Short Wave - From The Physics Of G-Force To Weightlessness: How It Feels To Launch Into Space

Episode Date: June 11, 2024

It feels like this is the summer of space launches. So, it's only appropriate that we kick off our new series Space Camp with a look at space launches. Throughout the series, Regina and Emily will plumb our universe to uncover the strange, wonderful things happening all around us. This episode, that entails answering a series of questions about getting to space: What does hurtling into space feel like? What physics are involved? And what's the "junk" in Earth's orbit? Space Camp episodes drop every Tuesday in the Short Wave feed in addition to our regular episodes happening every Monday, Wednesday and Friday. For a full explainer of Newton's third law of motion, g-forces and visuals on his cannonball thought experiment, check out our digital story.Have a particular aspect of space you want us to cover in a future episode? Email us at [e-mail] — we'd love to hear from you!See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, Short Wavers, Regina Barbara here with some exciting news all summer long. We'll be reporting out a new series we're calling Space Camp. Every Tuesday for the next nine weeks, me and my co-pilot Emily Kwong. Hi, Gina. Hey, we're going to travel deep into space, M. Yeah. And we're going to explore all of the wild, inspiring phenomena in our universe, like different kinds of planets, stars, and even black holes.

And we're starting right here on Plains. at Earth with launch to quite literally launch our series and also because there's been a lot of launches into space recently. In just the last week, there was Boeing's Starliner. Then there was Space X's starship, which was crewless and a bit more of a test. Yes, so let's buckle up M and let's start our launch of this series. Launch is something that Navy Captain and NASA astronaut Wendy Lawrence is very familiar with. She was an astronaut from 1992 to 2006 and her first launch was in 1995 on the space shuttle endeavor. Launch is one of those things that you always look forward to.

It never got boring. She remembers as a very surreal experience. The moment that really kind of crystallizes it for you is when all the engines cut off and suddenly you're kind of thrown forward in your seat up against your restraining harness. You have a view out the window and you're like, wow, look, the earth really is curved. Wendy said it was a beautiful view, but that she couldn't really fully take it in in that moment. You would think you would have more of an opportunity

to just really savour the fact that, oh, I'm in space, this is awesome. You unstrapped from your seat and instantly you're not very coordinated. And so with the help of Wendy and many other experts, we're about to boldly go where few have gone before, to outer space. Today on the show, we launch. Shortwave gets into the basics of a launch, from the physics to the weightlessness experience, and we ask why there is an increasing amount of things to avoid once you reach Earth's orbit. You're listening to Shortwave, the science podcast from NPR.

Okay, Am, let's get more into what it takes to launch a rocket with astronauts into space. Yes, okay, so for answers on just a basic physics level, I reached out to Moriba Jha. He's a professor at the University of Austin, Texas, co-founder of private, Veteer and Guy Vars Limited and an astrodynamicist. Academic speak for somebody that studies how things move in space. Correct. Yeah. And he threw it all the way back to 1686. There's this dude, his name's Isaac Newton. He had, you know, a few cool things to say. And one of the things that we can attribute to his work was a set of laws of motion.

Yes, I know those three laws very well. The law I think he's going to talk about is that for every action, there's an equal and opposite. reaction, right? That's Newton's third law. So imagine you blow up a balloon, hold the end, then you let go. What happens? The balloon should like move away from us. Yeah. But it's because the air in the balloon is going towards us. And the balloon itself is moving in the opposite direction. It's very similar to a rocket. So M, here's another example. So in physics 101, I used to do this demo when I teach in university and I would sit on my knees on this like plank thing with wheels that mechanics used to go under cars, and I would put a fire extinguisher between my knees. I would like let it rip, and then it would shoot me backwards as it fired. That sounds so fun.

Yeah, so basically the rocket has mass. It has fuel. And by this law, Newton's third law, the fuel goes out, and that's what's known as exhaust, and it generates power, known as thrust, and we go up. In five, four, three, two, one, lift off. Gina, escaping Earth's gravitational pull is not easy, right? No, it is not easy. We're overcoming the curvature of space time itself. Like, just a reminder, the fabric of our universe, space time, can be thought of as, like, a bendable sheet. The mass of Earth is making that flat fabric of space time curve down into this, like, funnel-like shape.

