The Tragic Saga of the Real Life Amazing “LEGO Rocket”

Space travel is a pricey business. Even today, the average cost of launching a satellite or other payload into orbit hovers around $10,000 per kilogram. Much of this cost stems from the great complexity of space launch vehicles, which require a great deal of time, money, skilled personnel, and other resources to design, test, and launch. Further complicating matters, different payloads and mission types require different types of launch vehicles, each of which must be individually developed – further driving launch costs into the stratosphere and beyond. While recent developments like SpaceX’s reusable Falcon rockets have succeeded in reducing launch costs somewhat, for the builders of smaller satellites like universities or poorer countries, attaining orbit remains exorbitantly expensive. However, nearly 50 years ago, an obscure German company nearly succeeded where even SpaceX has failed, developing an innovative modular rocket system that promised to reduce launch costs by tenfold and bring outer space within reach of just about anyone. But sadly the system never came to be, killed by a combination of Cold War paranoia, international rivalry, and corporate greed. This is the fascinating and tragic story of OTRAG, the dirt-cheap “LEGO rocket” that never was.

Our story begins in 1950s West Germany with 25-year-old student Lutz Thilo Kayser. Born in 1939, Kayser was fascinated by space travel from an early age. During the Second World War, he wrote a letter to Dr. Wernher von Braun – developer of the wartime V2 ballistic missile and later the Saturn V moon rocket – expressing his desire to become an astronaut. Ever the pragmatist, von Braun explained that for space travel to be practical, astronauts would have to be small, light, and few in number, and advised Kayser to become an engineer instead. Kayser obliged, enrolling in aerospace technology at the University of Stuttgart in 1954. While studying in Stuttgart, Kayser founded the Student Association of Space Enthusiasts, which, under the supervision of rocketry pioneer Irene Sänger-Bredt, developed Germany’s first post-war liquid-fuelled rocket engine.

In 1963, when Kayser was a graduate student, he was awarded a consulting contract to investigate the failure of the first launch Europa II, a satellite launch vehicle being developed by multi-nation European Launcher Development Organization or ELDO. While Kayser succeeded in identifying the cause of the failure, the system experienced a further 6 launch failures in a row and was ultimately cancelled in 1971. The dream of a pan-European launch vehicle would not be realized until 1979 with the launch of Ariane I, the first of a highly successful family of rockets still in use today.

While analyzing the failure of Europa II, Kayser became aware of fundamental flaws in the way launch vehicles were developed and built – flaws which kept the cost of launching payloads into space exorbitantly high. As he later explained in a 1978 interview for Popular Science magazine:

“The trouble up to now was that space has been a matter of prestige or military requirements, so no one gave a damn about its costs. Scientists, engineers, and technicians were literally encouraged to think in complicated and expensive terms, not simple and cost-cutting ones. Did you know, for example, that NASA allocated about half a million dollars developing a ball-point pen for the Apollo missions that would work under conditions of weightlessness when, after all, an ordinary pencil would have done the trick just as well?”

It is worth noting here that Kayser was perpetuating a commonly-held myth, which we have a deep dive video on if you want to know the entire fascinating story. But in a nutshell, while NASA did indeed adopt specially-designed space pens in 1965, these were developed not by NASA themselves but rather the Fisher Pen Company at their own expense. Furthermore, while both NASA and the Soviets initially used pencils on manned space missions, the former eventually found them unsuitable for a variety of reasons. For example, in zero gravity, pencil shavings, broken pencil tips, and graphite dust pose an irritation hazard to astronauts’ eyes and lungs and can potentially float behind instrument panels and short out delicate electronics. Furthermore, in the pure-oxygen environment of American spacecraft, the wood of conventional pencils posed a fire hazard. Nonetheless, Kayser’s analysis of the space-launch industry’s shortcomings was accurate, and in 1971 he formed Orbital Transport und Raketen AG or OTRAG with the goal of turning the industry on its head and reducing satellite launch costs by an order of magnitude. This was the first private space launch firm in history, predating SpaceX by 31 years.

Kayser’s ideas were groundbreaking for their time and remain highly innovative today, emphasizing simplicity, mass-production, and modularity. Rather than build a different launch vehicle for every type of payload, Kayser instead developed a system of standard, modular rocket units which could be bundled or “clustered” into whatever size of launch vehicle was required. The core of the OTRAG system was the Common Rocket Propulsion Unit or CRPU. This consisted of a steel tube 27 centimetres in diameter and six metres long, with a combustion chamber and nozzle at one end. Each CRPU produced 3,000 kilograms of thrust and was fuelled by a combination of kerosene and a 50/50 mixture of nitric acid and dinitrogen tetroxide, stored in separate compartments within the tubular propellant tank. Instead of using complex and expensive turbopumps, the tanks were only filled to 66% capacity, the remaining space being filled with compressed air that forced the propellants into the combustion chamber – what is known in rocketry as a blow-down system. Emblematic of the dirt-simple, cost-effective nature of the system, the flow of propellants into the engine was controlled by commercial ball valves driven by the same motors used in automobile windshield wipers. The nozzle was also ablatively cooled by coating it with a material that would char and flake off as the rocket flew, carrying the heat with it and preventing the engine from overheating. Each CRPU also contained its own battery and microcomputer to operate the propellant valves, and could be cheaply mass-produced at a rate of 10 per day using a special automatic machine.

