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Toward a smoother cosmic background.

Toward a smoother cosmic background

On Sept. 21, the last of the liquid helium aboard the Cosmic Background Explorer (COBE) spacecraft evaporated after 10 months of operation. As a result, one of the craft's three instruments can no longer take data. However, the remaining instruments continue to measure background radiation at a number of different wavelengths, and alla three instruments have already generated tremendous amounts of valuable information.

"We have in hand a powerful data set," says Michael G. Hauser of the NASA Goddard Space Flight Center in Greenbelt, Md. COBE investigators now face the time-consuming task of analyzing the data. In particular, they need to account for all the factors that may have influenced the measurements--such as mirror vibrations and transient increases in antenna temperature caused by surprisingly intense auroras--to determine the data's true accuracy.

Designed to probe the earliest observable events in the universe, COBE instruments have produced a remarkable set of maps depicting the distribution of radaition at various wave-lengths fluoss the sky (SN:4/21/90, p.245). New maps based on refined measurements still show no obvious signs of any fluctuations that would disturb the smoothness of the background radiation thought to be the remnant of the Big Bang, which started the universe's expansion. "You cannot see any features. It's surprisingly smooth," says George F. Smoot of the University of California, Berkeley.

Those measurements put stringent constraints on a number of proposed theories that attempt to account for how the universe evolved to its present, lumpy state of galaxies and supergalaxies (SN: 3/24/90, p.181). The data already seem to rule out several possibilities. Researchers explored the implications of the COBE results last month at an astrophysics meeting in College Park, Md.
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Publication:Science News
Date:Nov 10, 1990
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