This cryogenic camera will hunt exoplanets

The size of a small suitcase, the NIX infrared camera will soon be installed on the VLT (Very Large Telescope or Very Large Telescope, in French) at the Cerro Paranal Observatory, in the Atacama Desert in northern Chile. It will be responsible for chasing young giant exoplanets using an unequaled contrast system. The device, designed by the Science and Technology Facilities Council's (STFC) at the UK Astronomy Technology Center (UK ATC) in Edinburgh, will be part of the Eris instrument -- which also includes a spectrograph called Spiffier and a adaptive optics -- and which is currently being assembled in Germany.

The NIX camera has been specially designed to detect wavelengths between 3 and 5 µm, those emitted by young hot planets similar to Jupiter. The problem is that the thermal background noise, due to the own reflection of the various mirrors, becomes a major drawback at these wavelengths. In addition, the light of exoplanets can hide behind that of their star. To mitigate thermal radiation, NIX will operate in temperatures below -200°C, much lower than most cameras. And to block star glare, the device includes a sophisticated system of light blockers, baffles and anti-reflective coatings, as well as high-contrast imaging technology.

“All this material has to fit in a very small space. Each mechanism has been designed and configured in a miniature version to be very precise and stable at these low temperatures”, testifies Dr William Taylor, astronomer and instrument scientist at the ATC of the United Kingdom. The first discoveries are expected for 2022.