Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomy podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: Welcome back to the show. We are doing something a
Speaker 2: little different today. Usually when we sit down to talk
Speaker 2: about the bleeding edge of astrophysics, when we try to
Speaker 2: visualize what it looks like to steady worlds that are
Speaker 2: hundreds of light years away, we all have a very specific,
Speaker 2: almost Hollywood style image in our heads.
Speaker 3: Oh absolutely, it's the Cape Canaveral aesthetic, isn't it.
Speaker 2: Totally.
Speaker 3: We picture these massive vertical integration buildings, clouds of steam,
Speaker 3: you know, the whole countdown clock thing, and millions of
Speaker 3: pounds of thrust just fighting gravity.
Speaker 2: It's loud, it's fast, and it involves billions of dollars
Speaker 2: of titanium and composites hurling themselves into the vacuum of space.
Speaker 3: It's drama, pure raw power, right, and.
Speaker 2: So we have this conditioned bias that space science equals rockets.
Speaker 2: We just assume that to get high quality data, well,
Speaker 2: you need high velocity and extreme altitude.
Speaker 3: You need to escape Earth entirely.
Speaker 2: That's the assumption. But the documentation we're looking at today,
Speaker 2: specifically a fascinating report from Universe Today and fizz dot
Speaker 2: org about a mission called Excite, it completely dismantles that assumption.
Speaker 3: It really does. It's a wonderful reminder that sometimes the
Speaker 3: most sophisticated solution to a really high tech problem isn't
Speaker 3: about going faster or higher, or you know, just using
Speaker 3: more brute forests.
Speaker 2: Look about being smarter.
Speaker 3: It's about being smarter with where you put your instruments.
Speaker 3: It's about finding the clever workaround.
Speaker 2: Right, Because the vehicle at the center of our conversation
Speaker 2: today isn't a rocket, not at all. It doesn't have thrusters,
Speaker 2: it doesn't have a heat shield. It's a balloon, a.
Speaker 3: Balloon, and it's a balloon that, if everything goes according
Speaker 3: to plan, is going to tell us more about the
Speaker 3: weather on alien planets than perhaps any rocket based telescope
Speaker 3: currently in operation. We are talking about the Excite mission.
Speaker 2: Let's break down that acronym before we get into the physics.
Speaker 2: Because it sounds intense excite.
Speaker 3: It does sound pretty energetic. It stands for the Exoplanet
Speaker 3: Climate Infrared Telescope. Okay, And while the name suggests all
Speaker 3: this high energy and excitement, the actual method of deployment
Speaker 3: is remarkably gentle. It's almost floaty, floaty.
Speaker 2: I like that. So the plan is to float a
Speaker 2: telescope to the very edge of the Earth's atmosphere.
Speaker 3: Exactly and just have it sit there to stare uninterrupted
Speaker 3: at a very specific type of alien world.
Speaker 2: Okay, let's establish the scale here. When we say float
Speaker 2: a telescope, I mean, are we talking about something like
Speaker 2: a weather balloon you'd see on the local news or
Speaker 2: is this more like the red bull stratos jump? How
Speaker 2: high are we actually going?
Speaker 3: We are definitely talking stratospheric think, much much bigger than
Speaker 3: a standard weather balloon. The mission profile calls for an
Speaker 3: altitude of forty.
Speaker 2: Kilometers forty kilometers yep, and to put that.
Speaker 3: In imperial units for those of us who think that way,
Speaker 3: that's roughly twenty five miles straight out.
Speaker 2: Twenty five miles Okay. Can you contextualize that for me?
Speaker 2: If I'm looking out the window of a seven forty
Speaker 2: seven on a transatlantic flight. How far above me is
Speaker 2: this balloon?
Speaker 3: Right, So a commercial jet cruises at what between thirty thousand,
Speaker 3: forty thousand feet some like that. Yeah, so that's roughly
Speaker 3: ten to twelve kilometers up. This balloon is going four
Speaker 3: times higher than a.
Speaker 2: Commercial flight, four times higher.
Speaker 3: If you were in that jet looking up, the balloon
Speaker 3: would still be just a tiny dot in the black
Speaker 3: sky above you. It's not in the blue part of
Speaker 3: the sky anymore. It is cruising the upper stratosphere.
Speaker 2: But and this is a really important distinction we need
Speaker 2: to make. It's not technically space. Is it the Carmen line,
Speaker 2: which is sort of the international welcome to space sign,
Speaker 2: that's at one hundred kilometers.
Speaker 3: Correct, It is not technically outer space. You are still
Speaker 3: within the influence of Earth's atmosphere thin as it is
Speaker 3: up there. But here's the thing. For the specific scientific
Speaker 3: problem they're trying to solve. Forty kilometers is the magic number.
Speaker 2: The sweet spot.
