Made in orbit: How to sustain life in space
What does it take to build a society in space? Today on the Naked Scientists, we explore efforts to make microgravity amenable to humans; including how to harvest energy, make fresh food, and even birth the next generation of space explorers...
In this episode
00:47 - Going up: What can be made in orbit?
Going up: What can be made in orbit?
David Whitehouse
Since Yuri Gagarin’s trailblazing flight in 1961, humanity has been steadily extending its reach beyond Earth. For almost a quarter of a century, astronauts have lived and worked continuously aboard the International Space Station - a home in orbit that has redefined what is possible. Today, China’s Tiangong Station orbits alongside it, and new stations are already in development. Private companies are even hoping to develop space hotels, farms, renewable energy sources…everything that might be needed for orbital tourism. Behind every leap forward are scientists and engineers solving problems that once seemed insurmountable. To explore just how far we’ve come, and what’s next for life beyond our planet, I’ve been speaking to space writer and broadcaster David Whitehouse…
David - Space is a unique environment. We cannot recreate space here down on the ground. Principally, I mean microgravity. Now, you can do experiments with so-called drop towers, where you drop canisters from a large height, and for a few seconds they experience weightlessness. That is interesting, but it's not very effective if you want to examine what weightlessness does to drugs, materials, the human body, or structures. You really need to get up into space to see what this environment is like and what you can do there. Of course, there's an almost perfect vacuum up there in space, which also has its uses with experiments mounted on the outside of satellites. You have sunlight, which, if you're in the right orbit, provides perpetual energy. You have resources on the Moon, you have resources on asteroids which, potentially, if you have the means of getting up there and bringing the material back down, or even manufacturing and using it in orbit, is far more effective and much more interesting than the huge labour required to dig things up on the ground and launch them into space to work on. If we want to explore space, we've got to learn how to live off the land, if you like—live off the space.
Chris - So what steps have we taken towards those goals so far?
David - It depends on which area you're talking about. Since the 1950s, there has been a great debate about getting energy from space. Most studies aim to make electricity from sunlight and then transmit it back down to Earth. There are two big problems with that. First, you need a huge area to gather this sunlight, which involves a lot of space construction. And of course, you've got to get the energy back down. Most studies involve microwave beaming to a receiving station, and that has to be done very carefully, because where do you put the receiving station? And what are the health implications if the beam is misaligned or accidentally irradiates a city? So, it’s a great idea, but we're still in the early stages of working out the practicalities. The principal challenge is how to get so much material up into space.
Chris - What about making things in space? People are talking about exploiting microgravity because crystals grow in a certain way on Earth due to the influence of gravity. So can we get exciting, exotic crystals in space that you couldn't produce on the ground?
David - Theoretically, you could. There have been many experiments on the International Space Station and on the Space Shuttle to grow crystals and alloys. For example, John Brown, the tractor company, very famous in the United States, had an enormous project to mix alloys in space to see if they could be made stronger, cheaper, and lighter. They gathered some information, and that was instructive, because what they discovered didn’t mean they were going to manufacture in space, but it did improve their manufacturing on the ground. That was useful information. There are many case studies of purifying drugs, growing crystals, mixing alloys, and studying combustion in space, all of which have produced useful insights to help ground-based processes. None of them, however, has been exciting enough to scale up in the sense that the process, mixing, or alloy developed in space could be reproduced a hundred or a thousand times in quantity and then brought back to Earth to generate profit. Nobody has made that leap yet, because it is currently too expensive to send material into space and bring it back. We're waiting for people to develop proper, cheaper routes into space.
Chris - Is the alternative then to say, well, why bring it back? Why not envisage a future in space and build an industry around us living there?
David - That's a very good question, and that probably is the direction we are going to go. One of the most impressive developments in recent years has been Elon Musk's SpaceX launching Starlink satellites for internet communications across the world. Believe it or not, two-thirds of all operational satellites in space are Starlink internet satellites. He has launched thousands of them, and they work in an exquisitely coordinated way. You could imagine that the first solar farms would be mass-produced satellites like the Starlink satellites, launched aboard Falcon rockets. They would then automatically assemble themselves, in the same way drones fly in formation on Earth. They would form larger structures and experiment with beaming their energy back down to Earth. That would be fascinating, because AI could control the configuration. If a panel were damaged, it could fly away, and a new one could take its place. The system could change its shape and orientation. That is a very exciting conceptual idea using something we've already achieved. We've already put thousands of satellites of a similar design into space. That concept could be applied to space-based energy within the next 10 years.
