Astronomers now have a new tool at their disposal in their search for life in space: A telescope designed to scan distant planets’ atmospheres for gases that would only exist if there was life present there.
As a child in Florida, Jill Tarter would walk along the beaches and gaze upon the stars above, captivating by their many constellations and searching for alien life forms in them. Soon enough, this became her passion – something she later pursued professionally.
1. They look for signs of intelligent life.
Since Frank Drake first tuned his radio telescopes to frequencies he thought aliens might use for communication (and received no reply), searches for extraterrestrial life have skyrocketed. Astronomers now search the skies for signs of life through biosignatures – any chemical or physical signal which might indicate their existence.
Recent discoveries, such as planets in orbit around Proxima Centauri, have greatly increased the odds of alien life out there. One or more of those rocky planets could even lie within what’s known as the habitable zone – where temperatures would be warm enough for liquid water to exist on its surface.
Scientists are exploring what are known as technosignatures emitted by advanced alien civilizations. This includes looking out for signs that point toward technology-based life forms like complex industrial chemicals or reflective solar panels.
Detecting extraterrestrial life’s biosignatures won’t be simple. While dolphins or camels on Earth might be visible with cameras, extraterrestrial biosignatures will only likely be detectable through sophisticated astronomical instruments – and those tools are becoming ever more powerful; for instance, New Mexico’s Very Large Array will soon feature advanced biosignature detection technology.
2. They look for signs of primitive life.
Astrobiology was once seen as nearly dormant, but now its popularity has experienced a revival. Scientists are deploying space probes and conducting astronomical observations in search of habitats where simple forms of life could exist on other worlds.
Planetary scientists have made great strides in recent years towards increasing the likelihood that other planets in our solar system could host primitive life forms, as well as discovering that some exoplanets exist within a star’s “habitable zone,” where planets could support liquid water environments.
Mars may have provided the foundation of life on our planet at one time or another; we now know this because microbial traces were detected there, suggesting it once could have supported it in its early stages. And soon astronomers will start monitoring exoplanets (especially the nearest to Earth) to look for signs of organic chemistry or any indications of life.
Astrobiology seeks to uncover any sign of alien life – be it bacteria or an advanced civilization – but finding evidence will take time and scientists are searching for clues wherever they may be found, from clouds on Venus to methane lakes on Titan and industrial pollution on distant exoplanets to puzzling interstellar objects.
3. They look for signs of life on other planets.
Astrobiologists’ primary challenge in their search for life beyond Earth will be distinguishing “biosignatures” from nonliving chemicals. This step will determine whether any detected molecule actually derives from life; if a planet’s atmosphere contains biosignature gases like oxygen and methane, for example, this would indicate past presence.
But these molecules can also be produced by geological processes that do not involve living organisms, such as volcanic activity or hydrothermal reactions. To be certain that any release does not come from life on another world, scientists must conduct extensive laboratory work and model these conditions on distant worlds.
Astronomers stand a greater chance of discovering signs of life on exoplanets if they can use telescopes to observe potential habitable planets more effectively. NASA’s James Webb Space Telescope will scan atmospheres of potentially habitable exoplanets for biosignature gases; however, this method won’t work with distant or nearby stars because those planets would appear too brightly to detect.
On nearer planets, such as Mars and Europa Clipper/Titan, missions such as rover will search for signs of past life within rock samples collected, while Europa Clipper and ESA’s future mission to Titan will probe for signs of life beneath these moons’ shells.
4. They look for signs of life on other stars.
As technology improves, astronomers will soon be able to use telescopes to search for signs of life on distant planets light years away. For instance, the James Webb Space Telescope could measure how light passes through an exoplanet’s atmosphere – potentially revealing water or oxygen presence; future advanced instruments might even more precisely detect chemical traces known as biosignatures.
Astronomers have already identified thousands of exoplanets, such as Proxima Centauri b and Trappist-1 e, both rocky worlds that orbit sunlike stars within their “habitable zone.” That means liquid water would exist on these worlds – considered essential to life on Earth. Astronomers will also look for evidence of water-generating processes like photosynthetic life or volcanic activity which produces methane or carbon dioxide emissions to support their search.
Astrobiologists examine the host star for any exoplanet they discover. By studying its age and chemical make up, astrobiologists can better judge whether an exoplanet contains enough chemicals necessary for life to exist on its surface; additionally, its host star’s chemistry could impact how much oxygen or methane is released by an exoplanet’s host star.
Scientists have devised a “ladder” of possible biosignatures, beginning with basic building blocks such as carbon and moving up towards amino acids – although the exact order remains up for debate.