Moving up the funnel, escaping Earth's gravity is more difficult than moving down. So we need to go really fast. You need to have enough velocity to be able to no longer succumb to the curvature of space time based on the Earth's presence. And as all this is happening, the people inside the spaceship are experiencing intense G-forces M. So gravitational forces or G-forces come when your body experiences acceleration. So when you're sitting or walking around on Earth, you're probably not noticing them, even though you're always getting this pole-torting. the center of Earth or Earth's gravity, and that's 1G. When you're doing something like going up in an elevator, like really fast,

you feel heavier, and that's more than your regular 1G. But it's nothing compared to, like, what astronauts experienced during launch, like Captain Wendy. I remember on my first flight thinking, oh, my gosh, somebody just sat down on my chest. This was an incredibly heavy sensation. Then I tried to see if I could put my arm out in front of me, just extend my arm, I'm like, no, I cannot hold it out there against this tremendous power and acceleration being produced by this amazing space vehicle.

The G-Forces Wendy experienced were so intense because the acceleration she was feeling was actually three times the gravity we feel on Earth. And of course, like once the rocket reaches space, almost nine minutes later, she feels almost weightless. Wendy says that once she got past that uncoordinated stage of floating...

It's just awesome. You're just perfectly suspended. right in the middle of the air. And what's really fun about it is it doesn't take any effort on the part of your muscles or your body to maintain position. You just relax in front of a window and watch the world go by. Something that's actually really cool to me about weightlessness is it feels like you're floating and astronauts kind of are when they're in the International Space Station.

But in physics terms, you're actually very slowly falling towards Earth. You're falling? Yes, that's so bizarre. Do you feel like you're falling? Yeah, I asked Wendy that, and she said for her personally, No, I've never had that falling sensation. And sometimes you'll hear people who have had the opportunity to go out and do a spacewalk. They'll get that sensation when they first open the outer hatch of the airlock

and now are typically looking down at planet Earth. M. So I don't know if you know this, but you can actually experience this feeling here on Earth. Have you ever gone to the Tower of Terror in Disneyland? Actually a lot. I love that ride. Awesome. So you feel weightless for a bit when it drops, right? Yes. You kind of hover in the air. Even though you're falling. Oh, right. Right. What? I don't get it. In physics, we call that free fall. All the astronauts in the ISS orbiting Earth are just falling. That's why they feel weightless. Wait, so how are they falling, but still orbiting? Yeah, horizontal and vertical motion? Right. I get it.

Well, it all starts with projectile motion. Here's Wendy again. I think pretty much every kid has thrown a ball. Gravity pulls it eventually back down to Earth. So, you know, that ball kind of has an arc shape as it travels. So in general, that's happening to my spacecraft. It literally is falling back to Earth. I think I get it.

Wait, can you explain this some more? Yes. Isaac Newton, you know, the guy we've been talking about. That dude, yeah. He had this thought experiment that if you were to shoot a cannon ball, let's say like horizontally, that that ball will first travel pretty flat horizontally and then it'll start to fall in that curve path. Now imagine that we're doing this on a very, very tall mountain. And the ball would hit the ground even farther away because it had farther to fall and it would have been in the air longer.

The arc would have been bigger. Yeah, the arc would have been bigger, longer. Now imagine you could shoot the cannonball even faster. It would travel even farther. I can see this in my mind, like the arc is just getting bigger and bigger and more stretched. Right, right. So now imagine that the mountain was so high and the launch was so strong that the cannonball, when you shot it out, the curved path matched the curvature of Earth so that it never falls and never hits the ground.

