According to Newtonian gravity, an object orbiting a spherical planet must traverse exactly the same ellipse over and over for eons. But in 1913, Albert Einstein and his assistant Michele Besso, using a tentative version of general relativity, suggested that a rotating planet might cause a slight shift in the satellite’s orbit. The exact mathematical calculation of the effect was made in 1918 by Austrian physicists Joseph Lins and Hans Thiering. Recent calculations predict that the triple lens effect, a kind of relative “frame drag”, should cause the plane of the orbit to rotate about the Earth’s axis by 8.6 millionths of a degree per year.
In practice, the Earth itself isn’t a perfect sphere, but it is “potato-shaped,” says Ciofolini. The resulting irregularities in Earth’s gravitational field – which is exactly what LAGEOS was designed to measure – cause additional orbital pre-movement, which could complicate the measurement of relativistic influence. However, these irregularities can be compensated for by comparing the orbits of two satellites.
Ciufolini, who has been working on the LARES mission concept since his doctoral thesis in 1984, This principle was first applied in 2004To measure orbit shift by comparing the orbitals of LAGEOS and LAGEOS-2 – a similar probe launched by ASI. He and colleague Ericus Pavlis of the University of Maryland, Baltimore County, claimed to have determined the effect with an accuracy of 10 percent.
Although the result was still not very accurate, the team was able to thwart an $800 million NASA experiment that tried to use a different technique to measure frame change. Too complicated mission B gravity probe, Launched in 2004, it did not measure changes in the spacecraft’s trajectory, but rather the tilt of four spinning spheres, which were changing by a fraction of a degree per year. The unexpected complication meant that Gravity Probe B was only able to achieve an accuracy of 20 percent, away from the original 1 percent target.
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