Speaker 3: It's the absolute sweet spot where you get I mean,
Speaker 3: something like ninety nine percent of the benefits of being
Speaker 3: in space, but without the billion dollar price tag of
Speaker 3: a rocket launch.
Speaker 2: I want to really dig into that magic number concept,
Speaker 2: because that really seems to be the lynchpin of this
Speaker 2: whole project's economic and scientific argument. But first, what exactly
Speaker 2: is XITE looking at? You mentioned alien weather.
Speaker 3: Yes, the target is a very specific, very dramatic class
Speaker 3: of planets known as hot jupiters.
Speaker 2: Hot jupiters. It's a vivid name.
Speaker 3: It implies a lot, it does, and it's quite literal. Actually,
Speaker 3: these are gas giants, so planets with the mass and
Speaker 3: composition roughly similar to our own Jupiter. But they are
Speaker 3: not sitting out in the cold suburbs of their solar
Speaker 3: systems like our Jupiter.
Speaker 2: Is right Jupiter's way out there.
Speaker 3: These guys orbit incredibly close to their parent stars.
Speaker 2: How close are we talking? I mean, Mercury is close
Speaker 2: to our Sun is like.
Speaker 3: That, oh much much closer, so close that a year
Speaker 3: one full orbit around their star might only last two
Speaker 3: or three Earth days.
Speaker 2: Two or three days. That is incredibly fast. So they
Speaker 2: are just speed running their orbit.
Speaker 3: They are They're absolutely whipping around their stars. And because
Speaker 3: they are that close, they are just roasting. I can
Speaker 3: engine temperatures on the starfacing side can reach thousands of degrees.
Speaker 3: We are talking about worlds that are essentially glowing with
Speaker 3: their own heat, where the atmosphere is being constantly blasted
Speaker 3: by stellar radiation.
Speaker 2: So we have these massive, scorching, fast moving planets, and
Speaker 2: Excite is designed to map the climate of these these.
Speaker 3: Hellscapes, that's a good word for them, exactly. But to
Speaker 3: do that, you immediately run into a massive obstacle in
Speaker 3: observational astronomy. To see the heat signature of a planet,
Speaker 3: you need to observe in the infrared part of the spectrum. Infrared,
Speaker 3: that's heat radiation right right our eyes see visible light.
Speaker 3: But if you want to see temperature, if you want
Speaker 3: to see the thermal glow of a hot planet against
Speaker 3: the cold darkness of space, you have to look in infrared.
Speaker 3: It's the only.
Speaker 2: Way, Okay, So what's the problem with that.
Speaker 3: The problem is Earth's atmosphere absolutely hates infrared light.
Speaker 2: Hates it in what way it absorbs it.
Speaker 3: Specifically the water vapor in our atmosphere. You can think
Speaker 3: about humidity. Water molecules are incredibly good at absorbing infrared energy.
Speaker 3: It's the greenhouse effect basically. So if you put an
Speaker 3: infrared telescope on the ground, even on a super high
Speaker 3: Mountain in Hawaii or the Atacama Desert in Chile, where
Speaker 3: the air is really thin. You are still looking through
Speaker 3: this thick, soupy blanket of water vapor.
Speaker 2: So the signal from the planet just gets lost in
Speaker 2: the noise of our own atmosphere.
Speaker 3: It's worse than noise, it's a total block edge at
Speaker 3: certain wavelengths. It's like trying to look at the stars
Speaker 3: on a foggy night, or trying to see through steamy window.
Speaker 3: The signal just doesn't get through.
Speaker 2: And this is where the balloon comes in.
Speaker 3: This is where the balloon is the hero.
Speaker 2: Back to the forty kilometer figure right.
Speaker 3: Because if you can get a telescope up to forty kilometers,
Speaker 3: you are physically above ninety nine point five percent of
Speaker 3: the art's atmosphere. More importantly, you're above almost all of
Speaker 3: the water vapor.
Speaker 2: So suddenly the fog clears, the steamy window becomes transparent.
Speaker 3: Precisely, the sky becomes crystal clear in the infrared frequencies
Speaker 3: they need to see for the purpose of this specific
Speaker 3: telescope and this specific science. Forty kilometers is space. The
Speaker 3: photons from that distant planet can travel all that way
Speaker 3: and then hit the detector without bumping into any pesky
Speaker 3: water molecules in our atmosphere at the last second.
Speaker 2: That is a fascinatingly simple workaround. You don't need to
Speaker 2: leave Earth's gravity. You just need to get a blood
Speaker 2: the moisture.
Speaker 3: And you save a fortune in fuel and hardware doing it.
Speaker 3: But there is another layer to this strategy, and it's
Speaker 3: a really clever one. It has to do with where
Speaker 3: they are planning on launching it.
Speaker 2: Oh right, you mentioned this for.
