Sustainable use of space

PHOTO: ESA / J. FRIEND

Last month at the G7 Leaders’ Summit in Cornwall, UK, major industrial countries addressed the sustainable and safe use of space, making space debris a priority and calling on other countries to follow suit. not. This is good news as space is increasingly congested and strong political will is needed for the international space community to start using space sustainably and preserve the orbital environment for space activities for generations. futures.

There are more than 28,000 regularly tracked objects orbiting the Earth. The vast majority (85%) is space debris that is no longer used for nothing. These debris objects are dominated by fragments of some 560 known ruptures, explosions and collisions of satellites or rockets. These left behind around 900,000 objects larger than 1cm and an impressive 130 million objects larger than 1mm in Earth orbits of commercial and scientific value.

Today’s already active satellite infrastructure provides a host of services essential to modern society, including communications, weather, navigation and earth surveillance. Its loss would seriously damage modern society. In addition, a new space age has just begun, driven by low latency commercial broadband services that rely on large constellations of low Earth orbit satellites. These will revolutionize connectivity on the ground and in the air. However, they will also increase space traffic. The satellites that will be launched over the next 5 years will exceed the number launched around the world in the history of spaceflight. The congestion in space will only get worse.

It is evident that debris mitigation strategies, defined two decades ago by experts from the world’s major space agencies, are increasingly important. They aim to prevent explosive ruptures by removing residual energy from space systems at the end of their missions, and to “eliminate” a space object by a final maneuver which brings it back into the Earth’s atmosphere. Although these strategies are widely recognized, dozens of large space objects are still stranded each year in critical orbital regions where they will remain for several hundred years. And an average of eight in-orbit fragmentation events occur each year, adding more pollution and increasing the likelihood of more collisions. Space operations themselves face increased evasive maneuvers to avoid losing a mission. At the most densely populated orbital altitudes, space objects receive dozens of collision warnings per day, of which only the most critical can be avoided. The number of such alerts will increase as large constellations of satellites come online.

Another important aspect of the debris problem is the risk on Earth of reintegrating objects. Between 100 and 200 metric tons of human-made material enter the Earth’s atmosphere uncontrollably each year. A heat-resistant material, such as titanium or stainless steel, can survive harsh re-entry conditions.

Advances can be made by advancing technology to ensure the safety of spaceflight. For example, the European Space Agency’s space security program is developing solutions that make energy elimination and passivation actions safer. “Desorbit Kits” will provide redundant propulsion and communication to ensure the elimination of a spacecraft even after it has ceased to function. A new area of ​​’design to kill’ will aim to replace critical components with less heat resistant materials to limit their chances of reaching the ground on re-entry. In addition, a more systematic deployment of laser tracking on the ground could increase the accuracy of spatial surveillance data and therefore limit the number of collision avoidance alerts. Laser power could even transfer a small amount of pulse to objects to prevent their collisions. On top of that, missions, such as Clearspace-1, will aim to clear targeted debris through robotic capture.

An internationally binding regime for the management of debris and space traffic is pending. So far, space missions have only been supervised at the national level, and states have been encouraged to translate soft space debris guidelines into national regulations. Space, however, is a commonly used resource with limited capacity. International harmonization of space traffic would be necessary for efficient and interference-free use of space. The coordinated use of available radio frequencies could serve as a model. In addition, the implementation of space debris mitigation requirements should be monitored, in accordance with internationally binding principles. New and affordable technical solutions could spur more ambitious measures in international regulations to preserve space for the astronauts of tomorrow.