NASA Probe Observes Universe’s Oldest Light

October 8, 2010—After nine years of scanning the sky, the Wilkinson Microwave Anisotropy Probe, or WMAP, has concluded its observations of the cosmic microwave background, the oldest light in the universe. The spacecraft has not only given scientists their best look at this remnant glow, but also established the scientific model that describes the history and structure of the universe. “WMAP has opened a window into the earliest universe that we could scarcely imagine a generation ago,” said Gary Hinshaw, an astrophysicist at NASA’s Goddard Space Flight Center who manages the mission. WMAP, which launched in 2001, was designed to provide a more detailed look at subtle temperature differences in the cosmic microwave background that were first detected in 1992 by NASA’s Cosmic Background Explorer. WMAP acquired its final science data on Aug. 20. On Sept. 8, the satellite fired its thrusters, left its working orbit, and entered into a permanent parking orbit around the sun. WMAP is in the Guinness Book of World Records for “most accurate measure of the age of the universe.” The mission established that the cosmos is 13.75 billion years old, with a degree of error of 1 percent. WMAP also showed that normal atoms make up only 4.6 percent of today’s cosmos, and it verified that most of the universe consists of two entities scientists don’t yet understand. Another important WMAP breakthrough involves a hypothesized cosmic “growth spurt” called inflation. For decades, cosmologists have suggested that the universe went through an extremely rapid growth phase within the first trillionth of a second it existed. WMAP’s observations support the notion that inflation did occur, and its detailed measurements now rule out several well-studied inflation scenarios while providing new support for others. “It never ceases to amaze me that we can make a measurement that can distinguish between what may or may not have happened in the first trillionth of a second of the universe,” says Charles Bennett, WMAP’s principal investigator at Johns Hopkins University in Baltimore. “Scientists will use this information for years to come in their quest to better understand the universe,” says Jaya Bapayee, WMAP program executive at NASA Headquarters.

WMAP used the Moon to gain velocity for a slingshot to L2. After 3 phasing loops around the Earth, WMAP flew just behind the orbit of the Moon, three weeks after launch. Using the Moon’s gravity, WMAP steals an infinitesimal amount of the Moon’s energy to maneuver into the L2 Lagrange point, one million miles (1.5 million km) beyond the Earth. Credit: NASA/WMAP Science Team The detailed, all-sky picture of the infant universe created from seven years of WMAP data. The image reveals 13.7 billion year old temperature fluctuations (shown as color differences) that correspond to the seeds that grew to become the galaxies. The signal from our Galaxy was subtracted using the multi-frequency data. This image shows a temperature range of ± 200 microKelvin. Credit: NASA/WMAP Science Team

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