A DIY-rocket club’s risky dream of launching a human to the edge of space

In private spaceflight, there are fewer rules. One Copenhagen group is taking that to the extreme.

GROWING UP in a small Danish town, Carsten Olsen didn’t have much access to information about space. Until the internet came along. Once connected, Olsen started frequenting discussion forums, where real rocket scientists and even astronauts came to chat. He ordered rocketry books on Amazon and became obsessed with reaching toward that great beyond.

He didn’t grow up to become a rocket scientist himself—not professionally. He works at a public school in Copenhagen. But he did join an untamed, dangerous, and optimistic space endeavor: a hobbyist group hoping to build rockets that could, someday, send a volunteer astronaut to the edge of space. They call themselves Copenhagen Suborbitals, or CopSub, and work out of an old shipyard in Denmark’s capital city.

Olsen first heard about CopSub, an amateur human spaceflight endeavor, on the local news. “Something about some crazy guys,” he says. “Space cowboys.”

At the time, he was training for marathons, and he ran by the shipyard on a training route. “I noticed there were a lot of people there gathering together around something,” he says. That something was a rocket engine—firing in place. It looked like a white tube about 18 feet long, lying on its side, bolted to concrete pillars. Other CopSub tests have included a tiny passenger capsule with a crash dummy inside. “I stepped up and said, ‘I need to be part of this,’” Olsen recalls. 

space shuttle launch
On January 28, 1986, Space Shuttle Challenger exploded shortly after launch from Cape Canaveral, Florida. Seven crew members lost their lives. Corbis via Getty Images

Eventually, the group welcomed him into its ranks, even though he didn’t have any technical skills to speak of. Today, he’s one of CopSub’s approximately 70 volunteers, some of whom work in the space industry professionally and have rocketry or other technical expertise, and some of whom are more like Olsen. While other private spaceflight programs—from Jeff Bezos’ Blue Origin to commercial-space-station company Axiom Space—are sending amateurs and tourists beyond the bounds of the atmosphere, CopSub’s hobbyists aren’t just the club’s potential future astronauts; they’re also the ones responsible for every machine, schematic, and protocol getting the rocket off the ground, a proposition that comes with significant risk. 

Given that, “space cowboys” is a pretty accurate term for what CopSub is doing and for what the law allows it to do. But the label also applies to the cushy spaceflight capsules supplied by billionaire-backed companies. Policies do exist to protect people on the ground—by requiring that rockets operate as advertised, that they lift off from places where an accident wouldn’t harm nearby civilians, and that their crews be trained in emergency procedures. But, unlike with government-funded missions, there are practically no guidelines, national or international, regarding the safety of humans who strap themselves aboard private rockets. 

That could change around October of this year, when a US moratorium on such rule-making expires, and Americans, at least, are finally able to regulate the safety of space tourists. Policy experts say it may be time to lay down some laws, making a trip to space safer not just for astronauts flying under the flag of a nation but also for those flying under the logo of a company—or the banner of a club.

“We’ve got more international actors. We’ve got different types of space applications. And then you’ve seen those wonderful space-tourism efforts that launched,” says Uma Bruegman, head of the Space Safety Institute at The Aerospace Corporation. “It’s great. But it does bring into the equation space safety.” 

While the world figures out what to do about these private astronauts, and which risks and regulations should be accepted, CopSub is creeping forward. The group is currently working on and testing the design of a homemade rocket that might take a human more than 62 miles above Earth’s surface in another decade. Whether that cosmic cowpoke will come home or take a one-way trip, though, is an open question—one to which few rules apply.

NO MATTER WHOS in charge, there’s always risk involved in shooting humans into space. It requires sitting on top of what is essentially a missile—and that hasn’t always gone well, even in the highly regulated parts of the industry. In 1967, a NASA suborbital spacecraft called the X-15—which, like CopSub’s contraption, was meant to fly to the edge of space, but not circle Earth—broke apart after launch and killed its pilot. Then came the space shuttle Challenger and Columbia disasters in 1986 and 2003, respectively, which infamously caused 14 astronaut casualties in total. More recently, in 2014, Virgin Galactic’s suborbital test vehicle SpaceShipTwo disintegrated, resulting in the death of one pilot. In the 62 years since the first human went to space, the overall odds of an astronaut being in a fatal accident on a US craft has been 1 in 100. Compare that to a traveler on one of today’s passenger jets in the US and Europe—with their entirely different flight systems—for whom the odds are around 1 in 30 million.