Speaker 3: The main long duration mission. They aren't just sending this
Speaker 3: up from Florida or New Mexico. The source material highlights
Speaker 3: a launch plan for Antarctica.
Speaker 2: Antarctica that seems I mean logistically that sounds like a nightmare.
Speaker 2: Why go to the bottom of the world to look
Speaker 2: up at the sky?
Speaker 3: It does seem counterintuitive. There are two main reasons, and
Speaker 3: they're both brilliant. First, what are called the seeing conditions.
Speaker 3: Seeing conditions it's an astronomy term for how clear and
Speaker 3: stable the atmosphere is. The air above Antarctica is very,
Speaker 3: very stable. It's incredibly cold, and crucially it's the driest
Speaker 3: place on Earth, so you get even less of that
Speaker 3: residual water vapor so.
Speaker 2: It's the best possible place on Earth to be even
Speaker 2: before you go up exactly.
Speaker 3: But the second reason, and this is the real game changer,
Speaker 3: is about time.
Speaker 2: Time.
Speaker 3: This brings us to a concept they call loitering. Think
Speaker 3: about it. If you launch a satellite into low Earth orbit,
Speaker 3: like the Hubble Space Telescope or the International Space Station,
Speaker 3: it is moving fast, unbelievably fast. We're taking seventeen thousand
Speaker 3: miles per hour something like that. It orbits the entire
Speaker 3: Earth every ninety minutes.
Speaker 2: So from the satellite's perspective, the sun rises and sets
Speaker 2: every hour and a half exactly.
Speaker 3: And more importantly, from its perspective, the Earth gets in
Speaker 3: the way for roughly half of that orbit, about forty
Speaker 3: five minutes. The Earth itself is blocking your view of
Speaker 3: the stars you want to see.
Speaker 2: You're in Earth's shadow.
Speaker 3: You're in the shadow. You can't stare at anything for
Speaker 3: very long. It's a constant cycle of observation than blockage.
Speaker 3: It's constantly blinking sun shadow, sun shadow.
Speaker 2: I can see how that would be a huge problem
Speaker 2: if you're trying to, say, film a movie of a
Speaker 2: planet's weather system, you'd have these massive gaps in the
Speaker 2: footage every forty five minutes.
Speaker 3: Precisely, you'd lose all continuity. It would be a mess.
Speaker 3: But a balloon over Antarctica during the Antarctic summer.
Speaker 2: Ah, the twenty four hour daylight, you got it.
Speaker 3: The sun never sets because of the Earth's axial tilt.
Speaker 3: It just circles the horizon.
Speaker 2: So you never have to worry about the Earth getting
Speaker 2: in your.
Speaker 3: Way, not if you're looking outwards. If you point your
Speaker 3: telescope away from the Sun, the stars are always accessible
Speaker 3: twenty four to seven. And because of the polar vortex wines,
Speaker 3: these stable circular win that just go around and around
Speaker 3: the continent, the balloon just gently circles the pole.
Speaker 2: It doesn't fly off towards Australia.
Speaker 3: Nope, it just laps the continent.
Speaker 2: It loiters, it loiters, and that lets it stare at
Speaker 2: a single target, one of these hot jupiters continuously for
Speaker 2: days on end, no blinking, no Earth getting in the way,
Speaker 2: just a pure, uninterrupted stream of data.
Speaker 3: That is the whole ballgame.
Speaker 2: And that continuous stream is what allows them to get
Speaker 2: the very specific kind of data they are after. The
Speaker 2: report mentions something called phase curves, and I really want
Speaker 2: to spend some time here because the report makes it
Speaker 2: clear this isn't a side project. This is the core
Speaker 2: science of the mission.
Speaker 3: Yes, this is the holy grail for this kind of science.
Speaker 3: It's what you can do with that loitering capability.
Speaker 2: Okay, so let's untack this. We usually hear about transits
Speaker 2: in exoplanet news. That's how we find most of these planets. Right.
Speaker 2: The planet goes in front of the star, the light
Speaker 2: from the star dips a tiny bit, and we say,
Speaker 2: uh huh, there's a planet there.
Speaker 3: Correct. That is the transit method. It's fundamentally looking at
Speaker 3: a shadow, a silhouette. It's incredibly powerful. It tells you
Speaker 3: the size of the planet, how fast it orbits, and maybe,
Speaker 3: if you're lucky and the instrument is good enough, a
Speaker 3: little bit about the chemical makeup of the very edges
Speaker 3: of its atmosphere as the starlight.
Speaker 2: Filters through the edges. That's a keyword, a very keyword.
Speaker 3: Then you also have what's called the secondary.
Speaker 2: Eclipse, which is the opposite, the opposite.
Speaker 3: That's when the planet goes behind the star from our
Speaker 3: point of view.
Speaker 2: Okay, so it disappears, it.
