NASA's Galileo spacecraft will encounter Jupiter's volcanic moon Io on its 24th, 25th and 27th orbits. The ground tracks for these flybys of Io are labeled I24, I25 and I27 in this color image of Io, taken in 1996 by Galileo.

The Io flybys are scheduled for October 10, 1999, November 25, 1999 and February 22, 2000. Each large "X" marks the position of closest approach for a flyby, and the tic marks along each groundtrack show the position of the spacecraft in two-minute intervals before and after closest approach. The arrow next to the closest approach, labeled I25, indicates that this encounter occurs behind the limb of Io as it is seen in this image. The image shows approximately the hemisphere of Io that will be illuminated during the flybys (although the volcano Pele, shown here on the left limb, will actually be on the night side). Several of the active volcanic centers to be observed at close range are labeled. The blue background is Jupiter's atmosphere as seen through violet, green, and near-infrared filters.

North is to the top of the picture and the Sun illuminates the surface from almost directly behind the spacecraft. The image is centered at 0 degrees north latitude and 175 degrees west longitude. The resolution is 5 kilometers (3.1 miles) per picture element. The image was taken on September 7, 1996 at a range of about 487,000 kilometers (about 302,000 miles) by the camera onboard Galileo.

Image produced by: Cynthia Phillips, Planetary Image Research Lab. (PIRL), Lunar and Planetary Lab. (LPL), University of Arizona

The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/images/io/ioimages.html.

October 7, 1999