Saturday, September 10, 2011

A 182-page report issued September 1 by the United States National Research Council warns that the amount of debris in space is reaching “a tipping point”, and could cause damage to satellites or spacecraft. The report calls for regulations to reduce the amount of debris, and suggests that scientists increase research into methods to remove some of the debris from orbit, though it makes no recommendations about how to do so.

NASA sponsored the study.

A statement released along with the report warns that, according to some computer models, the debris “has reached a tipping point, with enough currently in orbit to continually collide and create even more debris, raising the risk of spacecraft failures”. According to the Satellite Industry Association, there are now about 1,000 working satellites in Earth orbit, and industry revenues last year were US$168 billion (£104.33 billion,€119.01 billion).

The debris consists of various objects, such as decommissioned satellites and exhausted boosters, but the vast majority of the particles are less than one centimetre across. 16,094 pieces of debris were being tracked as of July, although estimates put the current number at over 22,000. The total number of fragments is thought to be as high as tens of millions. While most of the debris is very small, some of it is travelling at speeds as high as 17,500 mi h^-1 (28,164 km h^-1; 7,823.3 m s^-1).

The International Space Station sometimes has to dodge larger fragments, and in June its crew was forced to prepare to evacuate due to a close encounter with debris.

The UK Space Agency told Wikinews that space flight “is likely to be made more difficult” by the debris. However, communications will “[n]ot directly” be affected, “but if the GEO ring became unusable, there is no other altitude at which objects appear [‘]geo-stationary[‘] and so all antennas on the ground would then have to move in order to track the motion of the satellites”.

Donald J. Kessler, the lead researcher and former head of NASA’s Orbital Debris Program Office, said that “[t]he current space environment is growing increasingly hazardous to spacecraft and astronauts,” and suggested that “NASA needs to determine the best path forward for tackling the multifaceted problems caused by meteoroids and orbital debris that put human and robotic space operations at risk.”

Two events are thought to be the largest individual sources of space debris. Kessler said that “[t]hose two single events doubled the amount of fragments in Earth orbit and completely wiped out what we had done in the last 25 years”.

The first of these was a controversial 2007 Chinese anti-satellite weapon test, which smashed the decommissioned weather satellite Fengyun-1C into approximately 150,000 fragments over a centimetre in size—making up roughly twenty percent of all tracked objects—537 miles above the Earth’s surface.

The Chinese government has so far failed to respond to Wikinews’s queries regarding the incident.

The other is a 2009 collision between twelve-year-old active satellite Iridium 33 and the defunct Russian Strela-2M satellite Kosmos-2251—both weighing in excess of 1,000 lbs (454 kg)—that occurred 490 miles over Siberia, the first such collision. The Iridium satellite was replaced within 22 days, according to Iridium Communications, who operated it.

In a statement released to Wikinews, Iridium Communications said that they “received no warning of the impending collision. Although commercial projections of close encounters (commonly called conjunctions) were available, the accuracy of those projections was not sufficient to allow collision avoidance action to be taken.” They also made the assurance that the Air Force Space Command and United States Strategic Command now provide them with information through the Joint Space Operations Center, and that “when necessary, [they] maneuver [their] satellites based on this information to avoid potential collisions. [They] believe this is a substantial first step in better information sharing between the government and industry and support even more robust interaction which can provide better and more efficient constellation operation.”

Iridium expressed their support for “[l]ong-term investment to improve Space Situational Awareness” and “[i]mproved information sharing between industry and the U.S. government”, as well as more “[g]overnment support for policy and processes which would permit sharing of high-accuracy data as required to allow reliable assessment and warning” and “[i]ncreased cooperation between the government and U.S. and foreign commercial operators.”

They maintained that “the Iridium constellation is uniquely designed to withstand such an event. Because of the resilient and distributed nature of the Iridium constellation, the effects of the loss of a single satellite were relatively minor”, and that “any other system, commercial or military, which experienced the loss of a satellite, would have suffered significant operational degradation for a period of months if not years.” Nonetheless, the company is “concerned over the increasing level of risk to operations resulting from the debris in space.”

The report makes more than thirty findings, and more than twenty recommendations to NASA. None of the recommendations regard how to clean up the debris. However, it does cite a report by the Defense Advanced Research Projects Agency (DARPA), which suggested various possible techniques for catching and removing space debris, such as magnetic nets.

However, international law does not allow one country to collect another’s debris. George J. Gleghorn, vice chair of the committee, observed that “[t]he Cold War is over, but the acute sensitivity regarding satellite technology remains”.

The debris will, in time, be pulled into the earth’s atmosphere—where it will burn up—by gravity, but more debris is being created faster than this can happen.

The report recommends collaborating with the United States Department of State on “economic, technological, political, and legal considerations.” As already mentioned, international law does not allow one country to collect another’s debris.

According to the report, “[t]he problem of space debris is similar to a host of other environmental problems and public concerns characterized by possibly significant differences between the short- and long-run damage accruing to society … Each has small short-run effects but, if left unaddressed, will have much larger impacts on society in the future.”

A spokesperson for the UK Space Agency told Wikinews that the organisation “does not have any plans to get directly involved with [the clean-up] initiative but through its involvement with NASA in the Inter-Agency Space Debris Coordination Committee, it is conducting studies to identify which objects present the biggest hazard and how many objects may need to be removed and from where.” It says that the viability of such an operation is “a question of treating the symptom or the cause of the problem. Building more physical protection is costly and if the environment deteriorates too far, becomes unviable. It is best to treat the root cause, the presence of debris in orbit, and remove the large objects before they can break up into many thousands of uncontrolled fragments capable of destroying a satellite on impact.”

The spokesperson also pointed out that “[u]nder current licensing regimes (such as in the UK), countries are now obliging operators to remove satellites from crowded regions of space at the end of operational life”.