Dear readers and followers,
the NASA’s spacecraft called MAVEN (Mars Atmosphere and Volatile Evolution) has obtained its first observations of the extended upper atmosphere surrounding Mars. Piling on to the good news from Mars this week, the US spacecraft Maven sent home its first ultraviolet images from Mars. While they may not be flashy, these images will help determine the composition and variability of the upper atmosphere, and investigate the mystery when the water escaped.
The Imaging Ultraviolet Spectrograph (IUVS) instrument obtained these false-color images eight hours after the successful completion of Mars orbit insertion by the spacecraft at 10:24 p.m. (EDT) on Sunday, September 21th.
Credit image: NASA
The MAVEN spacecraft has been sent with success by the space rocket Atlas 5 last November 2013. Its travel to Mars took 10 months.
The image shows the planet from an altitude of 36500 km in three ultraviolet wavelength bands:
- Blue shows the ultraviolet light from the sun scattered from atomic hydrogen gas in an extended cloud that goes to thousands of kilometers above the planet’s surface.
- Green shows a different wavelength of ultraviolet light that is primarily sunlight reflected off of atomic oxygen, showing the smaller oxygen cloud.
- 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. Over the course of its one-Earth-year primary science mission, MAVEN observations like these will be used to determine the loss rate of hydrogen and oxygen from the Martian atmosphere.
Tracking the spacial and temporal variation of these gases, along with carbon, nitrogen, carbon monoxide, carbon dioxide, and ionized carbon dioxide, will help scientists better understand what processes are driving the atmosphere's composition. The particularly interesting part for the water history of the planet involves measuring the ratio between light water and heavy water: hydrogen (121.567 nm) and deuterium (121.533 nm).
That's a task that requires a high level of precision, and has been successfully accomplished for the lower atmosphere on Mars before, but never for the upper atmosphere where gas loss is actually taking place. These observations will allow us to determine the amount of water that has escaped from the planet over time.
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