The Far-InfraRed Spectroscopic Explorer (FIRSPEX)
  The Far-InfraRed Spectroscopic Explorer (FIRSPEX) is a candidate mission in
response to a bi-lateral Small-mission call issued by the European Space Agency
(ESA) and the Chinese Academy of Sciences (CAS). FIRSPEX is a small satellite
(~1m telescope) operating from Low Earth Orbit (LEO). It consists of a number
of heterodyne detection bands targeting key molecular and atomic transitions in
the terahertz (THz) and Supra-Terahertz (>1 THz) frequency range. The FIRSPEX
bands are: [CII] 158 microns (1.9 THz), [NII] 205 microns (1.46 THz), [CI] 370
microns (0.89 THz), CO(6-5) 433 microns (0.69 THz). The primary goal of FIRSPEX
is to perform an unbiased all sky spectroscopic survey in four far-infrared
lines delivering the first 3D-maps (high spectral resolution) of the Galaxy.
The spectroscopic surveys will build on the heritage of Herschel and complement
the broad-band all-sky surveys carried out by the IRAS and AKARI observatories.
In addition FIRSPEX will enable targeted observations of nearby and distant
galaxies allowing for an in-depth study of the ISM components.
