The Results Are In From The Distant Asteroid Ryugu

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Later in the hour, we’ll be talking with the new chair of the House Science Committee, Congresswoman Eddie Bernice Johnson. Do you have a question for how Congress should spend your money on science research? Well, now is your chance. Give us a call. 844-724-8255. That’s 844-724-8255. Or you can tweet us @scifri. 

But first, this week, space researchers met in Houston for the Lunar and Planetary Science Conference. And one of the big topics was asteroids. Researchers from NASA’s OSIRIS-REx mission talked about its trip to asteroid Bennu. And members of the Japanese Hayabusa2 mission gave the first science results from their encounter with asteroid Ryugu. Here to talk about that and other selected subjects in science is Annalee Newitz, a science journalist and author based in San Francisco. Welcome back, Annalee. 

ANNALEE NEWITZ: Hey. Thanks for having me. 

IRA FLATOW: Let’s start off with Ryugu. What is it? Where is it? Why are people so interested in it? 

ANNALEE NEWITZ: So this is an asteroid that is shaped like a spinning top, which means it’s kind of wider in the middle and comes to two points on the top and the bottom. And Japanese researchers were interested in visiting because it seemed to have a high amount of carbon on its surface, which suggests that it might have some of the molecular precursors to life– to life on Earth, because that’s all we care about is life on Earth– and it might also have water. So they went and they found a couple of surprises. 

IRA FLATOW: Hmm, like what? 

ANNALEE NEWITZ: So first of all, sadly, it did not have very much water content, or so it appears at this point. But it also appears to not be a solid asteroid. It’s actually more like a bag of rubble being held together by gravity. So essentially, this is a ball of rocks that came together from an ancient collision, probably very early in the solar system’s formation. And it created this spinning top shape at some point earlier in its history when it was spinning a lot faster than it is now. So basically, it’s a bag of rocks. 

[LAUGHTER] 

And the NASA mission, which is visiting a different asteroid– Bennu– is actually visiting a very similar kind of asteroid. It’s also a top-shaped asteroid. It’s also probably a bag of rocks. And it also suggests– the carbon content suggests there might be water. And there’s already early signs that they may have discovered water there. So one of the big questions now is why are they so similar, yet one has virtually no water and the other one does? And also, both asteroids have had our probes land on them and are bringing back little pieces of asteroids to Earth. 

IRA FLATOW: Some of the bag of rocks is coming back. 

ANNALEE NEWITZ: Hopefully, yes. So in 2020, look out for that little tiny bag of rocks from Ryugu. 

IRA FLATOW: I will quote you on that. OK. 

[LAUGHTER] 

Let’s move on to other kinds of debris. There’s new research into the things left behind by otters. 

ANNALEE NEWITZ: That’s right. So one of the many adorable things that otters do is they are the only sea mammal that we know of that uses rocks to get their food. And what they do is they use rocks like anvils. They smash them against shellfish, or smash them against abalones to get them off of rocks and to get the yummy food inside. 

And this leaves behind a very characteristic wear pattern on the rocks, because otters tend to keep the rocks that they use. They find an anvil rock that they like and they kind of keep it in their pocket. They actually do have a little otter pocket on their bodies. And so as they use it over time, these rocks take on dings and bangs on them that are characteristic of breaking open shellfish. And this gave zoologists an idea about how they might study otter populations using tools taken from archeology, which I like because I like archeology. 

And so what they did was they spent 10 years on the California coast observing a group of otters. First, looking at their behavior with breaking open those rocks, and then looking at the rocks themselves. And found that just as when we study ancient humans from 100,000 years ago or 500,000 years ago, we know certain kinds of rocks have characteristic wear on them that show they were used as tools versus just being regular old rocks that have been banged around. They can do the same thing for otters. 

So they’re using this technique to discover tool rocks as opposed to just regular rocks. And what this lets them do is actually quite amazing. And it lets them recreate what historic otter populations might have been in the coastal areas, because otter populations are disappearing, so we’d like to know how many there were 100 years ago, 1,000 years ago. But it also can add data to our understanding of how big otter populations are today. If we can find a number of rocks, that can help us understand are there 20 otters, are there a million otters. It’d be nice if there were a million otters. 

[LAUGHTER] 

Maybe not. Maybe not a million. So this is just a great example of how you can import tools from one science to another and learn a lot. 

IRA FLATOW: Interesting. There’s a strange story this week about researchers who put zebrafish into contact with bees. Whoa! How did they– 

[LAUGHTER] 

–you’re going to have to connect the dots on that for us. 

ANNALEE NEWITZ: This is basically the kind of story that comes along maybe once a year where your brain is just blown. Basically, these researchers in Europe decided that they wanted to figure out a way to get bees and zebrafish to communicate using robots. And the reason they picked bees and zebrafish is that these are two animals whose behavior has been really well-studied. They both exhibit social behavior and collective decision making. 

So what the authors of this study wondered was, if we could get those two collectives– the fish collective and the bee collective– to talk to each other somehow, would they make one big decision as a group? And the answer is yes, strangely. They created a robot that could communicate with bees, that could get bees to move in a certain direction, left or right. And they also created a robot that swims around that could get the zebrafish to swim left or right. So the question was, could they get the robot that was talking to the bees to communicate to the zebrafish robot? The bees are moving left, you guys should move left too. 

So what they did in the experiment was first they had the bees move in a certain direction. They were attracted to this robot, because it was warm and bees are attracted to warmth. So they all moved left. And then the bee robot said to the zebrafish robot, hey, get the fish to go left. So that fish swims left and kind of pushes the school of fish to the left. So that worked out pretty well when the bees told the zebrafish what to do. 

Zebrafish telling the bees what to do– not so much. They couldn’t really get– the zebrafish– they do engage in collective behavior. It takes them a little longer. They tended to be a bit more chaotic. And so they would communicate to their zebrafish robot, hey, go whatever direction you want, we don’t care. And the bees would have what the scientists referred to as a lot of entropy in their behavior. 

[LAUGHTER] 

But the great part is, ultimately, they were able to create a loop where the bees were communicating with their robot, which communicated with the zebrafish robot with the fish, and it created– in under 30 minutes, they actually did reach a collective decision about which direction to move. And this really– the implications– 

IRA FLATOW: Pretty cool. 

ANNALEE NEWITZ: –for it are– yeah, it’s super cool. And what it means is, ultimately, there’s some kind of principle underlying collective decision making that transcends species. And that is just mind-blowing. 

IRA FLATOW: Well, you’re right. Poof! Mind-blown, Annalee. 

[LAUGHTER] 

ANNALEE NEWITZ: My work is done. 

IRA FLATOW: Your work is done. And have a good weekend. Annalee Newitz, science journalist and author based in San Francisco.

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