Machine Learning Will be one of the Best Ways to Identify Habitable Exoplanets

Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)

The field of extrasolar planet studies is undergoing a seismic shift. To date, 4,940 exoplanets have been confirmed in 3,711 planetary systems, with another 8,709 candidates awaiting confirmation. With so many planets available for study and improvements in telescope sensitivity and data analysis, the focus is transitioning from discovery to characterization. Instead of simply looking for more planets, astrobiologists will examine “potentially-habitable” worlds for potential “biosignatures.”

This refers to the chemical signatures associated with life and biological processes, one of the most important of which is water. As the only known solvent that life (as we know it) cannot exist, water is considered the divining rod for finding life. In a recent study, astrophysicists Dang Pham and Lisa Kaltenegger explain how future surveys (when combined with machine learning) could discern the presence of water, snow, and clouds on distant exoplanets.

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Water was Already Here Before the Earth Formed

The Juno spacecraft took this image of Earth during a gravity assist flyby of our planet in 2013. Credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill.

Where did Earth’s water come from? That’s one of the most compelling questions in the ongoing effort to understand life’s emergence. Earth’s inner solar system location was too hot for water to condense onto the primordial Earth. The prevailing view is that asteroids and comets brought water to Earth from regions of the Solar System beyond the frost line.

But a new study published in the journal Nature Astronomy proposes a further explanation for Earth’s water. As the prevailing view says, some of it could’ve come from asteroids and comets.

But most of the hydrogen was already here, waiting for Earth to form.

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We Might Know Why Mars Lost its Magnetic Field

This figure shows a cross-section of the planet Mars revealing an inner, high density core buried deep within the interior. Dipole magnetic field lines are drawn in blue, showing the global scale magnetic field that one associates with dynamo generation in the core. Mars must have one day had such a field, but today it is not evident. Perhaps the energy source that powered the early dynamo has shut down. The differentiation of the planet interior - heavy elements like iron sinking towards the center of the planet - can provide energy as can the formation of a solid core from the liquid. Credit: NASA/JPL/GSFC

Mars is a parched planet ruled by global dust storms. It’s also a frigid world, where night-time winter temperatures fall to -140 C (-220 F) at the poles. But it wasn’t always a dry, barren, freezing, inhospitable wasteland. It used to be a warm, wet, almost inviting place, where liquid water flowed across the surface, filling up lakes, carving channels, and leaving sediment deltas.

But then it lost its magnetic field, and without the protection it provided, the Sun stripped away the planet’s atmosphere. Without its atmosphere, the water went next. Now Mars is the Mars we’ve always known: A place that only robotic rovers find hospitable.

How exactly did it lose its magnetic shield? Scientists have puzzled over that for a long time.

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Even Tiny Mimas Seems to Have an Internal Ocean of Liquid Water

Mimas, as imaged by NASA's Cassini spacecraft and processed by @kevinmgill

Data from the Cassini mission keeps fuelling discoveries. The latest discovery is that Saturn’s tiny moon Mimas may have an internal ocean. If it does, the moon joins a growing list of natural satellites in our Solar System that may harbour liquid water under their surfaces.

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Chefs on the Moon Will be Cooking up Rocks to Make air and Water

Artist impression of a Moon Base concept. Credit: ESA – P. Carril

NASA has delayed their Artemis mission to the Moon, but that doesn’t mean a return to the Moon isn’t imminent. Space agencies around the world have their sights set on our rocky satellite. No matter who gets there, if they’re planning for a sustained presence on the Moon, they’ll require in-situ resources.

Oxygen and water are at the top of a list of resources that astronauts will need on the Moon. A team of engineers and scientists are figuring out how to cook Moon rocks and get vital oxygen and water from them. They presented their results at the Europlanet Science Congress 2021.

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How Does Water go From Interstellar Clouds to Habitable Worlds?

Water moves.  On Earth, it moves in the form of rivers, rain, or ocean swells.  In space, its movements are more subtle but no less more important, and so far we understand very little about that process.  Luckily, we had a tool to help us try to understand it better – the Hershel Space Observatory.  Though it has been out of commission for over 8 years, a team of scientists have now compiled all a review of all of the papers using Hershel data to track water from its birth in interstellar clouds to its eventual resting place on planets. There are still some gaps, but it’s a worthy step towards a better understanding.

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Brines Could be Present on the Surface of Mars for up to 12 Hours, Never for a Full day

This illustration shows Jezero Crater — the landing site of the Mars 2020 Perseverance rover — as it may have looked billions of years go on Mars, when it was a lake. An inlet and outlet are also visible on either side of the lake. Image Credit: NASA/JPL-Caltech

We are extremely interested in the possibility of water on Mars, because where there’s water, there’s the potential for life. But a new study throws a bit of a wet blanket (pun intended) on that tantalizing possibility. Unfortunately, it looks like even the saltiest of brines can only exist on the Martian surface for up to a few hours at a time.

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This is Mawrth Vallis on Mars, and it’s Positively Bursting with Evidence of Past Water Action on Mars

This image shows a small portion of Mawrth Vallis, one of the many outflow channels feeding north into the Chryse Basin. This ancient valley once hosted flowing water. The erosive power of the flowing water rapidly cut down into the underlying layers of rock to expose a host of diverse geologic landforms visible today. Image Credit: NASA/JPL/UArizona

Here on Earth, geologists seek out deep channels into Earth’s rock, carved over the ages by flowing water. The exposed rock walls are like a visual timeline of a region’s geological history. On Mars, the surface water is long gone. But it flowed long enough to expose layers of rock just like here on Earth.

One of those water-exposed areas on Mars is Mawrth Vallis, an outflow channel that feeds into the Chryse Basin.

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Beyond “Fermi’s Paradox” XII: What is the Waterworlds Hypothesis?

Artist's concept of Earth-like exoplanets, which (according to new research) need to strike the careful balance between water and landmass. Credit: NASA

Welcome back to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?” Today, we examine the possibility that the reason for the Great Silence is that many planets out there are just too watery!

In 1950, Italian-American physicist Enrico Fermi sat down to lunch with some of his colleagues at the Los Alamos National Laboratory, where he had worked five years prior as part of the Manhattan Project. According to various accounts, the conversation turned to aliens and the recent spate of UFOs. Into this, Fermi issued a statement that would go down in the annals of history: “Where is everybody?

This became the basis of the Fermi Paradox, which refers to the disparity between high probability estimates for the existence of extraterrestrial intelligence (ETI) and the apparent lack of evidence. Since Fermi’s time, there have been several proposed resolutions to his question, which includes the possibility that many exoplanets are Waterworlds, where water is so plentiful that life will be less likely to emerge and thrive.

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Mars Might Have Lost its Water Quickly

This artist's concept depicts the early Martian environment (right) – believed to contain liquid water and a thicker atmosphere – versus the cold, dry environment seen at Mars today (left). Image Credit: NASA's Goddard Space Flight Center

Mars is an arid place, and aside from a tiny amount of water vapour in the atmosphere, all water exists as ice. But it wasn’t always this arid. Evidence of the planet’s past wet chapter dots the surface. Paleolakes like Jezero Crater, soon to be explored by NASA’s Perseverance Rover, provide stark evidence of Mars’ ancient past. But what happened to all that water?

It disappeared into space, of course. But when? And how quickly?

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