NASA’s SOFIA Observatory in red skies over Earth, not Mars.
NASA
Mars is a cold, dead world today because it lost its magnetic field more than 4 billion years ago. Once the magnetic field was gone, the solar wind began to blow away an atmosphere from Mars once as thick as Earth’s. Even today, the red planet loses about 100 grams of its thin atmosphere every second.
In the 1970s, the Viking lander measured what was left of the Martian atmosphere after billions of years of devastation from the solar wind, and found a composition of 95 percent carbon dioxide, with small amounts of nitrogen and oxygen, as well as trace amounts of argon, hydrogen and other gases. But because these quantities are so small, they have not been measured until now.
NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), a modified Boeing 747 aircraft that makes observations as high as 14,000 feet, has again detected oxygen in Mars’ upper atmosphere. “To observe the far-infrared wavelengths necessary to detect atomic oxygen, researchers must be above most of the Earth’s atmosphere and use very sensitive instruments, in this case a spectrometer. SOFIA offers both possibilities,” says Pamela Marcum, a project scientist with the research aircraft.
The researchers found only about half the oxygen they expected based on the Viking observations, but they say the gas’s concentration likely varies around Mars’ atmosphere. Unlike on Earth, oxygen on Mars is clearly not produced by photosynthesis. Scientists say that water on Mars reacts with certain compounds in the Martian soil to release oxygen into the atmosphere.