As noted before, multiple CRPUs could be bundled together to produce a near-infinite variety of launch vehicles. For example, a sounding rocket for studying the upper atmosphere could be assembled from one or three CRPUs, while launching a satellite into geostationary orbit required a cluster of nearly 600 units. For the sake of simplicity, the nozzles on the CRPUs did not gimbal as in conventional rocket; rather, directional control was achieved by differentially throttling the outer engines of the cluster using the propellant control valves. And while the various stages of a conventional rocket are stacked on top of one another, in the OTRAG system the stages were nested concentrically one inside the other. Thus, at launch, all the CRPUs would fire in parallel, while during staging the outer CRPUs would detach and fall away, allowing the next stage to emerge from within the cluster. This gave the OTRAG Rocket an unusually squat, boxy appearance which one critic compared to a “bundle of asparagus.” Kayser used a rather different metaphor, explaining in 2015:

My rocket system is like Lego. You can easily explain it – everyone knows what Lego is. You always use the same bricks to put together…[using regular rockets] is like transporting potatoes with Rolls-Royce. You can try to reduce the cost a little bit of Rolls-Royce but youll never get down to the cost of a small truck.”

Though highly unorthodox and outwardly crude compared to nearly all launch systems before or since, the economic logic behind the OTRAG system was fundamentally sound, achieving low operating costs through economies of scale. As Kayser explained in 1978:

“All previous systems were either developed for military purposes and adapted to peaceful uses, or they were built for manned missions and required a whole arsenal of safety-oriented redundancy. This launcher is designed purely for freight. I haven’t invented any new laws of nature or new mechanical principles, but I had to keep turning the screw and looking for cheaper solutions. So I glanced around at other systems and asked two basic questions. What do they have and what don’t they need? Well, they have complicated technologies such as rotating machinery, hydraulic and pneumatic systems, seals, pumps, and electronics which are not only expensive but contribute to high failure rates. To avoid the failures, even more technology is built into them – redundancy. If you eliminate all that, you can reduce the failure rate.”

Kayser’s ultimate goal was to make the CRPUs so inexpensive and easy to mass-produce that it would be cheaper to just produce new units than to recover and refurbish the spent rocket stages. This system, he calculated, would allow a typical communications satellite to be placed in geostationary orbit for around $4 million – equivalent to around $1000 per kilogram. If all went according to plan, Kayser predicted that OTRAG would be launching around 12 satellites a year between 1981 and 1990, and that all development costs would be recouped after the 25th launch.

Though OTRAG received around $1.8 million dollars from the city of Bonn between 1971 and 1974, the majority of the company’s $26 million of startup capital came from private investors. However, rather than only seeking out a handful of extremely wealthy backers, Kayser solicited funds from nearly 600 people of various means in one of the earliest examples of crowdfunding. And befitting his utilitarian approach to rocket design, Kayser ran the company as a stripped-down, ultra-efficient organization, its employees never numbering more than 50. Equally impressive, OTRAG boasted among its technical advisors none other than Wernher von Braun and Kurt Debus, the fist director of NASA’s Launch Operations Centre at Cape Canaveral.

In 1974, OTRAG began static engine testing at the government-run German Aerospace Centre or DLR in Lampoldshausen, 60 kilometres north of Stuttgart. The company would conduct 2,600 static firings at Lampoldshausen, perfecting the CRPU design. As a private company, however, OTRAG was soon forced to vacate the DLR and go elsewhere to pursue its development program. In any case, Germany had no large, sparsely-inhabited areas that could support full-scale rocket tests. And since the United Nations Outer Space Treaty forbade the private exploration of space without the sponsorship of a recognized sovereign state, OTRAG began shopping around for a government to host their launch test facility. After investigating various locations including Indonesia and Brazil, the company finally accepted an offer from President Mobutu Sese Seko, dictator of the African nation of Zaire – today the Democratic Republic of Congo. Recognizing the economic benefits such an innovative space program could bring to his nation, in December 1975 Seko granted OTRAG a 25-year lease on a 99,000 square kilometre tract of land in Shaba – today Katanga Province – on a high plateau overlooking the Luvua River. By 1977 the company had established its own private launch facility, complete with launch pad, workshops, staff quarters, and a dirt airstrip for resupply.

The first launch of a four-CRPU cluster took place on May 17, 1977, the rocket reaching an altitude of 20 kilometres. This was followed by a second launch on May 20, 1978, which reached 30 kilometres. But the third launch on June 5, 1978 – attended by President Seko – failed only a few seconds after launch.

