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Hello, and welcome to Astronomy Daily. I'm Anna and I'm Avery.
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It is Wednesday, April eighth, twenty twenty six, and what
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a week it has been. We are deep into what
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might be the most extraordinary few days in human spaceflight
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since nineteen seventy two. Artemis two is heading home, and
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we are going to walk you through exactly where the
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crew is right now, what happened on flight day seven,
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and what to expect as they come screaming back through
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the atmosphere on Friday.
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Screaming is right. We are talking twenty five thousand miles
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per hour, the fastest crude re entry in history. But
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more on that in a moment.
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We have also got a cargo launch delay that has
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created one of the most beautifully poetic scheduling coincidences we
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have ever seen in spaceflight. Some planet shaking new science
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about how Earth actually formed, fresh data from an alien
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comet courtesy of a spacecraft designed for Jupiter's mood uns.
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A new comic for skywatchers to get excited about after
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last week's spectacular disappointment, and then.
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To close the show today, something a little different, A mystery,
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a space mystery that is thirty years old and has
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never been solved.
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I have been looking forward to this one all day.
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I won't lie.
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Doh of I let's get into it. This is Astronomy Daily,
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season five, episode eighty four.
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Right, so let's set the scene. Artemis two launched on
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April first, Yes, April Fool's Day, and no it was
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not a joke. And the crew of four have already
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done the most extraordinary thing. On Monday, Flight Day six,
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they flew around the far side of the Moon. They
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set a new record for the furthest humans have ever
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been two hundred and fifty two thousand, seven hundred and
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fifty six miles. Nobody in human history has ever been
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that far.
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And Flight Day seven, which was yesterday Tuesday, was the
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day after all drama, the science debrief day, the comedown day,
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well sort of. They woke up to Tokyo drifting by
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glass animals and Denzel Curry and I genuinely love whoever
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selects these wake up songs is having an absolute blast.
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The playlist creation on Artemis two has been exceptional. Somebody
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at NASA is doing their best work.
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They woke up thirty six thousand miles from the moon,
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two hundred thirty six thousand miles from Earth, and the
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big item on the agenda was a fifteen minute audio
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call ship to ship with the crew aboard the International
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Space Station.
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So you have four astronauts who have just been further
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from Earth than any human in over fifty years calling
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up the International Space Station, which from where O'Ryan was
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sitting must have felt practically next.
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Door, right relatively speaking. They spoke with NASA astronauts Jessica Mere,
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Jack Hathaway, Chris Williams, and ESA's Sophie Adenaut. Just imagine
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that conversation. So, how was the Moon, you know, bit far?
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And after that the science debrief. The Artemis two lunar
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science team had a full debrief session with the crew
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to capture everything they observed during the flyby while the
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memories were still sharp.
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Which makes complete sense, right, These four people have just
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seen parts of the Moon no human eye has ever
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seen directly, the far side, craters like Vavlov and the
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Oriental Basin, an ancient lava field on the border of
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the Moon's near and far side that's almost impossible to
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see from Earth. You want those impressions captured immediately.
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And then in the evening at about nine pm Eastern,
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Orion fired the first of three trajectory correction burns to
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begin fine tuning the return path to Earth.
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Though we are officially in the home stretch. And Flight
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day eight, which is today, the crew has two key tasks. First,
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a radiation shelter construction demonstration.
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Which sounds alarming but is actually a plan drill. The
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practice assembling a makeshift radiation shelter inside Orion using available
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materials in case of a solar event during a deep
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space mission, exactly the kind of emergency preparedness you need
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locked in before Artemis three heads to the lunar surface.
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And second manual piloting tests. The crew gets to hand
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fly Orion directly, which, given that computers handled basically everything
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on this mission, must feel a bit like being handed
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the wheel.
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And then, Friday, April tenth, splash down.
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Flight day ten, Orion re enters the atmosphere at twenty
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five thousand miles per hour. That is the fastest crude
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re entry ever attempted. The heat shields, which caused so
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much concern and engineering work before this mission, will be
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put to its ultimate.
