SFU (Space Flyer Unit) was a Japanese space laboratory launched by the same H-2 + SSB rocket that launched GMS 5. It carried an infrared telescope (IRTS), and instruments and supplies for microgravity experiments.
IRTS was Japan's first orbiting telescope dedicated to infrared observations (1 - 1000 micron range) of the interstellar medium, late type stars and interplanetary dust. IRTS instrumentation was attached to a multi-purpose Space Flyer Unit (SFU). The four primary science instruments were the Near Infrared Spectrometer (NIRS), the Mid Infrared Spectrometer (MIRS), the Far-Infrared Line Mapper (FILM), and the Far-Infrared Photometer (FIRP). All instruments were located at the focal plane of a 15-cm aperture telescope. Approximately 7 percent of the sky was surveyed during a four-week period.
SFU was retrieved by the Shuttle STS 72 on 13 January 1996 after jettisoning the solar panels.