The Stratospheric Observatory for Infrared Astronomy (SOFIA) has detected atomic oxygen in the mesosphere, or upper layers, of the Martian atmosphere.
SOFIA is a joint project between NASA and the German Aerospace Center (DLR). It is a modified Boeing 747SP that carries a telescope 100 inches in diameter. It is based at a NASA facility in Palmdale, California. SOFIA flies between 37,000-45,000 feet.
So why has it taken nearly a half-century for scientists to detect Martian oxygen again?
“Atomic oxygen in the Martian atmosphere is notoriously difficult to measure,” said Pamela Marcum, a SOFIA project scientist. “To observe the far-infrared wavelengths needed to detect atomic oxygen, researchers must be above the majority of Earth’s atmosphere.”
SOFIA flies between 37,000-45,000 feet—or, at a maximum, 8.5 miles above the ground.
With the majority of the moisture in the Earth’s atmosphere below this altitude, the aircraft can use its spectrometer to detect long-distance infrared wavelengths.
There is a notable difference between atomic oxygen and Earth’s oxygen. The air we breathe consists, amongst other elements, of two oxygen atoms. However, atomic oxygen consists of just a single atom.
On Mars, atomic oxygen affects how other gases escape the red planet’s atmosphere. Therefore, it can impact a planet’s atmosphere a great deal.
A particular instrument, the German Receiver for Astronomy at Terahertz Frequencies (GREAT) onboard the SOFIA allows scientists to distinguish between Earth’s atmospheric oxygen and Mars’s atmospheric oxygen.