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Chapter 1: What is asteroid Bennu and why is it significant?
Chuck, we're long overdue for devoting a show to asteroid Bennu. Not only have we been there, it has Earth in its sights as a near-Earth asteroid that might hit us in 200 years.
As a matter of fact, going to talk to Harold Connolly Jr. And if you want to find out exactly when the Earth is going to be destroyed, just stay tuned. Down to the hour.
Coming up on StarTalk. Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. Neil deGrasse Tyson, your personal astrophysicist. Chuck Nice is with me in the house. Chuck, how you doing, man?
I'm good. I'm in my house.
In the house remotely. How you doing, man? I am doing great. You know what we're going to do today? Something I think we long should have done long ago. We're going to take a look at the ingredients for life as they exist today. in the rest of the universe and how some of those ingredients may have influenced what happened on the early Earth. Nice. Yes, yes.
And we have a record of what the early solar system was like, and it's contained within our comets and asteroids. They've just been orbiting the sun since like day one. And they haven't been absorbed into a volcano. They haven't been rained on. They haven't been peed on by any animals. And so there's a pristine... I've never considered that as a... I know, right?
That is an obstacle for finding our origins. Well, you know, we would have found out, guys. But unfortunately, do you see how much deer pee is on this?
So we have one of the world's experts in this, and Harold Connolly Jr. Harold Connolly, welcome to StarTalk.
Oh, thank you so much for inviting me. It's a great pleasure and honor to be here.
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Chapter 2: What does the OSIRIS-REx mission aim to discover?
So within a day or two, you've already... and you're interacting with the atmosphere, little microbes start to eat them. I mean, imagine you're sitting around for four and a half billion years, as Neil said, and you've got nothing to do, nobody to bother you, really, except occasional collision and the sun hit you.
So the other idea was to bring back a sample of pristine material, keep it in a nitrogen environment and analyze it. And that turns out to be, as we'll see, absolutely critical to what we have been finding in both asteroid Rugu sample and, of course, asteroid Bennu So let me let me start some trouble.
Yeah. What what will we find more from? Because a comet has the water as its ice. Right. So would you what? What would we benefit more from? A sample collection of an actual asteroid, which we've done. That's what you guys did. Or being able to kind of either trail and capture or capture a piece of a comet, which has, you know, which will give you the water.
Well, that's a great question. And capturing the water and bringing it back to Earth is incredibly tricky. We have sampled from the back of comets in the coma and brought back the minerals that were actually in that comet meritorious, but not the ices. To actually freeze a sample and bring it back is really complicated and really expensive, most likely.
So you're saying it's hard to bring back the volatiles is the point here.
It's hard to bring back the volatiles and the ices and stuff because you've got to keep them cold the whole time and keep them cold coming through the atmosphere and then not interact with their Earth too much.
Actually, this brings, stop me if you want, but this brings sort of a square root of one question is that the OSIRIS-REx mission is a special class of missions, which is a sample return mission. of which if we don't include the Cold War Apollo and Luna samples, we've only had a couple of handfuls of those in the course of history. Basically three of them by the US, two by Japan, and two by China.
So you're looking at basically a large sack of potatoes of extraterrestrial material that was brought back to Earth, roughly eight pounds or so of material, That was a little over $2 billion worth of money spent to get these samples back for a scientific community that conservatively probably only 100, maybe, well, let's say 100.
maybe 1,500 people in the world work full-time at trying to understand. I don't have a problem with that. Last year, an American people spent $4 billion on candy for Halloween. So, you know, here we're pushing the frontiers of our...
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Chapter 3: How do meteorites inform us about the early solar system?
And I also know from a conversation with Neil that some asteroids are kind of like... pebbly because they're held together. They're not really a big solid rock. They're kind of pebbly and held together, you know, and it's easy to go in and do whatever you want to do. If we were talking about mining asteroids, if I recall the conversation.
Chuck, very important point there. So, Harold, What was your confidence in the structural integrity of Bennu to just come down and do a touch and go? Did you know enough about its structure to know that that would succeed in advance?
Yeah, great questions from both of you. First of all, Bennu is what we call a rubble pile asteroid. So it's literally an asteroid made up of accumulation of large boulders and teeny tiny little grains. And it rotates around its own axis in 4.2 hours. Actually, it rotates retrograde, which means opposite than what we normally would think. It rotates.
And all the information we had, we had designed originally the spacecraft for big ponds on the surface of really fine-grained material. You know, we're talking about less than an inch size material because our data, our science showed us that there should be a lot of it. We got there, we screamed because there were boulders 11 stories high. And it wasn't quite what we expected.
You can't fit a boulder 11 stories high into your canister.
Right.
We can't. Sorry, it's not that big.
