Translated with DeepL
What went through your mind when you heard that the ISS was to be replaced by private providers?
The ISS is reaching the end of its life anyway and has been in operation even longer than originally planned. So it's time for new solutions. After the first era during the Cold War in the 1960s, when the goal was to be the first to go into space or to the moon, the second era followed in the 1990s with increased international cooperation. The ISS was created as a joint project between NASA (National Aeronautics and Space Administration), ESA (European Space Agency), Roscosmos (State Space Corporation Roscosmos), JAXA (Japan Aerospace Exploration Agency) and CSA (Canadian Space Agency).
Since around 2002, the year SpaceX was founded, we have been in the third era, often referred to as "New Space". SpaceX has massively reduced the cost of access to space through reusable rocket systems. At the same time, the global strategy is moving back in the direction of national independence. The geopolitical developments of recent years are pushing nations towards greater resilience and independence.
What does this development mean in concrete terms?
It democratises access to space and promotes partnerships. This increases both competition and cooperation and drives innovation. However, this opening up also brings with it new challenges: traffic management in space, secure data transmission, communication and navigation to avoid collisions - and of course the problem of growing space debris.
What are the greatest achievements of the ISS from your point of view?
Definitely the international cooperation and the numerous innovations that have resulted from it. The ISS was and is a diverse and inclusive scientific laboratory in space, where people of different nationalities, cultures, genders, ages and educational backgrounds research and develop together. A wide variety of experiments are conducted there to analyse the effects of microgravity and radiation, such as the development of new materials.
What are the specific benefits?
Physical and chemical processes in materials or biological cells can be observed free of terrestrial factors, allowing us to better understand the dynamics of these processes. This leads to scientific discoveries, makes it possible to mix substances that cannot be combined on Earth - such as water and oil - or speeds up tests considerably.
Research on the ISS pursues several approaches: Solutions for space technology itself, applications for Earth such as Earth observation, weather forecasting, data transmission, energy, health or navigation as well as the exploration of other planets and solar systems to understand how our blue planet works and came into being.
Basic research is to be continued, but with a stronger focus on industry and production. Soon there will be products from space. How do you assess the potential?
The space economy is estimated to be worth 1.8 trillion dollars by 2035-2040. It is definitely expanding and the speed is increasing: time to market is shortening, innovation and commercialisation are accelerating.
The microgravity and radiation conditions in low Earth orbit (LEO), where the ISS orbits at an altitude of around 400 kilometres, offer perfect conditions for a test laboratory. These conditions can only be partially simulated on Earth, or only for a few minutes.
Where do you see specific applications?
The potential is far from exhausted. Production in orbit - so-called "in-orbit manufacturing" - is becoming increasingly realistic. Not only for research, but also for applications on Earth, for example for new medicines and materials. These applications require an extended infrastructure that goes beyond traditional satellites or spacecraft. New approaches are therefore needed to assemble them directly in space, capture them and recycle them at the end of their service life. Here are two examples:
Firstly, up to now satellites have been dimensioned precisely for their mission duration, orbit and launch vehicle, which has limited their mass and fuel volume. However, if individual parts are transported into space and assembled there, the dimensions can be much larger and more flexible. Satellites could be placed in LEO and transported from there to other orbits using kickstages, as developed by the Swiss start-up Pave Space. Origami design concepts, in which satellites unfold or inflate after separation from the rocket, also demonstrate this: There are no limits to creativity.
Secondly, the development of medical therapies was only possible to a limited extent, as it is very costly in terms of time and resources. The start-up Spark Microgravity has developed a new, fully automated bioreactor to investigate the effect of various therapies on cancer cells in a microgravity environment in an efficient and resource-saving manner.
What are the environmental consequences of satellites burning up in the atmosphere?
Most space materials have to fulfil very specific and high requirements: Radiation resistance, extreme temperature differences, vacuum, microgravity. This means that only a selection of materials has to undergo very specific qualification tests. This is why most satellite structures are made of aluminium such as Al 6061 or Al 7075.
However, this is not the best for burning up in the atmosphere at the end of their service life: on re-entry, the aluminium oxidises with the oxygen in the atmosphere to form aluminium oxide aerosols, which influence the ozone chemistry and dynamics in higher atmospheric layers.
Are there other problematic materials?
Yes, it's not just the structures. There are also electronic parts, solar cells, lubricants, adhesives and much more that can release various substances when they burn up. This is just one example of a material - the environmental consequences are complex.
What is the alternative to aluminium?
The start-up Swiss Wood Solutions, a spin-off of Empa and ETH Zurich, together with ETH Zurich | Space, came up with the idea of building satellite structures made from local compressed wood. The natural densification process was developed by Swiss Wood Solutions and brings the material close to the mechanical properties of aluminium so that it can be used as a structural material.
What are the advantages?
Natural sustainable material can be used and the supply chain is significantly shortened as local or regional wood is used. This is an important step towards more sustainability in space travel - away from problematic aluminium aerosols and towards natural materials.
How far along is the development?
The next steps in the research project are to find out how the wood behaves in space over a longer period of time, how it burns up on re-entry and what substances are released in the process. A possible test flight into space is planned, complemented by extensive ground tests.
At the end of 2030, the ISS, which is the size of a football pitch, is to crash into the sea in a controlled manner. How should we visualise this?
Firstly, Axiom Space will be the only private commercial company to dock its PPTM (Payload, Power and Thermal Module) and then AxH1 (Habitat 1) to the ISS between 2027 and 2029. Everything usable will be transferred there from the ISS. Once these modules have undocked, SpaceX's US Deorbit Vehicle (USDV) will then accompany the ISS into the Earth's atmosphere in a controlled manner so that it burns up over the Pacific Ocean, far away from any civilisation.
Will the ISS burn up completely?
Not completely. The impact location in the ocean is calculated using comprehensive risk analyses that take all technical and legal aspects into account. There are several analyses and scenarios to look at all possibilities and risks - from technical to legal.
The larger parts that do not burn up are very likely to be collected. The smaller ones will sink into the sea and corrode due to the salt content. They try to capture as much as possible of what doesn't burn up completely.
Could the crash trigger a tsunami or another natural disaster?
No. The risk analyses ensure that the impact site is selected in such a way that there is no danger to people or the environment. The impact site will be far away from sensitive ecosystems and any civilisation.
How can the additional environmental impact caused by the growth in space travel be reconciled with climate policy endeavours?
This is one of the biggest challenges of modern space travel. On the one hand, we need satellites for communication, navigation and earth observation - also for climate protection itself. Earth observation satellites provide us with critical data on climate change, weather phenomena and environmental developments.
On the other hand, we need to minimise the environmental impact. This is why innovations such as wood satellites, space debris capture technologies and international regulation are so important. The consequences of climate change are no longer just terrestrial - they also affect space, and vice versa.
Here you can read part 2 of the interview series: Space junk - the dark side of the boom
