“This project has been a victim of time,” says Kenneth Nordtvedt, a professor emeritus at Montana State University in Bozeman, who points out that other experiments have already measured these effects.
Ignazio Ciufolini, a physicist at the University of Salento in Lecce, Italy, and Erricos Parlis of the University of Maryland, Baltimore County confirmed frame dragging by analyzing the orbits of the two laser-ranged LAGEOS satellites (SN: 11/27/04, p. 348). Publishing in Nature in 2004, the pair reported a error of 10 percent. Two other groups of scientists in Germany and the United States have since checked his analysis, and a third satellite scheduled to be launched this year could help Ciufolini and Parlis improve their precision.
“We should be able to reach a test of frame dragging with an uncertainty of almost 1 percent,” he says.
Proponents of Gravity Probe B say that general relativity, which is currently incompatible with quantum mechanics, should be tested in as many ways as possible. But the project’s ultimate legacy may lie in its contributions to technology, not science. GPS systems developed for the spacecraft, for instance, now help farmers to plant perfectly straight rows of corn.
“The technology needed to do this test didn’t exist when the project started,” says John Mester, a 19-year veteran of the Gravity Probe B team at Stanford.
Mester hopes to help the team publish a series of papers detailing the equipment they developed. But otherwise their mission is complete.
“We’re basically done,” Mester says. “None of us have a job anymore.”
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