Why did we develop the International Space Station in the first place? What have we learned in its 25+ years of operation? When is it coming down, and why? And what’s coming up next? I discuss these questions and more in today’s Ask a Spaceman!

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EPISODE TRANSCRIPT (AUTO-GENERATED)

In 1979, NASA's first space station, Skylab, fell to Earth. The intention was for it to crash into the Indian Ocean, but it survived deeper into the atmosphere than anyone expected. And so once it finally broke apart, pieces of the lab reached as far as Western Australia. The largest pieces of debris landed near the town of Esperance. There were pieces of metal falling from the sky and so town leaders had to do something about it. They issued NASA a $400 citation for littering. The debt went unpaid, and yeah, technically it was just a humorous jab. They didn't really intend for NASA to collect the fine for littering, and in 2009 a California radio host raised the funds to pay off the debt. But it does highlight how Skylab, and especially Skylab's fate, became something of a joke in the 1970s. and how we let a space station fall to Earth without having a replacement waiting in the wings.

And here we are again, half a century later, facing the potential demise of our own space station with plans for it to fall to Earth without having a replacement waiting in the wings. So I know the title of this episode is what's going to happen after the ISS. And the answer is we don't really know. There are a few options on the table. But I want to explain to you how we got in such a tricky position where we're about to lose a space station. without a firm replacement for what comes after it. And so most of this episode is actually going to be the history of the International Space Station, our current space station, and how we got to this point because it looks like we're just repeating the mistakes from 50 years ago. And in some small ways we are. But in other ways, these mistakes were unavoidable, that NASA is a victim of its circumstances and political realities. And so I want to explain how we got this space station, what amazing things it's done.

And then, yes, I will talk about what will come after the International Space Station, or hopefully come after. why there isn't a firm plan for a space station 2.0. So we need to start with how we got here. To be fair, in the 1970s, as is true today, NASA was in a tricky place. The last moon landing happened in 1972 and public support for future missions had absolutely cratered. Not that they were all that high to begin with, but that's a different story. NASA had developed Skylab as a way to extend all the funding, knowledge, know-how, and personnel of the Apollo program into the new era. Skylab was essentially a repurposed upper-stage Saturn V rocket. This way, all the Saturn V people and companies and congressional districts and all that could stay employed and active in the space missions without having to massively retool for a brand new program and while keeping as much expertise in place.

Skylab was like, okay, if we can't keep doing moon landings, what else can we do with our fancy new rockets? I know we can turn them into space stations, but Skylab was never intended to be permanent. It was supposed to be the first of many and much larger stations as NASA transitioned into the post-Apollo era, but that never materialized because without popular support and political support, funding for NASA shrank and many of the agency's dreams just stayed as dreams. Back in 1969, right before the end of the Apollo era, President Nixon was given four options for what to prioritize with NASA, what to do in the coming decade. Option one was a human mission to Mars. Option two was to keep going to the moon and more Apollo missions. Option three was to develop low earth orbital infrastructure like a space station and a shuttle vehicle to easily go back and forth. And option four was to pull the plug and all spaceflight human activities.

Option two, going back to the moon, seemed politically infeasible and somewhat lame. Going to Mars was a total pipe dream. And option four was just sad. And so option three, it was. And also, it wasn't just NASA that we have to look at here. Anytime we're looking at the United States space program, it's not just NASA that's involved. It's also the Air Force. It's the wider Department of Defense. It's the National Reconnaissance Office. It's like there are a lot of agencies interested in putting stuff in space. And there was a lot of interest in this era by the Department of Defense and National Reconnaissance Office, this is the satellite spy agency, because this was the era before digital cameras and high-speed satellite communication. This is an era where we're launching satellites into space with film cameras taking a bunch of pictures, dropping the film cameras from orbit onto the ground, then go picking them up and taking them to the nearest photo lab to develop.

