galacticvoyages face a looming peril from cosmic debris
An army of minuscule particles swarms around Earth, posing a serious threat to spacecraft, space stations, and an escalating horde of satellites. The European Space Agency's Department of Space Safety discusses the gravity of the situation and potential strategies to combat it.
Is there a cosmic jurisprudence?
Space is far from lawless, despite appearances. As per the European Space Agency's Head of Space Safety at the European Space Operations Centre (ESOC) in Darmstadt, Holger Krag, the United Nations has promulgated guidelines that have garnered the endorsement of over 100 nations. "These guidelines essentially dictate that each country must monitor and authorize space activities within its territorial limits," Krag says. The so-called Space Treaty also assigns liability for damages caused by space activities. According to Germany's Federal Foreign Office (AA), countries responsible for launching, procuring launch, or providing launch sites or facilities are typically held liable for damage caused by their space objects on Earth, in the atmosphere, or in outer space if such damage is due to their negligence.
Countries are afforded sovereignty to establish their safety regulations. Efforts are underway in Germany to draft a Space Act, as per the Federal Foreign Office. The AA website states that the Space Treaty includes provisions for preventing harmful contamination of space, which have yet to have substantial real-world impact.
Preventing future cosmic debris
Beyond national policies, space agencies are taking action. The ESA has pledged to cease producing superfluous space debris by 2030. Recent agreements have been reached with three satellite manufacturers to develop cutting-edge satellite technologies for low orbit that generate no waste. Krag noted that every sixth object in space currently explodes, and every second is not disposed of properly. This situation is set to change. "We aim to assert that disposal is not a mere success, but that we need to intervene and say that the object must be retrieved," Krag says.
The ESA plans to deliberately re-enter an obsolete satellite into Earth's atmosphere over the South Pacific on September 8. Developing a spacecraft equipped with gripping arms to retrieve and destroy space debris is in the works. NASA and JAXA space agencies have similar projects in the pipeline, according to Krag. However, China and Russia remain tight-lipped about such systems due to potential military applications.
Space debris poses a palpable risk to space stations
Indubitably! Space debris poses a genuine threat to space stations, such as the Chinese space station "Tiangong" ("Heavenly Palace"), which required maintenance following a strike by space debris. The International Space Station (ISS) frequently evades debris fragments. In some instances, astronauts have sought refuge in docked spacecraft due to projectiles being on a potential collision course.
Where are collision risks most pronounced?
"We calculate the area near Earth up to 2,000 kilometers in height," says Krag, where three-fourths of all spacecraft reside. Collisions have already occurred, even with satellites. The altitude range between 600 and 800 kilometers brims with substantive traffic, while the self-cleansing effect of the atmosphere begins to wane above 800 kilometers due to decreasing gravity. Below 600 kilometers, debris typically re-enters the Earth's atmosphere within a few years. Above 1,000 kilometers, debris would remain in orbit for several thousand years.
The Starlink satellites of the US private space company SpaceX, led by tech billionaire Elon Musk, orbit at around 500 kilometers in altitude. If one were to fail, it would vanish in the atmosphere after about five years, according to Krag. The sheer quantity of satellites is the primary concern here.
According to the ESA, not all objects orbiting Earth are monitored. Estimates put the number of debris objects larger than ten centimeters at around 40,500, with 1,100,000 between one and ten centimeters, and 130 million up to one centimeter. The total mass of all space objects in Earth's orbit is estimated to exceed 12,400 tons.
The future of space travel
Over two decades ago, around 100 satellites were launched annually, said Krag. "However, in the past three to four years, this figure has ballooned to 2,000," and it could continue to rise or fall based on economic factors. Krag does not rule out the possibility of up to 10,000 satellites being launched per year in the future, as costs decrease, including through the utilization of reusable launch vehicles. He sees risks for spacecraft when they share an orbit with a substantial portion of space debris. However, once the initial 800 kilometers of altitude have been reached following a launch, it becomes a mere statistical issue, Krag asserts. "Regardless, we'll always prevail."
The United Nations has issued guidelines on space activities, emphasizing that each country is responsible for monitoring and authorizing activities within its territory due to the potential threat to spacecraft and space stations. The European Space Agency (ESA) is committed to diminishing space debris, including pledging to cease producing unnecessary debris by 2030 and developing a spacecraft to retrieve and destroy space debris.
Despite international efforts, China and Russia remain secretive about their space debris management systems due to potential military applications. The International Space Station (ISS) often avoids debris fragments, and maintenance was required on the Chinese space station "Tiangong" due to space debris collisions.
