NASA Considers Cheaper Ways To Retrieve Mars Samples | How Does A Hula Hoop Stay Up?

Scientists investigated how the shape of the human body makes hula hooping possible—and what hips and a waist have to do with it. And, the decision for how to proceed with NASA's Mars Sample Return Mission will fall to the incoming administration.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Ira Flatow?

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• 0:16Flora Lichtman?

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• 1:06Ira Flatow?

  This is Science Friday. I'm Ira Flatow.

• 1:08Flora Lichtman?

  And I'm Flora Lichtman. Today in the podcast, some bumps for a longstanding NASA mission.

• 1:14Speaker 02

  The frustrating part is it's been a couple of years now that we've been trying to figure out how to get this mission on the books.

• 1:25Flora Lichtman?

  We're talking about NASA's Mars Sample Return Mission. That's the ambitious project that aims to use the Perseverance Rover to collect Martian rocks and sand and even gulps of Martian air. And then, through a complicated handoff between different spacecraft, return those Martian samples back to Earth. In 2023, a review board said that the original plan to bring the samples back home would be much more expensive and take much longer than originally planned. So this week, NASA announced two options on how to cut costs and bring the samples back to Earth by the late 2030s. But the agency did not commit to a plan, leaving it to the next administration to sort out. So is the mission on the rocks?

• 2:09Flora Lichtman?

  Joining me now to get us up to speed is my guest, Dr. Jim Bell, Professor of Earth and Space Exploration at Arizona State University, based in Tempe, Arizona, and distinguished visiting scientist at NASA's Jet Propulsion Laboratory. Dr. Bell, welcome back to Science Friday.

• 2:25Speaker 02

  Thanks for having me on, Flora.

• 2:27Flora Lichtman?

  Okay, Jim, so what do you make of this announcement of these two possible plans with no commitment to either? Is this a good sign for the future of the mission? A bad sign? Neutral? What's your, what's your take?

• 2:39Speaker 02

  Well, the, the good news is that NASA is supportive of doing this mission, continuing to try to find ways to bring these spectacular samples that the Perseverance rover is collecting back to the earth. This has been the, the highest priority that's been identified by the National Academy of Sciences and the planetary science community for this next decade. The frustrating part is, as you said, you know, it's been a couple of years now that we've been trying to figure out how to get this mission on the books.

• 3:11Flora Lichtman?

  Yeah, so why has it taken this long to even just get some possible Plan Bs?

• 3:17Speaker 02

  Yeah, I think that the reason is it will be the most complicated robotic mission that NASA or any space agency has ever attempted. It's a hard thing to do. And there are pieces of what need to be done. The big lander to go back to Mars, a rocket to launch the samples off the surface, an orbiter to rendezvous with those samples in Mars orbit, bring the samples back. The pieces exist from past missions, but putting those pieces together, as you alluded to earlier, is incredibly complex.

• 3:52Flora Lichtman?

  Yes.

• 3:52Speaker 02

  And, and hard things take time and hard things take a lot of money.

• 3:56Flora Lichtman?

  Yeah, I mean, to me, it reminds me of like a relay in, you know, in the Olympics or something like you just, you have to pass this baton to all these different spacecraft, robot to spacecraft. Does that sound right to you?

• 4:09Speaker 02

  Yeah, or that game Mousetrap. I don't know if you ever played that as a kid, where you get all these different parts, you know, and this part has to integrate with that part and

• 4:17Flora Lichtman?

  Yeah.

• 4:17Speaker 02

  hand over to that part and the ball has to keep moving forward. In this case, the ball is a collection of at least 30 amazing samples, very carefully selected by the Perseverance rover team on Mars.

• 4:28Flora Lichtman?

  Yeah, I want to talk about that. So, you know, this, this mission has two parts. Part one is collect the samples. Part two is send them back to Earth. So your team is working on part one, working with the Perseverance rover to collect the samples.

• 4:43Flora Lichtman?

  What are you looking for? Like, what makes a good sample?

