MAVEN is the first spacecraft dedicated to exploring the tenuous upper atmosphere of Mars, and it has made its first observations of the extended upper atmosphere surrounding Mars. The Imaging Ultraviolet Spectrograph (IUVS) instrument obtained these false-color images eight hours after Mars orbit insertion.

The images show the planet from an altitude of 36,500 km in three ultraviolet wavelength bands. Data represented in blue shows UV light from the sun scattered by atomic hydrogen gas in an extended cloud that extends thousands of kilometers above the planet’s surface.  Green shows a different wavelength of ultraviolet light that is primarily sunlight reflected by atomic oxygen. Red shows ultraviolet sunlight reflected from the planet’s surface. The bright spot in the lower right is light reflected either from polar ice or clouds.

The oxygen gas is held close to the planet by Mars’ gravity, while lighter hydrogen gas is present to higher altitudes and extends past the edges of the image. These gases derive from the breakdown of water and carbon dioxide in Mars’ atmosphere. During its one-Earth-year-long primary science mission, MAVEN observations like these will be used to determine the loss rate of hydrogen and oxygen from the Martian atmosphere.  Those observations should allow an reasonable estimate of the amount of water that has escaped from Mars over time.

Image Credit: NASA