A 747 flying above Earth finds some oxygen in the Martian atmosphere

NASA's SOFIA observatory in red skies above Earth, not Mars. (credit: NASA)

Mars today is a cold, dead world because it lost its magnetic field more than 4 billion years ago. Once the magnetic field was gone, the solar wind began stripping away a Martian atmosphere that was once as thick as that of Earth. Even today the red planet loses about 100 grams of its thin atmosphere each second.

In the 1970s, the Viking lander measured what was left of the Martian atmosphere after billions of years of being ravaged by the solar wind, and it found a composition of 95 percent carbon dioxide, with tiny amounts of nitrogen and oxygen, as well as traces of argon, hydrogen, and other gases. But because these amounts are so small they haven't been measured again until now.

NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA), a modified Boeing 747 aircraft that makes observations at up to an altitude of 45,000 feet, has again detected oxygen in the upper atmosphere of Mars. "To observe the far-infrared wavelengths needed to detect atomic oxygen, researchers must be above the majority of Earth’s atmosphere and use highly sensitive instruments, in this case a spectrometer. SOFIA provides both capabilities," said Pamela Marcum, a project scientist with the research aircraft.

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