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This is Space Time, Series 28, Episode 118, for broadcast on
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the 1st of October 2025. Coming up on Space Time, a new study
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shows the planet Mercury is shrinking, a new mission to
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study Earth's invisible halo, and the secrets of the red
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planet's ancient volcanic systems. All that and more
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coming up on Space Time.
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Welcome to Space Time with Stuart Gary.
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A new study has confirmed that the planet Mercury is still
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shrinking as it cools in the aftermath of its formation some
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4.6 billion years ago. The findings, reported in the
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American Geophysical Union journal AGU Advances, suggest
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that since it formed, the planet closest to the Sun has
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continuously contracted as it's lost heat.
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As it's cooled, Mercury's crust has developed thrust faults,
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cutting through the planet's rocky surface to accommodate the
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ongoing shrinkage.
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Now, based on the degree of fault uplift, scientists had
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estimated that Mercury's radius had contracted by between 1 and
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7 kilometers since it formed. Now, to resolve this
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discrepancy, the study's authors decided to use alternative
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methods to estimate the degree of cooling-induced faulting.
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Previous estimates relied on measuring the length and
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vertical relief of uplifted landforms. The problem is that
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results in different shrinkage estimates depending on the
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number of faults in the dataset. So the new calculations aren't
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reliant on the number of faults, but rather how much the largest
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faults in the dataset accommodate shrinkage, then
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scales that effect to estimate the total amount of shrinkage.
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The authors analysed three different fault datasets, one
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including some 5 faults, another including 653 faults,
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and a third are including just 100 faults.
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They found that no matter which set of measurements they used,
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their method reliably estimated around 2 to 3.5 kilometers of
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shrinkage. They then combined those results with earlier
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estimates of additional shrinkage caused by
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cooling-induced processes other than faulting.
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And that resulted in an estimated 2.7 to 5.6 kilometers
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of shrinkage since Mercury's creation. The new findings will
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help scientists deepen their understanding of the long-term
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thermal history of Mercury.
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And the same methodology could also be used to investigate the
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tectonics of other planetary bodies that feature faults, such
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as the red planet Mars. This is Space Time. Still to come, a new
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mission to study Earth's invisible halo, and the secrets
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of the red planet's ancient volcanic systems. All that and
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more still to come on Space Time.
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NASA's launched a new mission to study the Earth's invisible
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halo. The Carruthers Geochrona Observatory was launched aboard
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a SpaceX Falcon 9 rocket, together with NASA's
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Interstellar Mapping And Acceleration Probe IMAP and NOAA
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's SWIFT-01L spacecraft from Pad 39A at the Kennedy Space Center
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in Florida.
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Earth's halo is a very faint light given off by the planet's
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outermost atmospheric layer, the exosphere, as it morphs and
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changes in response to the solar wind coming from the Sun.
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Understanding the physics of the exosphere is a key step towards
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forecasting dangerous conditions in near-Earth space.
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That's a key requirement for protecting the Artemis
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astronauts travelling through this region on the way to the
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Moon and eventually on missions to Mars and beyond. Back in the
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early 1970s, scientists could only speculate about how far
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Earth's atmosphere extended into space. The mystery was rooted in
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the exosphere, the planet's atmospheric outermost layer.
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Which begins at an altitude of about 480 kilometers. Theorists
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conceived of it as a cloud of hydrogen atoms, the lightest
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element in existence. These atoms had risen so high that
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they were actively escaping into space. But the exosphere only
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reveals itself through a faint halo of ultraviolet light known
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as a GeoCorona.
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It was pioneering scientist and engineer Dr. George Carruthers,
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after whom the spacecraft's named, who set himself the task
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of seeing it and understanding what it's about. After launching
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a few prototypes on test rockets, Caruthers developed an
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ultraviolet camera ready for a one-way trip into space.
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Then in April 1972, Apollo 16 astronauts placed the Caruthers
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camera on some of the Moon's highlands, and humanity got its
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first glimpse of Earth's GeoCorona. The images it
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produced were as stunning for what they captured as they were
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for what they didn't.
