Feb. 28, 2007 — By fortuitous timing, a robotic science probe flew by Jupiter on Wednesday as a massive volcano on one of its moons erupted, sending a thick plume of dust into space that served as a celestial welcome mat.
The plume from the volcano known as Tvashtar stretched about 150 miles above the surface of Io, a tortured moon baked and scrambled by the heavy grip of Jupiter's gravity.
The images from this encounter are among 700 scientists plan to take during a six-month study of the Jovian system by New Horizons, a NASA spacecraft that is heading toward Pluto. The probe passed as close as 1.4 million miles from Jupiter early Wednesday to pick up speed for the rest of its 3-billion mile journey to Pluto.
The slingshot maneuver off Jupiter added about 9,000 mph to New Horizons' speed, allowing it to clip three years off its trek. Even so, it will be 2015 before the spacecraft reaches Pluto and its primary moon Charon for the first detailed studies of the frozen, comet-like worlds.
New Horizons cannot rotate to point its communications antenna at Earth so most of the science data collected during the Jupiter encounter will be stored onboard the craft until it can be relayed to Earth. Scientists did manage to get a few pictures back, including two showing the volcanic eruptions on Io.
"This is the best image of a large volcanic plume on Io since the Voyager flybys in 1979," said John Spencer, deputy leader of the New Horizons Jupiter Encounter Science Team from Southwest Research Institute.
Ground-based telescopes and the Galileo Jupiter orbiter first spotted volcanic heat radiation from Tvashtar, which is one of Io's most active volcanoes, in November 1999, and the Cassini spacecraft saw a large plume when it flew past Jupiter in December 2000.
The Keck telescope in Hawaii picked up renewed heat radiation from Tvashtar in spring 2006, and just two weeks ago the Hubble Space Telescope imaged the Tvashtar plume in ultraviolet.
The New Horizons images were taken on Tuesday, the day before the probe's closest encounter with Jupiter. Scientists are hopeful even better pictures are among the images awaiting relay to Earth.