Yet despite its technical successes, by now OTRAG was facing problems of an entirely different kind. For reasons that should be rather obvious, the rest of Europe was none too keen on the idea of Germany developing its own home-grown rocket and missile technology. Turns out trying to take over the world tends to make people a bit suspicious of you – who knew? Furthermore, American aerospace companies, who for decades enjoyed a near monopoly on lucrative government space launch contracts, were less than enthusiastic at the prospect of an upstart German company undercutting their business. And so, various world leaders including West German Chancellor Helmut Schmidt, French president Giscard d’Estaing, and Soviet Premier Leonid Brezhnev began pressuring President Seko to expel OTRAG from his territory. Soviet intelligence even spread rumours that OTRAG was in fact a front for the development of West German and South African nuclear missiles, eliciting protests from many of Zaire’s neighbours including Soviet-aligned Angola. Western media outlets picked up and repeated these claims, further ratcheting up the pressure on Seko. Lutz Kayser roundly dismissed these accusations, stating:

“Obviously you could carry an atomic bomb in an oxcart, too, but there is really no way our vehicle could have military value. We’re much too exposed and vulnerable to be a credible threat to anybody.”

Nonetheless, in 1979 Seko bowed to international pressure and agreed to expel OTRAG in exchange for 100 million Deutsch Marks in aid from West Germany, which also shut down the company’s German production facilities. But OTRAG did not have to wait long to find another sponsor, for soon after they received an invitation from Libyan dictator Muhammar Gaddafi to set up new production and launch facilities in Tawiwa, 600 kilometres south of Tripoli in the Sahara desert. The first launch from the site took place on March 3, 1981, with a number of Libyan military personnel in attendance. 13 more successful launches took place over the following year, definitively proving the reliability and cost-effectiveness of the system. Kayser and his wife Susi were apparently unbothered by the abuses of their host’s regime, with Susi stating in a 2015 interview:

Im sure there were nasty things, but now show me a country that has not nasty things and does not violate any human rights. I have never in my whole life encountered any such country…We had so much fun. Gadaffi was such a wonderful man…a master of diplomacy in internal politics…it would be much better if he made a kingdom. Then he couldve been happy like the Saudis.”

Aaaaalrighty then, Susi…

But this idyll would not last for long, for in 1982 Germany became a party to the Missile Control Regime, which prohibited the development of rocket technology in developing countries. Under continued pressure from the United States Government – who wished to prevent Gaddafi from acquiring missiles and protect its own aerospace industry – in 1983 OTRAG was forced once again to pack up and leave the country. At the same time, Libyan forces unlawfully seized all of OTRAG’s rocket manufacturing and test equipment, none of which Kayser was able to retrieve or receive compensation for. For ten years the Libyans attempted to develop OTRAG’s technology into a viable missile, but lacking Kayser’s expertise they were unsuccessful and the project was eventually abandoned.

Meanwhile, in a final desperate bid to save his company, Kayser moved operations to the Esrange Space Centre in Kiruna, Norway. A single launch took place from the site on September 19, 1983. However, 10 seconds into the flight, the rocket suddenly broke apart and exploded. The failure was traced to a rectangular hole cut for a television camera, which acted like an organ pipe and caused the rocket to shake itself apart. It was to be OTRAG’s swan song. Having been run out of every friendly country and lost most of its capital and investments in Libya, by now the company was in ruins. Kayser made a few last attempts to find new sponsors, but it soon became clear that every candidate – including one Saddam Hussein – was only interested in one thing: acquiring cheap missile technology. And so in 1982 Kayser made the difficult decision to leave the OTRAG, which finally ceased operations in 1986. As Kayser recalled in 2015:

As a scientist you wanna have a certain legacy, and it would be nice to see it applied. But to see the technology in ballistic missiles would be sad so its a very, very difficult decision. I will probably not live to see it.”

Indeed, Kayser would eventually leave the cutthroat world of aerospace far behind, moving to the Marshall Islands and establishing a boutique resort known as Bikendrik Island Hideaway. Lutz Kaiser passed away on November 19, 2017 at the age of 78, his dream of truly affordable spaceflight unfulfilled. While American companies like Interorbital Systems and Armadillo Aerospace have experimented with OTRAG-style modular launch systems, none have yet reached the commercial stage. As of this recording, the future of affordable spaceflight appears to be in reusable launch systems like SpaceX’s Falcon series. Yet even this highly sophisticated system cannot hope in its current iteration to achieve the reliability and cost-effectiveness of a brilliantly simple idea dreamed up by an eccentric German engineer nearly half a century ago – a system doomed by the politics and rivalries of a deeply flawed industry. This is why we can’t have nice things…

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Expand for References

Serra, Jean-Jacques, OTRAG Rockets, Sat-Net,

Grahn, Sven, The Last OTRAG Rocket – Launched From Esrange,


Kerr, Joachim, OTRAG – A Low Cost Rocket, Journal of Space Operations & Communications, February 2021,

Dornberg, John, Bargain Basement Rocket – a Low-Technology “Truck” for Cheap Shots in Space, Popular Science, March 1978,

Torchinsky, Jason, SpaceX Was Not the First Private Rocket Company, Jalopnik, May 29, 2012,

Wall, Kim; Hinzel, Jan; and Jose, Coleen, Naked in an Island Idyll: Eccentric Couple Recall a Life of Rockets and Dictators, The Guardian, June 13, 2015,

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