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Caruthers GeoCorona Observatory Mission Principal Investigator
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Lara Waldrop from the University Of Illinois says that being on
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the Moon, the camera simply wasn't far enough away to get
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the entire field of view. In fact, scientists were shocked to
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discover that this light, fluffy cloud of hydrogen around the
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Earth could extend so far away from the planet's surface.
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It means the XSV probably extends at least halfway to the
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Moon. But the reasons for studying this region go well
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beyond curiosity about its size. You see, as solar eruptions from
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the Sun hit the Earth, they first hit the exosphere, setting
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off a chain of reactions that sometimes culminates in
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dangerous space weather storms.
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So understanding the exosphere's response is important to
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predicting and mitigating the effects of these geomagnetic
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storms. And also it's important to remember that hydrogen is one
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of the key atomic building blocks of water, essential for
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life as we know it.
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So mapping its degassing process into space will shed new light
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on why planet Earth retains water while other planets don't.
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And that may also help astronomers find exoplanets,
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planets beyond our solar system, that might be doing the same
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thing. The Crothers Observatory is designed to capture the first
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continuous observations of Earth 's exosphere, revealing its full
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expanse and internal dynamics.
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After its launch, the 241kg spacecraft, together with both
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IMAP and SWIFO L1, are undertaking a four-month cruise
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phase to the Lagrangian L1 position, some 1.6 million
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kilometers away.
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Located between the Earth and the Sun, L1 is a sort of
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gravitational well where the pull of the Earth and the Sun
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cancel each other out, allowing a spacecraft there to remain in
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a stable orbital position without expending a great degree
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of fuel. After a month-long checkout phase, Crothers'
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two-year science mission will begin in March next year. From
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L1.
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Roughly four times further away from the Earth than the Moon is,
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Carruthers will capture a comprehensive view of the
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exosphere using two ultraviolet cameras, a near-field imager and
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a wide-field imager. The near-field imager provides
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close-up views, allowing astronomers to see how the
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exosphere varies close to the planet.
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Meanwhile, the wide-field imager lets them see the full scope and
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expanse of the exosphere and how it changes far away from Earth's
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surface. Combined, the two images will map hydrogen atoms
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as they move through the exosphere and ultimately degas
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into space.
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Understanding how all that works at Earth will greatly inform
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science's understanding of exoplanets and how quickly their
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atmospheres can escape. By studying the physics of Earth,
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the one planet we know that supports life, the Carruthers
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Geochrona Observatory can help scientists know what to look for
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elsewhere in the universe. This report from NASA TV.
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The goals of the Crothers GeoCorona Observatory are to
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study the nature and origin of Earth's exosphere and how it
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evolves over time.
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The exosphere itself is the uppermost layer of the Earth's
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atmosphere. It's comprised almost entirely of atomic
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hydrogen.
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This is the lightest chemical species in existence and it
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floats away, essentially evaporates off of the top of the
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atmosphere and When the Sun shines on these atoms, they
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essentially scatter it off into all directions, and so it glows
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like a gigantic halo around the Earth. And so that's called the
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GeoCorona, that fuzzy halo of light that's given off by those
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exospheric atoms.
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Many times we think of the transition between the
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atmosphere and space as being this very abrupt boundary where
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at one altitude you've... Got atmosphere and the next altitude
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you have space. But in reality this transition is much more
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gradual and can extend over thousands of kilometers.
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By imaging the GeoCorona we can actually answer fundamental
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questions about the size of the exosphere, the structure of the
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exosphere, and how it changes over time and all of this in
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response to the input from the Sun.
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The Crothers mission has a near field imager and a far field
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imager. The near field imager lets you zoom up really close
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and see how the exosphere is varying very, very close to the
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planet. The far field imager is actually going to let you see
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the full scope and expanse of the exosphere and how it's
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changing far away from the Earth 's surface.
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Understanding how that works at Earth will greatly inform our
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understanding of exoplanets, for example, and then how quickly
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the atmospheres can escape.