This is what we're doing. So there's a lot of interest at the time for orbital infrastructure, for having humans in low Earth orbit so you don't need to send photographic equipment up. You can have people taking the pictures themselves and maybe developing them on station so you can see what the Soviets are up to. So there was a lot of interest in developing the technologies and capabilities for having people in space. And if you're going to have lots of stuff in space and especially a lot of people in space, you need a truck to get them there. You need a bus. You can't just have these one-off Apollo rockets that are just going to be blow up and ditched into the ocean and send a couple of people to the moon. No, you need infrastructure. But NASA didn't have enough money to develop both a space station and a reusable shuttle at the same time. So Skylab went up as quickly as it could, refurbished rocket parts, while Focus shifted to developing the space shuttle.

With the hopes that if you build a space truck, you could then have the capacity to build whatever you wanted in low Earth orbit. You know, if you build the truck and you build the road, then a town is going to spring up at the other end. That was the thing. So with limited funding, NASA decide, solve the truck problem first, and then you just cross your fingers on the rest. And the Space Shuttle deserves an episode in its own right, but it does serve as a supporting actor in our story today, as the fates of the shuttle and the space station are intertwined. As for Skylab, this shuttle was simply too late, and the problem was atmospheric drag. Even in low Earth orbit, at 250-300 miles above the surface of the Earth, there's still a tiny, tiny little bit of atmosphere. It's not much. It's 10 to the minus 12, a thousandth of a billion of what the air pressure here is at sea level. But it's not zero.

And that's critical because that leads to a little bit of drag as this space station is orbiting Earth at tens of thousands of miles per hour. It does encounter Bing, Bing, Bing. These little bits of atmosphere, one molecule, one atom at a time, but it's plying through them at tens of thousands of miles per hour. So over time, the kinetic energy adds up. Over time, this lowers the speed of the space station, which lowers its orbit. And if it lowers its speed and lowers its orbit too much, that's called crashing back to Earth. So the hope was that maybe we could develop the shuttle, launch the shuttle, and use it to re-boost Skylab. Give it a little rocket boost, get it back up into a higher orbit, give it a few more years. But the shuttle was delayed, because of course it was, and it wouldn't launch until 1981.

So by the late 1970s, as the shuttle is becoming clear that the shuttle program is being delayed, there was nothing left to do but let Skylab sink further and further into the atmosphere. Without Skylab, at least NASA would have the shuttle. And the hope was that the shuttle would get online, would do two to four launches per month. Like I said, different episode, just ask. And with that kind of capability at your disposal, by having a fully functional, reusable space truck, you could build space stations galore. Who cares about Skylab? It can burn up in the atmosphere. We're going to have 20 Skylabs. all over the place. We're going to have space hotels, space casinos, space research stations, space spy satellites, all that. We're going to do it all because we got a truck. But then the shuttle was delayed even more, got even more expensive, turned out to be incredibly difficult and expensive to reuse and while different episode.

But the point is that the space shuttle dreams didn't really turn into space truck reality. And so by the late 1980s, a decade later, NASA had a big problem. The shuttle was here. We were having a shuttle doing its thing, not as easy to use as we hoped, it was far less reusable as we had hoped, but even then it didn't have much to do. The deployment of space stations was supposed to go alongside it, but that part of the plan had been left to the wayside because there wasn't enough budget to do both. Remember, this was an era before Patreon, that's patreon.com slash pmsetter. where you can make all of our knowledge of time and space dreams come true. That's patreon.com slash p m s u t t e r. I greatly appreciate it. There wasn't enough budget to do both a shuttle and a space station simultaneously. We were able to get the shuttle. It didn't work out exactly how we hoped or expected, but it was here.

And if the shuttle was going to be a going concern, because everyone's like, hey, we've got this really expensive truck that needs to be rebuilt every time we use it. Um, what exactly is it doing? Okay. If the shuttle is going to be a going concern, it needed a job. If we're going to have a space truck, even an overly expensive one, we need it to do truck stuff. But once again, so we needed a space station to go along with the shuttle. That was the original plan anyway, but NASA didn't have enough money to do what they wanted. So they looked around the world and found that every major space agency was already developing plans for their own space station. And they said, hey, if we build a space station and you build a space station and then your buddy down the street builds a space station, maybe we can put all these space stations on my truck and we put them together in space and have a gigantic space station. Voila, the ISS.