Speaker 3: Disappears completely, and just before it vanishes. We're seeing the
Speaker 3: light from the star plus the light reflected and emitted
Speaker 3: from the planet's day side. Then it's gone and we
Speaker 3: only see the star.
Speaker 2: So you subtract the star only light from the star
Speaker 2: plus planet light.
Speaker 3: And the difference is the light from the planet's day side.
Speaker 3: That tells us how bright it is, how hot it
Speaker 3: is on that side facing the star. But both of
Speaker 3: those methods, transits and secondary eclipses, they're just shots. They
Speaker 3: are momentary events.
Speaker 2: You see the front when it passes by, or you
Speaker 2: see the back before it hides right.
Speaker 3: It's like trying to understand a marathon runner. By taking
Speaker 3: a single photo of them at the starting line and
Speaker 3: a single photo of them at the finish line.
Speaker 2: You miss the entire race.
Speaker 3: You miss the whole race. You don't know how they
Speaker 3: handled the hills. You don't know what their pacing strategy was.
Speaker 3: You don't know if they struggled at mile twenty. Phase
Speaker 3: curves are the video of the entire race.
Speaker 2: So instead of just watching the planet cross the starter
Speaker 2: finish line, Excite watches the whole orbit.
Speaker 3: It watches the planet go all the way around for days.
Speaker 3: And this is where the physics of hot Jupiter's gets
Speaker 3: really really cool. Because these planets are so close to
Speaker 3: their stars, they are subject to these massive gravitational forces
Speaker 3: that lead to a phenomenon called tidal locking.
Speaker 2: We see this with our own moon, right, Yeah, we
Speaker 2: always see the same face the Moon.
Speaker 3: Exactly the same principle. The immense gravity of the star
Speaker 3: has grabbed the planet and basically forced it to rotate
Speaker 3: at the exact same speed that it orbits.
Speaker 2: So one side faces the star.
Speaker 3: Forever eternal noon, and the other side faces deep space
Speaker 3: forever eternal midnight.
Speaker 2: That sounds incredibly extreme. One side must be boiling and
Speaker 2: the other must be what near absolute zero.
Speaker 3: In theory, yes, if there were no atmosphere, the day
Speaker 3: side would be molten rock and metal, and the night
Speaker 3: side would be unimaginably cold. But here is the mystery.
Speaker 3: These planets do have atmospheres, and atmospheres move heat around
Speaker 3: massive supersonic winds. So as we watch this tidally locked
Speaker 3: planet orbit its star from our vantage point here on Earth,
Speaker 3: we see different amounts of its day and night sides.
Speaker 3: We see different phases, just like the phases of our moon.
Speaker 2: So we see the full night side, then a crescent
Speaker 2: of the day side appears, then.
Speaker 3: It gets bigger. We see half in half. That's the
Speaker 3: terminator line, the sunrise sunset line. Then we see the
Speaker 3: full day side, and then it wins back to a
Speaker 3: crescent and finally back to the night side again.
Speaker 2: And by measuring the infrared light the heat during all
Speaker 2: of those different phases, we can build a map.
Speaker 3: We are building a three temperature map of the entire world.
Speaker 3: We're not just getting one number for the day side
Speaker 3: and one for the night side. We can see the gradient.
Speaker 3: We can see how effectively the winds are dragging that
Speaker 3: immense heat from the day side around the night side.
Speaker 2: So if the night side is surprisingly warm, it means
Speaker 2: the winds are really efficient at circulating heat exactly. And
Speaker 2: if the night side is freezing cold, it means the
Speaker 2: winds aren't doing their job, or the atmosphere is too
Speaker 2: thin to hold the heat.
Speaker 3: Precisely, we are literally measuring the efficiency of the planetary
Speaker 3: heat engine, and we can get even more granular than that.
Speaker 3: This is the really wild part. On many of these
Speaker 3: hot jupiters we've studied, we find that the hottest point
Speaker 3: on the planet isn't where you'd expect it to be.
Speaker 2: Wait, how is that possible? If I stand directly under
Speaker 2: a heat lamp, the hottest pot is right on top
Speaker 2: of my head. That's just basic physics.
Speaker 3: It is unless there is a five thousand mile per
Speaker 3: hour wind blowing across your head. If the wind is
Speaker 3: strong enough, it physically pushes the heated mass of air,
Speaker 3: It advects the heat. It shifts the hot spot away
Speaker 3: from the point directly under the star, usually to the
Speaker 3: ist in the direction of the planet's rotation.
Speaker 2: So the hottest part of the day isn't noon, it's
Speaker 2: more like three PM.
Speaker 3: A very extreme version of that. Yes, And by measuring
Speaker 3: exactly where that hot spot is located using the continuous
Speaker 3: phase curve, excite can actually calculate the wind speeds and
Speaker 3: infer the atmospheric pressure on an alien world.