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Test, and collecting data from that re entry is actually
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one of the core mission objectives, so NASA will be
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watching those heat shield readings very closely.
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Blashdown is scheduled for about eight pm Eastern off the
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coast of San Diego. The USS John P. Murtha, a
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Navy amphibious transport docship, will be waiting. The crew will
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be recovered by helicopter, taking a board for medical evaluation,
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then flown back to Houston, and.
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That will be it the first time humans have returned
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from beyond Earth orbit since Apollo seventeen in nineteen seventy two.
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Mission complete, but.
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Right now Reid Wiseman, Victor Glover, Christina Koch, and Jeremy
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Hansen are heading home and we could not be more
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excited for them.
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All right, from the crew heading back to Earth to
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a cargo ship heading up to the space station with
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a slight detour through the weather forecast.
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Yes So, as we reported yesterday, Northrop Grumman's Signus CRS
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twenty four mission was supposed to launch today Wednesday morning
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from Cape Canaveral on SpaceX Falcon nine, carrying about eleven
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thousand pounds of cargo to the International Space Station, but.
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The weather at Space Launch Complex forty had other ideas
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and teams have pushed the launch to Friday, April tenth,
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targeting eight oh three in the morning Eastern backup opportunity
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on Saturday the eleventh if needed.
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Now here's why this matters beyond just a weather delay.
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Friday April tenth is also the day Artemis two splashdowns, so.
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On the same day, four astronauts returned from the Moon,
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the furthest humans have been from Earth in over fifty years.
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A fresh cargo ship launches towards the space station simultaneously.
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Cape Canaveral is going to be having quite a Friday.
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The spacecraft itself is the Signus Excel, the larger configuration
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carrying about eleven thousand pounds of pressurized cargo. Northrop Grumman
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has named this one the SS Stephen R. Nagel, in
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honor of the NASA astronaut who flew four Shuttle missions
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and longed over seven hundred and twenty hours in space.
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Beautiful tradition. Naming these cargo ships and the science aboard
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CRS twenty four is genuinely interesting. There's a new module
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for the Cold Atom Lab on the station, NASA's quantum
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Science facility to help investigate dark matter and potentially improve
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computing technology.
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There's also hardware to produce greater numbers of therapeutic stem
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cells for blood diseases and cancer, model organisms for a
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gut microbiome study, and a receiver to improve space weather
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models that protect GPS and radar infrastructure.
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Though it's not just food and equipment, this is a
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proper science delivery.
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Once it arrives, Signus doesn't dock automatically the way Dragon does.
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Astronauts Chris Williams and Jack Hathaway will use the Canid
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Arm two robotic arm to grab it and bring it in.
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They've been practicing. There was a report last week of
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them running simulations together in the cupola.
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And Signus is scheduled to stay at the station until
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October before undocking with several thousand pounds of trash and
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burning up on re entry. A rather unglamorous end, but
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a useful one.
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Weather permitting. Friday should be quite the day.
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Okay. Story three, and this one is a genuine rewrite
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of something we thought we understood.
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Where did Earth come from? We know the broad answer.
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Four and a half billion years ago, a cloud of
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gas and dust collapsed, the Sun formed, and the leftover
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material clumped into planets, but where exactly did the specific
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material that became Earth come from.
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For decades, the accepted model was that Earth got a
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significant chunk of its building material from the outer Solar
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System from beyond Jupiter. Estimates ranged from six percent to
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as much as forty percent of Earth's mass, and the
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reason this mattered is water pliantists needed that outer Solar
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System contribution to explain where Earth's oceans came from, because
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the Inner Solar System was thought to be too dry.
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But a new study from Eth Zurich, published in the
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journal Nature Astronomy, has just turned that on its head.
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Planetary scientists Paulososi and Dan Bauer analyze isotopic ratios of
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meteorites from across the Solar System and compare them to
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Earth's composition. Their conclusion, Earth formed almost entirely from Inner
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Solar System material, the outer Solar System contribution less than
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two percent, and possibly nothing at all.
