Far-Infrared Surveyor, one of the four science and technology definition
studies to be submitted by NASA Headquarters to the 2020 Astronomy and
Astrophysics Decadal survey. The observatory will provide orders of
magnitude improvements in sensitivity over prior missions, in particular
for spectroscopy, enabling breakthrough science across astrophysics. The
observatory will cover a wavelength range between 5 ¦Ìm and 600 ¦Ìm in
order to enable the study of the formation of proto-planetary disks,
detection of bio-signatures from extra-solar planet's atmospheres,
characterization of the first galaxies in the universe, and many more.
     Key technologies enabling the mission include large cryogenic
optics (the ~10 m telescope will be cooled to 4 K) and the associated
cryo-coolers, plus sub-Kelvin coolers for the science instruments using
superconducting detectors for the incoherent far-infrared imager/
polarimeter and spectrometers. The five instruments that are currently
studied are two imaging far-infrared spectrometers using incoherent
detectors, providing up to R~ 10^5 spectral resolution, one far-infrared
heterodyne instrument for even higher spectral resolving powers, one
far-infrared continuum imager and polarimeter, plus a mid-infrared
coronograph with imaging and spectroscopy mode.  In particular, current
superconducting detector technologies will need to be matured
significantly in terms of sensitivity, dynamic range and
multiplexability while the warm readout electronics will need to operate
within the low power constraints provided by the observatory.
     I will describe both, the scientific capabilities, and the
technological requirements for the observatory.