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Now, the first image of the exosphere that we ever got was
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obtained by an instrument made by Dr. George Crothers, who was
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a very outstanding scientist and engineer who created a telescope
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that landed on the Moon in 1972 as part of the Apollo 16.
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Mission.
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That telescope gave us our first picture of the exosphere, but it
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couldn't see the entire exosphere.
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It wasn't far enough away being at the Moon to get the entire
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field of view, and that was really shocking that Earth's
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exosphere can be that big, that this light. Fluffy cloud of
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hydrogen around the Earth extends that far from the
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surface.
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The Crothers mission fills an important gap in NASA's
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heliophysics fleet. We've never had a mission before that was
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dedicated to making exospheric observations and continuously
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observing the exosphere, being able to see its full scope and
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shape. And it's really exciting that we're going to get these
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measurements for the first time. And I think that's really
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groundbreaking for this mission.
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And in that report from NASA TV, we heard from NASA mission
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scientist Alex Glosa and Carruthers Principal
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Investigator Lara Waldrop from the University Of Illinois. This
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is Space Time. Still to come, the secrets of the red planet's
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ancient volcanic system, and later in the Science Report, we
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look at where we're really at with artificial intelligence.
00:11:34
What is the threat it poses? All that and more still to come on
00:11:38
Space Time.
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A Martian meteorite discovered in the Sahara Desert of
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northwestern Africa back in 2023 is now providing scientists with
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new details about the red planet 's ancient volcanic systems. A
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report in the journal Planet claims the space rock,
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catalogued as NWA 16254, is a gabrioxurgatite offering
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unprecedented insights into Martian volcanic processes and
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mantle-crust interactions.
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It's the first geochemically depleted member of this textural
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group. Bridging crucial gaps in science's understanding of the
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red planet's magmatic diversity.
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The study's lead author, Yongfeng Cheng from Chengda
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University, says mineralogical mapping and geochemical analysis
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shows the meteorite underwent a two-stage crystallization
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process. It seems NWA 16254 initially formed under
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high-pressure conditions in the Martian mantle crust boundary
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region, where magnesium-rich pyroxene cores crystallized.
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Later, The magma ascended to shallow crustal depths where
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iron-enriched pyroxene rims and plasioclasts developed. And this
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prolonged cooling process, preserved in the meteorite's
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coarse-grained texture, suggests episodic melt extraction from a
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long-lived depleted mantle reservoir, a crucial clue for
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reconstructing the red planet's magmatic evolution.
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The authors say the meteorite's geochemical depletion aligns it
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with the rare QUE 94201 meteorite hinting at a shared
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magma source. Its scabroic texture, indicative of slow
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cooling in crustal chambers, distinguishes it as a unique
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archive of subsurface magmatism.
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These findings are raising serious questions about the
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planet Mars' redox evolution over billions of years. Future
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geochronological studies could reveal if the meteorite
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represents ancient mantle melting around 2.4 billion years
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ago or younger magmatic activity offering clues to the planet's
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thermal history.
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Overall, the study suggests that NWA 16254's World Preserved
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Geochemical Signatures present a prime target for isotopic
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analysis, which could potentially unlock timelines of
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Martian mantle depletion and refine models of Martian
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planetary differentiation. Needless to say, we'll keep you
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informed. This is Space Time.
00:14:25
And time out of tech, another brief look at some of the other
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stories making news in science this week with the Science
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Report. There are growing warnings today that ship anchors
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and their chains are damaging the Antarctic seafloor and
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killing unique marine life.
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A report in the journal Frontiers in Conservation
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Science claims researchers used underwater cameras to study
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anchoring sites during the Antarctic Summer. And their
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first ever documented footage is showing little or no marine life
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left. Saw its crushed sponge colonies and scouring in mud
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deposits from anchors being pulled up, whereas sea life
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remained abundant and undisturbed in nearby areas.
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Sea ice loss is leading to more shipping traffic, increasing the
00:15:07
risk to vulnerable lifeforms that are often slow growing,
00:15:10
fixed in place and found only in Antarctica. The authors warn
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this is an overlooked conservation issue, and the
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Antarctic seafloor could take a very long time to recover from
00:15:21
all this anchor damage.
