal. This information was invaluable for the mission controllers in that they had confirmation that the spacecraft had successfully executed the most critical phase of the manoeuvre. About 50 minutes later, the on-board software repositioned the high-gain antenna after estimation of the actual principal inertia axis (that is, the real spin axis). The strength of the signal received on-ground increased sharply to the expected level (that is, the same level as was observed when the spacecraft was not spinning); this was visible at both DSS-43 and New Norcia. This confirmed that:

  • All the autonomous pre-hibernation checks were successful, otherwise a safe mode would have been triggered;
  • The difference between the estimated and the measured principal inertia axis was between 4.5 and 8 degrees, otherwise either a stronger signal would have been observed or a safe mode would have been triggered by the on-board software;
  • The inertial pointing of the spacecraft was very good, otherwise the signal strength would not have been as strong as before the spin-up, when the spacecraft was perfectly pointing to Earth.

Once all the planned ground checks had been completed (strobing period and signal strength) the telecommand link was verified by switching the spacecraft telemetry modulation on and off twice and monitoring the change in signal strength. The pulsing signal received at DSS-43 at the time of the test confirmed that signal was transitioning to a lower level when the telemetry modulation was on.

The final telecommand to authorise hibernation entry was released at 12:57:40 UTC and confirmation of successful transition into hibernation mode came at 14:12:00 UTC when the last pulse from the spacecraft was received by the ground stations.

A passive monitoring phase of six days was then completed to ensure that the spacecraft had not aborted the operation due to multiple failures. The wake-up time has been set to 2014.020:10:00:00 UTC (20 January 2014 at 10:00 UTC) with a planned downlink signal a few hours later, following a warm-up phase and spin-down via Safe Mode.

During the reporting period, mission operations were conducted using the ESA New Norcia (NNO) and Cebreros (CEB) ground stations and the DSS-14 (Goldstone, 70 metres) and DSS-43 (Canberra, 70 metres) NASA DSN antennas.

Main activities during reporting period

DoY Date Pass Activity
157 6-Jun-2011 NNO 2659 Setting of wake-up time
158 7-Jun-2011 NNO 2660
CEB 2661
Configuration of spin-up parameters
Go/no-go decision for spin-up
159 8-Jun-2011

DSS-14 2661
DSS-43 2661
NNO 2661

Spin-up manoeuvre and hibernation entry
160 9-Jun-2011 DSS-14 2662
NNO 2662
Passive monitor
161 10-Jun-2011 NNO 2663 Passive monitor
162 11-Jun-2011 NNO 2664 Passive monitor
163 12-Jun-2011 NNO 2665 Passive monitor
164 13-Jun-2011 NNO 2666
DSS-14 2666
Passive monitor
165 14-Jun-2011 NNO 2667 Passive monitor

DoY = Day of year

At the end of the reporting period on 14 June, Rosetta was 562 million kilometres from Earth (3.75 AU); one-way signal travel time was 1875 seconds (31 minutes 15 seconds). The spacecraft distance from the Sun was 671 million kilometres (4.48 AU).

During the hibernation phase, Rosetta will reach the following record distances:

  • 792 million kilometres (5.29 AU) from the Sun on 3 October 2012
  • 937 million kilometres (6.26 AU) from Earth on 1 December 2012
At exit from the hibernation phase on 20 January 2014, Rosetta will be at 807 million kilometres (5.39 AU) from Earth and 672 million kilometres (4.49 AU) from the Sun.

Spacecraft

Payload Status
ALICE The instrument is currently OFF.
CONSERT The instrument is currently OFF.
COSIMA The instrument is currently OFF.
GIADA The instrument is currently OFF.
MIDAS The instrument is currently OFF.
MIRO The instrument is currently OFF.
OSIRIS The instrument is currently OFF.
ROSINA The instrument is currently OFF.
RPC The instrument is currently OFF.
RSI The instrument is currently OFF.
VIRTIS The instrument is currently OFF.
Lander (Philae) The instrument is currently OFF.
SREM The instrument is currently OFF.

Future milestones

The spacecraft is now in Deep Space Hibernation Mode and will remain in this status until 20 January 2014, when it will initiate the hibernation exit sequence:

  • 10:00:00 – 10:15:00 UTC: Wake-up time detected and start of star trackers warm-up phase
  • 16:25:00 – 16:40:00 UTC: End of warm-up phase and spin-down via Safe Mode
  • 17:35:00 – 17:50:00 UTC: Expected S-band downlink signal on-ground

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Legal disclaimer
This report is based on the ESOC mission operations report, WOR #158. Please see the copyright section of the legal disclaimer (linked from the home page http://sci.esa.int) for terms of use.

Last Update: 1 September 2019
28-Nov-2020 15:13 UT

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