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Dr. Tim Flohrer from the ESA in Darmstadt discusses the growing threat from debris in space and the urgent measures for sustainable space travel
What actually happens to artificial spacecraft when they stop working? Since 1957, over 6,000 satellites have been launched into Earth's orbit, but only about 800 are still functional. The rest orbit the Earth as space debris, along with broken rocket parts and other space-related debris. According to estimates by the European Space Agency (ESA), there are currently over 700,000 such objects, larger than one centimeter, moving at breakneck speed in Earth's orbit. Dr. Tim Flohrer heads the ESA's Space Debris Office in Darmstadt and is a key figure in the field of space safety. In his role, he monitors the development and spread of space debris, analyzes potential hazards, and develops strategies to reduce the risk of collisions in space. An important part of his work involves coordinating international efforts and collaborating with scientists and engineers to promote innovative technologies for debris removal and prevention. Flohrer is committed to making orbit more sustainable and ensuring the safety of future space missions. We spoke with him at ESOC in Darmstadt.
Mr. Flohrer, how serious is the problem of space debris at present and how does it affect the future use of space?
In the late 1970s, NASA scientist Donald J. Kessler published a paper demonstrating the potential for a chain reaction of collisions and fragmentation of space objects. Initially, the topic was primarily of scientific interest. Later, space agencies and operators increasingly addressed it. In February 2009, the first satellite collision in Earth orbit occurred. This event, if not before, brought the issue into the public eye, and for the past two to three years, it has even been perceived as an environmental problem, particularly by the younger generation. Indeed, "space debris" impacts space travel in many ways. Collisions could not only lead to malfunctions but also to significant cost increases for space companies and pose a substantial risk to manned space missions.
What specific measures is the ESA taking to reduce or eliminate the increasing amount of space debris?
As an intergovernmental organization, we are heavily involved in developing and addressing this problem. In doing so, we act as a role model, a good example for other operators. Space is no longer solely a scientific domain. More than 90% of space is operated by commercial entities; just think of Elon Musk (SpaceX). Over 100 nations use satellites. This is because the costs of space programs have decreased significantly. Therefore, in 2023, building on decades of work, we launched the Zero Debris Charter as a guideline to significantly limit the amount of space debris in Earth and Moon orbit by 2030 for all future missions, programs, and activities of the agency. ESA relies on technological innovation, clear guidelines, and international cooperation to achieve this goal. Because one thing must be clear: space, however vast it may seem, is a finite resource, comparable to drinking water.
Are there specific examples of space missions or technologies where ESA has successfully contributed to reducing space debris?
In Darmstadt, we have developed world-leading "Space Safety" models for the active removal of space debris. One example is the planned ClearSpace-1 mission, which will, for the first time, capture a defective satellite component and deorbit it in a controlled manner. This mission serves as a prototype for future cleanup operations in space.
Furthermore, ESA is focusing on preventative measures by developing new guidelines for satellite design that ensure no debris remains in orbit after missions end. This includes the requirement to build satellites capable of autonomously removing themselves from orbit at the end of their operational life. Through this combined strategy of monitoring, prevention, and targeted disposal, ESA is actively working towards the sustainable use of space.
How does your office in Darmstadt work with international partners to develop a global strategy to combat space debris, and are there any legal or political challenges facing ESA in combating space debris, particularly in an international context?
Our space law dates back to the 1970s and 1980s and, in its current form, is not geared towards the problem of space debris. The guidelines developed to minimize space debris should be urgently incorporated into international law. The importance of this implementation is particularly high for some countries, while others appear to be less affected. Nevertheless, the risk posed by space debris remains the same for everyone – a global challenge that requires joint action by nations.
This makes the development and significance of the Zero Debris Charter, drafted by ESOC in collaboration with other space industry stakeholders, all the more important. They defined both overarching guiding principles and specific targets to significantly reduce the amount of space debris by 2030. More than 100 signatories underscore the commitment of states and operators to address sustainability and the responsible management of space resources as serious issues.
What role does cooperation with private space companies play in reducing space debris, and how does increasing space tourism affect this issue?
Coordination with commercial operators, such as Elon Musk, is of paramount importance, as the commercial share of services in space is constantly increasing. The quantity and diversity of satellite data are growing rapidly, for example in areas such as telecommunications or services like Google Maps. Even though space tourism currently takes place in significantly lower orbits, where debris burns up more quickly, the increasing use of space necessitates close cooperation to ensure the safety of ESOC missions and projects by other actors.
What long-term strategies and innovations is the ESA planning to combat the problem of space debris in the coming decades?
Further developments in combating space debris increasingly rely on innovative technologies in so-called "orbit services." The focus here is on transitioning from a linear to a circular economy, enabling the repair, modification, or upgrade of satellites in space instead of leaving them uncontrolled as debris after their operational lifespan. These approaches aim to utilize the limited resource of space more efficiently, as space is becoming increasingly scarce and the risk of collisions is rising. Repairing and modifying satellites is intended not only to increase sustainability but also to extend the lifespan of the devices. At the same time, the challenge arises of developing sustainable and financially viable business models to cover the costs of such complex missions.