Made in orbit: Solar energy
Martin Soltau, Space Solar
Nothing, of course, can be manufactured in space without power. For sustained space flight, we have to start capturing energy on a space craft, rather than using stores sent up from Earth. But generating electricity from space is more difficult: there is no wind, no waves, no coal, oil or gas. But there is, of course, the Sun. Frequencies of light blocked by the atmosphere are free to access the space stations that sit above, meaning the light is more powerful and will generate more electricity than it will on the planet’s surface. Could this be the key to space-power? Martin Soltau, CEO of Space Solar, joins me to discuss how we can harness the Sun’s energy from space…
Martin - Energy demand is going to quadruple over the next 25 years with demographics, rising living standards, and in particular, technology. I mean, AI data centers is already consuming twice the whole energy demand of Japan, and it's growing exponentially. And this provides gigawatt scale, 24-7, all-weather energy. And it can really democratize energy for all nations. So it's hugely exciting new technology that we absolutely need if we're going to transition to clean energy by the mid-century and also meet this huge energy demand.
Chris - In practical terms, what does it involve?
Martin - These are large satellites, very large, talking kilometer scale. Lightweight solar panels, they harvest the solar energy, typically in a geostationary or geosynchronous orbit, which is about 36,000 kilometers above the Earth. And you turn the electricity into high-frequency radio waves, and then you beam it down to Earth. And it forms this narrow beam, quite low intensity, safe, and the right frequency, we pick a frequency of 5.8 gigahertz, and that goes through the atmosphere and weather with next to no loss. They are large, so they need to be assembled in orbit. So they're made of hundreds of thousands of identical modules. And this modularity gives great resilience, low unit production costs, because you've got the sort of volume of iPhones, really. And then it gives you a clear way to scale up.
Chris - Is it just one craft this would comprise then? Or would it be almost like a fleet of these enormous solar collecting systems in space, and they're all interconnected?
Martin - Think of each one as a large power station, just like a gas-fired power station or a nuclear power station. Each of these satellites produces about 600 megawatts to a gigawatt, so city-scale power. So yes, there would be a fleet of them. So you could potentially see 20 to 50 percent of our future energy demand coming from space-based solar power. And that'll be hundreds of these satellites.
Chris - You say they're going to sit at about 36,000 kilometres. That's the geostationary orbit, where they go round at the same rate that the planet's turning. So they're always in roughly the same position over the Earth's surface. That presumably is because you want to beam the power down to a collecting point on Earth. Does that mean, though, that some of the time they're going to see darkness, so they're not going to work? Or will they be in such a position they'll always see the sun, so it is 24-7 on?
Martin - Because the Earth's axis is tilted, a satellite in a geostationary orbit actually is in the sun all the time, even when the point below it on Earth is at night-time, the satellite is still in the sun.
Chris - And you're going to beam the power down to a collecting point on Earth. You say it's safe. So how big is the beam that's coming down? Is it like a death ray, James Bond-style, that's coming in from space? Or is this a fairly dispersed, that you'll need a massive collector to pick the radio waves back up and then convert them back into electricity on the Earth's surface?
Martin - It's the latter. So even at the peak of the beam, which is in the centre, it's about 230 watts per square metre. It's about a quarter of the intensity of sunlight. That's well below the certification limits for civil and military aircraft. It's benign for flora and fauna.
Chris - What's the reason for doing this in space other than the distribution? Do you get more bang for your buck because there's much more solar power there? You haven't got the effect of the atmosphere.
Martin - That's exactly right. So if you put a solar panel in space, you get 13 times the amount of energy that that same panel on Earth would, because there's no night or weather or atmosphere. And you've got 40% more solar intensity than you have even in the desert at midday on Earth.
Chris - And you mentioned economics. At the end of the day, that is where the buck stops. So how much is this going to cost? How long is this going to take to build? And therefore, ultimately, how practical is it?
Martin - Our economics for the mature systems are $30 a megawatt hour. It's about £25 a megawatt hour, which is incredibly cheap if you think that the current price of wind in the latest auctions is well over £100 a megawatt hour. We've got a very deliverable plan to have a pilot plant in orbit within five years. By 2035, we'll have our first system in geosynchronous orbit beaming about 100 megawatts and then scaling up very quickly to the gigawatt-scale systems. And so by the mid-2040s, we'll have 15 gigawatts of power. That's about 30% of the UK's total demand.