Speaker 2: That is just incredible. We are effectively doing meteorology calculating
Speaker 2: wind speeds on a planet that's hundreds of light years
Speaker 2: away using a telescope hanging from a balloon floating over Antarctica.
Speaker 3: It's a huge leap forward. It moves us from what
Speaker 3: some astronomers call stamp collecting, just finding planets and cataloging them,
Speaker 3: to characterization, which is actually understanding them as complex, dynamic
Speaker 3: physical places.
Speaker 2: Now I have to play Devil's advocate here for a minute,
Speaker 2: because whenever we talk about space telescopes, there is a giant,
Speaker 2: ten billion dollar elephant in the room. We have the
Speaker 2: James Webb Space Telescope JWST. It is the most powerful,
Speaker 2: most expensive, most advanced observatory humanity has ever built. It's
Speaker 2: an infrared telescope. Why on Earth do we need a
Speaker 2: balloon if we have WEB.
Speaker 3: It's a great question, and it's one that the scientific
Speaker 3: community asks itself all the time. You would absolutely think
Speaker 3: the ten billion dollar telescope would win every single time,
Speaker 3: But ironically WEB actually suffers from being too good for
Speaker 3: this specific job.
Speaker 2: Too good. How can a telescope be too good? I
Speaker 2: don't understand that it's too sensitive.
Speaker 3: You have to remember what WEB was originally built for.
Speaker 3: Its primary design mission was to see the cosmic dawn.
Speaker 2: The very first stars and galaxies.
Speaker 3: The first galaxies born after the Big Bang. We're talking
Speaker 3: about objects that are incredibly far away, incredibly red shifted,
Speaker 3: and unbelievably faint.
Speaker 2: So it's designed to see a single candle on the Moon.
Speaker 3: It's designed to see something even fainter than that. So
Speaker 3: what happens when you take that exquisite instrument and you
Speaker 3: point it at a relatively bright star in our local
Speaker 3: galactic neighborhood. It's over It's completely overwhelmed. It's like using
Speaker 3: military grade night vision goggles to stare directly at a
Speaker 3: football stadium's floodlights.
Speaker 2: You just see white. You get no information exactly.
Speaker 3: The sensors saturate, the pixels on the detector fill up
Speaker 3: with electrons faster than the electronics can read them out.
Speaker 3: You just lose the data. Astronomers call it blowing out
Speaker 3: the image.
Speaker 2: So the data is totally useless.
Speaker 3: In many cases for the brightest targets. Yes, and this
Speaker 3: is especially true for the specific instrument mode on Web
Speaker 3: it's called prism that is actually the best tool for
Speaker 3: this kind of continuous atmospheric study. Many of the stars
Speaker 3: that host these interesting hot jupiters are relatively bright nearby
Speaker 3: stars in our galaxy. Web literally cannot look at them
Speaker 3: in this mode without getting blinded.
Speaker 2: So Excite is filling a really specific niche. It designed
Speaker 2: to be less sensitive, which paradoxically allows it to look
Speaker 2: at the bright stuff that Web can.
Speaker 3: It has a higher dynamic range, that's the technical term.
Speaker 3: It can handle the glare. And then, of course there
Speaker 3: is the time and cost factor, which we just cannot ignore.
Speaker 3: Web's observing time is arguably the most valuable single resource
Speaker 3: in all of astronomy.
Speaker 2: I can imagine the line to use. It must be
Speaker 2: miles long.
Speaker 3: The proposal acceptance rate is tiny, something like one in ten,
Speaker 3: maybe even less. So to go to the time Allocation
Speaker 3: Committee and ask for five continuous days of Web time
Speaker 3: to just stare at one.
Speaker 2: Planet, that's a very hard cell.
Speaker 3: It's an almost impossible cell, because in those five days,
Speaker 3: Web could have looked at one hundred distant galaxies, or
Speaker 3: analyzed the light from ten different supernovae, or mapped a
Speaker 3: star forming region. There's an opportunity cost, a massive opportunity cost.
Speaker 3: Excite is a specialist, it's a dedicated mission. It can
Speaker 3: afford to just sit there and stare at one target
Speaker 3: for a week or more because it isn't competing with
Speaker 3: the entire rest of the universe for its attention.
Speaker 2: Okay, that makes sense for Web, but what about Hubble.
Speaker 2: It's been up there for decades. It's certainly less sensitive
Speaker 2: than Web. Can it do this kind of work.
Speaker 3: Hubble has done some of this work, and it's been groundbreaking,
Speaker 3: but it runs smack into the orbit problem we mentioned earlier.
Speaker 3: It's in low Earth orbit.
Speaker 2: Right, the blinking issue in and out of shadow every
Speaker 2: ninety minutes exactly.