International Space Station, five agencies, 15 countries, 420 metric tons of trusses, solar arrays, way more cabling than you think should be necessary, and a rotating crew of anywhere from just two people just after the Columbia disaster in 2003, to 13 people in 2009 during one particular crowded rotation. The ISS is a big deal. Ever since it first launched, the first modules launched in 1998, we've had permanent, continuous presence of humans in space ever since then. For over a quarter century, there have been people in space, something that was impossible before the space station. quarter century of continuous use. Just to think about how big of a deal that is, have you ever used the phrase or heard the phrase like, oh, nobody on earth would believe you? Well, when you say that, like no one on earth would ever do such a thing. When you say that, you're leaving out some humans and you've been leaving out some humans ever since 1998.

If you associate humanity with living on the Earth, you are ever so slightly wrong and you have been since 1998. Since that time, there has always been at least two people not on the Earth. That's a big deal. I don't know what it takes to qualify in the galactic census as a spacefaring species, but I don't know, a quarter century of continuous habitation in space? Does that count? I don't know. Maybe. I'd like to think of humanity as a spacefaring species already. We've already done it. That's how big of a deal the space station is. The ISS, or between you and me just space station, yes I know the Chinese have their own thing going on but that's not today's story, has hosted over 290 individuals from 26 countries. It's been a mix of government astronauts, private spaceflight folks, all launched from either space shuttles, Russian Soyuz rockets, or more recently SpaceX Dragon spacecraft.

It's incredibly expensive, unwieldy, fraught with political entanglements, and an amazing laboratory for doing science. 4,000. 4,000 scientific studies and counting. Think of the ISS as the ultimate space wet lab. You want to study coral reefs? You go to a coral reef. You want to study volcanoes? You go to a volcano. You want to study space? You go to space. The only way we can learn about space is by going there and being there and staying there. Instead of a few days or even weeks with a space station, a single crew member can spend months doing lots of things. And the most important thing we're learning is how to stay in space even longer. In 2015, NASA launched the TWINS study, which sent Scott Kelly to the ISS for a year-long stay. They kept his twin brother, retired astronaut Mark Kelly, down here on Earth. Then they brought Scott back and compared the two, closest we could get to a controlled experiment of the effects of spaceflight and microgravity on the human body.

and the results were… unexpected. In one experiment, Scott was given a vaccine while on the station, the first vaccine ever given during spaceflight. His response was… normal. Totally normal, just like you got a vaccine on Earth. That's crucial because long-term spaceflight is going to require vaccines or boosters and all that, and it's good to know that low-G environments don't cause any weird, unexpected issues. Like you get a vaccine and then you grow a third arm in zero gravity. I don't know. Weird things have happened. There's this other experiment. The ends of our DNA strands are capped by these little things called telomeres, which protect the strands. Telomeres tend to get shorter as we age, and shorter telomeres are associated with increased risk of, uh, death. Weirdly, Scott's telomeres got longer while he was in space, but then shortened once he got back to Earth. That's interesting. We're not exactly sure what the implications of that are.

On the other hand, Scott did suffer some genetic damage, almost certainly from exposure to cosmic rays. And while much of this damage was repaired when he returned, not all of it was. This is something we're going to have to mitigate for long-term space travel. Scott's cognition seemed fine, although his fitness did change during the flight. His gut microbiome was severely reduced, probably because he was just eating freeze-dried and temperature-stabilized prepackaged food, which isn't exactly cultured, if you will, and his body mass decreased by 7% during the flight. There was a lot more to the study, and the study itself was just one of thousands conducted on the effects of spaceflight on the human body. The good news is that us humans are remarkably plastic and can quickly adapt to life in space. The bad news is that those adaptations can make return to Earth difficult or outright impossible and can lead to further complications. One of the creepiest complications is this.

