Also on flight day two, the crew lifted with the orbiter remote manipulator system arm the SPARTAN-204 from its support structure in payload bay. SPARTAN remained suspended on arm for observation of orbiter glow phenomenon and thruster jet firings. SPARTAN-204 was later released from the arm to complete about 40 hours of free-flight, during which time its Far Ultraviolet Imaging Spectrograph instrument studied celestial targets in the interstellar medium, the gas and dust which fills the space between the stars and which is the material from which new stars and planets are formed.