China's Antisatellite Missile Test: Why?

We may not yet know enough to understand China's intentions.

On January 11, 2007, an aging Chinese Feng Yun 1C polar weather satellite orbiting 865 kilometers above Earth was struck by a kinetic kill vehicle carried on a ballistic missile launched from China's Xichang Space Center. It was a successful antisatellite (ASAT) weapons test that showed that the Chinese could, in the future, knock down U.S. satellites. On February 23, U.S. vice president Dick Cheney responded during a speech in Sydney, Australia, first by noting China's "important role" in the recent treaty with North Korea, then by stressing that "last month's antisatellite test, and China's fast-paced military buildup, are less constructive and are not consistent with China's stated goal of a 'peaceful rise.'"

The aftermath: In both images above, the red band represents debris from the recent Chinese destruction of a satellite. In the top image, the green band represents the orbital path of the International Space Station; in the bottom image, it represents the many low-Earth orbit satellites currently in use. Credit: Dr. Thomas Kelso at CSSI (Center for Space Standards and Innovation)

Multimedia •  View individual, larger versions of the above images.

In fact, what the People's Republic intended with its ASAT demonstration isn't obvious, given contradictory signals that have emerged from China. But one thing is for sure: the Chinese ASAT test is the largest debris-generating event in Earth orbit ever recorded. NORAD has catalogued 917 pieces of debris. Yet that figure represents only what's trackable; NASA's Orbital Debris Program Office estimates that more than 35,000 pieces of debris larger than one centimeter were also created.

Furthermore, analysis by the Center for Space Standards and Innovation (CSSI), in Colorado, just after the Chinese test was first reported showed debris spread from below 200 kilometers up to almost 4,000 kilometers, posing a threat to many operational satellites due to the debris cloud's polar orbit. According to Thomas Kelso at the CSSI, computer modeling predicted that during the week following February 28 there would be 1,033 occasions when a Feng Yun 1C fragment would come within five kilometers of a satellite payload in low-Earth orbit (LEO). "Over any seven-day period, we're now routinely seeing 1,000 to 1,100 conjunctions within five kilometers between the Feng Yun satellite's fragments and payloads in Earth orbit," Kelso says.

Graphics supplied by the CSSI illustrate the possible hazards to other satellites in LEO, including the International Space Station (ISS). The first graphic shows how the ISS passes through the ring of debris at the southern part of its orbit. The second figure shows the larger population of LEO satellites that could also be affected (view graphics). "At CSSI, we have orbital data for 2,792 payloads in Earth orbit," Kelso reports. "Out of that total, 1,866 of these payloads pass through the zone now affected by the debris from the Chinese ASAT test--in other words, that's two-thirds of all payloads in Earth orbit."