weird vision problems that astronauts get. So your circulatory system is constantly fighting against gravity. It assumes that blood is going to pool in your feet, in your legs, and is always pushing up, always fighting gravity. But in zero-g, there's nothing to push against, but no one told that system. So your circulatory system still biases, still tries to push up. As you end up with extra fluids, in your abdomen, in your chest, in your neck, in your head, and then you get extra pressure around your eyeballs that distorts the shape of your eyeballs and you start to have vision problems from weightlessness. These are big deals. This is stuff we have to navigate, that we have to solve. If we seriously want to send people to Mars, if we seriously want to send people to asteroids, if we seriously want to send people to the surface of the moon for long periods of time, we have to solve this. And the only way we can solve it is by learning about it.

And the only way we can learn about it is by sending up human guinea pigs to the ISS. There's also tons of non-human related science on board the station, making direct observations of the Earth, handling and adjusting sensitive detectors for cosmic rays, studying how materials and crystals form in low gravity environments, the list goes on and on. Why can't we just send satellites up to do some of these experiments? We can. We can. We send a lot of satellites up for a lot of experiments, but if you've ever had to handle even somewhat complex or delicate machinery, you know that they take a lot of babysitting. Things break down, you need to change something, you need to tighten something over there or loosen something over here. There are experiments that can only be performed in space but can't be just left to roam free like on a satellite because they need constant babysitting.

As an example of this, there's the Alpha Magnetic Spectrometer, one of the longest running experiments on the ISS. It detects cosmic rays. You can't easily do this on the Earth because our magnetic field and atmosphere are really, really good at blocking cosmic rays, but it's also a delicate experiment. And there have been four spacewalks to change it, upgrade it, fix it, maintain it. This kind of experiment can only exist on something like the space station. And on top of all the science experiments, human experiments, there's just the experience. It's like, I don't know, going to college. You know, in college you're technically independent from your parents, maybe you have a car and a debit card and a job, but you're also in a structured environment with rules and oversight and accountability, and most of your bills are paid for you.

Then when you graduate and get a real job and a real apartment and real roommates, and there's a lot you have to learn to be fully independent, the ISS is humanity moving into their first apartment after college. We're learning so much on how to exist in space. What things tend to go wrong? When do they tend to go wrong? What systems do we need on the ground to support the people in space? What kind of policies and agencies and protocols and agreements make the whole thing work? What ideas are good ones? Which ones should be scrap? We've gained a quarter century of experience of how to become a long term spacefaring species. We got to crawl before we can walk and all that. The ISS has done all that and in a few years it's all going to come crashing down. I'm recording this episode in September 2025, so hello from the past, greetings to you people of the future. The first modules of the space station went up in 1998, and NASA currently plans to decommission it in 2030.

Why not keep it longer? Well, I'll be honest with you, the station ain't doing so hot these days. It's getting old. There are cracks, leaks. It runs on outdated technology that's hard to maintain. It's expensive to keep all that equipment running. It was never intended to be permanent. Just like Skylab, this was supposed to be another stepping stone, not the end of the road. The International Space Station was always meant to be temporary. It was always meant to be one big station for us to get a lot of science done, decades worth of research done more than any other space station, and then pass the torch, pass the baton to another station, another series of stations. We could try to keep it running longer. We could try to fix the leaks, send up fresh equipment, replace solar panels, all that. But like all things in space and on the ground, the people running it and paying the bills have to decide if this giant expensive risky project needs to come to an end. Which is bigger?

Which is more expensive? Which is riskier? To keep it going with refurbishments or just design a replacement? And the decision between fix the station or fly a new one was um came out to be neither. Listen folks NASA doesn't have a lot of money. I'm telling you, they should have thought of Patreon. In the past couple decades, the agency has been troubled by shifting priorities with every new presidential administration. Each president wants to put their own mark on space, not just do what the last guy did. So there hasn't been a lot of political will to design a space station 2.0. And if this sounds like the challenge that NASA was facing in the post-Apollo era, well, history may not always repeat itself, but it does rhyme. Here we are. We're coming to the close of an era, and this era really started to come to a close with the retiring of the space shuttle. After the last flight over a decade ago, the shuttle and the space station were always supposed to be two sides of the same coin.