“If we want to reap the full benefits of human spaceflight in the future, whether it be for exploration, scientific research, business, or tourism, we will need to find ways to improve the safety of those operations,” reads a 2020 paper titled “Human Spaceflight Safety: Regulatory Issues and Mitigating Concepts,” written by Josef Koller, systems director for the Center for Space Policy and Strategy at the Aerospace Corporation, and George Nield, president of the company Commercial Space Technologies.

One of those ways is through setting rules. But at this moment, at least in the private sector, there isn’t legal oversight of the safety of crew members. “There is no particular regulation with regards to putting people on board rockets and blasting them off into space,” says Jacob Larsen, who works in the satellite industry by day and for CopSub in his spare time. 

two workers on ladders reach into rocket part
CopSub volunteers John Bjerregaard and Peter Scott connect two tanks from the DIY Spica rocket in 2021 in Copenhagen. The group’s ultimate goal is to launch a human to the Earth-space boundary and back when the vessel is complete. Carsten Olsen / Copenhagen Suborbitals

That’s as true of a for-profit company as it is of a volunteer-led organization like CopSub. “The only difference is, they’re not making any money,” says Scott Steele, a lawyer specializing in space issues. 

But is hobbyist spaceflight like CopSub’s too risky, even with a code of conduct? And if so, should a person be permitted to do it anyway, just like someone who is allowed to plop a raft into whitewater, dig a crampon into a glacier, or ride a mountain bike along a cliff’s edge? Does DIY human spaceflight lie beyond the border of any other extreme sport or hobby?

At the moment, no governing body—in Denmark, Europe more broadly, or even more space-centric countries like the US—is setting those rules. CopSub’s communications director, Mads Wilson, who works as a data scientist, doesn’t seem distressed by that fact. “There’s no laws against being stupid,” he says. “People have killed themselves in stupid ways.”

That’s certainly true of our species’s long and fraught fascination with flying. But when—and if—CopSub’s rocket gets its first joyrider, that person’s life will depend on the quality of work done in a group of tinkerers’ spare time, with homemade rocket parts, cobbled together into a combustible machine that no outside body is charged with inspecting. And that’s not an easy proposition to swallow.

WHEN COPSUB STARTED started in 2008, the team consisted of just two volunteers, the co-founders Kristian von Bengtson and Peter Madsen, and a single thought. “They wanted to try to build a rocket that could put a human in space,” says Wilson. “And that was basically it.”

Von Bengtson had previously been on contract with NASA, working on human-centered spacecraft design, and Madsen was an entrepreneur who, later, would be convicted of the murder of journalist Kim Wall. Three years before the murder took place, CopSub and Madsen parted ways, and the space organization cut all ties with its co-founder.

At the start of the endeavor, though, the pair holed up in an artists’ collective in Copenhagen Harbor. Soon, their group—and creative space—grew. “Most of the guys that I know say that they just showed up one day at the workshop and asked, ‘Hey, can I do something?’” says Wilson, who became one of those “guys” in 2013, a couple of years after CopSub started building rockets and launching them a mile or more into the air. It used a floating platform, which members built themselves, off the Danish coast in international waters. In the early days, the company was finishing and testing a new rocket every year or so, with the builds taking a year or two each.

CopSub’s first attempt—with a 30-something-foot-tall, 3,587-pound rocket in 2010—was a failure. In 2011, a ship with that same design (which resembled that of a ballpoint pen) went up, flopped sideways, and came down too fast. The booster slammed into the water, disintegrated, and sank. The prototype of the capsule meant for passengers separated from the rocket and floated across the Baltic Sea, but was also damaged. In 2012, the group shot up a rocket intended to test communications and GPS equipment for future crewed CopSub missions. Around two seconds after liftoff, the nose cone, which housed all those electronics, separated from the rocket. The vehicle completed its trip, which was designed to take it more than 12 miles up, as planned, but the flight didn’t yield any useful data. That year, CopSub tested a capsule with passenger safety features like an escape system, springs to protect a rider from a hard landing, and air bags that could flip the capsule right-side up should it splash facedown. It tumbled through the air and slammed hard into the water. CopSub was not able to send the command to flip the capsule upright because of the high-impact landing.

astronaut reclines in seat in unfinished rocket as another person holds her helmet
CopSub’s “astronaut candidates” Anna Olsen and Mads Wilson try out the Spica test seat in 2021. The capsule would have just enough room to fit a passenger tightly inside. Carsten Olsen / Copenhagen Suborbitals

The next year, CopSub sent up a much smaller rocket—447 pounds and nearly 28 feet high—to try out navigation and directional systems. That one worked pretty well, surpassing the speed of sound and shooting more than 5 miles up, arriving at the top of its trajectory just 600 feet off from the engineers’ expectations. Still, the technology was a far cry from something that could transport an actual person to space. “It started out really crude,” says Wilson. “But that was also kind of the idea—it doesn’t need to be more than good enough.” (What Wilson means is that it doesn’t need to be more than good enough to fulfill its purpose.)

