NASA revealed on May 7 that an instrument aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) detected atomic oxygen in the atmosphere of planet Mars.
It was the first time such observation was made since astronomers found Martian atmospheric oxygen 40 years ago.
Atomic oxygen influences how other gases escape the Red Planet and thus has a significant effect on the planet's atmosphere. It also impacts radiative cooling from the carbon-dioxide bands above the mesosphere, the upper layer of the planet's atmosphere where the atoms were discovered.
Astronomers said they detected only about half the amount of oxygen that was anticipated. The low readings could be attributed to fluctuations in the Martian atmosphere.
NASA researchers said they will continue to use SOFIA to make sure their reading is not the result of simple variations in the atmosphere.
Atomic oxygen was last detected in the Red Planet's atmosphere during the Mariner and Viking missions in the 1970s. It has taken quite a while to make another observation because of Earth's skies.
Our planet's skies are dense and moist enough to prevent researchers from accurately seeing what lies beyond it.
The atomic oxygen was discovered by an instrument aboard SOFIA, a Boeing 747SP jet that was modified to carry a 100-inch diameter telescope for research purposes.
The flying observatory can fly up to 45,000 feet above Earth's atmosphere, making it possible for researchers to observe far-infrared wavelengths.
"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 SOFIA Project Scientist Pamela Marcum.
Researchers used the German Receiver for Astronomy at Terahertz Frequencies, or GREAT, to distinguish between oxygen from Earth's atmosphere and that of the Mars's atmosphere.
Astronomers are eager to know the composition of the Martian atmosphere amid plans for a manned mission to the Red Planet.
Atomic oxygen is also a subject of interest among NASA researchers, as the presence of atomic oxygen caused some problems during the early days of America's space shuttle missions.
"In the first few shuttle flights, materials looked frosty because they were actually being eroded and textured," said physicist Bruce Banks. "Atomic oxygen reacts with organic materials on spacecraft exteriors, gradually damaging them."
The findings were presented in a paper published in the journal Astronomy and Astrophysics in 2015.