your connection to The Boston Globe

Decades after project began, NASA launches gravity probe

LOS ANGELES -- NASA yesterday launched a $750 million satellite conceived during the Eisenhower administration to test two of Albert Einstein's fundamental theories about the universe.

Gravity Probe B blasted off from an oceanside pad at Vandenberg Air Force Base, one day after officials scrubbed an earlier attempt. The launch of the 6,800-pound spacecraft, built by Lockheed Martin Corp., marked the end of the longest development period of any mission in the history of the National Aeronautics and Space Administration.

Scientists first proposed what became Gravity Probe B in 1959, a year after the launch of the first US satellite and the creation of NASA. Over the decades, the project weathered more than a half-dozen attempts at cancellation amid concerns over cost overruns and technical hurdles.

The Earth-orbiting satellite was built to test two of Einstein's predictions about the nature of space and time and how the rotating Earth warps and twists the fabric that combines the two.

Scientists at Stanford University designed the spacecraft around four spheres of quartz the size of ping-pong balls. They are the most perfect manmade spheres ever created.

Theory predicts that by lining up the satellite in space with a distant star and setting the balls spinning, their alignment should shift off kilter in small but measurable amounts in response to the mass and rotation of the Earth.

Today (free)
Yesterday (free)
Past 30 days
Last 12 months
 Advanced search / Historic Archives