status reports 20-January-2019 12:09:25

No. 125 - Earth swingby clean-up manoeuvre

02 December 2009

Report for Period 14 November to 27 November 2009

The reporting period covers the first two weeks after Rosetta's third Earth swingby. The scientific observations linked to the Earth swingby phase were concluded successfully. Fine orbit determination computations were conducted after the Earth swingby to verify Rosetta was on the desired outbound trajectory. These indicated that a clean-up trajectory correction manoeuvre (TCM) was necessary to correct for a small inaccuracy. The clean-up TCM, with a delta-V of about 58 cm/s, was successfully performed on 23 November.

During the second half of the reporting period the bulk of the activities required for the refresh of all spacecraft Electrically Erasable Programmable Read Only Memory (EEPROM) were conducted. This included refreshing the EEPROMs of the four processor modules (PM) of Rosetta's on-board Data Management System.

Mission operations have been mainly conducted with support of the ESA New Norcia (NNO) ground station. In addition several tracking passes with the NASA DSN ground stations Goldstone (DSS-24) and Madrid (DSS-54) were scheduled.

DOY Date Pass Main Activity
318 14/11/09 NNO 2089

Monitoring pass

319 15/11/09 DSS-24 2090
NNO 2090

Monitoring pass

320 16/11/09 NNO 2091

Monitoring pass

321 17/11/09

DSS-54 2092
DSS-24 2092
NNO 2092

Monitoring pass

322 18/11/09

DSS-24 2093
NNO 2093

Monitoring pass

323 19/11/09

NNO 2094

Monitoring pass

324 20/11/09 NNO 2095

Monitoring pass

326 22/11/09 DSS-54 2097

Refresh PM2/PM3 EEPROM images

327 23/11/09 NNO 2098

Clean-up TCM

328 24/11/09

NNO 2099

Refresh EEPROM images of star tracker B/navigation camera B

329 25/11/09

NNO 2100

Refresh PM1/PM4 EEPROM images

330 26/11/09

NNO 2101

Refresh EEPROM images of star tracker A/navigation camera A

331 27/11/09

NNO 2102

Monitoring pass

At the end of the reporting period (DoY 331) Rosetta was at 11 million km from Earth (0.073 AU) and the one-way signal travel time was 37 seconds. The distance to the Sun was 146.87 million km (0.982 AU).

On 23 November 2009 Rosetta was at the perihelion of its current orbit, 146.6 million km (0.98 AU) from the Sun. Rosetta will never come as close to the Sun again; two deep space manoeuvres in 2011 and 2014 will synchronize Rosetta's orbit with that of comet 67P/Churyumov-Gerasimenko, whose orbit around the Sun lies well beyond that of the Earth.

Earth swingby navigation campaign

Based on orbit determination results obtained using the radiometric data starting with the New Norcia pass on 8 November and ending with the New Norcia pass that finished early on 18 November, the following summary can be made of the Earth swingby:

  • The altitude at perigee (assuming an Earth radius of 6378.136 km) was 2479.523 km. The 3-sigma uncertainty on this result is less than 2 metres.
  • The time of perigee passage was 07:45:39.9908 UTC on 13 November. The 3-sigma uncertainty on this result is about 0.2 milliseconds.

Spacecraft

Payload
The Earth swingby science campaign has concluded and all instruments are now switched off. The Standard Radiation Environment Monitor (SREM) continues to run in the background.

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 muted.

VIRTIS
The instrument is currently OFF.

LANDER Philae
The instrument is currently OFF.

SREM
Since DoY 251/2009 the accumulation settings are configured for active cruise mode.

Future Milestones

With the successful execution of the clean-up TCM on 23 November, the Earth swingby phase of the Rosetta mission operations is now almost completed. Few minor spacecraft configuration changes will mark the transition into the next cruise phase that will lead to the encounter with asteroid Lutetia in July 2010.

The upcoming period will see the preparation for the test of the Deep Space Hibernation Mode. This test is planned between 20 and 27 January 2010 and is needed to validate the procedure planned for June-July 2011, when Rosetta will go into deep space hibernation for a period of two and a half years.


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Legal disclaimer
This report is based on the ESOC mission operations report, WOR #125. Please see the copyright section of the legal disclaimer (bottom of this page) for terms of use.


Last Update: 08 June 2010

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