• 4:46Speaker 02

  Yeah, and that's a great question. And we've thought a lot about that and started thinking about that, you know, a decade ago, when the mission was sort of dreamed up and thinking about where to send it. You know, think about where would you go on the earth to collect samples to learn about the early history of life on earth and the environment of the planet as a whole. And it's a, it's a tough problem. And there are dozens and dozens of places that were proposed. And ultimately, we chose a place that, you know, was by earth standards, we, we thought would be considered habitable a long time ago on Mars. An ancient delta, ancient crater lake, place where there was water ponding and flowing on the surface, where there were sedimentary rocks preserving

• 5:27Speaker 02

  anything that was flowing down into that lake. And, you know, on, on earth, deltas, like the Mississippi River Delta, those are, those are amazing places to preserve evidence of biology and life. And maybe that's true on Mars, we thought. And so we've been trying to sample sedimentary rocks, mudstones, sandstones, delta deposits, the soil itself, and the basic kinds of chemistry and neurology in the rocks, the volcanic rocks. Really try to get a snapshot of, of an ancient environment that may preserve evidence of, of past life or past habitability on Mars. And also

• 6:08Speaker 02

  will tell us lots, we believe, about Mars just as a planet itself.

• 6:13Flora Lichtman?

  So perseverance has already collected the samples, is what I'm, what I'm gathering.

• 6:18Speaker 02

  Many of them, not all of them, but we've got more than 20 now collected.

• 6:22Flora Lichtman?

  Do people fight for it? Or they're like, no, I want this delta. And someone's like, no, I want this, this mudstone.

• 6:28Speaker 02

  Fight, yes, in a collegial way. We're all on the same team. So, you know, there's lots of heated discussions about, you know, do we, do we sample here? Do we drill there? Do we drive left? Do we drive right? But, but in the end, we're all working towards the same goal.

• 6:44Flora Lichtman?

  So where are they stored? Is there like a little hidey hole somewhere on Mars? Is there a shoebox in the rover? Where do you put them?

• 6:51Speaker 02

  There's two places that they're stored. The main place is inside the rover, inside the front of the belly of the rover. There's a tray and an entire collection of sample tubes and a little tiny robotic arm. I think about it like a little tiny Tyrannosaurus Rex arm inside the rover that moves those sample tubes around. It can pick them up and deliver them to the drill and the coring system and then collect them from the coring system and put them back into the tray and seal them hermetically. So, most of the samples are stored in that tray, but 10 of the samples have already been dropped onto the surface. And so as a contingency, as a just in case, the rover doesn't survive long enough to

• 7:34Speaker 02

  transfer the samples to this Mars sample return lander. In case that doesn't happen, there are 10 of them out in a very flat parking lot kind of place in the crater that we're at, just spread out across the surface and a future mission could go pick those 10 up if we can't get the primary samples out of the rover itself.

• 7:53Flora Lichtman?

  Sample takeout. They're just waiting for them to be picked up.

• 7:56Speaker 02

  That's a great way to think of it, yes.

• 7:58Flora Lichtman?

  Okay, so NASA had this press conference talking about how to possibly get these samples back. Can you just give me a high level overview of the options?

• 8:08Speaker 02

  So, as you mentioned earlier, the plan of record, it just has proven untenable in terms of schedule because the samples wouldn't come back until sometime in the 2040s. And in terms of cost, because some estimates of cost had it over 10, 11 billion dollars. So, the plans put forward are a combination of try to trim the size of some of the components, lower the costs, use more what NASA calls heritage components, pieces that have flown into space before, like the sky crane system that landed the Curiosity and Perseverance rovers on Mars. NASA engineers and others were able to sharpen their pencils

• 8:48Speaker 02

  and reduce the size of this rocket that needs to take the samples off of Mars and lower the mass and get it into the The sort of realm of being able to use the sky crane and other kinds of equipment. So that that lowers cost. And the other part of it is bringing in more involvement of commercial space. Companies like SpaceX or Tuited Machines, Firefly. So there's a there's a big commercial space industry out there that is eager to get involved in NASA science missions. And while I don't know all the details, I know a lot of us are looking forward to seeing what parts of the commercial space world NASA can bring in to help solve this problem.

• 9:29Flora Lichtman?

  Best case scenario, when do you think we might see these samples back on Earth?

