The spacecraft also found indications that two other moons, Ganymede and Callisto, have layers of liquid saltwater as well. Galileo discovered strong evidence that Jupiter's moon Europa has a melted saltwater ocean under an ice layer on its surface. Its two-year, primary mission ended in December 1997, but the mission was continued with an initial two-year extension. The Galileo spacecraft, meanwhile, orbited Jupiter and its moons for nearly four years, beaming back to Earth thousands of pictures and a wealth of scientific data. The probe descended deeper into the atmosphere than expected, but was finally overcome by Jupiter's high temperatures and pressures. When it dropped 156 kilometers (97 miles) through Jupiter's atmosphere, the Galileo probe relayed data back to the main Galileo spacecraft more than 209,215 kilometers (130,000 miles) overhead for storage and transmission to Earth. Tiny traces of these gases are found in Earth's atmosphere, and argon is sometimes used like neon in advertising signs. The spectrometer detected in Jupiter's atmosphere higher than expected concentrations of argon, krypton and xenon, three chemical elements called noble gases because they are very independent and do not combine with other chemicals. "These latest probe results have done exactly that, and the measurements are the sort that could only have been obtained by in-situ measurements from an entry probe." Richard Young of NASA Ames Research Center, Moffett Field, Calif. "Measuring the composition of Jupiter's atmosphere was a primary scientific objective of the probe, because we knew it could change our understanding of Jupiter's formation and evolution," said Galileo probe project scientist Dr. The probe also included a mass spectrometer that measured the chemical composition of Jupiter's atmosphere. The Atmosphere Structure Instrument (ASI) measured temperature, pressure and density.
Measurements of temperature, pressure and vertical winds revealed several discoveries as the Galileo Probe plunged into Jupiter's atmosphere. The Galileo atmospheric probe was managed by NASA Ames Research Center, Moffett Field, Calif. 7, 1995, entering orbit and dropping its instrumented probe into the giant planet's atmosphere. During the latter part of its interplanetary cruise, Galileo was used to observe the collisions of fragments of Comet Shoemaker-Levy with Jupiter in July 1994. It encountered the asteroid Gaspra on Oct.
8, 1992.Īlso en route to Jupiter, Galileo flew close to two asteroids, the first such visits by any spacecraft. 10, 1990, and then twice past Earth - once on Dec. Although earlier plans called for Galileo to use a more powerful upper stage so that it could fly directly to Jupiter, the final flight took the spacecraft by other planets first so that it could gain energy from the gravity of each. A two-stage solid-fuel motor called an inertial upper stage then propelled Galileo onto its interplanetary flight path. 18, 1989, from Kennedy Space Center, Florida, carried into Earth orbit in the cargo bay of space shuttle Atlantis. 21, 2003, when the spacecraft plunged into Jupiter's atmosphere. The orbiter completed many flybys of Jupiter's major moons, reaping a variety of science discoveries. Upon arrival at Jupiter in December 1995, the Galileo spacecraft delivered a probe that descended into the giant planet's atmosphere. Launched in 1989 aboard space shuttle Atlantis, Galileo explored Jupiter and its moons.
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