Made in orbit: Homes and living space
Annika Rollock, Aurelia Institute
Once an energy source has been secured, humans need somewhere to live. Currently astronauts live in space stations such as the ISS, but in an eventuality where space exploration is widely accessible to the public, larger solutions to housing would be necessary. But space is a cold and unforgiving place to be. All the current ‘architecture’ in space stations is purely functional to keep its inhabitants alive. But the space craft of the future will need to have a few bells and whistles on them, lest the inhabitants go mad looking at the same grey and silver walls. So how amenable will the spacecraft of the future be to getting a facelift? I’ve been speaking to Annika Rollock, from the Aurelia Institute, who’s worked with NASA HOME on deep space habitats…
Annika - What we work on, we like to call more like IKEA furniture, if it were able to self-assemble. Our structures are launched in a flat pack: tiles that stack, kind of like in a Pez dispenser or IKEA furniture. In space, they’re autonomous, so they self-assemble using the onboard computers and magnets. No human assembly required. And what are they made of? Right now, the tiles are basically plastic, electronics, and magnets, but in the future they’ll be made of space-grade aluminium alloys.
Chris - And what will actually be in the structure that you’re envisaging? Once you put all this together and it self-assembles, if I walk around it, can you take me on a virtual tour? Can we walk around together?
Annika - Yes, so the space would be divided up depending on who you’re hosting. We’d like to imagine a combination of career astronauts—people trained to be up there to help prepare and do science—as well as potentially tourists and pure scientists who might not be as accustomed to the harsh living conditions as astronauts. There would be crew quarters, one for each crew member. And as you manoeuvre, there would be handholds because in zero gravity you obviously can’t walk down the corridor—you have to move using your hands and feet. Through our experience on the International Space Station, we’ve really underscored the importance of common areas, having places for the crew to convene and share a meal, to gather around—even if it’s only a symbolic table.
Chris - Hopefully a magnetic table so you can stop your food floating off. Otherwise, people will say the food’s out of this world, but not for the reason you had in mind.
Annika - Velcro is big. That’s why we use Velcro.
Chris - Is that the solution? It’s Velcro?
Annika - Yes, a lot of the time.
Chris - And what would the shape of it be? Are we thinking 2001: A Space Odyssey, something like a giant spinning wheel in space to give some semblance of gravity because you’re basically throwing people out to the walls? Or are we going to accept the fact that people are floating around and that’s how it’s going to be?
Annika - We’re looking at what’s called a truncated icosahedron, also known as a buckyball. It’s effectively a football, or soccer ball. The idea is to maximise the amount of internal space while minimising the amount of structure you have to bring with you. It’s a close approximation to a sphere.
Chris - And does that mean you’ve got a structure that supports the outside, and then you partition the inside so you could reconfigure it relatively easily as long as it’s airtight on the outside? Once you’ve got that enclosed ball, you can do a lot with it?
Annika - Yes, precisely. We call that the secondary structure inside. It’s not as strong as the external structure, but it still divides the space and allows astronauts to mount things and manoeuvre within.
Chris - What sort of altitudes are you going to be at? The ISS is about 400 kilometres up. It’s so low it needs periodic reboosting because it slows down and would fall to Earth otherwise. What altitude have you got in mind for this?
Annika - A similar altitude. That’s where most commercial space stations have envisioned themselves—low Earth orbit. That’s mainly for ease of access.
Chris - And what’s the lifetime? How long do you think this will have to run to recoup the costs?
Annika - We like to say 10 to 15 years, but we’ve clearly seen from the ISS that it has outlived its initial estimate. We’d love our structure to be reconfigurable and reusable. That’s a huge advantage of using these tiles that self-assemble rather than prefabricated specific modules. But we say 10 years. And the cost? We don’t know yet. That’s something we’ll work out with more testing. With launch costs going down, it’s certainly cheaper than the ISS, but you never really know. In space, you can’t make that kind of estimate in good faith this far out.
Chris - So the answer is going to be a lot.
Annika - It’s going to be a lot, yes. It’s expensive.
Chris - And when? Because that’s the other question. Is this pie in the sky—like nuclear fusion, always 10 years away—or have you got a definite “it will fly by this date” in mind?
Annika - For the full station, we don’t have a date yet. But we do have a full assembly of a very small version of this buckyball flying to the station—inside the station—next spring. After that, we’ll test outside the ISS with the actual space-grade aluminium structure I mentioned. So within the next few years, that demonstration will be flying.