It's just, so it never falls and never hits the ground, like it just keeps missing the ball. planet? Yeah, now you're in orbit. No, that's all it is. Yeah? That's all it is. Projectile motion. That is so cool. Gina, thank you for explaining this to me. There is one thing that, or I really should say thousands of things that are just not so awe-inspiring about getting to the International Space Station these days. And that is all the stuff that is starting to clog up low Earth orbit. You know about this, right, Gina? Yeah. Yeah, we call it space junk. And looking into it for this episode, it reminded me a lot of that scene in Wally.

Do you know the one I'm talking about? I do. I love Wally. Where Wally and Eve had to, like, cut through a cluster of satellites to get off the planet. Right now, you know, that debris isn't as close, but yeah, there is debris out there. Yeah, like low Earth orbit is just becoming a little bit of a junkyard for orbital debris. It's generated from these satellite collisions and stuff just breaking down and falling apart. Even a fleck of paint off an old satellite can do damage because we're talking about a tremendous rate of speed to stay in orbit. Space Station right now is probably also about 250 miles above the Earth's surface.

It's going five miles a second, eight kilometers a second to stay in orbit. Same with the orbital debris. So it doesn't have to have a high amount of mass to do a lot of damage. So that's why the space station has to monitor for space junk all the time. Moribaja, our astrodynamicist from earlier, says space junk is an escalating environmental issue. And we're on kind of a dangerous trajectory. Think about single-use plastic and the danger it poses to the environment here on Earth. But that's what we're doing in space, because nothing that we launch into space is this reusable thing, except for maybe the space station.

Yeah, the ISS, Gina, did you know it has to monitor for space junk to avoid a collision? I do. I do know that. Yeah. It's like part of the gig. And when I spoke to Moore about five years ago, there were about 20,000 objects that the U.S. Department of Defense was tracking, like satellites, rocket bodies, debris, most of it, 90% of it is just trash. Like, it doesn't work. Now the catalog has grown to over 45,000 objects. Wow. That's a huge jump. Yeah. And it has to do with this trend. Okay. In the last few years, commercial entities have launched thousands of satellites.

It's like SpaceX alone has launched 6,000 of the over 9,000 working satellites to create the internet network Starlink. And Morba, he supports a global internet, you know, giving people access in remote locations. But he's worried about these unforeseen costs to our environment. Okay, you're really making me think very differently about launch. Like, once stuff is up there, like, what happens to it? This is the question for our age. I mean, there is no international treaty that, say, limits. space junk or sets standards for negligence if a country creates more.

Moriba wants to see space become a much more sustainable place. Countries, governments need to incentivize their industry to say you're going to get some kind of incentive or tax cut or whatever if you design, build, and operate reusable and recyclable satellites. And he thinks those same parties need to be held accountable for responsible disposal, but until that future comes to pass, we're going to see more launches, but also more space junk.

Littering the sky. Well, let's not contribute to the stuff in orbit right now and let's move on to Pluto. I like how you think, Regina Barber. We will be back tomorrow with more regular shortwave, but you don't want to miss this series. Every Tuesday, tune in to our next installment of Space Camp.

Yeah, Tuesday we will continue our exploration of the universe with a push deeper into space. So, M. I have this clip ahead of our next SpaceCap episode reporting on something at the edge of our solar system. I have this, like, message from one of our experts. This is Vladimir Lyra, you're a planetary officer here on Earth. This is ground control to major tone. You're about to pass Pluto after a long, cold journey, saying hello to Pluto and getting to know close up in person. Look at the other side and you see the crescent of Karen.

About the stars look very different today. And before we head out, we want to hear from you. We want you to send us your favorite planet in a voice memo in 20 seconds or less. Say what your favorite planet is, why you love it, your name and location, and email it to shortwave at npr.org, and we may feature your voice in an upcoming episode. This episode was produced by Burley McCoy. It was edited by our showrunner, Rebecca Ramirez, and backcheck by me and Gina. The audio engineer was Gilly Moon, who is not from space, but is awesome.

Julia Carney is our project manager, Beth Donovan, is. is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. And I'm Emily Kwong. Thank you for listening to Space Camp. A science summer series from NPR. A space science summer series. The science.

So many S's. Yes. The science summer series. A special space science summer series. From NPR.