Space Debris Situation Becomes Critical for Satellite Operators
[Satellite News 10-26-10] The global race to save outer space could lead to sustainable development of space resources. While the very idea of outer space brings to mind concepts such as boundless expanses, immensity and even infinity, it would be a mistake to assume that outer space is an infinite resource. The reality is that the portion of outer space currently used for orbiting man-made satellites is a finite resource, and one that is coming under serious threat from what could be described as man-made pollution: space debris.
Space debris, commonly defined as pieces of man-made hardware orbiting around the earth and no longer functional, is littering low, medium and geostationary orbits, threatening the sustainability of the satellite industry.
The phenomenon has been known for years and comes as no surprise. The first space debris was a consequence of the first satellite launch in 1957, when the upper stage of a Vostock rocket was left orbiting the earth until it re-entered the atmosphere the following year. Similarly, the first space debris in geostationary orbit is believed to date back to 1964.
What has changed, however, is the scale of the problem. In 1991, US engineer Donald Kessler stated that the space debris problem could reach a tipping point where the issue could get out of control, with a cascade of in-orbit collisions knocking out functional satellites. Naturally, the risk of the so-called Kessler Syndrome becoming a reality is that large parts of outer space could become overcrowded with debris and therefore impossible to be used for decades.
“We believe that unless action is taken immediately, such a scenario could become a reality in a few years,” explained Tommaso Sgobba, who heads the European Space Agency’s (ESA) Office of Independent Flight Safety and Planetary Protection, at a roundtable discussion on the issue of space debris organised in Vienna, Austria, by the United Nations Office for Outer Space Affairs (UNOOSA) and the Diplomatic Academy of Vienna. The event was part of the 2010 World Space Week.
The seriousness of the situation should not be underestimated, as the 2009 in-orbit collision between an Iridium satellite and an out of control Russian spacecraft clearly illustrates. In other words, there should be a global race to save valuable outer space resources. The numbers are quite simply staggering. “Whether through radars or optical systems, we can only see objects larger than 30cm in GEO and 10cm in LEO,” said Sgobba. “Of these, there are a total of around 17,000 to 20,000 items.”
But there are also fragments that we cannot see but that we can safely assume exist: 300,000,000 fragments of less than 1mm, and 600,000 less than 1 cm. Sgobba explained eloquently what the impact of these debris could be on the satellite industry.
“In orbit, 1mm objects can damage a satellite sub-system, 1 cm objects are likely to disable satellites while 10 cm objects are likely to cause catastrophic satellite break-ups.”
It is worth considering that the issue of space debris does not only affect the space industry, aviation traffic is also at risk as a fragment of 300g could bring down an airplane. While the vast majority of these objects are made up of fragments (59 percent), satellites, whether operational or retired, make up 22 percent, rocket orbital stages 12 percent, and mission related objects 7 percent. Recent episodes, such as the 2007 test of a Chinese missile that took down a satellite in LEO creating a cloud of debris, suggest that the problem is here to stay. Even with the natural decay of debris re-entering the atmosphere, the amount of debris is set to grow in coming years.
The international community is responding to the issue through a number of initiatives. “The Space Debris Mitigation Guidelines were issued in 2007,” said UNOOSA’s Niklas Hedman, who heads the Committee Services and Research Section. “It is non-binding but was adopted by the UN General Assembly. Other initiatives include the creation of a UN Register of objects launched in outer space. It is clear, however, that despite the rules in place, the amount of debris is growing, if anything because of the large number of satellites launched before the Mitigation Guideline was issued. In other words, proactive mitigation action is needed.”
The problem’s solution exists from a technical point of view, Sgobba explained. “In 2008, the US demonstrated that ‘space tugs’ can be orbited with the task of recovering stray satellites. It is estimated that 10-15 big items need to be eliminated every year to have a balanced population.”
As often happens, however, the availability of technology is a red herring. The crucial issue, in fact, is not so much whether this can be done, but who will pick up the bill. International law is also another sore point. “There is an issue of liability: how is the functionality of an orbiting object defined? Who has the right to remove a satellite from orbit?” said Hedman.
Under Article 6 of the Space Treaty, states are ultimately responsible for space resources, but the issue may not be as clearcut in many instances, especially in an environment where it might not be possible to establish where a debris is coming from.
“The Mitigation Guidelines are a good instrument that took more than 10 years to produce,” said Hedman. “Yet, we are aware that it is not enough.”
This is because the issue is not just space debris, but space resource management – the long-term sustainability of outer space activity and resources. In this sense, if one were to play the Devil’s advocate, it could be said that space debris is a blessing in disguise. New rules governing man’s activity in outer space are needed and history shows that common rules are only developed in the face of impending disasters. Yet, the satellite community should be aware that we are reaching a point where the situation could be fatal. It is no longer possible to wait.