European Space Agency (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 Alenia Space (France) 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 2008 and will operate in Lissajous orbits around the Lagrange point L2 of the Sun-Earth system.
Herschel and Planck payloads - developed respectively by ASTRIUM and Alcatel Alenia Space (France) 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.
Alcatel Alenia Space (Italy) is the System level responsible of the Service Module (SVM) of both programs and, in particular is also responsible of the Thermal Control provision and of all the verification aspects at SVM level.
Herschel SVM was tested in ESTEC facilities (Netherlands) in May, 2005 and Planck SVM was tested in Centre Spatial Liégeois (CSL) facilities (Belgium) in March, 2006.
The purpose of the paper is:
to recall the main requirements and describe the associated thermal control design
to describe the development plan followed for the verification of the thermal performance
to present the thermal test configuration for both Herschel and Planck
to present the thermal test correlation findings and mathematical model updates
to identify the thermal test lessons learnt