Oxygen in space could lead to new methods for detecting aliens. Here's how

Scientists believe they have detected a form of oxygen created by living organisms in space surrounding our planet, as per a new study outlining their findings.

The new discovery, made using data from NASA's now-retired Stratospheric Observatory for Infrared Astronomy (SOFIA) flying telescope, could help develop new methods for tracing life on distant habitable exoplanets.

NASA's SOFIA observatory detected heavy oxygen surrounding Earth

NASA's SOFIA telescope was retired in late 2022 due in large part to budget issues. The telescope was mounted aboard an adapted Boeing 747 that would fly to an altitude of up to 42,000 ft (12,800 m). This took it above 99.9 percent of the water vapor on Earth, which blocks much of the infrared light that would otherwise reach observatories on the ground.

Now though, a new study published in the journal Physical Review Research details how researchers used archival data from the telescope to detect heavy atomic oxygen in the upper layers of Earth's atmosphere, the mesosphere, and the lower thermosphere. 

Heavy oxygen is a form of oxygen that features ten neutrons in its nucleus instead of the eight present in the air we typically breathe. High concentrations of heavy oxygen are found close to Earth's surface, as it is produced by photosynthetic organisms, much like normal oxygen.

"It's tracing biological activity — that's well-proven," Helmut Wiesemeyer, a scientist at the Max Planck Institute for Radio Astronomy in Germany and lead author of the new study, explained in a press statement. "So far, the altitude to which this signature extends was thought to be 60 kilometers [around 37 miles] — so, barely the lower part of the mesosphere."

Searching for extraterrestrial life

The new study shows that SOFIA detected heavy oxygen roughly 120 miles (200 km) above the surface of the Earth. An analysis of the concentration of this oxygen suggested it originated on Earth.

"The question was, does it reach higher altitudes? And if it does, because there are no living organisms up there, the only way to reach higher altitudes would be an efficient vertical mixing [of air in Earth's atmosphere]," Wiesemeyer said. 

The findings could prove to be important in the growing global effort to detect extraterrestrial life on distant planets. "The idea is to first understand what happens in front of your own door before you go into deeper studies elsewhere," Wiesemeyer explained.

If the new discovery is confirmed, we could have a new way of searching for extraterrestrial life by detecting the presence of biosignatures in distant alien worlds.