The Service Module Thermal Control of ESA Herschel and Planck Satellites 2004-01-2391
ESA has planned two important missions for performing astronomical investigations in the infrared and sub-millimetre wavelength range:
Herschel satellite has an observatory type mission and is the fourth cornerstone mission (CS4) of the “Horizon 2000” programme. It will carry three instruments (HIFI, SPIRE, and PACS) for high and medium resolution spectroscopy, imaging and photometry over the sub-millimetre and far-infrared range. A 3.5 m telescope will focus the incoming radiation on the Focal Plane Units of these instruments.
Planck satellite has a survey type mission and is the third Medium mission (M3) of the “Horizon 2000” programme. It will provide a definitive high-angular resolution map of the cosmic microwave background anisotropies over at least 95% of the sky and over a wide frequency range. A 1.5 m telescope will focus the incoming radiation on the focal plane shared by the two instruments (LFI and HFI).
Alcatel Space has the role of Prime Contractor for the development of the two Herschel and Planck satellites that will be launched together by Ariane 5 in the first quarter of 2007 and will operate in Lissajous orbits around the Lagrange point L2 of the Sun-Earth system.
Herschel and Planck payloads (developed respectively by EADS Astrium in Friedrichshafen and Alcatel Space in Cannes) will be supported by Service Modules ensuring proper S/C Thermal Environment during the full lifetime for both, scientific observations and communications with ground. The two service modules will have large similarities.
Alenia Spazio is the System level responsible of the Service Module (SVM) of both programs and, in particular is also responsible of the TCS provision and of all the verification aspects at SVM level.
Purpose of the paper is:
to discuss the key thermal requirements, applicable to the program
to present the major thermal design concepts of the two service modules, giving particular attention to the specific thermal issues: very stringent thermal stability of Herschel HIFI units (0.03K/100sec), thermal design of Planck Sorption Cooler Compressor and thermal design solution to meet the very accurate pointing requirements of Star trackers Sensors,
to show the commonality approach followed in the thermal design development and the analytical modelling aspects
to provide a general overview of the integrated verification approach, including analysis and thermal balance testing of the two SVM's.