Speaker 3: But there is a secondary, much more subtle issue that
Speaker 3: comes with that shadow. Temperature swings. The telescope gets cold,
Speaker 3: it gets cold, and then it gets hot again, over
Speaker 3: and over. When Hubble dips into Earth's shadow, it cools
Speaker 3: down significantly. When it pops back out into the direct,
Speaker 3: unfiltered sunlight of space, it heats up very.
Speaker 2: Quickly, and that causes the structure to expand and contract.
Speaker 3: Yes, thermal expansion and contraction. We all learn about it
Speaker 3: in high school physics with railroad tracks, sure, But in
Speaker 3: a telescope that's trying to measure infinitesimal changes in light,
Speaker 3: even a microscopic amount of expansion or contraction is a
Speaker 3: potential disaster. The whole structure sort of breathe.
Speaker 2: Breathing that sounds very ominous for a precision machine.
Speaker 3: It creates noise and jitter in the data. The focus
Speaker 3: changes slightly, the align of the mirror's drifts every time
Speaker 3: Hubble comes out of the Earth's shadow. The scientists have
Speaker 3: to basically discard the first chunk of data from that
Speaker 3: orbit while the telescope settles and stops shivering from the
Speaker 3: temperature change.
Speaker 2: So you get these unavoidable gaps in the data. Even
Speaker 2: when you're not behind the Earth.
Speaker 3: You get gaps, and you get wobbles. It makes it
Speaker 3: incredibly difficult to stitch together a perfectly smooth, continuous phase curve. Excite,
Speaker 3: on the other hand, floating in the eternal, gentle sunshine
Speaker 3: of the Antarctic summer, stays at a much much more
Speaker 3: stable temperature. It doesn't shiver.
Speaker 2: It all sounds like the perfect solution on paper, a
Speaker 2: stable platform above the water vapor, relatively low cost, with
Speaker 2: specialized sensors for the job. But paper is not reality,
Speaker 2: and the report does mention they actually took this whole
Speaker 2: thing for a test drive. Recently.
Speaker 3: They did, and this is where the strike gets really
Speaker 3: interesting from an engineering perspective. In August of twenty twenty four,
Speaker 3: they launched a test version from Fort Sumner, New Mexico.
Speaker 2: New Mexico, not Antarctica yet, no absolute not.
Speaker 3: You don't go to the most logistically challenging and hostile
Speaker 3: continent on Earth for your first try.
Speaker 2: That would be brave or foolish.
Speaker 3: You do a shakedown cruise somewhere accessible. If something falls
Speaker 3: off in the New Mexico desert, you can drive a
Speaker 3: truck out and pick it up. If it falls off
Speaker 3: on the Antarctic ice sheet, it's gone forever.
Speaker 2: Right, good point.
Speaker 3: So it was a short flight, relatively short, yes, about
Speaker 3: ten hours. The goal wasn't to do science. It was
Speaker 3: just to prove that the core systems work in that environment.
Speaker 2: And how did it go? Did it, you know, work?
Speaker 3: There was a classic engineering story, a mix. There were
Speaker 3: some absolutely spectacular successes and some really frustrating but ultimately
Speaker 3: very illuminating failures.
Speaker 2: Okay, let's start with the winds. What went right?
Speaker 3: The biggest win by far was stability. You have to remember,
Speaker 3: this telescope isn't bolted to bedrock. It's a heavy instrument package.
Speaker 3: The gondola hanging from a giant balloon on a long.
Speaker 2: Cable, so it twists its ways.
Speaker 3: It bobs in the stratospheric winds. It's a pendulum, a giant,
Speaker 3: multi ton pendulum. And yet the planing system, the gondola
Speaker 3: itself achieved what they call sub arcsecond precision pointing.
Speaker 2: Okay, break that down for me. What is an arcsecond
Speaker 2: in real terms?
Speaker 3: Okay, so imagine a circle is three hundred and sixty degrees.
Speaker 3: Each degree is split into sixty arc minutes. Each arc
Speaker 3: minute is split into sixty arcseconds. So an arcsecond is
Speaker 3: one three thousand, six hundredth of a single degree.
Speaker 2: That's a tiny, tiny sliver of the sky.
Speaker 3: It's incredibly small. It's like the width of a human
Speaker 3: hair seen from about sixty feet away.
Speaker 2: And they kept the telescope pointed that steady.
Speaker 3: They kept it steady within that tiny sliver while dangling
Speaker 3: from a balloon twenty five miles up in the air.
Speaker 3: It's the equivalent of standing in one city and holding
Speaker 3: a laser pointer perfectly steady on a specific dime in
Speaker 3: another city miles.
Speaker 2: Away, while you're hanging from a rope.
