This mosaic of Tohil Mons and two nearby paterae (volcanic craters) on Jupiter's moon Io was acquired by NASA's Galileo spacecraft during a close flyby on 16 October, 2002. Taken soon after sunrise at a resolution of 50 meters (160 feet) per picture element the images show details of mountainous terrain in Tohil Mons (lower left), a small dark-floored patera bordered by mountain walls (middle), and intricate patterns of lava flows on the floor of Tohil Patera (upper right). Another view showing the entire mountain at lower resolution was also acquired. Tohil Mons rises up to 6 kilometers (19,700 feet) above the surrounding plains. In contrast the paterae are only about 100 meters (330 feet) deep.

Despite Io's extremely high rate of volcanic activity, its mountains do not resemble volcanoes seen elsewhere in the solar system. Instead, the mountains appear to be formed by the uplift of large blocks of Io's crust. Galileo scientists targeted Tohil to investigate the relationship between Io's mountains and its volcanoes. The images show evidence of numerous landslides from the mountain (bottom left). However, one of the most fascinating revelations from this observation is that despite the proximity of the small, dark-floored patera to the mountain walls, the patera floor is not covered with any landslide debris. This indicates that the patera floor has been resurfaced with lava more recently than any landslides have occurred. Another possibility is that this patera, like others on Io, is actually a lava lake and completely consumes debris that falls into it from the mountain.

North is to the top of the picture and the sun illuminates the surface from the right. The mosaic is centered at 27.2 S latitude and 159.4 W longitude and covers 280 kilometers (170 miles) from upper right to lower left.

Image produced by: Zibi Turtle, 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.

NASA's Planetary Photojournal PIA-03527

May 28, 2002