The shuttle was the truck. The station was the thing we were building with the supplies carried on the truck. It was supposed to be all done in the 80s. Didn't work out. Well, we got both. We got a space shuttle, we got a truck, and we got a space station out of it. But then once the shuttle retired, it was the end of the line. The writing was on the wall for this space station. You can't have one without the other. So the space station is gonna go, just the way Skylab went. I mean, maybe there are other options. The current plan is to decommission it in 2030. Or maybe later. It might get delayed a few years, but either way, it's coming down. We gotta leave. We can't stay there forever. Here are some things we can't do with it. We can't leave it there. It'll just degrade anyway like a supersized Skylab and come plunging into the atmosphere uncontrollably. We can't send it into the sun. It's way too much energy.

It's actually super expensive to get stuff down into the sun because stuff goes really, really fast and you have to slow it down. It's a hot mess to get stuff down there. can't send it to the moon don't want to crash on the moon that'd be weird not really any stable orbits out there around the moon plus it would take energy to send it to the moon and it'll just fall apart once it's there and it's not like we can just leave it idling in space and then someday send a repair truck over to fix it up and refurbish it you know latest episode costly in its own way and lead to unforeseen disasters down the line. No, we gotta ditch it. In the ocean it goes. So, the space station is going to go away sometime in the next decade. I'm not going to promise 2030, but almost certainly within the next decade, it's going down. But let's also assume that continuing human exploration of space is a good idea. Go ahead, fight me on that one. And that the more we can stay in space, the better.

So what's coming next? Why don't we have a plan? Well, we kind of sort of do. It's it's really a series of small plans rather than one big plan. You know, we left the Apollo era and said we're going to build a space truck and a big space station. That's what we're going to do. We did it. It took us a few decades, but we did it. So what's next? Well, NASA has plans of its own. There are a few ideas floating around. Nothing's advanced much more than the prototyping stage, with one exception. And honestly, most of these ideas won't work out because most ideas don't work out most of the time. One idea is something called the Lunar Gateway. It's like a smaller version of the ISS, and you're like, wow, what a leap to go from a big space station to a small station, but wait, hear me out. This would be a space station in lunar orbit, which would serve as a way station between Earth and lunar surface activities.

The idea would be for it not to be fully staffed year long, but to serve two to three month missions. The downside, it's very expensive, not very capable, and it's unclear if it's really needed. That's because the current Artemis project for getting us back to the moon has a relatively small underpowered spacecraft, the Orion spacecraft, which deserves an episode on its own. uh isn't really super capable and so it needs some support and like you know it needs like a little station to be able to dock to so you can you know have some air and water and grab a snack before you go down to the moon it's possible we could do all of it with just a single spacex lander skipping the lunar gateway On the upside, it would be the farthest human outpost ever, where we get critical data and practice for eventual Mars missions where the crew will be totally cut off from Earth.

A mission to Mars is two years, unsupported, untethered from Earth, no hope of rescue whatsoever, everything has to go right the first time. That's a big leap. Gateway would give us some some practice on a distant lunar outpost or distant space outpost where rescue or help or fixes are days away. That's that's a step in the direction of Mars and further on. So it's still interesting, but between you and me, it's almost certainly going to be canceled at some point. Just a hunch. Option two is something called Orbital Reef. It's a joint venture between Blue Origins and Sierra Space. It was going well for a while but seems to have been delayed with not much new activity or hiring or spending going on for the past year or so. Blue Origins, this is Jeff Bezos' company, is hustling to get its orbital rocket finally done and maybe once that development is finished. This orbital reef project may gather steam. We'll wait to see. Another option, option three is Starlab.