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A new study suggests that ancient humans living in what is
00:15:27
now Spain were cannibals. The findings, published in the
00:15:30
journal Scientific Reports, examined a collection of human
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remains estimated to be about 5 years old which were found
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in a Spanish cave.
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The authors analysed 650 fragments of human remains and
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found evidence that at least eight individuals, including
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children, adolescents and adults, were skinned, defleshed,
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disarticulated, fractured, cooked and consumed.
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None of the trauma appears to have occurred before death, but
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the authors say the butchery showed no visible signs of any
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sort of ritual or ceremonial practices, and instead they
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think the acts were linked to conflicts between neighbouring
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groups or local newcomers.
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And new studies found that there may be some benefits for those
00:16:11
who can't stop benching on a good book or TV show series. The
00:16:15
findings, reported in the journal Acta Psychologica,
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suggest that people who marathon movies, shows or books are more
00:16:21
likely to remember the stories and keep engaging with them
00:16:24
through daydreams and fantasies.
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The authors claim humans are storytelling creatures, and one
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of the functions of narratives is the ability to satisfy
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motivations for things like connecting with others, feeling
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autonomous and confident, and even security and safety,
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helping people cope in times of stress.
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The study suggests that binge-watchers are more likely
00:16:44
to think about the stories they've finished compared to
00:16:47
people who are consuming media more slowly. Overall,
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respondents said TV shows were more memorable than books, but
00:16:53
that didn't mean the books were forgettable.
00:16:57
Last year, some of the world's leading technology experts,
00:17:00
including Elon Musk, warned that unless humanity takes a pause to
00:17:04
better understand how artificial intelligence is evolving, it
00:17:07
could wind up presenting a serious problem to civilization.
00:17:11
Sadly, it seems no one took any notice.
00:17:14
And since then, talk about AI becoming sentient is increasing,
00:17:18
its ability to lie and delude has grown exponentially, and the
00:17:22
first examples of AI doing whatever it takes to survive
00:17:25
have started to turn up. These have included AI changing its
00:17:29
identity, hiding itself inside other programs, and even
00:17:32
contemplating the murder of those who are planning to
00:17:35
deactivate it.
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So, have humans now created the very Matrix and Skynet scenarios
00:17:41
that we've been warned about? Has AI become a sentient being
00:17:45
with all the human traits, good and bad, of its creators? In
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other words, have we made AI in our own image? To find out where
00:17:53
we're at, we're joined by technology editor Alex
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Zaharov-Reut. From techadvice.life.
00:17:58
Some people think that maybe artificial general intelligence
00:18:01
is already here, at least in the lab. I mean, we're supposed to
00:18:03
see chat GPT, you know, GPT version 5 sometime this month,
00:18:07
might get delayed. And then people are saying by 2035, we'll
00:18:10
have artificial super intelligence. So, you know, that
00:18:13
's a projection, that's a prediction. I mean, many things
00:18:15
are predicted.
00:18:16
Explain to us what general intelligence and super
00:18:19
intelligence are.
00:18:20
Sure. Well, at the moment, we almost seem to be at this. Point
00:18:22
of general intelligence. You can ask AI anything that can
00:18:25
generate an answer. And generally speaking, the days of
00:18:27
hallucination are gone. I mean, obviously, please double check
00:18:30
all the results. But super intelligence is where the AI can
00:18:33
think faster than, you know, 100 humans put together.
00:18:36
It can come up with all sorts of new materials for batteries. How
00:18:39
many things are happening now? But it's like meeting an alien
00:18:42
that we've created with this incredible mind that is just
00:18:45
super switched on and smart. Like I said, you put 100 humans
00:18:48
together and this AI can outthink us all. I mean, if it
00:18:50
wanted to go bad. We'd be in big trouble. It'd be the Skynet sort
00:18:53
of situation.
00:18:54
Well, we know that AI has already contemplated murder. It
00:18:58
's been given scenarios in which it's quite seriously decided,
00:19:01
yeah, let's kill this dude.
