Report to Solar System and Exploration Working Group (SSEWG) on Solar System Missions in Operation - February 2010

Gerhard Schwehm, Head of Solar System Science Operations Division/SRE-OS

For SOHO, the Solar and Heliospheric Observatory, the spacecraft status continues to be nominal, with the High Gain Antenna (HGA) Z-axis in a fixed position. All 12 instruments continue to provide data. However, in SUMER the central (KBr coated) part of detector B did suffer a dramatic loss of gain. Only the "bare" side parts of the detector remain usable. Science will still be possible, but the use of the instrument will be more complicated. Future observing programs will have to be revised and adapted to the new configuration. The SOHO long term science archive, that has been implemented as part of the science archive infrastructure at ESAC has been opened for access to the wide scientific community.

Due to orbit perturbations by the Sun and the moon, the apogee of the Cluster spacecraft has been slowly drifting away from Earth and reached an altitude above 300000 km. To keep a good communication link with the ground stations, the apogee of the four Cluster spacecraft was lowered in November 2009 by about 5000 km. Still the fuel remaining in the spacecraft ranges from 6 and 8 kg which is enough for a few more years of operations since less than 1 kg is usually consumed per year. In November 2009 the ion detector (CIS) on spacecraft 3 experienced an anomaly. Attempts to switch it on again were not successful. The PI team is investigating the cause of the anomaly. The spacecraft passed successfully the long eclipse season between September and November 2009. In the meantime the flight control team at ESOC and the science operation team at JSOC have prepared for the short eclipse season that just started mid January and will last until end of June 2010. Contact with Double Star TC2 spacecraft still has not been re-established. As end of 2009 should have been the last opportunity to contact the spacecraft again, we are waiting for our Chinese colleagues to declare the end of the operational mission. Under the umbrella of Cluster we are preparing the Double Star science data archive. The Cluster Active Archive (CAA) continues to distribute data to the user community. The CAA will soon welcome its 1000th registered user. From Oct. 09 to Dec. 09, the averaged data download rate was about 1.2 TB per month.

Mars Express and its payload performed nominally during the reporting period. As part of the routine checks of the MELACOM system, Mars Express successfully supported two communication passes on 20 and 26 October 2009, with NASA’s Rover Spirit. The anticipated close encounter between Mars Express and Mars Odyssey that was predicted for early December with a closest approach within 32 km did not occur as Mars Odyssey entered a safe mode just before that date. This generated enough delta-V to fully remove the risk. The eclipse season, which started early-Nov 2009 reached its maximum duration of about 56 minutes on 13 December 2009; up to now no problems were experienced. The eclipse season will end in April 2010. As this was an eclipse season at aphelion, there was potentially a fairly severe (power induced) impact on the science observations.

1 The change to the newly defined Mars Express orbit (a so-called 88:25 resonance) will be executed in two steps. The Phobos phasing manoeuvres will take place mid- February followed by the orbit change manoeuvres end of March. The science planning for the upcoming sequence of (very) close Phobos flybys is about to be finalized. The planned transfer of the Mars Express/Venus Express bench model (EFVB) to ESOC, following the closure of the ASTRIUM contract end of April-2009, is becoming increasingly unlikely, largely due to technical problems. It is very difficult to quantify the impact of this.