In fact, the amateur space program’s safety status banks on its rockets’ simplicity: Much of it is based on technology similar to what NASA used in the 1950s and 1960s. Just as a smart fridge has more points of failure than one made of mere coils and refrigerant, CopSub contends that a less complex space system has fewer breakable parts than one ruled by robotics and computers. If done right, it could leave fewer ways for a human passenger to get hurt. But if done sloppily or without adequate checks, it still could put the team’s future astronaut in fatal danger.

The group has made some improvements. To make their rockets easier to control, it had to rethink its original hybrid-propellant engines, which contained both solid and liquid rocket fuel. When it was go time, the two mixed together and combusted. “That turned out to be, to put it politely, unfeasible,” says Wilson. After building its Sapphire rocket in 2013, CopSub pivoted toward liquid-only engines—which are more complex but also more predictable. 

Madsen’s departure also brought much-needed change to the collective. In those early days, Madsen wasn’t getting along with von Bengtson, or, really, anyone. In February 2014, von Bengtson finally left. A few months later, CopSub and Madsen parted ways permanently. Madsen murdered Kim Wall in 2017 and was sentenced to life in prison in 2018. 

After the founders’ departure, the project didn’t dissolve. “This is too fantastic to just let everything drop on the floor,” says Wilson. Plus, much of the technical know-how came from the newer volunteers. The quest continued with the personnel who remained.

But the technical problems continued as well. In late 2014 an experiment, recorded on a GoPro, went awry. It was a static rocket-engine test using liquid fuel, in which the rocket was supposed to stay strapped to the ground. Just after ignition, flames broke out and engulfed both the craft and its stand. As the initial burst died down, the wrecked machine made moaning noises, like the cries of a lonely, whale-like alien. Wilson was standing in a bunker about 300 feet away. Even there, everything smelled like alcohol. No one was hurt, but the rocket was unsalvageable—two years of work burnt to the ground. What would they do now? 

“We’ve gotta build another one!” Olsen recalls thinking at the time.

Group members decided to emphasize working piecemeal, building smaller rockets and using them to test subsystems like computers, communications, and parachutes, a mission they’ve been working on after the fire. “Then, once that is done, we can scale [up] and build something bigger,” says Wilson. The ultimate goal is to create Spica, a rocket big enough to reach the Earth-space boundary and send a capsule splashing back down into the ocean—with a human inside. “We’ve meticulously chipped away at it,” says Larsen, since the last big test launch of a smaller rocket in 2018. Several sections sit in the workshop as the engineers tinker with the engine technology, which they’ll try out in a shipping container they transformed into a test stand. Once completed, the capsule will be just big enough for a person to sit inside, with only enough wiggle room that they don’t lose circulation. No astronaut suit or ability to control the flight, just a Top Gun–ish fighter-pilot get-up and a pressurized cabin. 

The collective’s biggest success so far came in 2018, when its liquid-fueled Nexø II rocket did everything it was supposed to do. It flew in the correct trajectory 4 miles up. The nose cone separated at the top of the flight, the parachute floated the rocket back down to the sea, and teams recovered both parts. The splashdown speed was slow enough that a human would have survived the force of impact.

Larsen was watching from a rigid inflatable boat nearby. As the craft ended its countdown and began its journey, time slowed down. “It just kept going and going and going,” he says. “I’m never, ever gonna forget this wonderous thundering sound under a clear sky…on a flat, warm sea, with nothing but blue and blue around us.” 

The capsule drifted down about eight minutes after the flight began—“Ever gently,” says Larsen. Only 58 miles left to go for the spaceflight to count as suborbital.

AS COPSUB INCHES CLOSER to its “moonshot,” private spaceflight is taking off an ocean away.

Only American companies have sent tourists to space. Still, Congress explicitly forbids the Federal Aviation Administration (FAA) from making rules to protect private astronauts. Under a 2004 law, “The FAA is prohibited from regulating the safety of individuals on board,” says the agency’s own website. This legal moratorium, the thinking goes, allows commercial space companies to get enough experience to understand what safety principles should exist—and keeps them from being stifled by inspections and red tape in the meantime. According to Koller, who works with Bruegman and co-wrote the “Human Spaceflight Safety” paper, the idea is that companies should be allowed to innovate, try hard things, and perhaps even fail before regulations come into play.