And, you know, the problem is when you fly down to the surface of the asteroid, you may not come back out the same way either. So there's challenges with the navigation that you have to think about.
And to get to your questions and your comments here, we had designed the touch-and-go sample acquisition mechanism to basically just touch the surface, as Neil said, and we fire some nitrogen gas, and it basically fluidizes or moves the gravel up, and then it gets collected into this little sort of reverse mechanism. hoover or vacuum head, and then we would pull back.
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Chapter 4: What are carbonaceous chondrites and their importance?
So that's better for you.
Correct. Absolutely correct. Wow. The problem was, and you did ask another question there when I get to that, the problem was that when we pulled back up, you know, and did the first test to see what kind of sample we got, we literally moved that three meter arm backwards to a camera to take pictures.
And I can remember about four o'clock in the morning waking up and downloading from our mainframe the images and started looking at it. It had all these little spots all over the place. I'm thinking, What the heck are these spots? Long story short, as the world knows, several stones got caught keeping the flap open. And we were losing sample every time we articulated the arm. Wow.
There's another PhD thesis. There's another PhD thesis. Come on, come on, come on. That's tough. Yeah, always right. That's tough. Yeah, so the PI had to make some quick decisions with the associate administrator of NASA and other people to basically stow the sample much quicker than we had expected to prevent more from loss.
But of course, as you know, we got 122 grams of sample, 121.6, and we needed to get 60 grams to meet our scientific goals.
That's a success. That's a success. Yeah. So, so you bring it back to earth and now it's, you've got it in the lab. And so you're a geologist. I don't know. Do you guys use microscopes or do you use stuff that dissolves the material and you do mass spectrometer? What's your, what's a geologist's dream lab when you have something from space?
That's a great question. You know, we brought the sample out of the field. By the way, the sample cavister, the SRC, sample return capsule, landed in the Utah desert basically perfectly in the end. It had rained there three days earlier, but it chose to land in a dry spot, which was perfect. And then we take it to a makeshift facility at the UTTR, Utah Test and Training Range.
We get the sample canister and it's, you know, the guts of the sample return capsule out and get it under nitrogen so that the sample is constantly bathed in nitrogen. So, I mean, that took literally almost four hours to the mark to get that under the perfect timing.
I have a quick chemistry question. You speak of nitrogen as though it's neutral. In fact, there are some sort of wine air replacement canisters that send nitrogen in as the air comes out. But to me, nitrogen can make ammonia, nitrous oxide. It's not like argon, where we're taught in chemistry class is just inert because it's got no electrons available. Just nothing to do with it. No interaction.
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Chapter 5: How does the composition of asteroids relate to the origins of life?
Now, other folks, other scientists do dissolve samples. But if you dissolve the sample without knowing what you dissolved, other than it came from this mountain, I mean, you know, how many different layers of rock are in the mountain? And you say it came from that mountain. Well, I don't know where it came from.
That doesn't help you recreate the geology and then put it into context of a special question such as, you know, looking at the potential origins of what we know is life.
So I don't mean to diss your entire profession, but most people, when we look out into... into space rocks. We're kind of interested in the organics, not in the minerals. And I know geologists love them some minerals, but at the end of the day, the headline is not what kind of new rock you found. It's what kind of organics might be there. So how close were you to that analysis?
Or was that a whole other group?
So, uh, That's a very good point you raise. And the problem with the organic chemistry, not a problem, but the challenge is that you have to know what the rock is that you're analyzing. What processes, geologic processes has it been through?
In order to know the geologic processes that rock has been to, in this case, an apparent body that was probably the size of Ceres, the asteroid Ceres, for example, that Fluid moved through that asteroid four and a half billion years ago because the asteroid became active.
When the asteroid created rock in the earliest time period, it created ices, not just water ice, but ammonia, carbon dioxide, carbon monoxide, etc. And then the asteroid internally began to heat up and you have fluid moving through. Now, why is that any relevance whatsoever to prebiotic compound? Because prebiotic compounds... may very well have formed in that aqueous or water-rich environment.
The evaporite minerals that we talked about are the late stage product of the fluid that moved through, that formed other minerals first, and they're the very last stage. Now, if you're an organic chemist
and you want to get organics to come out of a solution, one of the time classic methods of doing that in a laboratory is you salt the solution, and the organics go with the evaporated minerals or the salt when you evaporate the fluid.
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Chapter 6: What challenges are faced in sample collection from asteroids?
And I ask that because Bennu, last I checked, is bigger than the Empire State Building, something like 500 meters across. And so that seems like...
a big enough body to be its own body in in in the universe but tell me turn the clock back on this was there some proto-planet that had already sort of as you the gel just say differentiated its materials and then shattered to become Bennu and if that's the case you might be able to find other rocks that are like Bennu that are out there
Yeah, absolutely great question. First of all, the main type of meteorite we find on Earth that's like Bennu is called a CI-like meteorite, and there's only two handfuls of them in existence. And it's very clear from both studying the sample from Ugu and the sample from Bennu that our sample collection is biased on Earth.
