Space Debris in LEO Continues to Increase

The Secure World Foundation and Canada’s Project Ploughshares released the latest edition of their Space Security Index this week. The report assesses trends in eight indicators of space security. The 2011 report is the eighth in the series.

The first trend pointed out in the report is that the amount of debris in low Earth orbit (LEO) continued to increase during the past year (2010). Debris from China’s 2007 antisatellite (ASAT) test against one of its own satellites has surpassed 3,000 objects according to the report. Some of the increase can be attributed to discovery of additional debris from the test itself, but some is also caused by debris impacting other debris and creating more of it. Even though there is more awareness of the problem, “space debris continues to pose an increasing threat to operational satellites and the long-term sustainability of space activities,” says the report.

The report also notes that the U.S. Department of Defense (DOD) is adding to its capabilities to track and catalog such objects in Earth orbit through space situational awareness (SSA) activities such as plans to build a new Space Fence of ground-based radars. Information in the report is current through the end of 2010. More recently, the House Appropriations Committee recommended significant cuts to the proposed Space Fence and other DOD SSA plans in the defense appropriations bill (H.R. 2219).

During a panel discussion at the Canadian Embassy on Wednesday where the report was formally released, Andrew D’Uva, President of Providence Access Company, provided an update on the Space Data Association (SDA). One of the issues facing satellite operators is to know not only where satellites are, but where they are going. Operators often deliberately move their satellites from one orbital location to another, and occasionally lose control of a satellite entirely and it drifts through space affected by forces such as the solar wind.

For the first many decades of the Space Age, there were few satellites compared to the vastness of space in Earth orbit. Satellite owners did not worry about bumping into other satellites. But with the growth in operational and defunct satellites, not to mention space debris, collision avoidance based on luck alone no longer can be taken for granted. The 2009 collision of a commercial Iridium satellite with a defunct Russian satellite in low Earth orbit (LEO) drove home that point.

The U.S. Air Force provides a public catalog of thousands of space objects (http://www.space-track.org/), but it does not include classified satellites and the data it does make public are not always precise. Created by three of the major satellite operators – Intelsat, Inmarsat, and SES – SDA uses data provided by its members to more accurately track their satellites and coordinate actions. Likening the movement of satellites in orbit to traffic on a highway, D’Uva said that “SDA is putting turn signals on satellites.” He said enlightened self-interest motivated creation of SDA, not criticism that DOD does a poor job with its publicly available database. However, he noted that in a recent episode where Intelsat operators lost control of a satellite (Galaxy 15) and it drifted across a wide expanse of geostationary orbit (GEO), the data about the satellite’s location in the publicly available DOD database were incorrect 15 percent of the time. “We can’t rely on the TLEs,” he said, referring to the DOD database of “two line element” sets. SDA provides collision avoidance monitoring for 222 commercial satellites from 15 satellite operators in GEO, plus 112 satellites from seven operators in LEO. He estimated that is about 60 percent of commercial GEO satellites and a smaller percentage of commercial LEO satellites.

The Space Security Index tracks trends in eight indicators of space security grouped into three categories: the condition of the space environment (such as space debris); the type of actors in space and how space is used; and the status of space-related technology as it pertains to protecting or interfering with space systems, or harming Earth from space. In previous editions, a ninth indicator was included – space-based strike weapons (SBSW). The authors of the report concluded this year, however, that there is “an absence of reliably documented SBSW” and they would reinstate it if and when there is “clear evidence…that such weapons are being developed or deployed.”