biosignatures Archives

September 13, 2023September 13, 2023 by Brian Koberlein

Has the First Biosignature Been Found on an Exoplanet?

Artist's impression of Earth in the early Archean with a purplish hydrosphere and coastal regions. Even in this early period, life flourished and was gaining complexity. Credit: Oleg Kuznetsov — Artist's impression of Earth in the early Archean with a purplish hydrosphere and coastal regions. Even in this early period, life flourished and was gaining complexity, and distant exoplanets might begin similarly. Credit: Oleg Kuznetsov

Recently I wrote about the discovery of a hycean world. A potentially habitable exoplanet with a deep warm ocean and thick, hydrogen-rich atmosphere. Such planets are thought to be somewhat common orbiting red dwarf stars, and they are an excellent candidate for life. While it’s an exciting discovery, buried in the research article was something even more exciting. Tentative evidence of a biosignature, hinting at the presence of life. You can guess which discovery started making headlines. But have astronomers really found life on another planet?

August 22, 2023August 22, 2023 by Matt Williams

The Most Compelling Places to Search for Life Will Look Like “Anomalies”

Will it be possible someday for astrobiologists to search for life "as we don't know it"? Credit: NASA/Jenny Mottar

In the past two and a half years, two next-generation telescopes have been sent to space: NASA’s James Webb Space Telescope (JWST) and the ESA’s Euclid Observatory. Before the decade is over, they will be joined by NASA’s Nancy Grace Roman Space Telescope (RST), Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx), and the ESA’s PLAnetary Transits and Oscillations of stars (PLATO) and ARIEL telescopes. These observatories will rely on advanced optics and instruments to aid in the search and characterization of exoplanets with the ultimate goal of finding habitable planets.

Along with still operational missions, these observatories will gather massive volumes of high-resolution spectroscopic data. Sorting through this data will require cutting-edge machine-learning techniques to look for indications of life and biological processes (aka. biosignatures). In a recent paper, a team of scientists from the Institute for Fundamental Theory at the University of Florida (UF-IFL) recommended that future surveys use machine learning to look for anomalies in the spectra, which could reveal unusual chemical signatures and unknown biosignatures.

July 7, 2023July 7, 2023 by Matt Williams

Venus has Clouds of Concentrated Sulfuric Acid, but Life Could Still Survive

Image from NASA's Mariner 10 spacecraft in February 1974 as it traveled away from Venus. (Credit: NASA/JPL-Caltech)

The surface of Venus is like a scene from Dante’s Inferno – “Abandon all hope, ye who enter here!” and so forth. The temperature is hot enough to melt lead, the air pressure is almost one hundred times that of Earth’s at sea level, and there are clouds of sulfuric acid rain to boot! But roughly 48 to 60 km (30 to 37.3 mi) above the surface, the temperatures are much cooler, and the air pressure is roughly equal to Earth’s at sea level. As such, scientists have speculated that life could exist above the cloud deck (possibly in the form of microbes) as it does on Earth.

Unfortunately, these clouds are not composed of water but of concentrated sulfuric acid, making the likelihood that life could survive among them doubtful. However, a new study led by scientists from the Massachusetts Institute of Technology (MIT) reveals that the basic building blocks of life (nucleic acid bases) are stable in concentrated sulfuric acid. These findings indicate that Venus’ atmosphere could support the complex chemistry needed for life to survive, which could have profound implications in the search for habitable planets and extraterrestrial life.

March 14, 2023March 14, 2023 by Andy Tomaswick

Finding Life in the Solar System Means Crunching a Lot of Data. The Perfect Job for Machine Learning

There are plenty of places for life to hide. Even on our blue planet, where we know there is abundant life, it is sometimes difficult to predict all the different environments it might crop up in. Exploring worlds other than our own for life would make it exponentially more difficult to detect it because, realistically, we don’t really know what we’re looking for. But life will probably present itself with some sort of pattern. And there is one new technology that is exceptional at detecting patterns: machine learning. Researchers at the SETI Institute have started working on a machine-learning-based AI system that will do just that.

February 28, 2023March 1, 2023 by Matt Williams

Do Red Dwarfs Provide Enough Sunlight for Plants to Grow?

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface. Credit: ESO/M. Kornmesser

To date, 5,250 extrasolar planets have been confirmed in 3,921 systems, with another 9,208 candidates awaiting confirmation. Of these, 195 planets have been identified as “terrestrial” (or “Earth-like“), meaning that they are similar in size, mass, and composition to Earth. Interestingly, many of these planets have been found orbiting within the circumsolar habitable zones (aka. “Goldilocks zone”) of M-type red dwarf stars. Examples include the closest exoplanet to the Solar System (Proxima b) and the seven-planet system of TRAPPIST-1.

