Ground Segment

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Geographical distribution of the Planck Ground Segment

The Planck Ground Segment consists of four geographically distributed centres.

The Mission Operations Centre

The mission operations centre (MOC[ESA's] Mission Operation Center [Darmstadt, Germany]), located at ESAEuropean Space Agency’s operations centre in Darmstadt (Germany), was responsible for all aspects of flight control and of the health and safety of the Planck spacecraft, including both instruments. It planned and executed all necessary satellite activities, including instrument commanding requests by the instrument operations centres.

The European Space Operations Centre in Darmstadt, Germany, home of the Planck Mission Operations Centre.

MOC[ESA's] Mission Operation Center [Darmstadt, Germany] communicated with the satellite using ESAEuropean Space Agency’s 35-m antenna located in New Norcia (Australia), or that in Cebreros (Spain), over a daily 3-h period, during which it uplinked a scheduled activity timeline which was autonomously executed by the satellite, and downlinked the science and housekeeping (HKHouse Keeping) data acquired by the satellite during the past 24 h. The downlinked data were transferred from the antenna to the MOC[ESA's] Mission Operation Center [Darmstadt, Germany] over a period of typically 8 h; at MOC[ESA's] Mission Operation Center [Darmstadt, Germany] they were put onto a data server from where they were retrieved by the two data processing centres.

The Planck Science Office

The European Space Astronomy Centre in Villanueva de la Cañada, Madrid, Spain, site of the Planck Science Office.

The Planck Science Office (PSOPlanck Science Office) is located at ESAEuropean Space Agency’s European Space Astronomy Centre in Villanueva de la Cañada surroundings (Madrid, Spain).

Its main responsibilities include:

  • coordinating scientific operations of the Planck instruments;
  • designing, planning and executing the Planck observation strategy;
  • providing MOC[ESA's] Mission Operation Center [Darmstadt, Germany] with a detailed pointing plan with a periodicity of about one month;
  • creating and updating the specifications of the Planck Legacy Archive (PLAPlanck Legacy Archive) developed by the Science Archives Team at ESAC;
  • testing and operating the PLAPlanck Legacy Archive.

The LFI(Planck) Low Frequency Instrument instrument operations and data-processing centre

The LFI(Planck) Low Frequency Instrument instrument operations and data processing centre, located at the Osservatorio Astronomico di Trieste (Italy), is responsible for the operation of the LFI(Planck) Low Frequency Instrument instrument, and the processing of the data acquired by LFI(Planck) Low Frequency Instrument into the final scientific products of the mission.

The HFI(Planck) High Frequency Instrument instrument operations and data-processing centre

The HFI(Planck) High Frequency Instrument instrument operations and data processing centres, located, respectively, at the Institut d’Astrophysique Spatiale in Orsay (France) and at the Institut d’Astrophysique de Paris (France), are similarly responsible for the operation of the HFI(Planck) High Frequency Instrument instrument, and (with several other institutes in France and the UK) for the processing of the data acquired by HFI(Planck) High Frequency Instrument into the final scientific products of the mission.

Data flow in the Planck Ground Segment

The PSOPlanck Science Office sent the Pre-Programmed Pointing Lists (PPLPre-programmed Pointing List) to the MOC[ESA's] Mission Operation Center [Darmstadt, Germany]. The Flight Dynamics team at ESOCEuropean Space Operations Centre (Darmstadt) adapted them into Augmented Pre-Programmed Pointing Lists (APPLAugmented Preprogrammed Pointing List) taking into account ground station scheduling, Operational Day (ODOperation Day definition is geometric visibility driven as it runs from the start of a DTCP (satellite Acquisition Of Signal) to the start of the next DTCP. Given the different ground stations and spacecraft will takes which station for how long, the OD duration varies but it is basically once a day.) boundaries and other issues.

General schematics of European Space Agency Science Ground Segments, showing how ESAEuropean Space Agency Ground Segments are generally organized.
Specific schematics of the Planck Science Ground Segment, showing how the specific Planck Science Ground Segment worked.

MOC[ESA's] Mission Operation Center [Darmstadt, Germany] sent pointing and instrument commands to the spacecraft, and received the house-keeping telemetry and science data through the ground stations (for Planck, mostly the New Norcia and Cebreros ones).

Science data were then transferred to both data processing centres (DPCs), which processed the data and sent quality reports to PSOPlanck Science Office.

Science products (timelines, maps, etc) have been regularly exchanged between DPCs in order to assist with calibration[LFI meaning]: absolute calibration refers to the 0th order calibration for each channel, 1 single number, while the relative calibration refers to the component of the calibration that varies pointing period by pointing period., systematics, and scientific issues.

More information about the Planck Ground Segment may be found in Planck-PreLaunch-XI[1].

References

  1. Planck pre-launch status: The Planck mission, J. A. Tauber, N. Mandolesi, J.-L. Puget, T. Banos, M. Bersanelli, F. R. Bouchet, R. C. Butler, J. Charra, G. Crone, J. Dodsworth, et al., A&A, 520, A1+, (2010).