Thermal control design of SUNRISE, a balloon-borne solar telescope

Paper number

IAC-06-C2.P.2.08

Author

Dr. Isabel Pérez Grande, Universidad Politecnica de Madrid, Spain

Coauthor

Mr. Klaus Haertel, Kayser-Threde GmbH, Germany

Year

2006

Abstract

SUNRISE is a solar telescope with an aperture of 1 m for spectro-polarimetric observation of the solar atmosphere. It will be flown with a long-duration balloon from Antarctica, in summer, reaching an altitude of about 38 km with permanent Sun view. It is the precursor of a space-borne solar observatory.
The size of the telescope and the high power requirements of the instruments, joined to the hostile environment at 38 km over Antarctica (almost vacuum environment, very high Earth albedo coefficient and permanent solar irradiation) have made of SUNRISE a quite challenging mission from the thermal point of view.
A dedicated thermal analysis has been carried out to find a solution that allows keeping all the devices within their appropriate temperature ranges, without exceeding the allowable temperature gradients. A thermal mathematical model of the whole system has been established. It consists of the telescope itself, the optical platform, the electronics racks, the data storage system, the solar panels, the gondola structure and the balloon. Devoted detailed analyses for the most critical elements have also been performed. Extreme hot and cold cases in the Antarctica environment have been considered.
As result, the thermal control of the primary mirror requires reflective blades on its rear side as well as a radiation shield to block the high albedo loads on the system. The electronics rack has to be located behind the solar panels to avoid direct solar irradiation and has to be tilted appropriately in order to decrease Earth albedo and infrared radiation. For the optical platform, it is necessary to used radiators to dump the heat dissipated by the instruments in space. An adequate thermal finish has also been defined for all the elements SUNRISE consists of.

Abstract document

IAC-06-C2.P.2.08.pdf

Manuscript document

IAC-06-C2.P.2.08.pdf (🔒 authorized access only).

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