BepiColombo is a joint ESA-JAXA mission approaching Mercury to study three open puzzles: why polar craters hold ice despite the planet's extreme heat, why Mercury still generates a magnetic field, and what causes strange surface features called hollows. Launched in 2018, it has completed multiple gravity-assist flybys and is scheduled to arrive at Mercury around December 2026, with routine science operations beginning around April 2027 using a planetary orbiter (ESA) and a magnetospheric orbiter (JAXA). The hosts also discuss why Mercury has an unusually large iron core relative to its size, tied to heavier elements settling closer to the sun during solar system formation, and why a magnetic field is puzzling given the core should have cooled and solidified by now, unlike the similarly sized Moon which has no magnetic field.
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The mission is named after Giuseppe 'Bepi' Colombo, an Italian mathematician who first proposed the interplanetary gravity-assist maneuver later used by the 1974 Mariner 10 mission.
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BepiColombo has already performed several Mercury flybys in October 2021, June 2022, June 2023, September 2024, and January 2025 while tuning its approach trajectory.
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The hosts compare Mercury's structure to a chocolate with a thin shell around a large solid core, contrasting it with Earth's much smaller core relative to its mantle.
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Mercury's magnetic field is described as puzzling because charged particle movement in a planet's core is what generates such fields, and Mercury's small size should have let its core cool and stop moving long ago.
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54:40>> Uh so this is again in this fall window, something that's super exciting and we'll keep an eye on. >> Yeah, that is super exciting. >> Uh speaking of ions, which is something we've talked about a lot in the brain in recent episodes. No, I'm kidding. Uh for for our last piece of coverage here, we will talk about surprisingly another space story. All right. Uh, and this is the Bey Columbo Mercury Arrival. So, this is what is the second and most complex mission to orbit Mercury, the first rock from the sun. Um, going towards Mercury's tough
55:21because it's so close to the sun. There's so many challenges of of doing that. We've had some solar, you know, missions go and have been very impressive. >> Yeah. I mean, some of the ones like straight up like go and like touch the sun. >> It's very impressive. >> Yeah. Like the Parker Solar Probe, which is named after Eugene Parker, who we um cover in the America 250. He's the one who um postulated that something like the solar wind should exist. So, again, plugging that episode. That's a great episode. Interestingly, Mercury is the least explored planet of the inner solar system. And one of the goals of learning about
56:01Mercury would be to shed light on the history of the entire solar system given given its proximity to the parent star. It's named after >> uh Jeppe Bey Columbo >> uh who's a scientist, mathematician, and engineer. Yes, they exist. Triple threat at the University of Padua in Italy. who first proposed this idea of interplanetary gravity assist maneuvers which was used by the 1974 Mariner 10 mission. And if anyone has watched Interstellar >> is is now it's in every movie. It's everything when we do >> it's how we got to Pluto. It's how we get anywhere. >> It's how we get anywhere. Um it's packed
56:43with a bunch of scientific instruments. And so part of what they're looking to do in terms of the questions they're trying to answer is why is there ice in the polar craters of Mercury given how close it is to the sun and how hot it is? >> Oh, interesting. Yeah. >> Um why does Mercury have a magnetic field? >> That is a weird [clears throat] one actually. [laughter] >> Right. And what are the mysterious hollows on its surface? Because it has these sort of hollow areas on its surface. Um and so there's a couple of different uh components to the mission. It has the Mercury planetary orbiter. It has the Mercury magneettospheric orbiter which is specifically around this idea of uh studying the magnetic fields. And
57:25it has the Mercury transfer module. Now it launched in 2018 uh from Europe's spaceport. Europe still in the game. >> Um it's in operation and on route to Mercury. It's done several Mercury flybys already. >> Oh, okay. October 21, June 22, June 23, September 24, de uh uh September 24, December 24, and January 25. Its arrival at Mercury is scheduled, and it's basically it's been tuning its >> It's tuning [clears throat] its approach. They've been testing the systems. >> Yep. It's expected to arrive around Christmas time 2026, December 2026, and
58:08to begin routine scientific operation hopefully around April of 2027. Um, and the the two orbiters that we discussed, the ESA is going to be doing the uh planetary orbiter [clears throat] that's studying Mercury itself. JAXA, Japanese Space Agency, is going to be the one studying the uh magneettosphere. And so it's it's a weird planet. >> It is. >> And we don't really have enough data to make any conclusions around it. And so this has been an 8-year road trip and we're finally getting to our destination to be able to do the science. >> Yeah. >> Uh and this should be pretty interesting. Yeah. I I'm I'm actually quite excited about that. Mercury, you
58:49know, you remind me of all the things that make Mercury so weird. One of the things is as you mentioned here um in the notes, enormous iron core. That's a weird one because like if if you've ever seen the um a photo of Earth and its core, um the core is about the size of the pit of a peach and then the meat of the peach is like the mantle. With Mercury, it's kind of like um you know those lint chocolates. >> Yeah. Yeah. Yeah. >> Or something where the it's mostly the core and then there's a there's a layer of like crust. >> That's what mercury is like. most of it is iron and then and then the crust and mantle are like very very thin. Now one
59:31of the reasons for that is because Mercury is closer to the sun and so when the solar system formed the heavier elements were closer to the sun while the lighter elements sort of just got like blown off by the protostellar wind that happens when you start first start like making that furnace of of of a star, right? Like imagine you've got the gas cloud that's like collapsing. The heavier elements are in the in the in the center. The lighter elements are in the in the in the periphery. And then when you create fusion, there's going to be intense stellar wind that's going to blow off everything. That's why Jupiter and Saturn and Neptune and Uranus are the gas giants that are on the outside
1:00:12and the rocky planets are on the inside. Well, Mercury is like the extreme version of the rocky planets, right? where like the heaviest elements like iron, which is where fusion stops, >> right? >> So that's that's where you're going to have most abundance, that mercury is going to have most of the iron. But what's weird is like for how small Mercury is, for how small Mercury is, its core should basically be solid. Like it should have cooled off. But the fact that it still has a magnetic field means that there's some activity happening within the core that is creating the magnetosphere. That's how magnetic fields originate, right? Is because of charged particles moving around. That's
1:00:53why the earth has a magnetic field is because the core, the outer core mostly is like moving around and that's why we think >> got a little jiggle. >> Yeah. Have you seen the movie The Core? It's a great movie. >> No. No, I haven't. >> Dude, it's a great movie. Um, actually, even though a lot of a lot of science people hate on it because it's like terrible science. Yeah. It's terrible science, but like >> it's a great movie. >> Look, it's I'm not going to lie. >> It's entertaining. >> Yeah. Yeah. The the the Earth's core stops spinning. So, then the magnetic field stops being a magnetic field and then we're about to get roasted by the sun. So, they have to like go into the core to restart the core by nuking it. Come on. Like, that's that that's dope.
1:01:34>> That sounds very entertaining to me. It's dope, dude. Um the the the science not so much, but like the the human stories behind it. Stanley Tucci's in it. He's like he's like one of the main big scientists. >> Of course he is. >> Um who's like who's like one of the famous scientists and the ego of the Stanley Tucci character is just so very on point with some of the big egos that I've interacted with in [laughter] academia. Anyways, so Mercury is like this enigma because it still has a magnetic field, but it shouldn't because it's small enough to have cooled off. You know, the moon doesn't have a magnetic field and the moon is comparable to the size of Mercury. So, it it is a bit weird.
1:02:14>> What's going on? >> Yeah. >> Um, thank you all for uh dealing with us
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