The moratorium is currently set to expire in October 2023, though it has been extended before (first to 2015, and then again for eight more years). Anticipating the coming rules, Koller and his co-author suggested ways the FAA and other governing bodies across the world could prepare. The broadest of these is by “establishing a collaborative framework to create safety guidance and best practices,” their report says. That could take the form of what it calls a “Space Safety Institute,” an independent group that provides expertise and support to government and industry but doesn’t set or enforce regulations itself. 

It didn’t take long for the authors’ vision to come to life. Last year, The Aerospace Corporation, headquartered in El Segundo, California, launched an institute to “enhance the safety of space and space-related activities for government, commercial, and international customers,” as described on its website. But one of the new group’s significant challenges will be coming up with recommendations for private space vehicles that vary wildly. Virgin Galactic, for example, wants to drop a rocket-powered spaceship from a double-hulled airplane, while Blue Origin is planning a much larger rocket powered by liquefied natural gas. CopSub, in comparison, still has its vintage ethanol-based rocket. There are even balloon companies that hope to heft humans to the edge of space in the future. 

Despite the fact that space vehicles rely on different technologies, they do share one thing. “The common element really, at the core, is people,” says Koller. “People are the ones that make mistakes. But people also need to feel safe enough to speak up when you see an unsafe situation or unsafe environment.” Perhaps the most important way to keep space tourists safe, Koller posits, is by creating a “safety culture,” one where engineers and technicians aren’t afraid to point out something that seems dangerous or sloppy. 

Bruegman’s institute also suggests voluntary safety audits, as well as collecting system and safety data in a centralized and accessible place, ideally so that companies can predict and prevent accidents based on others’ experience. (Meanwhile, a standard way companies manage their liabilities is by having passengers on private space vehicles sign an informed consent document stating that they know that what they are about to do has its risks. Passengers also sign waivers of claims stating that they will not sue the company in case of injury and that their families will not sue in case of the passengers’ injury or death.)

“Most of the guys that I know say that they just showed up one
day at the workshop and asked, ‘Hey, can I do something?’”

—Mads Wilson, CopSub Volunteer

Self-starters in and outside the US can look to experienced agencies like NASA for more inspiration. In 2014, the FAA produced a document for private companies, detailing “Recommended Practices for Human Space Flight Occupant Safety.” It doesn’t get into much technical detail because, again, every organization’s system is so different, but rather prescribes high-level guidance about what safety really means. 

A spacecraft, for instance, shouldn’t accelerate or vibrate so fast or hard that the motions hurt occupants, and it should make sure they “are protected from serious injuries and safety-critical operations can be performed successfully.” Every system inside the ship that’s critical to crew safety should demonstrate that it can work as planned in maximally extreme conditions. Similarly, all those plopped into passenger seats should be evaluated to make sure they can withstand those conditions. Each crew member should have a pressurized suit and a personal air supply, and the cabin should have an abort or escape system. CopSub has plans only for the personal air supply at the moment. 

The technology aboard modern spaceships is complex in part so it can diagnose problems and introduce redundancy; that allows the craft to fail in numerous ways—without killing the crew. That complexity is one NASA requirement that CopSub won’t meet, but, Larsen points out, their craft only needs to be safe and dependable for a 4-minute flight, rather than days or weeks. The space agency also only certifies a private space company for its commercial crew program if the overall chance of “loss of crew” is less than 1 in 270 over a 210-day mission. That could be true of CopSub’s future Spica, but as things stand right now, no one is doing the math.

CopSub is currently testing its rocket subsystems to make sure they work both independently and together, but it won’t have the full results until Spica is completed years from now. At this point no outside agency will make the group conduct a full-scale test before putting a human aboard, or to ensure that that human passes extensive medical and high-G evaluations, as professional astronauts typically would. CopSub says it will do its own testing before it straps a person into its rocket, but for now, the Danish government and European Space Agency are just as hands-off as American authorities. 

rocket on water-borne platform with boats and people
In 2018, CopSub successfully launched its small, unoccupied Nexø II rocket 4 miles up. It floated back down to sea on a parachute. Carsten Olsen / Copenhagen Suborbitals

It’s possible that the future will have enforceable rules, to which the team will have to adjust if its efforts are to go forward. Because space endeavors are often international and involve a borderless frontier, no single country—whether that be Denmark or the US—can think about rules in isolation. “There is more international coordination necessary,” says Koller. It could be something like the Safety of Life at Sea Treaty, an agreement first put in place after the Titanic disaster to specify safety requirements for merchant ships, including a minimum number of lifeboats. The International Space Station is another example of how nations at odds—Russia and the US—have played nice with each other.  

