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Jupiter is slightly smaller and flatter than scientists thought for decades, a new study finds. Researchers used radio data from the Juno spacecraft to refine measurements of the solar system's largest planet. Although the differences between the current and previous measurements are small, they are improving models of Jupiter's interior and of other gas giants like it outside the solar system, the team reported Feb. 2 in the journal Nature Astronomy. "Textbooks will need to be updated," study co-author Yohai Kaspi, a planetary scientist at the Weizmann Institute of Science in Israel, said in a statement. "The size of Jupiter...

Most of these interstellar spacecraft carry messages intended to introduce ourselves to any aliens that find them along the way. In 1972, NASA hadn't even finished sending Apollo astronauts to the Moon yet when it started launching the first missions that would ultimately wind up in interstellar space. That wasn't the end goal though. Pioneer 10 and 11 were primarily intended to do humanity's first major reconnaisance of other planets in our solar system. Pioneer 10 achieved the first flyby of Mars, the first trip through the asteroid belt, and the first flyby of Jupiter. And the secret to its...

Mysterious force holds back Nasa probe in deep space By Robert Matthews, Science Correspondent (Filed: 10/02/2002) A SPACE probe launched 30 years ago has come under the influence of a force that has baffled scientists and could rewrite the laws of physics. Researchers say Pioneer 10, which took the first close-up pictures of Jupiter before leaving our solar system in 1983, is being pulled back to the sun by an unknown force. The effect shows no sign of getting weaker as the spacecraft travels deeper into space, and scientists are considering the possibility that the probe has revealed a new ...

Thirty years ago, NASA scientists noticed that two of their spacecraft, Pioneer 10 and Pioneer 11, were veering off course slightly, as if subject to a mysterious, unknown force. In 1998, the wider scientific community got wind of that veering—termed the Pioneer anomaly—and took aim at it with incessant, mind-blowingly detailed scrutiny that has since raised it to the physics equivalent of cult status. Now, though, after spawning close to 1000 academic papers, numerous international conferences, and many entire scientific careers, this beloved cosmic mystery may be on its way out. Slava Turyshev, a scientist at the Jet Propulsion Laboratory...

Ten years ago, NASA researchers discovered that the Pioneer 10 and 11 spacecraft had fallen slightly behind course during their 35-year journeys to the outer reaches of the solar system. In what has become known as the Pioneer anomaly, which was the subject of one of the talks this weekend at the American Physical Society here in St. Louis, nobody knows for sure why it happened. It probably stemmed from leaking gas or heat. But there's also the possibility, however remote, that gravity doesn't behave the way we expect. Until recently, researchers haven't had the data to distinguish the different...