Not only is the sample collection contaminated, but what actually is out in space is biased because we have a lot of carbonaceous asteroids. Now, turn the clock backward. Bennu is fragments from collisions that occurred of different bodies together. One of those bodies was a parent body, as we call it, a previous incarnation of Bennu at a much larger scale.
And that was something that was indeed forming probably some of the early proto-planets that may have existed. And once the objects get to a certain size, around 10 kilometers or so in diameter, the internal mechanism begins to turn on for geologic process. That internal mechanism is heat begins to move around. That's generated from the decay of radioactivity and pressure.
It becomes a cosmic body at that level.
It becomes a cosmic body. It begins to melt the ices that were created with it. It begins to have fluid. And we call that the early stages of metamorphism in geology. And the early stages of metamorphosis, that fluid moves through and begins to interact with the minerals that are there.
And it begins to change those minerals and pick up different kinds of chemicals as it's moving through the fluid. It moves in different parts of the asteroid because it cracks and all kinds of things that happen. And then what we think happened is that at some point, the poor parent body asteroid gets collided into with something else. And it stops the process.
So you have a snapshot in geologic time of that moment that all the processes geologically were active. Wow.
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Chapter 7: What role do organic compounds from Bennu play in understanding life?
Yeah, so there's a whole sequence that forms of these different minerals, the calcium-rich ones, then the phosphorus-rich ones, right? And they go down through what's left in the fluid to come out of the fluid and start forming new minerals. You get things like sodium, et cetera. And phosphorus is one of those key minerals that makes things like phosphates.
And of course, phosphorus is one of the key kind of elements that gets bound together with things like carbon and hydrogen, et cetera, to form prebiotic compounds that are important. And it's the whole suite of these evaporite minerals, not just the phosphorus. The phosphorus is critical, though, but it's not just that.
It's the whole suite of them that we, as life, have to have in different ways and different proportions. Now, I'm not a biologist, so keep that in mind.
Yeah. So tell me about pre-solar grains. There's a lot of research papers on this. In fact, we have some on display here at the Rose Center for Earth and Sprays. In fact, they're pre-solar diamonds, I think. And I think it's kind of cool. I just don't know its relevance. It's cool to think of.
Grains that might have predated the formation of the solar system, which gets you even farther back than the four and a half billion years. So I think that's kind of cool. But is it just sort of cool to know or does it have other relevance to any of this?
Well, I mean, you know, they're saying better than I. You know, we are stardust. We are made up of stardust, right? And stardust means dust that literally comes from stars, either evolving stars or dying stars that eject material. And in that ejection, that gas that comes out, like the fluid with minerals condensing, these new minerals condense out of the gas.
And these are from stars that are not part of our... were not part of our solar system and seeded what was there in the beginning before our solar system formed, which was a molecular cloud. And there are different kinds of... Pretty solid grains. Diamonds are one of them. We had downstairs in the museum's meteorite hall. There are diamonds in a little capsule in there, which is fantastic.
It looks like a grayish mixture inside of the little vial. There are silicon carbide grains. But then there are what we call corundum or little teeny tiny. And we're talking really so small, smaller than what we can see, certainly with the naked eye, nanometer size.
Isn't some of these that you're describing used as fake diamonds on Earth?
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Chapter 8: How do findings from Bennu compare to those from Mars?
Isn't gypsum on the Mohs scale? I have some memory of that.
So I got that right? You got that right. You got that right.
Gypsum is very soft. It's like one or two.
It's a hydrated mineral, so it has water attached to it, which makes it structure. And then gregite is another mineral that form, and that's an iron sulfur-rich mineral. But that is an interesting mineral because it's on a pathway. The final product forming would be pyrite, which everybody knows is school scope.
The mineral before that is not an all right, big name, but that mineral was recently discovered in both Rugu and Bennu for the first time. Now, why is this mineral important? Because it's sampling different abundances of oxygen that is around in order to produce itself.
Okay. Now, oxygen is not uncommon in the universe, but it's highly reactive, right? So it's going to be binding with almost everything. And so where is it getting its oxygen from? What's its source?
Oh, that's a great question. We assume it's coming from a fluid interaction, a fluid that has evolved. But how that fluid's evolving, I don't know. When that fluid evolved, I don't know. And the landscape certainly is such that you know fluid was moving around water.
In the Cheva Falls, in that, those deposits, I don't know, is that the right word? Inclusions, those, yeah.
Yeah, the sedimentary rock deposits.
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