Spaceflight Insider

Vita ignotum: How will NASA recognize life as we do not know it?

NASA image of exoplanets orbiting distant star. Image Credit NASA

NASA image of exoplanets orbiting distant star. Image Credit: NASA

Since humanity realized that other worlds orbited distant stars, we have wondered what life on these far-flung planets might look like. While Star Trek and other series have depicted the life of these planets as, essentially, humans with bumpy heads – NASA is considering all the possibilities of what alien life might actually be like.

Indeed, while the general public might view a species’ warp drive as the key determining factor of alien life is – the space agency is taking its cues from extremophiles. as well as other naturally-produced effects given off by biological organisms. However, when it comes to life beyond Earth, one of the most important factors involved – is having an open mind.

“What does a living planet look like?” said Mary Parenteau, an astrobiologist and microbiologist at NASA’s Ames Research Center via an agency-issed release. “We have to be open to the possibility that life may arise in many contexts in a galaxy with so many diverse worlds — perhaps with purple-colored life instead of the familiar green-dominated life forms on Earth, for example. That’s why we are considering a broad range of biosignatures.”

However, no one element is the most critical. Instead, looking for an array of signs is considered a guiding principle in the search for worlds that also support life.

Five reviews papers were recently published in the scientific journal Astrobiology, they detail how scientists working as part of the Nexus for Exoplanet System Science (NExSS) program.

“On early Earth, we wouldn’t be able to see oxygen, despite abundant life,” said Victoria Meadows, an astronomer at the University of Washington and lead author of one of the papers. “Oxygen teaches us that seeing, or not seeing, a single biosignature is insufficient evidence for or against life — overall context matters.”

The James Webb Space Telescoped is currently slated to launch in 2019. Image Credit: Nathan Koga / SpaceFlight Insider

The James Webb Space Telescoped is currently slated to launch in 2019. Image Credit: Nathan Koga / SpaceFlight Insider

Some of the things that scientists will be on the lookout for are whether-or-not the planet falls within the habitable range that we’re aware of, what type of star the planet is orbiting and other factors.

With the use of a diverse array of processes, including looking for the dimming of a parent star as one of its’ planets passes in front of it, thousands of far-flung worlds have been discovered since 1992.

Perhaps one of the most prevalent questions is, if one of these planets is habitable – how will the agency be able to tell if it supports life?

“We’re moving from theorizing about life elsewhere in our galaxy to a robust science that will eventually give us the answer we seek to that profound question: Are we alone?” said Martin Still, an exoplanet scientist with NASA.

Four scientists operating out of NASA’s Jet Propulsion Laboratory in Pasadena, California are working to determine what to look for when studying these exoplanets. Worlds devoid of life might give off false positives.

One potential example of this is the planet Mars which gives off seasonal methane, a gas that can indicate the presence of life. Whether or not this serves as evidence of life on the Red Planet remains to be seen. Other gases are viewed by scientists looking into the prospects of alien life are thought to be far more important in the search for worlds like our own.

More data is hoped to be acquired by space and ground-based telescopes. The as-yet to be launched James Webb Space Telescope and the Giant Magellan Telescope and the Extremely Large Telescope (both of the latter are located in Chile) represent some of the tools scientists will employ. Observing the light from these distant planets is the only current means available to review how the atmosphere changes from season-to-season, as well as what comprises these worlds’ atmospheres.

It is hoped that scientists might be able to detect the tell-tale signatures in exoplanets’ atmospheres before 2030. Having said that, scientists have their work cut out for them as this is a complex task.

“We won’t have a ‘yes’ or ‘no’ answer to finding life elsewhere,” said Shawn Domagal-Goldman, an astrobiologist at NASA’s Goddard Space Flight Center and a co-author. “What we will have is a high level of confidence that a planet appears alive for reasons that can only be explained by the presence of life.”

In 1992 terrestrial-mass planets were discovered around pulsar PSR B1257+12. Three years later 51 Pegasi – was also determined to have a so-called “hot Jupiter” with a four-day orbit around the main sequence star.




Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

Reader Comments

How did Pasteur identify living things in his famous study on Pasteurization? Turbidity increases due to multiplication. Probably the best way in this solar system now that we understand the metabolism of Archaebacteria. Follow up with microscopy. A no-brainet. I can’t imagine why I dont hear about these kind of experiments on Mars and moons with water. So simple.

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