What asteroid Bennu samples are revealing about photo voltaic system

Researchers proceed to research the pattern introduced again to Earth from the asteroid Bennu — and among the many issues they’ve discovered is that Bennu’s mum or dad asteroid was made up of supplies from everywhere in the photo voltaic system.

Those findings are amongst these revealed in a trio of recent papers primarily based on the outcomes of 2023’s OSIRIS-Rex mission.

Tom Zega is a professor of Planetary Sciences on the Lunar and Planetary Laboratory on the University of Arizona. He’s been among the many scientists learning the return pattern.

Zega joined The Show to speak about a few of what he and his colleagues have discovered.

Jacob Bernal/University of Arizona

Full dialog

MARK BRODIE: What stands out to you about what the group has came upon thus far in regards to the composition of Bennu?

TOM ZEGA: Yeah, so the sort of work that we do in learning meteorites and samples returned from asteroids and folks at different establishments that do that, we type of have been on the mercy of what falls from the sky, proper? So we won’t get into our Battlestar Galactica or Starship Enterprise and fly out someplace within the photo voltaic system and simply acquire stuff. Not till we had pattern return missions like this one, like OSIRIS-REx.

And one of many distinctive issues about having a pattern return mission like that is that it brings again samples from the floor of an asteroid that aren’t weathered or altered in any method by Earth’s environment. And among the many main findings from our research is that the pattern consists of 80% or extra of water-bearing clay materials.

BRODIE: What is the importance of that?

ZEGA: Well, we all know, in fact, that life, not less than life on Earth, requires water, and we all know that two-thirds of Earth’s floor consists of water. So one large query is the place did all this water come from? How, how did the early Earth get its water? And there are totally different hypotheses within the scientific literature about how Earth acquired its water. Among them, is issues like comets may have delivered water to the early Earth as a result of we expect comets have plenty of water locked up inside them within the type of ice or in different water bearing minerals like clay minerals.

It seems, taking a look at a carbonaceous asteroid like Bennu, a variety of it, most of it’s composed of this water-bearing materials and natural compounds. And so it’s totally attainable that materials like what we’re discovering in an asteroid venue may have very, very doubtless seeded the early Earth with natural compounds and presumably even, even water.

BRODIE: And that may, I’d think about, point out that there’s, if not at the moment, then at one level the potential for water elsewhere someplace within the photo voltaic system, proper?

ZEGA: Absolutely. So once we have a look at the, you already know, once we have a look at the minerals which are comprising the asteroid samples, not simply Benu but in addition Ryugu, which was materials returned by the Japanese aerospace Exploration Agency, or JAXA, these two comprise plenty of, of, of water-bearing clay materials. And we expect that what was taking place some 4.5 billion years in the past is that these asteroids accreted a mixture of silicate mud, some steel with some carbon, natural materials and icy materials from the outer photo voltaic system.

It may have been water ice. It may have been CO2 ice. It may have been ammonia bearing ice. It may have been a mixture of these issues. So as soon as that ice accreted along with all this dusty materials from the early photo voltaic system, all we wanted, or all it wanted was a bit of bit of warmth to soften that ice, make a liquid. That liquid now could be in touch with solids, and now you might have the whole lot you’ll want to begin doing every kind of chemistry.

BRODIE: So what questions then does that increase for you? Like, what do you wish to discover out subsequent primarily based on that specific discovering from Bennu?

ZEGA: Well, among the many subsequent phases of the mission can be, we all know what it is largely composed of. We typically know the sorts of chemical reactions that led to the merchandise that we see at the moment. One of the excellent questions is when precisely did that occur? Can we truly put a time stamp on it?

And so there is a approach to measure the timing or courting of that, and that is by taking a look at radioactive isotopes that will have been a part of the pattern for, early within the photo voltaic system historical past. And so by measuring among the radiogenic isotopes with refined devices and mass spectrometers, we will get a way of when all this chemistry occurred and truly put a really exact age date on a few of this chemistry.

Another one of many key questions, in fact, is once we have a look at the natural compounds within the pattern, and there are fairly a couple of natural compounds. We’ve recognized 15 of the 20 amino acids that life makes use of to construct proteins, and we have recognized all 5 nucleo bases which are the genetic parts of DNA within the return pattern.

So we would prefer to know is that the entire variety of these natural compounds, or will we see extra natural compounds within the pattern? And so the subsequent phases of pattern evaluation will nearly definitely contain continued measurements of the natural element.

BRODIE: So I do know that one of many different issues that you simply guys discovered with this pattern is that the mum or dad comet the place Bennu, the belief is, broke off from, had materials from type of everywhere, and I’m questioning how typical or atypical is one thing like that.

ZEGA: Yeah, that is a superb query. So, once more, these of us which have been learning meteorites for, for a lot of many years, there’s all the time been this normal thought or speculation about how meteorites kind and the place they arrive from. So to offer you, to offer you a really feel for it, meteorites come from mum or dad asteroids. And asteroids largely reside in a belt between the orbits of Mars and Jupiter, OK? And so we have a tendency to consider this belt as being static, it is there, not a lot is de facto occurring.

But within the early photo voltaic system, we do not assume it was so static. Things had been transferring round, there have been plenty of impacts, issues had been dynamic, proper? And because it seems, once we have a look at the return pattern, we do not discover some options in it that we might have anticipated primarily based on what we had seen from meteorites or what we have checked out in meteorites for a lot of many years now. And so it is type of upending our thought of how the photo voltaic system perhaps was put collectively.

And so samples from asteroids like Bennu and Ryugu look similar to one other group of meteorites that we’ve got in our terrestrial collections referred to as CI chondrites, they usually appear to recommend that a lot of the fabric that comprised these asteroids got here from the outer photo voltaic system fairly than the internal photo voltaic system. And there could also be much more of them within the asteroid belt than we beforehand thought primarily based on what we’ve got in our terrestrial collections.