Passive Cooling of Infrared Interferometers in Space

Abstract

We examine three possible design approaches for radiative cooling of multiple-aperture missions of the sort required for space IR interferometry, particularly those to be sent out to 5 AU which are aimed at detecting extrasolar terrestrial planets.

• – Individually cooled free-flyers (c.f. MOFFIT): This approach offers adapt-able geometry but access to a limited fraction of the sky, perhaps less than half from elliptical trans-asteroid orbits.

• – Large semi-independent sunshade: This may allow free-flyers access to more of the sky but has many technical challenges.

• – Structurally-linked individually-protected telescopes: This concept can offer protection of the beam lines from all stray light and gives good sky cover-age, but geometry changes may be difficult, limiting its applications to general astronomy.

A possible solution to the last problem is suggested. A unit design based on the PRISM studies at NASA Marshall Space Flight Center is outlined, together with a mission scenario