The most important event for Rosetta was the spin-up of the spacecraft on 20 January to test the Deep Space Hibernation Mode (DSHM). The spacecraft was spinning at 4 deg per sec. Exit from the DSHM was triggered early on 27 January. The spacecraft was configured back into cruise mode in the evening of that day. Despite a second safe mode in addition to the planned when exiting the DSHM everything went very smoothly due to the excellent preparation by the mission team in very close collaboration with experts from industry. Mission performance has been nominal except one glitch on 1 January 2010. The scientific observations linked to the Earth swing-by phase were concluded successfully. On the 23rd of November a correction manoeuvre (ca. 58 cm/s) was executed to clean-up the small inaccuracy of the swing-by. Rosetta started the New Year with a safe mode triggered by a problem on the SS RTU. The spacecraft was fully recovered within a very short time and the problem proved to be not permanent and very similar to previous problems occurred on the Mars Express spacecraft flying the same RTU. Due to the nature of the failure the spacecraft was prevented to switch on the reaction wheels after the safe mode and stayed on thrusters control for 3 days until it was monitored and then recovered. The preparation of the last Active Payload Check-out to be performed in spring proceeded according to plan. This required close interaction with the instrument teams, the spacecraft operations team and RSOC. The Lutetia flyby will occur on 10 July 2010; observation timelines have been iterated and are being implemented. The coming months will be extremely busy for both RSOC and RMOC due to the active check out starting end-of March and the preparation of the Lutetia flyby. In addition individual instruments will have dedicated passes scheduled for onboard software upgrades and tests. The approach to the close comet operations was discussed in detail with experts from the PI teams and the NASA – JPL Rosetta team during the Rosetta Science Working Team Meeting that took place at ESOC during the first week of December.

Spacecraft and payload operations for Venus Express continue as planned. Only minor problems, affecting individual observations, occurred. From 28 December 2009 until 22 January 2010 the spacecraft went through solar conjunction, which prevented any science operations. A successful Venus Express science working team meeting was held in London from 11-13 November 2009. At this meeting the PIs expressed their appreciation for the way the Venus Express Science Ground Segment executes the science planning, and for the way the ESOC Flight Control/Flight Dynamics team has been running the mission.

2 The Hinode spacecraft performed nominally, with data downlink through S-band. All three instruments are nominal and collecting high-quality science data. All Hinode data are available to the community through the Hinode Science Data Centre Europe in Norway usually less than 24 hours after they have been taken: http://sdc.uio.no/sdc/

Chandrayaan-1 mission operations ceased on 29 August 2009, with the European payload instruments onboard Chandrayaan-1 having for the most part met their initial scientific objectives. As a result, the ESA-supported instrument teams C1XS/XSM, SARA and SIR-2 in the post operational phase have been focusing their efforts on improving data calibration and conducting data analysis and archiving. Support is being provided from ESAC, in coordination with the Project Scientist, toward ensuring that the three PI teams deliver their data archiving documentation and products to India by the deadlines agreed with ISRO. The data validation for the SARA instrument had experienced some delay and the Mission Manager at ESAC has been in close contact with the PI team to resolve some of the problems. Following the delivery to ISRO of PDS-compliant datasets covering the period from beginning of mission to 30 April 2009, the C1XS/XSM and SIR-2 teams have started to prepare the data products for the remaining part of the mission. The ESAC Chandrayaan-1 team prepared and supported a workshop in India to train Indian colleagues to prepare the science data for long-term archiving.

PROBA 2 was launched as a passenger with SMOS on 2 November 2009 from Pletsesk at 01:50 UT. After separation of SMOS and the final ignition of the Breeze- KM upper stage, the Proba2 spacecraft was released to the intended sun-synchronous orbit at ~720km altitude. After health check of the platform subsystems, the commissioning of the technology and the science instruments was initiated. This phase will end early February 2010. All scientific instruments successfully passed their health checks. The Thermal Measurement Unit (TMU, Czech Academy of Science) and the Dual-Segmented Langmuir Probe (DSLP, Czech Academy of Science) were switched on and commissioned in November 2009. The SWAP imager (Royal Observatory of Belgium) saw its ‘first light’ in December 2009 and participated in the first Joint Operations Procedure with Soho and Stereo in January 2010. Compression, on-board image priority handling and many more features of SWAP have been tested. The Lyman-Alpha Radiometer, LYRA (Royal Observatory of Belgium), observed the Sun for the first time beginning of January 2010 and observed its first flare on 12 January 2010. As for SWAP also the LYRA team has been testing all instrument features to be ready for the operational phase. A Press Conference to present the mission and its first results was held at the Royal Observatory of Belgium, Brussels, on 26 January. The Royal Observatory hosts the PROBA 2 Science Centre. The satellite platform and its subsystems have been stable and operating nominally. A recent orbit analysis confirmed the long-term stability of the orbital parameters. The commissioning review is planned for early March 2010.

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