University of Colorado at Boulder Professor Michael Shull has been selected to be a co-investigator on a NASA space mission to map the cosmic web of hot gas that spans the universe.
The spacecraft, known as the Spectroscopy and Photometry of the Intergalactic Medium's Diffuse Radiation, or SPIDR, is one of two "Small Explorer" satellite missions announced yesterday by NASA. The second was AIM, a satellite that will look at polar mesospheric clouds. CU-Boulder will design and build two of the four instruments and control the AIM satellite from campus.
The SPIDR satellite was the sole astrophysics explorer chosen by NASA in a competition among more than 30 proposals, said Shull, professor and chair of CU-Boulder's astrophysical and planetary sciences department.Ìý
"In an aptly chosen name, the SPIDR mission will be used to explore the cosmic web of hot gas spread throughout intergalactic space," said Shull. "SPIDR also will be used to understand the life cycles of matter and energy controlled by the birth and death of stars in supernova explosions."
SPIDR will be designed and built by a team from Boston University and scientists from several institutions, including CU-Boulder and Princeton University. Shull and CU-Boulder students and researchers will be involved in the scientific data analysis from SPIDR, scheduled for launch in 2005.
Hot gas in space is produced by powerful events like supernova explosions that end the lives of massive stars, said Shull. It also is produced by shocks from the gravitational collapse of intergalactic gas early in the life of the universe.Ìý
"Shaped by the forces of gravity, this gas is believed to form a cosmic web of large filaments, extending millions of light years across intergalactic space," he said.
The hot gas, reaching temperatures of 100,000 degrees to 1 million degrees Celsius, radiates in the ultraviolet portion of the electromagnetic spectrum, Shull said. Using an innovative imaging process similar to medical CAT-scans, SPIDR will search for emissions from highly ionized carbon and oxygen gas across the sky and throughout intergalactic space.
The accepted theory behind the beginning of the universe -- the Big Bang -- predicts that it started around 15 billion years ago from an infinitesimally small point with infinitely large mass, he said. The violent expansion of the universe created space, time and matter.
"Some of this matter later coalesced into stars and galaxies, but a significant portion of the gas remains distributed throughout space, in undetected form -- so-called 'dark matter,'" he said.
Shull and his students hope to answer the important cosmological question of how much of the unobserved dark matter exists in the form of hot gas.
The research from SPIDR will complement studies of galaxy formation to be done with the Cosmic Origins Spectrograph, being built at CU-Boulder's astrophysics laboratories for installation on the Hubble Space Telescope in March 2004.