Ground-based telescopes

FMOS lens
FMOS lens

Although our main focus is spacecraft payloads, we also carry out thermal design and analysis for ground based telescopes. ALMA, FMOS and VISTA are among our recent projects.

ALMA

The UK is participating in the construction of the Atacama Large Millimetre Array (ALMA (link opens in a new window)) in the Atacama Desert of Northern Chile. The ALMA Observatory will have 64 twelve-metre diameter telescopes working together as an interferometric imaging array equivalent to a single telescope 15km in diameter. We provided thermal analysis of the cryogenic detector system down to 4K.

FMOS detector and thermal strap
FMOS detector and thermal strap

FMOS

The Fibre-Multi-Object Spectrograph (FMOS) is a collaboration to design and construct a fibre-fed infrared spectrograph system for the Subaru (link opens in a new window) 8m telescope on Mauna Kea in Hawaii. RAL Space has overall responsibility for the thermal and optical design of the spectrograph. We have designed a system to cool the detector to 70K using a Sumitomo CH-210 Gifford-McMahon cryocooler.

VISTA Camera

VISTA camera thermal model
VISTA camera thermal model

The Visible and Infrared Survey Telescope (VISTA) (link opens in a new window) for Astronomy is a 4m diameter wide-field survey telescope dedicated to conducting detailed imaging surveys of the sky. The telescope began operations at the Cerro Paranal Observatory in Chile during 2007.

RAL Space were responsible for the thermal engineering of the three tonne infra-red camera. The design utilises three two-stage Leybold 5/100T cryocoolers. The first stage cools the optical bench and optics to around 100°K, whilst the second stage cools the detectors to < 77°K.

The success of the design hinges on the optimisation of heat flow to minimise thermal loads on the detectors whilst holding external temperatures very close to ambient to reduce misting and convective disturbances in the field of view.


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