Innovations in space travel

13 March 2025

Away from the various state space agencies, private companies have long since discovered space for themselves. Among other things, they are working to make rocket launches more affordable. Start-ups are developing innovative propulsion systems, and researchers are simulating the moon on Earth or turning to unusual and traditional building materials to reduce space debris. We present four interesting approaches and developments.

13 October 2024, Boca Chica, Texas: The scene resembles a video recording played in reverse. A few minutes after the launch of a space shuttle, the 71-metre-long first stage of the Starship returns to the launch pad, where it is held fast by huge gripper arms. Mighty cheers erupt from the SpaceX team: The private space company has succeeded for the first time in “parking” a rocket stage safely back on the launch pad, in another big step towards SpaceX’s declared goal of developing a fully reusable rocket system that will take humans to the moon and later to Mars.

Even the first stage of SpaceX’s Falcon 9 launch vehicle can land on a floating platform in the ocean or near the launch site after a return flight. The rocket’s payload fairing can also be fished out of the ocean and reused. Combined with serial production of its rockets, SpaceX has been able to significantly reduce launch costs, turning it into a leading company for commercial space transport. But while the first stage of a Falcon 9 has been reused up to 25 times so far, the idea is for the Starship’s first stage to be used up to 1,000 times, which would further drastically reduce costs.

However, SpaceX is not the only space company working on reusable rockets. The New Shepard rocket from Blue Origin, the space company of Amazon founder Jeff Bezos, used parachutes to touch down undamaged for the first time in 2015 and has since been relaunched several times. However, at only 18 metres in length it counts as a small rocket, and its primary function is to transport space tourists to a comparatively low altitude of 110 kilometres. Unlike SpaceX’s rockets, it is not designed for larger payloads and flights into Earth orbit and beyond. But Blue Origin has since gained ground on its big competitor, having launched its new heavy-lift rocket, New Glenn, the first stage of which is said to be reusable, into orbit for the first time in January. And the Chinese space agency is also planning a recyclable rocket, as is the European Space Agency, ESA. However, the reusable successor to Ariane 6 is not expected until the next decade.

Since December 2024, a small cube has been circling around the Earth. Its cuboid shape and size are not unusual, because CubeSats, with an edge length of ten centimetres, have been used more and more over the course of many years. What makes this one special is its material: The LignoSat, as the development team at Kyoto University calls its mini-satellite, is made of magnolia wood. The idea is for the wooden satellite to burn up completely during re-entry into the Earth's atmosphere at the end of its service life and to produce nothing more than a spray of biodegradable ash. Unlike conventional satellites, as the developers of the LignoSat from Kyoto University emphasise, it would therefore not release the kinds of metal particles that can damage the atmosphere and impair telecommunications.

In principle, wood is more durable in space than on Earth. After all, there is neither water nor oxygen there to decompose or ignite it. How the natural building material will cope with the temperatures and radiation found in orbit is now being measured by the researchers with sensors as the cube undergoes tests. Monitoring is also being carried out to determine whether the Earth’s magnetic field will be able to penetrate the wooden structure and interfere with the built-in technology. If the test is successful, the research group hopes that wood might be able to replace aluminium in satellite construction. And one day, wooden habitats might even be constructed on the moon or Mars.

In Germany, for example, Isar Aerospace from Munich and the Rocket Factory Augsburg are also developing their own systems. Potential customers include the automotive industry, which needs satellites for navigation and self-driving cars. HyImpulse’s SR75 is said to be able to take satellites weighing up to 250 kilogrammes to an altitude of 250 kilometres. The start-up is also working on a larger rocket that will release small satellites with a payload of up to 600 kilogrammes in a low Earth orbit of 500 kilometres from 2026.

Astronauts can now prepare in Cologne for what it will be like to work and live on the moon. In the city’s Luna Hall, ESA and the German Aerospace Centre (DLR) have simulated the surface of our satellite over an area of 700 square metres in extent. The moon dust – regolith – was replaced by 900 tons of sand from volcanic rock, which corresponds to its special properties: Because there is no atmosphere on the moon, sand and dust are not smoothed out by wind and weather, but remain extremely sharp-edged. This makes the moon dust “dangerous to breathe in and also capable of damaging the equipment”, as ESA astronaut Matthias Maurer, advisor to the project, told Euronews. In humans, moon dust causes respiratory irritation and can lead to cancer in the medium term; in machines it can get into seals and mechanical components and thus drastically shorten their service life. According to a NASA study, this makes it one of the biggest challenges for future lunar missions.

In the Luna Hall, manufacturers of spacesuits or rovers can now test whether they can withstand the extremely fine moon dust and remain leak-proof. Further protective measures against the dangerous dust are also going to be tested here to make deployment on the hostile lunar surface as safe as possible. Future moon explorers can also prepare for the conditions there: The fact that they weigh only one-sixth as much on the moon as on Earth due to its lower gravity is simulated with a special rope suspension system. And thanks to a solar simulator, lunar explorers in Cologne can get used to the special light conditions at the lunar poles to prevent them from being dazzled on landing.