Speaker 3: While you're hanging from a rope. It proved that the
Speaker 3: stabilization technology, the reaction wheels, the star trekers, the control software,
Speaker 3: it all works flawlessly. That is a massive engineering hurdle
Speaker 3: to clear.
Speaker 2: That's a huge way. What else worked.
Speaker 3: The cryogenics, the cooling system for the infrared detectors worked perfectly,
Speaker 3: and that's essential because remember, infrared is heat. The detector
Speaker 3: itself must be kept incredibly cold or its own sheet
Speaker 3: will blind it. So two huge successes.
Speaker 2: Okay, that's the good news. Now for the growing pains.
Speaker 2: The report mentioned some failures, and I want to get
Speaker 2: into the details here because usually, you know, these press
Speaker 2: releases just say successful test. They rarely get into the
Speaker 2: nitty gritty of what actually broke.
Speaker 3: And that's what's so great about this report. They were
Speaker 3: very open about the failures, which is how science moves forward. First,
Speaker 3: a simple one, the GPS went down.
Speaker 2: Even NASA has GPS issues. Yeah, that makes me feel
Speaker 2: so much better about my phone's mapping app failing in
Speaker 2: the middle of a city.
Speaker 3: It happens. High altitude GPS can be tricky, but that
Speaker 3: was a minor glitch. The more fascinating failure, and the
Speaker 3: one that really teaches us about material science and extreme environments,
Speaker 3: was the aluminum housing for the telescope s bearings.
Speaker 2: Ok what happened there?
Speaker 3: So the telescope needs to be able to tilt up
Speaker 3: and down. It's called changing its elevation. It has to
Speaker 3: do that to track the stars as they move across
Speaker 3: the sky. The bearings that allow the smooth tilting motion.
Speaker 3: The joints effectively were housed inside a casing made of aluminum.
Speaker 2: Okay, aluminum seems pretty standard for aerospace stuff. It's light, it's.
Speaker 3: Strong, it is it's a great material for a lot
Speaker 3: of things. But at forty kilometers up, the ambient temperature
Speaker 3: is brutal. We're talking around medic of sixty degrees celsia's
Speaker 3: maybe even lower. It's a deep freeze.
Speaker 2: Colder than an Antarctic winter on the ground.
Speaker 3: Much colder. And when metal gets that cold, it shrinks.
Speaker 3: It's called thermal contraction. But here is the crucial catch.
Speaker 3: Different metals shrink at different rates. That property is called
Speaker 3: the coefficient of thermal expansion.
Speaker 2: I think I see where this is going.
Speaker 3: The aluminum housing shrank more and shrank faster than the
Speaker 3: steel bearings that were housed inside it. It crushed them,
Speaker 3: not crushed, but it clamped down on them. It's called
Speaker 3: a pferential contraction. The housing, which should be a loose
Speaker 3: sleeve for the bearings, effectively became a powerful vice.
Speaker 2: It squeezed them so tight they couldn't move.
Speaker 3: It froze the mechanism solid. The telescope got stuck looking
Speaker 3: at one spot in the sky. It couldn't tilt, it
Speaker 3: couldn't track anything. The science part of the mission was
Speaker 3: a total failure because of this.
Speaker 2: That sounds absolutely catastrophic. You launched this incredibly complex mission
Speaker 2: and a simple shrinking piece of metal ruins the whole thing.
Speaker 3: On a real science mission, Yes, it would be a
Speaker 3: complete disaster if that had happened on the first day
Speaker 3: over Antarctica. The mission is over. You have a very expensive,
Speaker 3: frozen telescope staring at nothing useful for weeks.
Speaker 2: But this was the test flight exactly.
Speaker 3: This is why we test. To an engineer, this failure
Speaker 3: isn't a disaster, it's a gift. It's a piece of
Speaker 3: priceless data. How so, because now they know they have
Speaker 3: the data. If they had skipped this test and gone
Speaker 3: straight to Antarctica, they would have lost the entire season
Speaker 3: millions of dollars. Now they know, Okay, the tolerance on
Speaker 3: that aluminum housing was wrong for these temperatures, the materials
Speaker 3: are incompatible. They can go back to the lap and
Speaker 3: fix it. And fix it. They can swap the aluminum
Speaker 3: for a material with a lower thermal coefficient that shrinks
Speaker 3: less like titanium or a special alloy called invar or.
Speaker 3: They can simply redesign the housing with a slightly larger
Speaker 3: gap to account for the shrinkage they now know will happen.
Speaker 2: So it's a cheap lesson learned in the New Mexico
Speaker 2: Desert that saves a very expensive, very important mission in Antarctica.
Speaker 3: Precisely, the report says, the engineers are already hard at
Speaker 3: work fixing those thermal contraction issues. It's a completely solvable problem,
Speaker 3: but you only find it by actually going there and
Speaker 3: trying it.
