Infrared astronomy beyond JWST: the Moon perspective

In the first special issue on 'Astronomy from the Moon: the next decades', two projects for the infrared domain, considered as justifying a lunar implementation, were presented: a general purpose light collector for the 1-200 μm range, of diameter much larger than any ELT on Earth and a specialized instrument in the very far-infrared aiming at the detection of the weak CMB spectral distortions. Learning from the launch of JWST, to surpass it in spatial, spectral resolution, spectral coverage and sensitivity, the concept of a large infrared, lunar collector is revisited to be specified on a more realistic approach. The telescope is designed to fit in its stowed configuration into the fairing of a future cargo launcher, in order to be deployed on the Moon in robotic mode from a single launch. With these constraints, its diameter is limited to 13 m, i.e. just twice JWST. The choice of the potential sites is also better defined, by selecting the coldest lunar spots that could provide a passive cooling, on average colder than is obtained for JWST at L2. In conclusion, the advantages and the requirements for the development of such a facility on the Moon in the next decades are reviewed. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.