Made in orbit: Fresh food
Jen Bromley, University of Cambridge
Food and drink are crucial for sustaining human presence in space. We’ve all seen the dehydrated food packets sent up with astronauts to keep them fed, and how unappetising they look. This is done to keep resources light for easy flight, and to extend its shelf life. But what if we could make fresh food in space? The ISS is already making efforts to grow vegetables in orbit, so what other produce may be possible. Jennifer Bromley is a researcher in plant sciences at Churchill College, Cambridge. She studies the impact of space on the way plants grow, and whether it is possible to grow fresh produce in orbit…
Jen - Getting food into space—getting anything into space—costs approximately 20,000 US dollars per kilo. When you consider that the average astronaut eats about 1.2 kilos of packaged freeze-dried food per day, that’s around 34,000–35,000 US dollars a day to feed them. By contrast, you can send a thousand lettuce seeds, which weigh about a gram, for the same upmass cost. A thousand lettuces can be grown for that single gram’s worth of launch cost. The water is generally already up there, because astronauts use water daily. The ISS and other commercial space stations currently being built have very high water recycling efficiencies, so once the water is up there it generally stays there. You can rely on the system to be self-sustaining once the equipment is in place.
Chris - How do plants take to being in space though?
Jen - Surprisingly well. Plants respond to gravity: normally shoots grow upwards away from gravity and roots grow downwards towards it. In microgravity that stimulus is almost absent. But gravity is not the only stimulus. Light, nutrients, and water are also crucial. Roots will grow towards nutrients and water, while shoots grow towards light, just as in a commercial greenhouse with supplemental lighting. That’s the sort of system used on space stations where plants are grown. What do you grow them in? We use small closed pods for the roots. Nutrient solution—water and nutrients combined—is delivered using simple pump systems. In recent projects we tested these on zero-gravity parabolic flights and they worked just as expected, exactly as on Earth. It’s a simple hydroponic system using sealed units: the seed is placed inside, the shoot bursts out, and the root stays enclosed. You don’t want something too hygroscopic, which soaks up water without releasing it; you want something that holds water but releases it to the roots on contact.
Chris - How do plants breathe in space though? They have little holes in their leaves, stomata, through which carbon dioxide goes in and oxygen comes out. If there’s no up and down, then it’s harder to move gases around. Do plants cope with that?
Jen - In space, one big challenge is convection—the natural movement of air doesn’t occur unless you mechanically create it. We install fans around the plants to create turbulence around the leaves, just as wind does on Earth. On Earth, some leaves also have small hairs to create boundary layers. These break up the static air around the leaf, allowing for gas exchange between the inside and outside of the leaf.
Chris - And how about timing? One amazing thing about plants is that they have body clocks, just like we do. You can jet lag a plant. How do they cope? On the ISS, astronauts say it’s a challenge seeing the Sun rise and set every 90 minutes. Do plants have to be kept isolated from that with artificial light, or are they okay with lots of sunrises and sunsets?
Jen - Lots of sunrises and sunsets would cause problems, but because the ISS has only small windows, the natural light is insufficient for plants to grow effectively. So we provide artificial light. Above the growing space there is a panel that emits the full visible spectrum plus parts of the invisible spectrum important for growth, from UV through to far red. These wavelengths dictate how the plant grows—photomorphogenesis. The balance of light can make them more compact, darker in colour, or change other growth habits. Darker leaves often mean more antioxidants, so you can make the plants accumulate more beneficial biochemistry for astronauts.
Chris - And what’s the productivity like? Is it comparable to a greenhouse in ideal conditions on Earth?
Jen - It’s not as productive as a greenhouse on Earth. We can’t provide the same space, and the conditions are more challenging in space than in a greenhouse. CO₂ is higher on the ISS than on Earth, and we also have strict power limits. Power means heat, and we must consider the heat from the lights as well as the heat produced by the plants through respiration. We sometimes have to curtail plant growth to ensure the environment remains safe for humans.
Chris - And the taste? Even if productivity is lower, do they taste as good?
Jen - They can taste better, frankly. Providing more blue light produces darker leaves with stronger flavours than you’d normally get from greenhouse-grown plants. For astronauts, one big thing lacking in freeze-dried food is texture. Providing fresh plants gives them crunch, which is incredibly important—not just flavour, but texture too.