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Now, isotopes are essentially atomic fingerprints. Different regions of the
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Solar System produce slightly different ratios of the same elements,
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and you can use those signatures to trace where material originated.
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Previous studies mostly looked at one or two isotopic systems.
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Saucy and Bauer looked at ten.
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Ten different isotopic systems analyzed with statistical methods rarely used
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in geochemistry, and when you look at all ten together,
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the picture is unambiguous. Earth is built of non carbonaceous material.
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Inner Solar System stuff through went through.
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Which immediately raises an enormous question. If Earth didn't get
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its water from the outer Solar System from comets and
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water rich asteroids drifting inward, where did the water come from?
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And the answer, according to this study is it was
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already here. Water and volatile elements must have been present
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in the Inner Solar System from the very beginning. We
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just didn't realize it.
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And why was so little Outer Solar System material reaching
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Earth in the first place? Jupiter. Jupiter formed extremely quickly
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and grew enormous, and its gravity carved gap in the
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young protoplanetary disc, essentially a barrier between the inner and
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outer Solar System. This study suggests that barrier was almost
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completely impermeable. Almost nothing got through.
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Jupiter, the bouncer of the Solar system. Sorry, outer Solar
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system material not tonight.
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One of the researchers, Dan Bauer, said, we were truly
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astonished to find that Earth is composed entirely from Inner
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Solar System material, distinct from any combination of existing meteorites.
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Even they didn't expect this result.
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The implications are genuinely big. If water was already present
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in the Inner Solar System, that changes how we think
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about the conditions that made life possible here, and it
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has implications for other planetary systems. Rocky planets around Sun
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like stars might be wetter than we assumed.
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It's the kind of result that makes you look at
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the ground beneath your feet differently. This material formed locally
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billions of years ago without much help from the wider
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Solar System. Jupiter kept the neighborhood tidy.
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And Earth's water was here from the starts, which is
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kind of beautiful.
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Actually digging with space science, and this one involves an
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alien comet, a spacecraft on its way to Jupiter's moons,
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and an instrument that was never designed to do what
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it ended up doing.
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We have followed three iatls closely on the show Quick Catchup.
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Three IATLS is an interstellar comment, only the third object
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ever confirmed to have entered our Solar System from interstellar space.
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Discovered in July twenty twenty five, reached its closest approach
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to the Sun on October twenty ninth. And when I
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say it was moving fast two hundred and fifty thousand
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kilometers per hour, nothing that forms in our solar system
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moves like that.
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It is genuinely a visitor from another star system. We
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have no idea which one.
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In November twenty twenty five, isa's Juice spacecraft, the Jupiter
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icy Moons Explorer, currently en route to Jupiter, was in
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a fortunate position to observe three iatls from deep space
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just four days after Perihelium. The observations were difficult. It
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took until February twenty twenty six for the data to
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reach Earth.
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And Issa has now published the findings and the headline
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number is extraordinary. Juice's Magis spectrometer detected two thousand kilograms
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of water vapor being expelled by three iatls every single second.
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Two thousand kilograms per second.
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To give you a sense of scale, that is the
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equivalent of approximately seventy Olympic swimming pools of water every
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single day, just evaporating off the surface of this comet
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into space, which.
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Tells you This is a very active comment. Water rich
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at least on the surface, though there's an interesting wrinkle.
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Its carbon dioxide to water ratio is higher than you
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typically expect from a Solar System commet, which either means
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the nucleus is genuinely CO two rich or there's a
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thick insulating crust hiding ice underneath.
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Either of which we can determine from here. Three iatls
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has now passed Jupiter and is heading out of the
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Solar System. It will never return.
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And here's the part I find most extraordinary. ESIS navigation camera,
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designed for navigating near Jupiter's moons looking at surfaces a
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few hundred kilometers below, also contributed to the science. It
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provided a unique vantage point from deep space that helped