All this talk about rules and limits can get the more hands-off-my-rockets side of the industry riled up. But Bruegman, Koller, and Steele don’t want to hold any rocket scientists, even the hobbyist ones, down. On the contrary, they want to make private spaceflight secure and predictable precisely so it can blossom, Bruegman says. “We feel like it’s like ‘good fences make good neighbors.’”

AT COPSUB, the volunteers are proud of their own safety record so far: zero accidents resulting in injury or death. They claim they adhere to NASA’s protocols for handling rocket fuel and safety at the launch site. They also point out that they chose ethanol for fuel because it’s more environmentally friendly than methane and hydrocarbon-based rocket fuel and evaporates quickly if something goes wrong. Wilson and Larsen say the members do speak up when something feels iffy to them, promoting the kind of safety culture Koller referred to. 

But one part of CopSub’s light-touch approach might work in its favor, at least when it comes to developing rocket hardware. “I think both NASA and the European Space Agency have felt the pressure to be perfect,” says Larsen. “And I was so relieved when a certain American made it popular to start blowing things up in succession.”

He is referring to Elon Musk and SpaceX, a company with a blooper reel full of its rockets tipping, tumbling, and exploding. Despite those wipeouts, SpaceX has never had a launch accident that harmed humans, and it is the only company certified to NASA’s safety standards. 

“I think both NASA and the European Space Agency have felt the
pressure to be perfect. And I was so relieved when a certain American
made it popular to start blowing things up in succession.”


—Jacob Larsen, CopSub Volunteer

Ethics don’t stop and start at the launchpad, however. In the fall of 2022, OSHA fined SpaceX after an employee was seriously injured while working on a rocket engine. Blue Origin, Jeff Bezos’ space company, has had six successful human spaceflights with zero injuries or deaths. Still, in 2021, a group of 21 current and former employees penned an open letter saying that taxing working conditions and intimidation were hampering the company’s safety culture. (SpaceX did not respond to a request for comment, and Blue Origin declined to comment.)

Working for a corporation full of professionals doesn’t, then, seem to guarantee a totally safe environment on the ground or in the skies. But CopSub’s organizational structure, which you wouldn’t see at a business that has to comply with labor laws and the demands of investors, may make accountability difficult: There is no top-down bureaucracy—no project managers, not even an inventory management system—which means checks and balances don’t automatically exist. Accountability is as voluntary as the gig itself.

The CopSub website puts the risk of Spica’s flight quite frankly. “We work meticulously to make the flight as safe as possible, as we’re courageous, not reckless,” it says. “But it will obviously be dangerous, so our astronaut must be mentally prepared and at ease with the risk.” 

While it’s clear that CopSub’s technology is decades behind the sophistication of modern companies like SpaceX and government agencies like NASA, its goals are simpler. But being the best, first, or fastest is not usually the point of hobbies; the point is to do something you like, with people you like, because you like it and them, and to feel empowered because you have done it on your own. The difference between constructing a rocket ship and knitting a sweater or building a homemade radio, though, is that sweaters and radios have little potential to kill the people who use them.

Of course, Olsen, Larsen, Wilson, and their fellow DIYers are aiming for survival. And they’re only hopeful, not certain, that they can even get to the point where they strap someone into Spica’s capsule. Still, optimism reigns. Olsen offers a quote from Pippi Longstocking, a famous figure in Scandinavia. “I have never tried that before,” she says, “so I think I should definitely be able to do that.” Will anyone make sure that this attitude doesn’t doom the first passenger in a DIY space mission? That’s up in the air.

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Correction 4/10/23: A previous version of the article stated that with a possible expiration of a US moratorium, Americans would be able to “legislate” the safety of space tourists, instead of “regulate.” PopSci regrets the error.

Sarah Scoles Avatar

Sarah Scoles

Contributing Editor

Sarah Scoles is a freelance science journalist and regular Popular Science contributor, who’s been writing for the publication since 2014. She covers the ways that science and technology interact with societal, corporate, and national security interests. The author of the books Making Contact, They Are Already Here, Astronomical Mindfulness, and the forthcoming Mass Defect, she lives in Denver and escapes to the mountains to search for abandoned mines and ghost towns as often as she can.  
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