I have been working 3 years on the FIREBall experiment. This path finder mission aims at imaging 7 bilions-light-year away galaxies' circumgalactic medium. This region around galaxies, hosting important mechanisms regulating their replenishment in gas through inflows and outflows, is the keystone to understand how galaxies evolve, how they feed and breath to create stars and how they give back to the intergalactic medium the metals they have created.
In order to understand these exchanges, the FIREBall instrument attempts to image the CGM in emission via specific spectral lines redshifted to 205nm for the close universe. The instrument is a balloon-borne 1m telescope coupled to an ultraviolet multi-object spectrograph designed to measure this emission from the stratosphere.