MAVEN spacecraft finds oxygen and hydrogen in Mars' atmosphere

© NASA/Univ. of Colorado

These are two views of Mars' escaping atmospheric gases -- oxygen and hydrogen -- obtained by MAVEN's Imaging Ultraviolet Spectrograph.

Early results from NASA's recently arrived MAVEN Mars spacecraft show an extensive, tenuous cloud of hydrogen surrounding the Red Planet, the result of water breaking down in the atmosphere, scientists said Tuesday.

MAVEN, an acronym for Mars Atmosphere and Volatile Evolution, arrived on Sept. 21 to help answer questions about what caused a planet that was once warm and wet to turn into the cold, dry desert that appears today.

MAVEN has not yet reached its intended operational orbit, but during three early, high-altitude passes around Mars, the spacecraft's science instruments measured hydrogen, as well as oxygen and carbon atoms in the planet's atmosphere. The atoms come from the breakdown of water, carbon dioxide and other molecules.

The hydrogen cloud is the most extensive, as the lightweight atoms float to the top of the atmosphere, where they can be stripped away by the solar wind.

"It's measurements like these that will allow us to estimate the escape rate of hydrogen from the Martian atmosphere to space today. It's an important measurement to make because the hydrogen ... comes from water lower down in the atmosphere," MAVEN scientist Mike Chaffin, with the University of Colorado, Boulder, told reporters on a conference call.

Over the coming year, scientists plan to use MAVEN to collect data on seasonal changes in Mars' upper and lower atmosphere. The information will be used in computer models to calculate how much of the atmosphere is being stripped away today.

Scientists also want to use the data to extrapolate back in time to determine exactly when Mars had a thick enough atmosphere to support liquid surface water. Water is believed to be necessary to life.

Scientists expect to spend another two weeks calibrating MAVEN's science instruments and lowering the spacecraft's orbit. This weekend, MAVEN will join the fleet of Mars probes studying Comet Siding Spring, which is due to make a close flyby on Sunday.

Next month, scientists hope to nail down a collaboration plan with another newly arrived Mars spacecraft, India's Mars Orbiter Mission, or MOM, MAVEN lead science Bruce Jakosky, with the University of Colorado, told .

MOM reached Mars three days after MAVEN.