This article was originally published conversation. This publication contributed article to an article on Space.com Experts: op-ed & Insights.
The exploration of life beyond the earth is an important driving force in modern astronomy and planetary science. The US is building several major telescopes and planetary probes to advance this search. But the signs of life that scientists may find – called biosignatures – It’s going to be difficult to interpret. Knowing where you can see exactly is also challenging.
I an Astrophysicists and astrobiologists We have over 20 years of experience studying extsolar planets, planets that transcend our solar system.
My colleague and I developed a A new approach It helps you identify the most interesting planet or moon to search for life and interpret the potential biological signatures. We do this by modelling how different living things are fed in different environments, informed by research on the limits of life on Earth.
A new telescope for finding life
Astronomers are developing plans and technology for increasingly powerful space telescopes. For example, NASA is working on what is being proposed. Living World Observatorytakes an Ultra Sharp image directly showing a planet orbiting a nearby star.
My colleague and I are developing another concept Nautilus Space Telescope constellations are designed to study hundreds of potentially Earth-like planets as they pass in front of host stars.
These and other future telescopes aim to provide more sensitive research into a more heterogeneous world. Their development prompts two important questions: “Where should I look?” And “Are we really thinking that the signs of life can be inhabited?”
Strongly controversial claims of potential Signs of Life for Xplanet K2-18bIt was announced in April 2025 Previous similar claims on Venusshows how difficult it is to identify at the end The existence of life from remote sensing data.
When is the alien world inhabitable?
Oxford Language “Living” is defined as “sufficient or good enough to live in.” But how do scientists know what extraterrestrial life is “sufficient” to “live”? Alien microorganisms playing in a lake of boiling acids or cold liquid methane, or they could float in water droplets The atmosphere above Venus?
To keep it simple, NASA’s mantra is to “traverse the water.” This makes sense – Water is essential For all the life of the earth we know. Planets containing liquid water also have temperate environments. It won’t be cold enough to slow down chemical reactions, and it won’t be very hot, destroying the complex molecules needed for life.
However, astronomers’ rapidly growing ability to characterize the alien world means that astronomers need a more quantitative and subtle approach than water and no water classification.
As part of NASA funding Alien Earth My leading project, Astrobiologist Rory Burns And I worked on this issue with a group of astrobiologists, planetary scientists, deplanetary experts, ecologists, biologists and chemists. Nexss.
Over 100 colleagues provided us with ideas and two questions frequently came up.
beginning, How can you know what life needs?what if you don’t understand the full scope of extraterrestrial life? Scientists know a lot about life on Earth, but most astrobiologists agree that more exotic types of life are possible, perhaps based on various combinations of chemical elements and solvents. How do you determine the conditions necessary for other types of living?
Second, the approach should work with incomplete data. Potential sites for trans-earth life – “Extsolar habitats” are extremely difficult to study in person, and are often impossible to visit and sample.
for example, Underground on Mars It remains almost out of our reach. A place like the moon of Jupiter Europe And the moon of Saturn Underground oceans of Enceladus And all extsolar planets remain virtually unreachable. Scientists indirectly study them, and often use only remote observations. These measurements cannot convey as much as actual samples.
Worse, measurements often have uncertainty. For example, only 88% are convinced that water vapor exists in the atmosphere of explanet. Our framework needs to be able to handle uncertainty using small amounts of data. And we need to accept that the answer is often not black or white.
A new approach to livability
A new approach called Quantitative Living Frameworkthere are two distinctive features.
First, we moved away from trying to answer the vague “liveable living” questions and narrowed it down to more specific and practically answerable questions. Does habitat conditions allow certain (known or unknown) species or ecosystems to survive, as we know?
Even on Earth, living things require different states to survive. There are no camels in the Antarctic. I answered the questions simply by talking about a particular organism.
Second, quantitative livability frameworks do not argue for black or white answers. Compare computer models to calculate probabilistic answers. Instead of assuming liquid water is an important limiting factor, we compare understanding of the conditions required by an organism (the “biological model”) that exist in the environment (the “habitat model”).
There is uncertainty in both. Each understanding is incomplete. However, it can handle uncertainty mathematically. By comparing the two models, one can determine whether the organism and habitat may be compatible.
A simple example is that Antarctic habitat models may state that temperatures are often below freezing. And the camel biological model may say it won’t survive long under cold temperatures. Naturally, it correctly predicts the near-zero probability that Antarctica is a good habitat for camels.
I’m working on this project. Literary data on extreme living organisms were collected to study the limits of life. From insects living in the Himalayas to high altitude and cold insects to thriving microorganisms Hot water holes in the seabed Eats chemical energy.
We investigated through our model whether they might survive underground on Mars or in European seas. We also investigated whether marine bacteria that produce oxygen in Earth’s oceans could potentially survive on known exoplanets.
Though comprehensive and detailed, this approach makes an important simplification. For example, we have not yet modelled how life forms planets, nor have we described the complete array of nutrients that living things require. These simplifications are by design.
In most of the environments we are currently studying, it is too unclear what conditions are to make meaningful attempts to such models. Enceladus of Saturn.
The quantitative habitability framework allows my team to answer questions such as whether Astrobiologists are interested in Mars’ underground locations, or whether they should turn to Planet A or Planet B during their lifetime searches, taking into account the available data. Our framework can be used as an open source computer model. It has become easier for astrobiologists to use and further develop to support current and future projects.
If scientists detect potential signatures of life, this approach can help you assess whether the detected environment can actually support the type of life that leads to the signatures that were detected.
The next step is to live in extreme environments and build a database of terrestrial creatures that represent the limits of life. You can also add a virtual alien life model to this data. By integrating them into a quantitative addictive framework, you can manipulate scenarios, interpret new data coming from other worlds, and guide the signatures of life across the globe.
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