Speaker 2: So looking forward, we've done the test flight, we've found
Speaker 2: the bugs, we've under a lesson about shrinking aluminum. When
Speaker 2: is the main event? When does this thing fly for real?
Speaker 3: The target, the big show is the Antarctic summer of
Speaker 3: twenty twenty six, twenty twenty seven.
Speaker 2: That's coming up pretty fast in the world of space missions.
Speaker 3: It is. Yeah, they are going to take the full
Speaker 3: flight ready excite apparatus down to the ice. And this
Speaker 3: time they aren't aiming for a ten hour joy ride.
Speaker 3: They are aiming for a proper long duration balloon flight.
Speaker 2: How long is long in this context.
Speaker 3: It can be weeks. The record for these kinds of
Speaker 3: scientific balloons is over fifty days. They'll be drifting in
Speaker 3: that polar vortex circling the south pole, just soaking up
Speaker 3: that continuous uninterrupted starlight.
Speaker 2: And if it works, if the bearings don't seize up
Speaker 2: this time, what is the potential scientific payoff here?
Speaker 3: It's huge. The scientists on the project estimate that the
Speaker 3: single balloon flight one mission could double the total number
Speaker 3: of exoplanet phase curves known to humanity.
Speaker 2: Double with one flight double.
Speaker 3: Just think about that. Think about all the billions of
Speaker 3: dollars we've spent on all the space telescope so far,
Speaker 3: all the decades of Hubble, the Spixer space telescope, Kepler,
Speaker 3: now Web one balloon ride over Antarctica could equal the
Speaker 3: total historical output for this very specific, very important type
Speaker 3: of data.
Speaker 2: That really puts into perspective how data starved we are
Speaker 2: when it comes to really characterizing these atmospheres.
Speaker 3: We are so data starved. We have a good sensus
Speaker 3: of planets now thanks to missions like Kepler and tests.
Speaker 3: We know they're out there in their thousands, but we
Speaker 3: don't know what they're like. We are just now moving
Speaker 3: from the era of pure discovery to the era of characterization.
Speaker 2: It's the difference between knowing your neighbor exists because you
Speaker 2: see their car in the driveway and actually knowing what
Speaker 2: they cook for dinner or what music they listen to.
Speaker 3: That's a perfect analogy, and xcite is the tool that
Speaker 3: kicks that door wide open for these hot jupiters.
Speaker 2: It really feels like a shift in mindset. Then we
Speaker 2: aren't just looking for little dips in light anymore, for dots.
Speaker 2: We're looking for weather patterns. We are looking for wind, and.
Speaker 3: We're proving that you don't always need a flagship, multi
Speaker 3: billion dollar spacecraft to do flagship quality science. Sometimes you
Speaker 3: just need a really big balloon, a clever location, and
Speaker 3: some very careful engineering.
Speaker 2: I think that's a perfect place to wrap this up.
Speaker 2: We've gone from the common misconception that space requires rockets
Speaker 2: all the way down to the physics of infrared light
Speaker 2: and the mechanics of a freezing aluminum bearing.
Speaker 3: It's been quite a journey from forty kilometers up down
Speaker 3: to the micrometer level of a bearing contracting.
Speaker 2: It really has. And I want to leave our listeners
Speaker 2: with one final thought that really stood out to me
Speaker 2: from all this. We usually draw a very hard line
Speaker 2: between atmospheric science studding Earth's weather and climate, and astronomy
Speaker 2: studying space.
Speaker 3: Right, they're totally separate disciplines. One looks down, one looks up.
Speaker 3: They are different departments at the university, they go to
Speaker 3: different conferences exactly.
Speaker 2: But Excite just completely blurs that line. We're using the
Speaker 2: unique properties of our own upper atmosphere. It's coldness, it's dryness,
Speaker 2: it's stable polar winds as a tool to understand the
Speaker 2: atmosphere of a world that is hundreds of light years away.
Speaker 3: We're standing on the roof of our own atmosphere to
Speaker 3: peek into theirs.
Speaker 2: That's a beautiful way to put it. It shows that
Speaker 2: our planet isn't just a barrier to look through. It's
Speaker 2: an integral part of the observatory itself. It's a tool
Speaker 2: that we can use.
Speaker 3: Our atmosphere becomes part of the solution, not just part.
Speaker 2: Of the problem. So keep an eye on the news.
Speaker 2: In late twenty twenty six, if you hear about a
Speaker 2: giant balloon launching from Antarctica, you'll know that it's not
Speaker 2: just checking the weather here. It's checking the forecast for
Speaker 2: a hot.
Speaker 3: Jupiter let's just hope they got the math right on
Speaker 3: that aluminum this.
Speaker 2: Time, fingers crossed. Thanks for listening everyone, We'll catch you
Speaker 2: next time. Past the Sad
Speaker 3: Sad stea