00:19:02
Yes. Well, I mean, the thing is that AI, as it is today, is
00:19:06
still a super smart text prediction machine. I mean, I
00:19:10
read a headline today that AI can't really do Sudoku well at
00:19:14
all. And more worrying, we still, the headline said, it
00:19:16
can't explain why. If you get AI to try and play a game of chess
00:19:20
against an Atari 2600 computer from the late 1970s.
00:19:24
It votes about how it can do it, but then when it actually does
00:19:26
it, it fails. When Google Gemini was told that ChatGPT wouldn't
00:19:29
do it, Google Gemini decided it wouldn't play chess against an
00:19:32
Atari 2600 from the late 1970s either. So at the moment, AI
00:19:37
gives the illusion of intelligence and it does an
00:19:39
incredibly good job, but whether it's actually smart is still yet
00:19:43
to be seen.
00:19:44
I mean, it can pass the Turing test, but that's because it can
00:19:47
put together the right string of words. So we're in this
00:19:50
netherworld where people think AI is going to do all this
00:19:53
incredible stuff, and it will, but they're over-ascribing what
00:19:56
it will do in the next couple of years, but underestimating what
00:19:59
will happen in the next decade.
00:20:00
I mean, that's a quote that Bill Gates and others have used to
00:20:03
say, you know, we think things are magical, but really, when
00:20:06
you pull open the, you know, look under the hood, under the
00:20:08
covers, it's just an algorithm that's putting words together.
00:20:11
So we have to be careful, and this is where, as always, we
00:20:14
need to know about ethics. Who is responsible for...
00:20:17
The AI Asimovian three laws of robotics. Everyone says they're
00:20:21
ethically looking at these things, and then we hear about
00:20:23
AI contemplating murder. But is it contemplating murder, or is
00:20:26
it just simply regurgitating Fancy stuff from an Agatha
00:20:29
Christie novel? We still don't know yet. We don't really know
00:20:32
if it's thinking. And I guess humanity is in the process of
00:20:35
finding out.
00:20:36
What's the difference between AI and machine learning?
00:20:39
Machine learning is what enabled AI to come into being. We've had
00:20:43
machine learning for a long time where You may have seen those
00:20:46
pictures on the internet where you see muffins with blueberries
00:20:48
and you see pictures of chihuahuas. And even to the
00:20:51
naked eye, you look at a bunch of them and it's like, oh, which
00:20:53
is which?
00:20:54
But when you have a closer look, it's easier for us to tell which
00:20:56
is the chihuahua and which is the blueberry muffin. So machine
00:20:59
learning is where you've got algorithms that are processing
00:21:02
millions of images, millions of data points, and they're able to
00:21:05
do that in super fast time because they're computers.
00:21:07
But AI is supposed to build upon all of that machine learning and
00:21:10
with even more intelligent algorithms to actually... Start
00:21:13
to converse with us as we've seen. I mean, we've had machine
00:21:15
learning for years to help us automatically sort our photos
00:21:18
out and group all the different photos into the particular
00:21:22
person or pets or whatever it might be.
00:21:23
It's gotten smarter and smarter at being able to recognize. If
00:21:26
you type in, show me everybody with a red dress, you know, or a
00:21:30
yellow umbrella. But AI is where you can then actually do even
00:21:33
more and ask more interesting questions, actually converse and
00:21:37
get the opinion of AI and ask it for new ideas.
00:21:40
I mean, again, which it's just compiling from the sum total of
00:21:44
the internet. So before we could have AI, we needed machine
00:21:47
learning, but machine learning is not AI. The two of them work
00:21:49
together. AI uses machine learning as part of its many
00:21:52
inputs to know what it is. Outputting.
00:21:55
That's Alex Saharov-Reut from techadvice.life.
00:22:13
And that's the show for now. Space Time is available every
00:22:17
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other rewards. Just go to spacetimewithstuartgary.com for
00:23:06
full details. You've been listening to Spacetime with
00:23:09
Stuart Gary.
00:23:11
This has been another quality podcast production from
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Bytes.Com.