It's a joint venture between Voyager Technologies and Airbus, you know, the airplane people. Design is currently finished and undergoing review as we speak. They've even started to build the hardware. The most furthest along. I mean, they've built pieces of Lunar Gateway, but its political future remains very uncertain. And so the last option, the option I'm saving for last, is something called Axiom Station. That seems to be the most promising successor to the ISS. It's a private modular space station in development by Axiom Space. The first modules are intended to go up in 2027 and actually attach to the ISS, then get lots of data, get lots of practice, share knowledge, share expertise, you know, kind of get their feet wet and then detach and then form its own space station, which will be good once the ISS burns up. You don't want to be connected to that. The plans are for it to have double the usable volume of the ISS.

It may not look a lot bigger on paper, but it will use modern technologies, materials, design to be a lot more efficient and have more interior space. It's the current favorite. Axiom Station is the current favorite to take over the main, oh, we have a space station duties. They've already, they're already building their first module. And in June of 2025, they sent four private astronauts up to the ISS to get the hang of ground crew coordination, figuring out how to, where the bathroom is, how to run some experiments and so on. Essentially using the ISS as a practice drill for the real thing. And aside from the Lunar Gateway, all of these are private companies. They've been awarded money from a competition that NASA set up to develop the commercial aspects of low-Earth orbit. So this is the plan going forward because we don't want to repeat the mistakes of the past. We went from Skylab to Shuttle International Space Station.

Both of those projects were way over budget, took way too long, were developed in an old space model where NASA has a big pot of money. They point to one of their best friends in the aerospace industry and say, you, you build me this and take whatever money you need to make the thing happen, which works sometimes and sometimes it doesn't work. NASA's got other goals. And so they want to leave the whole business of space stationing to other people. And the idea here is that NASA funds the development, but then becomes just one of many customers of a future station where private companies will want to book time on the Axiom station or the Starlab or whatever comes next, or if all three come next, that'd be great. We have three private space stations. where private companies are sending up experiments for materials, for research, for developing things. You know, whatever you want to do in space that you need a human to do it. Same justifications as the International Space Station.

Not everything can be done on a satellite. Sometimes you need a human in the loop. You need a space wet lab, a space lab. Oh wait, that name's taken. Skylab, Starlab, they're all the same. This model has worked really, really well for crew launches. One of the reasons that SpaceX is so successful with the Falcon rocket is that NASA provided much of the early funding and was primary customer for a very long time. Like, hey, we need to get, we don't have a shuttle anymore. We need to get people up to the station. We need to get people into orbit. Uh, here's what we need you to do. We're not going to tell you very specifically how to do it. We just need you to succeed. And, uh, here's some money, you, there's some money, there's some money. We're going to play some bets and hopefully one of you figures it out. This is the idea. We hope to always have space stations. We hope to have a successor to the international space station.

We don't want to leave the space station legacy, like the Skylab legacy, where there's this giant gap in funding and time and political will and public support. NASA has already invested the money and time to figure out how to do long term space habitation, how to keep a space station in orbit for a quarter century and have it continuously operated. And now they're setting their sights on other goals. They're looking farther afield. We still need to learn a lot about how to live and work in space, but it will be up to private companies to figure that out. As for NASA, their attitude is in there. Done that. Thanks to Erica B. for the question that led to today's episode. Thank you to everyone. Thank you for listening. Thank you for your support on patreon.com slash PM Sutter. Thank you for dropping reviews on your favorite podcasting platform. And of course, thank you for sending me questions that keep this show going. That's askaspaceman at gmail.com or askaspaceman.com.

And I'd like to thank my top Patreon contributors this month. They are Justin G, Chris L, Alberto M, Duncan M, Corey D, Michael P, Nyla, Sam R, Joshua, Scott M, Rob H, Scott M, Louis M, John W, Alexis, Gilbert M, Rob W, Jessica M, Jules R, Jim L, David S, Scott R, Heather, Mike S, Pete H, Steve S, Lisa R, Kevin B, Michael B, Eileen G, Steven W, Deb A, Michael J, and Phillip L. Thank you to you and all the other Patreon contributors, that's patreon.com slash PM Sutter. And I'll see you next time for more Complete Knowledge of Time and Space. you

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