• 9:35Speaker 02

  Best case scenario for me is like the the the second half of the 2030s, hopefully before 2040.

• 9:42Flora Lichtman?

  Are there people who are like, I will not retire until these samples come back?

• 9:47Speaker 02

  Yes, sign me up, yes.

• 9:50Flora Lichtman?

  Is that you? Are you that person, Jim?

• 9:53Speaker 02

  I'm among them. Yes, I absolutely want to see, I'd love to see the dust on Mars with my own eyes and studying it with telescopes and spacecraft for decades. But, you know, more importantly, there's there's a lot of amazing lab equipment and skill here on Earth that has been working on lunar samples and meteorite samples and asteroid samples, ready to to get samples from Mars and uncover those secrets. So the sooner we get those samples into amazing laboratories around the world, the better.

• 10:25Flora Lichtman?

  So imagine these samples have just arrived in the lab. You're unboxing them. What would that moment feel like for you?

• 10:33Speaker 02

  Oh, Christmas morning.

• 10:37Speaker 02

  I mean, one of the realities of being involved in space exploration is it takes a lot of time. It takes years, decades, sometimes of your professional career.

• 10:48Speaker 02

  To realize these kinds of missions and their success, in the case of bringing back samples from Mars, it's been something that hundreds and hundreds of people have been working to try to make happen, literally for decades.

• 11:03Flora Lichtman?

  Because this is the way that we would figure out whether there was life on Mars, right? Like, this is the way.

• 11:09Speaker 02

  Yeah, you know, I mean, unless something just gets up and walks in front of our cameras, you're absolutely right. There's, you know, we don't actually have any evidence of anything like that happening, and we don't expect it because life on Mars appears to, if there was life on Mars, it probably existed very early in the history of the planet. And we know from our own planet that the early history of life on Earth was very simple, single-celled, multicellular colonies of organisms, soft-bodied, no fossils. And the traces of that early life on the Earth, on our own planet, are incredibly difficult to find and study. And our expectation

• 11:50Speaker 02

  is that's going to be true on Mars. And so the best that we can do is go to a place that has the best odds of preserving that subtle evidence, and then get those samples into the same kind of laboratories, the cutting-edge laboratories on the Earth that study that subtle evidence for early life on our own planet.

• 12:12Flora Lichtman?

  That's just about all the time we have. I'd like to thank my guest, Dr. Jim Bell, Professor of Earth and Space Exploration at Arizona State University, based in Tempe, Arizona, and distinguished visiting scientist at NASA's Jet Propulsion Laboratory. Thank you, Jim.

• 12:26Speaker 02

  Thanks, Flor. It's been a lot of fun.

• 12:30Flora Lichtman?

  Don't go away, because after the break, we are going to close the loop on a very important question.

• 12:36Speaker 03

  We found that hula-hooping isn't even understood at a basic physics level.

• 12:45Speaker 04

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• 13:30Speaker 04

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• 14:09Speaker 05

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• 14:50Flora Lichtman?

  As you know, we strive to bring you the most important science news stories of the week, the stories you absolutely must be looped in on. And there's one more we just couldn't drop, a new paper that clears up a longstanding mystery about the hula hoop, specifically, why doesn't it fall down? Researchers at NYU looked into the head spinning physics and math of hooping. And as a bonus, they investigated what body types make for the best hoopers? I'm not going to leave you hanging. Here to tell us more is my next guest, Olivia Pomerank. She's a PhD candidate in mathematics at New York University and an author on this new paper. Welcome to Science Friday, Olivia.

• 15:32Speaker 03

  Thank you so much for having me. It's great to be here.

• 15:35Flora Lichtman?

  Why hula hoops?

• 15:36Speaker 03

  So there's actually evidence of hula hooping in the human historical record as far back as 500 BCE. It shows up for the first time in ancient Greece.

• 15:48Flora Lichtman?

  Wow.

• 15:49Speaker 03

  Yeah, so it shows up kind of again and again throughout history, independently in a myriad of different cultures. It's used as a form of recreation, religious ceremony, even exercise. And even today, artists and performers can do some really impressive stuff with hula hoops. And so we were actually just kind of inspired by just sort of seeing performers in Washington Square Park, right outside NYU. And we kind of, we figured, oh, hula hoops must have been sort of studied to death at this point.

