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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How did the Earth get its water? The answer might be found on Mercury

Artist's conception of early planetary formation from gas and dust around a young star. Outbursts from newborn and adolescent stars might drive planetary water beneath the surface of rocky worlds. Credit: NASA/NASA/JPL-Caltech

I don’t know if you’ve noticed by now, but the Earth is a little bit wet. How Earth got all its water is one of the major mysteries in the formation of the solar system, and a team of Japanese researchers have just uncovered a major clue. But not on Earth – the clue is on Mercury.

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Organic Matter Could Have Delivered Earth’s Water

This view of Earth’s horizon was taken by an Expedition 7 crewmember onboard the International Space Station, using a wide-angle lens while the Station was over the Pacific Ocean. A new study suggests that Earth's water didn't all come from comets, but likely also came from water-rich planetesimals. Credit: NASA
This view of Earth’s horizon was taken by an Expedition 7 crewmember onboard the International Space Station, using a wide-angle lens while the Station was over the Pacific Ocean. A new study suggests that Earth's water didn't all come from comets, but likely also came from water-rich planetesimals. Credit: NASA

The origin of Earth’s water is a big piece of the puzzle in Earth’s history. Did it come from comets and asteroids? From water-bearing space dust? The scientific debate is not settled.

Now a new study shows that water could have been delivered to Earth by organic matter.

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The Moon Might Be More Metal-Rich Than We Thought

The Moon contains more metal than previously thought, according to a new study. Is it time to re-think the giant impact hypothesis? Image Credit: NASA / GSFC / Arizona State University

A new study shows that the Moon is more metal-rich than previously thought. That has some far-reaching implications for our understanding of the Moon’s formation. If their results are solid, it means that we may need to re-think the giant impact hypothesis for the formation of the Moon.

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Deep Down in Ocean Worlds, it’s Difficult to Tell Where the Oceans End and the Rock Begins

This artist’s concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. The composition of such water worlds has fascinated astronomers and astrophysicists for years. (Image by NASA/JPL-Caltech.)

We all know what water is. And what rock is. The difference is crystal clear. Well, here on Earth it is.

But on other worlds? The difference might not be so clear.

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The Bare Minimum Number of Martian Settlers? 110

If we ever colonize Mars, nature will have to accompany us. Artist's concept of a habitat for a Mars colony. Credit: NASA

So you want to colonize Mars, huh? Well Mars is a long ways away, and in order for a colony to function that far from Earthly support, things have to be thought out very carefully. Including how many people are needed to make it work.

A new study pegs the minimum number of settlers at 110.

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Space Dust Delivered Water to Vesta, Could it Have Done the Same for Earth?

An artful image of dwarf planet Vesta, with an image of micrometeorite overlaid. Image Credit: Ogliore Lab

One of the most enduring questions about Earth regards the origins of its water. Where did it come from? One widely-held theory gives comets the honor of bringing water to Earth. Another one says that Earth’s water came when a protoplanet crashed into early Earth, not only delivering a vast quantity of water, but creating the Moon.

Now a new study shows that the minor planet Vesta got its water from space dust. Could that help explain the origin of Earth’s water?

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3 Billion Years Ago, the World Might Have Been a Waterworld, With No Continents At All

Artist's depiction of a waterworld. A new study suggests that Earth is in a minority when it comes to planets, and that most habitable planets may be greater than 90% ocean. Credit: David A. Aguilar (CfA)
Artist's depiction of a waterworld. A new study suggests that Earth is in a minority when it comes to planets, and that most habitable planets may be greater than 90% ocean. Credit: David A. Aguilar (CfA)

Evidence from an ancient section of the Earth’s crust suggest that Earth was once a water-world, some three billion years ago. If true, it’ll mean scientists need to reconsider some thinking around exoplanets and habitability. They’ll also need to reconsider their understanding of how life began on our planet.

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