These discoveries have further fueled the debate of whether or not these planets could be “potentially-habitable,” with arguments emphasizing everything from tidal locking, flare activity, the presence of water, too much water (i.e., “water worlds“), and more. In a new study from the University of Padua, a team of astrobiologists simulated how photosynthetic organisms (cyanobacteria) would fare on a planet orbiting a red dwarf. Their results experimentally demonstrated that oxygen photosynthesis could occur under red suns, which is good news for those looking for life beyond Earth!

January 18, 2023January 18, 2023 by Evan Gough

Could Next-Generation Telescopes See That Earth Has Life?

In this image, Earthshine lights up the dark portion of the lunar surface. Image Credit: NASA

While the Earth absorbs a lot of energy from the Sun, a lot of it is reflected back into space. The sunlight reflected from Earth is called Earthshine. We can see it on the dark portion of the Moon during a crescent Moon. The Farmer’s Almanac said it used to be called “the new Moon in the old Moon’s arms.”

Earthshine is one instance of planetshine, and when we look at the light from distant exoplanets, we’re looking directly at their planetshine without it bouncing off another object.

If distant astronomers were looking at Earthshine the way we look at exoplanet shine, would the light tell them our planet is rippling with life?

January 9, 2023January 9, 2023 by Matt Williams

How Could We Detect Life Inside Enceladus?

Scientists recently determined that a certain strain of Earth bacteria could thrive under conditions found on Enceladus. Credit: NASA/JPL/Space Science Institute

For astrobiologists, the scientists dedicated to the search for life beyond Earth, the moons of Saturn are a virtual treasure trove of possibilities. Enceladus is especially compelling because of the active plumes of water emanating from its southern polar region. Not only are these vents thought to be connected directly to an ocean beneath the moon’s icy surface, but the Cassini mission detected traces of organic molecules and other chemicals associated with biological processes. Like Europa, Ganymede, and other “Ocean Worlds,” astrobiologists think this could indicate hydrothermal activity at the core-mantle boundary.

Both NASA and the ESA are hoping to send missions to Enceladus that could study its plumes in more detail. These include the Enceladus Orbitlander recommended in the Planetary Science and Astrobiology Decadal Survey 2023-2032 and the ESA’s Enceladus Moonraker, which could depart Earth in the next decade, taking advantage of a favorable alignment between the planets. In anticipation of what these missions could find, an international team of researchers used data from the Cassini mission to establish how samples of plume material could constrain how much biomass Enceladus has within it.

October 27, 2022October 27, 2022 by Matt Williams

Here are Four Ways JWST Could Detect Alien Life

Artist conception of the James Webb Space Telescope. Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez

Less than a year after it went to space, the James Webb Space Telescope (JWST) has already demonstrated its worth many times over. The images it has acquired of distant galaxies, nebulae, exoplanet atmospheres, and deep fields are the most detailed and sensitive ever taken. And yet, one of the most exciting aspects of its mission is just getting started: the search for evidence of life beyond Earth. This will consist of Webb using its powerful infrared instruments to look for chemical signatures associated with life and biological processes (aka. biosignatures).

The chemical signatures vary, each representing a different pathway toward the potential discovery of life. According to The Conversation’s Joanna Barstow, a planetary scientist and an Ernest Rutherford Fellow at The Open University specializing in the study of exoplanet atmospheres, there are four ways that Webb could do this. These include looking for chemicals that lifeforms depend on, chemical byproducts produced by living organisms, chemicals essential to maintaining a stable climate, and chemicals that shouldn’t coexist.

October 26, 2022October 26, 2022 by Laurence Tognetti

Webb Can Detect Planets Orbiting White Dwarfs, And Maybe Even See Signs of Life

In a recent study accepted to the Monthly Notices of the Royal Astronomical Society, an international team of researchers led by Texas A&M University investigate how the James Webb Space Telescope (JWST) can detect a variety of exoplanets orbiting the nearest 15 white dwarfs to Earth using its Mid-Infrared Instrument (MIRI) Medium Resolution Spectrograph (MRS). This study holds the potential to expand our knowledge of exoplanets, their planetary compositions, and if they can support life.

October 14, 2022October 16, 2022 by Evan Gough

If Earth Were an Exoplanet, it Would Still be Tricky to Figure Out if There’s Life Here

Earth as seen by the JUNO spacecraft in 2013. Credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill.

How would Earth appear to alien astronomers? What would their observations tell them about Earth if they searched the heavens for signs of habitability like we are? It’s a fun thought experiment.

But the experiment is more than just fun: it’s scientifically instructive. In many ways, it’s easier to study our planet and how it appears and then extrapolate those results as far as they go.

A new study shows that finding evidence of life on Earth may depend on the season alien astronomers are observing.