An airborne observatory on Earth has detected oxygen atoms in the atmosphere of Mars for the first time in 40 years,
NASA reports.
The reading was made by an instrument carried on the Stratospheric Observatory for Infrared Astronomy (SOFIA), which is a Boeing 747SP jetliner that has been modified to carry a 100-inch diameter telescope. The atoms were able to be detected because SOFIA flies between 37,000 and 45,000 above Earth, which takes it above most of Earth's infrared-blocking moisture, NASA said.
The oxygen atoms are difficult to measure, and only about half as many were found as NASA had expected. But fluctuations in the amount of oxygen across Mars was attributed for the difference.
"Atomic oxygen in the Martian atmosphere is notoriously difficult to measure," Pamela Marcum, SOFIA project scientist, said. "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."
Researchers were able to distinguish oxygen in Earth's atmosphere from that in Mars' atmosphere using the German Receiver for Astronomy at Terahertz Frequencies (GREAT.)
The last readings were made in the 1970s by the Viking and Mariner space missions.
The findings were reported in the journal Astronomy Astrophysics in 2015.