Pictures get all the glamour, but the business end of astronomy is spectroscopy –the nitty-gritty analysis of the light from stars, galaxies and the stuff in between. If a picture is worth a thousand words then, to an astronomer, a spectrum is worth a thousand pictures.

Having built much of the Far Ultraviolet Spectroscopic Explorer (a satellite launched in June, 1999), CU astronomers are now busily digesting spectra from the telescope. They are resolving a decades-long debate over one of the most fundamental processes in cosmic evolution: How are gases from exploding stars recycled into new stars?

Every substance absorbs or emits light with specific characteristics. The light collected from celestial objects by a telescope is passed through a spectrograph which separates the light into different colors or wavelengths. Spectra look like supermarket bar codes, and the arrangement of lines tells us about the composition, density, temperature and motion of gases.

Vital information about stars can only be detected in ultraviolet light which contains, in particular, the signature of hydrogen, the most abundant gas in the universe. Luckily for the sensitive skins of humans, UV light from the Sun and stars does not penetrate far into the Earth's atmosphere. But the atmosphere also prevents us "seeing" UV light from stars with ground-based telescopes. That's why we need telescopes in space. The Hubble Space Telescope has been pushing back the frontiers of astronomy for 10 years–but it does not measure these critical UV wavelengths.

CU and the Johns Hopkins University have long been buddies/rivals in ultraviolet astronomy, competing or collaborating on projects from the early days of sounding rockets. On the FUSE mission JHU have the lead. But when times got tough, CU made the major play. In 1994, just as engineers were about to start cutting metal, NASA announced a drastic 60 percent curb in the mission budget. CU's Jim Green came up with an innovative new design that fit the budget constraints while salvaging nearly all the original science goals.

For months delicate instruments were carefully calibrated and integrated onto the 20-foot high spacecraft in the cavernous Center for Astrophysics and Space Astronomy facility on CU's eastcampus. I got a chance to peel the gleaming machine–the cosmic bar code reader–as it sat in a specially sqeaky-clean environment, while white- suited engineers hovered, twiddled and tweaked.

CU students Ryan McClean and Kurt Kunderson got more than a peek at the FUSE spectrograph. CASA is a training ground for the next generation of space telescope builders, where students pull allnighters watching instrument dials.

CU astronomers are feasting on the spectroscopic data from FUSE. :Mike Shull is examining how superheated gas from exploding stars forms a halo of hot gas around our galaxy. Ted Snow is studying cold clumps of interstellar gas, particularly molecular hydrogen, "the most abundant thing in space and the raw material for the formation of new stars."

Out on east campus Jim Green's group has moved on the next project, a spectrograph scheduled to improve Hubble's ultraviolet vision in 2003. CU astronomers hope the Cosmic Origins Spectrograph will reveal how galaxies condensed from the intergalactic medium over the past 10-12 billion years.

See http://fuse.pha.jhu.edu for information about the FUSE mission, including animations of exploding stars (e.g. http://fuse.pha.jhu.edu/pubinfo/AAS195/HotGas.mpg). For information about COS see http://cos.colorado.edu.