Could Life Survive on Frigid Exo-Earths? Maybe Under Ice Sheets

This artist's illustration shows what an icy exo-Earth might look like. A new study says liquid water could persist under ice sheets on planets outside of their habitable zones. Image Credit: NASA

Our understanding of habitability relies entirely on the availability of liquid water. All life on Earth needs it, and there’s every indication that life elsewhere needs it, too.

Can planets with frozen surfaces somehow have enough water to sustain life?

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Scientists Piece Together the Shoreline of an Ancient Ocean on Mars

Stitched together from 28 images, this view from NASA's Curiosity Mars rover was captured after the rover ascended the steep slope of a geologic feature called "Greenheugh Pediment." In the distance at the top of the image is the floor of Gale Crater, which is near a region called Aeolis Dorsa that researchers believe was once a massive ocean. The layered structure of the rocks indicated they were created by waterborne sediment. Credit: NASA/JPL-Caltech/MSSS.

Scientists have long suspected that Mars was once warm and wet in its ancient past. The Mars Ocean Hypothesis says that the planet was home to a large ocean around 4 billion years ago. The ocean filled the Vastitas Borealis basin in the planet’s northern hemisphere. The basin is 4–5 km (2.5–3 miles) below Mars’ mean elevation.

A new topographic map of Mars reinforces the hypothesis and adds more detail.

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Underground Liquid Water Detected on Mars? Maybe not

This image from NASA’s Mars Reconnaissance Orbiter shows the edge of the Martian South Pole Layered Deposit. Credit: NASA/JPL-Caltech/University of Arizona

When planning crewed missions to Mars, the key phrase is “follow the water.” When astronauts set down on the Red Planet in the next decade, they will need access to water to meet their basic needs. Following the water is also crucial to our ongoing exploration of Mars and learning more about its past. While all of the water on the Martian surface exists as ice today (the majority locked away in the polar ice caps), it is now known that rivers, lakes, and an ocean covered much of the planet billions of years ago.

Determining where this water went is essential to learning how Mars underwent its historic transformation to become the dry and cold place it is today. Close to twenty years ago, the ESA’s Mars Express orbiter made a huge discovery when it detected what appeared to be a massive deposit of water ice beneath the southern polar region. However, recent findings by a team of researchers from Cornell University indicate that the radar reflections from the South Pole Layered Deposit (SPLD) may be the result of geological layering.

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Socks, The Final Frontier

ISS026-E-011334 (18 Dec. 2010) --- NASA astronaut Catherine (Cady) Coleman, Expedition 26 flight engineer, is pictured with a stowage container and its contents in the Harmony node of the International Space Station.
ISS026-E-011334 (18 Dec. 2010) --- NASA astronaut Catherine (Cady) Coleman, Expedition 26 flight engineer, is pictured with a stowage container and its contents in the Harmony node of the International Space Station.

What is the greatest challenge facing humans as we prepare for the first crewed missions to Mars? Solar and cosmic radiation? Atrophying bone and muscle? Growing food? How about laundry? It’s strange but true, right now we don’t have a way to clean laundry in space.

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A Mars Meteorite Shows Evidence of a Massive Impact Billions of Years ago

This artist’s impression shows how Mars may have looked about four billion years ago. The young planet Mars would have had enough water to cover its entire surface in a liquid layer about 140 metres deep, but it is more likely that the liquid would have pooled to form an ocean occupying almost half of Mars’s northern hemisphere, and in some regions reaching depths greater than 1.6 kilometres. Credit: ESO/M. Kornmesser

Researchers at Australia’s Curtin University have discovered evidence of a massive impact on the Martian surface after 4.45 billion years ago. This may not seem like a surprising revelation – after all, we know that there were several large impacts on Mars, like Hellas and Argyre, and we know that large impacts happened frequently in the early solar system – so why is this a big deal?

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Water was Already Here Before the Earth Formed

Earth as seen by the JUNO spacecraft 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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There are Places Where Salty Water Could Emerge Onto the Surface of Mars

A computer generated view of Mars, with an area including Gale Crater beginning to catch morning light. Image Credit: NASA/JPL-Caltech

The existence of water on Mars is a contentious subject. We know there used to be water on the surface of the planet, though it’s long gone now. We know there’s frozen water underground in the world, and we know there’s water vapour in the air. But life needs liquid water.

Could there be liquid water on Mars?

A new study shows how salty water could emerge from the atmosphere onto Mars’ surface under the right conditions.

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Is the Underground Lake on Mars Just Volcanic Rock?

Ice at Mars' south pole. Image Credit: ESA/DLR/FU Berlin/Bill Dunford

Is Mars home to an underwater lake? Different researchers are reaching different conclusions. Some say remote sensing from the Mars Express orbiter shows liquid water in an underground lake at Mars’ south polar region. Other researchers say clays or minerals explain the data better.

Who’s right? Maybe none of them.

A new study says that volcanic rock can explain the Mars Express data and that it’s a more plausible explanation.

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The Scientific Debate Rages on: Is there Water Under Mars’ South Pole?

The South Pole on Mars. Image: NASA.
The South Pole on Mars. Image: NASA.

There’s no surface water on Mars now, but there was a long time ago. If you ask most people interested in Mars, what’s left of it is underground and probably frozen.

But some previous evidence shows there’s a lake of liquid water under the planet’s South Pole Layered Deposits (SPLD). Other evidence refutes it. So what’s going on?

Science, that’s what.

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Ice Peeks out of a Cliffside on Mars

This area, on the western edge of Milankovic Crater on Mars, has a thick deposit of sediment that covers a layer rich in ice. The ice is not obvious unless you look in color. In the red-green-blue images that are close to what the human eye would see, the ice looks bright white, while the surroundings are a rusty red. The ice stands out even more clearly in the infrared-red-blue images where it has a striking bluish-purple tone while the surroundings have a yellowish-grey color. The ice-rich material is most visible when the cliff is oriented east-west and is shielded from the sun as it arcs through the sky to the south. Image Credit: NASA/JPL/UArizona

The HiRISE (High-Resolution Imaging Science Experiment) camera on the Mars Reconnaissance Orbiter has captured another beauty. This time the image shows water ice peeking out from a cliffside on Mars. A layer of sediment obscures most of the ice, but fingers of it are visible.

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