26:05 - Made in orbit: Babies
Made in orbit: Babies
Egbert Edelbroek, SpaceBorn United
Modern methods of reproduction stretch beyond traditional conception. In vitro fertilisation, or IVF, has been used to create human life for more than 50 years. But is it a viable method in space? Preserving reproductive cells and embryos in space certainly comes with technological challenges, but also ethical ones. It also requires a large amount of investment, much like most space-related research and development. This absurd-sounding area of space research is not one that leading organisations like NASA have explored, but it could be crucial for the continuation of human life outside Earth. Egbert Edelbroek, founder of SpaceBorn United, is developing a ‘space-embryo-incubator’ with his team, in an attempt to concur the first stage of conception in orbit…
Egbert - What we need to do is mitigate the two main challenges in space for living organisms, especially embryos: the lack of gravity, which is not healthy for a developing embryo, and radiation. We have a rotating disc, and inside this disc there are initially mammalian gametes to prove that it is all safe. By rotating the disc, these developing embryos will experience Earth-like gravity.
Chris - It’s almost like a sperm centrifuge, spinning around so they’re flung outwards a bit, as though they are being pulled towards the ground, except they’re being pulled to the outside edge of the disc. That’s how you get them to have their feet on the ground, as it were.
Egbert - Exactly. Another benefit is that we can adjust the rotation speed so the embryos experience lower gravity—not microgravity, but the gravity of Mars or the Moon. That way we can also study whether embryo development can safely happen in a Martian environment.
Chris - And does that make a difference? Do these different amounts of gravity affect the way sperm and eggs interact? Have you got enough data yet?
Egbert - No, that is part of our homework. In April this year we had our first technology demonstration in space. Our mini-lab went on a SpaceX rocket launched from Cape Canaveral. The next step will be to have mammalian early embryos inside, and gradually we will transition towards using human gametes and creating human embryos in space. After that, we will start to lower the gravity level to study environments like Martian gravity. That is a few missions ahead. The other issue besides gravity that we need to mitigate is the higher radiation levels above the atmosphere. On the surface of Earth, you are protected by a thick layer of atmosphere and the magnetosphere, the Earth’s magnetic field, but above the atmosphere you have much less radiation protection. So you have to select a specific altitude and inclination for the orbit of our mini-lab where radiation challenges are minimised.
Chris - Are you putting this on little satellites then, or is this going onto space stations where you’re doing these experiments?
Egbert - A shoebox-sized mini-lab is designed to operate inside independent small satellites, about a metre in diameter or even less. They will orbit the Earth and bring the embryos back to the surface. That’s not standard for a satellite—usually it stays in orbit—but in our case we also want the embryos back after a week, so these satellites can perform re-entry manoeuvres.
Chris - Is the idea to almost freeze time, so you let conception happen and then stop it?
Egbert - Indeed. We pause the development stage of the embryo, similar to how it is done on Earth. In IVF clinics, embryos are cryogenically frozen at the blastocyst stage, after six days of development. We will do the same in space, freezing them after six days, to safely send them back to Earth. In IVF clinics they can then be safely thawed and examined.
Chris - And what sorts of questions are you going to be asking of the embryos?
Egbert - There are all these biomarkers and standard IVF examinations to determine whether an embryo is healthy: checking for DNA damage, ensuring morphology is intact, and so on. The embryos will undergo exactly the same examinations to confirm they are completely healthy.
Chris - What sorts of ethical hoops have you had to jump through for this?
Egbert - You cannot just send live material into space without approval from ethical committees. To get approval, we have to clearly explain the scientific benefits of studying live samples in space. That’s the formal perspective, but from a societal perspective it can be very different. It is similar to IVF when it was invented 46 years ago: it met with resistance and took 10 years before being accepted as offering opportunities to couples who could not conceive naturally. Now we are extending this technology into space, introducing new challenges and hazards that we must mitigate, and of course there are legitimate concerns from different perspectives. Fortunately, there are checks and balances.
Chris - Obviously we’ve dwelled so far on the very earliest stages of conception. Pregnancy takes 40 weeks, so is the ultimate goal to take the project further and see what happens if you actually try to grow a baby in space?
Egbert - Yes, absolutely. We chose the name SpaceBorn United as a clear hint towards the very end of the nine-month cycle—childbirth in space. The work we are doing now is in that wider context. About 80–90% of our time and resources go into the first stages because it has to be a step-by-step process, but we are also drafting a multi-decade research roadmap that will eventually enable all of those stages—the whole nine-month cycle in space.
Chris - When do you think we’re going to see the first baby born in space?
Egbert - I think that can happen in 25 to 30 years, depending on a few factors: how it is funded—more funding could accelerate things—and how the global ethical discussion progresses towards safe, feasible childbirth in space.
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