Io
This picture of Io, Jupiter's innermost Galilean satellite, was taken by Voyager 1 on the morning of March 5, 1979, during the closest approach to this satellite. The picture was recorded on the onboard tape recorder and then sent back to Earth on the morning of March 7, 1979. Voyager 1 was at a range of 30,800 km (18,480 mi) from Io when the picture was taken. This region of Io is centered at 67 degrees south latitude and 328 degrees longitude. The picture width is about 246 km (147 mi). The smallest features visible are about 0.3 km (0.2 mi) across. The picture shows an irregularly shaped composite crater about 50 km (30 mi) in diameter with dark flows radiating from its rim. The crater is a volcanic caldera and the dark flows are probably low viscosity lavas possibly of basaltic composition. Some of the lava flows are over 100 km long and 15 km wide. Similar but smaller flows and craters occur on the island of Hawaii. JPL manages and controls the Voyager Project for NASA's Office of Space Science.