Astronaut Garrett Reisman on Space Junk and Micrometeorites

One thing I wanted to ask you about space is we always hear stuff about space junk, about satellites and just junk that's floating around the atmosphere. How much of a concern is that and what could be done about that stuff? It's a huge concern. It's a very, very big problem in certain orbits around the Earth, low Earth orbit and also at the geostationary orbits that are very, that's where you could put like communication satellites and they stay over one spot of the Earth. Those are very polluted. There's a lot of junk and it is very dangerous and it's a real problem. It's hard to clean up. Over time, eventually, even at higher altitudes, there's still a little bit of atmosphere like individual atoms. Eventually that slows you down. Those collisions eventually slow you down. So eventually it comes back, but it could take a long, long time. Come back to Earth, you mean? Yeah. It'll come back and it'll burn up. So the most important thing is don't make any more junk. That's like the best thing we can do. And we're getting much smarter. Like at SpaceX, we take our second stages and all of our NASA missions and after we it's accomplished its mission, we keep enough gas in the tank to burn the engine one more time and bring it back in one piece. So it doesn't blow up into smithereens and cause more junk. Whenever we do anti-satellite tests though, China did one relatively recently and we've done them in the past. Those are like the worst because they create giant clouds of junk and we still have to live with that. Is there any concepts on the table for how to take that stuff out? There's some ideas of using lasers to laser things and make subtle changes to their trajectories and orbits. But all the technical solutions are challenging and expensive. So I don't know of any one idea that's going to solve this problem easily. Because we've seen the map of the earth and all the different satellites that orbit it now and all the different pieces of junk that have been identified. It's crazy. Yeah. The amount of stuff and it seems like nobody kind of thought it through. They just sort of did it and left the junk up there. That's what humans do, man. I mean like we've been dumping stuff in the oceans forever and not really giving much thought to it and now we're finding giant gyres of plastic or down. So yeah, we tend to not really react until it's a really big problem. But it's a big problem. When I did my first spacewalk, one of the things we had to do was we had to bring in this handle that we're going to use on a subsequent spacewalk. We call it D-handle. It's just basically a half inch piece of aluminum around like this that you can attach to something and then carry things. So we had this big chunk of aluminum and we brought it inside and my spacewalk partner, Rick, looked at the thing when we came inside and saw a hole shot straight through it. It's like about a millimeter in diameter. It's really small but it went right through this half inch thick solid aluminum. And he looked at that and he said, man, if that hit one of us. And he didn't have to finish that statement because if this stuff is moving, generally speaking about 10 kilometers per second, so that's like roughly 10 times as fast as a rifle bullet. So if something like that hits you, it could be a fleck of paint hitting you at that velocity. If it hits you in the suit, you're in a 100% oxygen environment and you're just going to flame up. I mean, you're going to instantly combust. It's going to be a really bad day. So he didn't have to like, he said, when he said that, he didn't have to finish it. And we both looked at it. And then I looked at him and said, yeah, but you're six foot four. So statistically, much more likely it's going to hit you. More object. And besides that, I was kind of behind you most of the way out there. But it'd probably go right through him and right through you too. It probably am. That's what's so crazy about it is there's so much of that stuff up there. I'm always wondering like, why doesn't it hit the space station? It does. It does. There's a couple of times I was inside the space station, I heard us take a hit. Whoa. So I heard the ping, but fortunately I didn't hear the ping followed by the pshh. Oh, you're leaving. So that ping is probably something bouncing off something or going through something? So the station has shielding. It's called Whipple shielding. And it's basically a piece of a wall, a thin piece of metal that stands off from the hull. So the thin piece of metal is never going to stop this thing. But when it hits at that hypervelocity, it breaks up into lots of little tiny pieces. And it's almost like a fluid at that point. It's like almost a cloud of dust. And then when it hits the hull, those individual pieces don't penetrate. So it just shatters it. And that works. What if it hits that window? It has hit the shuttle window. It has multiple panes and it's really, really strong. But we came home with big... It looks like when a rocket's kicked up and it takes... Really? Yeah, we've seen that. Yeah. Wow. That's a little scary. Jesus Christ, a little? Yeah. What about micrometres and things along those lines? Well depending on where you are... So in Earth orbit, there's much more of manmade junk than there are micrometreoids. But there are those too. When you get out away from Earth orbit, like if we're going to go back to the moon, then there's no more human-made junk. But those micrometreoids are still out there. And they can do the same kind of damage. But there's a lot fewer of them. The density of those things is a lot less than what you experience. So if you go to Mars, I'd worry about the radiation first and then the micrometreoids are like down the list. It just seems there's so many things to think about. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah. Yeah.