FIREBALL (the Faint Intergalactic Redshifted Emission Balloon) is a balloon-borne 1m telescope coupled to an ultraviolet fiber-fed spectrograph. FIREBALL is designed to study the faint and diffuse emission of the intergalactic medium, until now detected primarily in absorption. FIREBALL is a path finding mission to test new technology and make new constraints on the temperature and density of this gas.

FIREBALL is designed to discover and map faint emission from the Intergalactic Medium (IGM). Emission from strong resonance lines of abundant elements, HI Lya (1216), OVI (1033) and CIV (1549) are redshifted into the 1950-2250 stratospheric balloon window at redshifts of z(Lya)~0.7, z(OVI)~1.0, and z(CIV)~0.3. FIREBALL observes regions of the cosmos with known large-scale structures (traced by galaxy redshift surveys, QSO emission and absorption lines) to search for and eventually map emission from the IGM surrounding and delineating these structures.