• 16:19Flora Lichtman?

  That was your assumption?

• 16:20Speaker 03

  Yeah, that was the assumption because it's been, it's been around for, you know, millennia. But it actually hasn't been. We dug into the literature, just kind of driven by curiosity. And we found that hula hooping isn't, or wasn't, I guess, even understood at a basic physics level. And so previous studies have sort of looked at the problem sort of from a top-down view, like in two dimensions, and studied the kind of twirling dynamics. But nobody's answered the really obvious kind of glaring question, which is, how does the hoop even stay up? And that's the question that we kind of set out to answer.

• 16:55Flora Lichtman?

  That does seem like the fundamental mystery of hula hooping. Why doesn't it fall?

• 16:59Speaker 03

  Exactly.

• 17:01Flora Lichtman?

  Okay, tell me how you figured it out. I hear there are robots involved.

• 17:06Speaker 03

  Yes, there are robots involved. So it seems like all of the forces kind of exerted during hula hooping should be directed horizontally. Right? It's not immediately clear what's counteracting the gravitational force that's pointing down. So what's keeping it up? And so we sort of guessed that the shape of the body executing the hula hooping may be important. And so we, we 3D printed a bunch of different body types in order to test, maybe about the size of your hand.

• 17:34Flora Lichtman?

  Okay.

• 17:34Speaker 03

  Um, and we made a cylinder, a cone, so pointy part facing upwards. Uh, and then we also made basically an hourglass shaped body. And so we basically gyrated each of these. So that means translating in a circle without rotating it, drove that robotically and just by hand tossed plastic hoops around each of the bodies.

• 17:58Flora Lichtman?

  Tiny little baby hula hoops.

• 17:59Speaker 03

  Tiny little baby hula hoops, exactly. So it was, it definitely, it's a funny looking experimental setup.

• 18:04Flora Lichtman?

  Okay. So it seems like there's two questions. There's like, what's the best body shape to keep a hula hoop spinning? That's one. And what is the answer?

• 18:13Speaker 03

  So the answer is basically that you need to have sort of a sufficiently sloped and sufficiently curved body. So translating that to humans basically means that you need uh, kind of hips, which provides slope as well as a waist, which provides curvature. And there's sort of a sweet spot in there where the hula hoop will sort of naturally want to sit just below kind of the narrowest part of your waist. Then the hoop is sort of resting almost on like a tiny little sort of surface.

• 18:47Flora Lichtman?

  A ledge, your hip ledge.

• 18:49Speaker 03

  Exactly. And so there's a tiny little force pointing upwards if you have slope.

• 18:53Flora Lichtman?

  So that's it. That's what's counteracting gravity, your hips.

• 18:56Speaker 03

  Exactly, exactly, your hips. And then the reason you also need a waist and hips aren't enough uh, is that it's not enough to just counteract gravity. You also need the hoop to be sort of trapped in place. And so if you have a waist and you have sort of a curved profile, then you actually get the hoop to be trapped in place. So if it goes up a tiny bit, it'll be pushed down. And if it goes down a tiny bit, it'll be pushed up.

• 19:23Flora Lichtman?

  I love that there's a physics answer to this. When you defend your dissertation, will you be hula hooping the whole time?

• 19:31Speaker 03

  There is a chance that I bring one along as a prop. Not the whole time, definitely not the whole time. I don't, I don't know if I have the, the hula hoops prowess necessarily to do that.

• 19:41Flora Lichtman?

  Olivia, thank you so much for closing the loop on this mystery.

• 19:45Speaker 03

  Yeah, thank you so much for, for having me. It's always fun to talk about this kind of stuff.

• 19:49Flora Lichtman?

  Olivia Pomerank is a PhD candidate in mathematics at New York University.

• 19:56Flora Lichtman?

  And that is about all we have time for. Lots of folks helped make this show happen, including

• 20:02Speaker 06

  Rasha Reedy.

• 20:04Speaker 07

  Sandy Roberts. Shoshana Buckstall. Danielle Johnson.

• 20:07Flora Lichtman?

  I'm Flora Lixman. Thanks for listening.