This picture was stitched together from over 100 images taken by the Viking Orbiters back in the ’70s. It shows the largest canyon in the Solar System cutting a wide swath across the face of Mars. Valles Marineris is over 3,000 km long, is as much as 600 km across, and is as much as 8 km deep. The Earth’s Grand Canyon is 800 km long, 30 km wide, and not quite 2 km deep. The origin of the Valles Marineris remains a mystery, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled.
Image Credit: USGS / NASA
The last missions that NASA had with orbits around Mars that were synched to view the morning weather on the planet was the Viking orbiters back in 1976. This picture was taken in August, 1976, and shows water-ice clouds in the Valles Marineris area of equatorial Mars during local morning time. North is to the upper left, and the scene is about 1,000 km across.
Although a few observations of Mars in morning daylight have come from the Viking orbiters and the European Space Agency’s Mars Express orbiter, no mission has systematically studied how morning features such as clouds, fogs, and surface frost develop during different Martian seasons on different parts of the planet. NASA’s Mars Odyssey orbiter is in the process of changing its orbit to begin systematic morning daylight observations.
Image Credit: NASA