Chinese ASAT Test Raises Debris Threat to EO Sats
Director, World Security Institute’s Center for Defense Information
As of March 9, the total space debris created by China's Jan. 11 test of an anti-satellite (ASAT) weapon had leapt to 1,500 pieces(1) and counting—and those are just the larger bits that can be seen. According to Nicholas Johnson, chief scientist for NASA's Orbital Debris Program Office at Johnson Space Center in Houston, Texas, the Chinese test “represents the most prolific and serious fragmentation in the course of 50 years of space operations.”(2)
Unfortunately for operators of Earth observation (EO) satellites, China's destruction of the aging Fengyun-1C (FY-1C) weather satellite happened right smack in the middle of their neighborhood at an altitude of 860 kilometers in the highly popular sun-synchronous, polar orbit. Not only does the new debris represent an increased near- and mid-term threat to today's satellites, the specter of further tests—or wartime use—of destructive, direct-ascent ASATs poses an even greater threat to the existence of all EO operations. Even more unfortunately, there are no easy options for eluding those threats.
Code Red for LEO?
The Chinese space debris now being tracked by the U.S. Space Surveillance Network has migrated from the FY-1C impact point to become a cloud stretching from 3,850 kilometers high down to about 200 kilometers, in essence polluting all of low Earth orbit (LEO). Again, this is only what can be seen: debris chunks larger than 10 centimeters in diameter, about the size of a baseball. NASA is estimating that at least 35,000 smaller pieces of FY-1C (between one and 10 centimeters in diameter) are also floating in the same general vicinity. Such debris may be small, but it can be deadly. Traveling at 10 times the speed of a rifle bullet, even flecks of paint can be hazardous to a satellite's health. According to Johnson, any of the Chinese debris bits “has the potential for seriously disrupting or terminating the mission of operational spacecraft in low Earth orbit.”(3)
Owned and/or operated by 33 countries plus the European Space Agency, 130 known Earth imaging satellites (commercial, civil and military) are active today. Of that total, at least 102 will routinely pass through the new debris cloud.(4)
Figure 2 Screen shot from AGI viewer file - view of LEO satellites (green) and debris ring (red) from Chinese ASAT test. Xichang Space Center is also shown. STK-generated images courtesy of CSSI (www.centerforspace.com).
The new Chinese debris adds to an already worrisome problem. LEO currently is the most polluted orbit, with significant concentrations of space junk in the 800-kilometer band frequented by EO and weather satellites.5 According to T.S. Kelso, technical program manager for the Center for Space Standards & Innovation (Colorado Springs, Colo.), of the 10,453 space objects for which the U.S. releases orbital data, 7,636 of them are in LEO, defined as 2,000 kilometers and below. (Most, but not all, of those objects are debris, but that figure also includes the some 389 working satellites in LEO and a handful of satellites with elliptical orbits that pass through LEO.)
Prior to the Chinese test, debris experts put the aggregate chances of a destructive collision in LEO at about one in a decade—the approximate lifetime of a satellite in LEO—although the chances of any one satellite being hit by a piece of debris was shown to be significantly smaller, with the meantime between impact with a debris piece larger than 10 centimeters something like 15,000 years.6 Assessing collision risk is so complicated as to sometimes appear a “black art” rather than a science, and experts have yet to get a handle on how much the Chinese test might have raised the odds of a destructive impact in LEO. However, Kelso has calculated that the Chinese test has raised the likely number of “close conjunctions” between space objects larger than 10 centimeters (when objects pass within five kilometers of each other) by 19.47 percent. “Not insignificant,” he said.
The UN Committee on the Peaceful Uses of Outer Space offers hope in the pending agreement on a voluntary debris-mitigation regimen that includes a pledge by nations to refrain from deliberate creation of space debris. Still, it is starkly clear that if debris threats in LEO increase significantly, at some point the question of costs versus benefits for operators will arise, not only in insurance but also in viable life-span of assets.
Long-Term ASAT Threat?
Beyond the near- and mid-term ramifications of the debris threat, the Chinese ASAT test raises long-term cause for concern about the safety of EO satellites: the possible introduction of destructive ASATs into future arsenals. The Chinese test was the first dedicated ASAT-weapons test in more than 20 years, highlighting the growing tensions in space caused largely by the increased reliance on space assets by the world's militaries, especially that of the United States. In addition, some developing nations have begun to question the legitimacy of satellites for Earth observation and “spying” that were established by the former Soviet Union and the United States during the Cold War as a means of reducing nuclear tensions. Indian leaders, for example, have complained that Google Earth is enabling a potential threat from terrorism or arch-rival Pakistan.(7)
While the Chinese are the first to break the unspoken taboo against ASATs that has existed for the past two decades, other nations—including the United States, India and Israel—are known to be considering satellite attack methods as part of their military strategies for the future. And although the U.S. military continues to shy away from destructive ASAT weapons in favor of what the Air Force terms “temporary and reversible means” such as jamming, it is highly unclear (as witnessed by the Chinese test) that others would follow that high-technology route in the event of an ASAT competition.
This possible future use of ASATs is doubly bad news for EO operators. While jamming (or possible laser blinding) attempts can be thwarted or at least made more difficult with technological protections, there aren't really any escape routes from a direct ascent attack for LEO-based satellites. Enabling the capability for rapid and significant maneuvering is simply too costly.
While one future solution might be the replacement of today's constellations of a few large satellites with more numerous small or micro-satellites (a capability proven feasible by the five-nation Disaster Monitoring Constellation),(8) the current reality is that a world where ASAT warfare is possible is a world in which EO satellites are in grave danger. While EO operators up to now have largely been ignoring the growing international debate about the wisdom of ASATs, it is apparent that they now are no longer able to do so.
Theresa Hitchens is Director of the Center for Defense Information, and a consultant for Secure World Foundation, which works towards efforts to establish the secure and sustainable use of space through enforceable, law-based global systems.
Note Editor Ray Williamson also writes about orbital debris in Policy Watch.
- The number of pieces being tracked, according to NASA; the number entered into the official catalog on Mar. 9, 2007 was 1,117.
- Leonard David, “China”s Anti-Satellite Test: Worrisome Debris Cloud Circles Earth,” Space.com, Feb. 2, 2007, www.space.com/news/070202_china_spacedebris.html
- Data from the Union of Concerned Scientists' Satellite Database,
- “Orbital Debris Frequently Asked Questions,” NASA Orbital Debris Program Office website, http://orbitaldebris.jsc.nasa.gov/faqs.html
- “Space Debris: Assessing the Risk,” European Space Agency, March 16, 2005,
- Elizabeth Svoboda, “Google”s open skies raise cries,” The Christian Science Monitor, Dec. 1, 2005, www.csmonitor.com/2005/1201/p13s01-stct.html
- The project involves Algeria, China, Nigeria, Turkey and the United Kingdom, and provides medium-resolution capability based on a micro-satellite design by Surrey Satellite Technology, Ltd. of the United Kingdom.