GUSTO
(for Galactic / Extragalactic ULDB Spectroscopic Terahertz Observatory,
ULDB for Ultralong-Duration Balloon)
is a balloon-borne 0.9-meter far infraredreflector telescope
in development for a flight over Antarctica of 2-4 months at
about 120,000 feet.
It was launched December 31, 2023, remaining aloft for 57 days.
It has a cryogenically-cooled three-channel camera, to map
oxygen, nitrogen and carbonlines
in the Milky Way and Large Magellanic Cloud (LMC).
It builds on two previous such missions to test the
concept, STO (for Spectroscopic Terahertz Observatory) in 2012,
and STO2 in 2016.