One week ago, a major “space first” occurred high over west central China — and in total darkness. No fiery explosion or glowing clouds would have been seen. But an aging Chinese satellite was instantaneously converted into a 542-mile-high cloud of metallic confetti.
As first reported in Aviation Week and Space Technology, and confirmed a few hours later by National Security Council spokesman Gordon Johndroe, U.S. intelligence agencies believe that China launched a medium-range military missile from its Xichang spaceport and guided it into a high-speed, head-on collision with a weather satellite called Fengyun-1C.
For the first known time in history, a missile launched from the ground destroyed an orbiting satellite. The event is supposed to have occurred about 5:30 p.m. ET on Jan. 11, or 6:30 a.m. Beijing time Jan. 12.
Previous anti-satellite weapons tests, conducted during the Cold War, involved either co-orbiting killer satellites (the Soviet approach) or an air-launched anti-satellite missile (the U.S. approach, also considered by the Soviets but never attempted). Some tests involved shooting ground-based anti-missile missiles toward satellites, but those missiles never hit their mark. And a NASA flub of a robot rendezvous in 2004 resulted in the active satellite accidentally hitting — but not damaging — its target satellite.
Extraordinary chain of events
Many of the details surrounding last week's event are classified — but even the unclassified information confirms that something extraordinary occurred.
The North American Aerospace Defense Command, or NORAD, routinely releases reports on the orbits of hundreds of satellites of interest. Fengyun was the subject of about one or two reports per day throughout 2006, going into early January. But there were three reports on Jan. 10, then five reports on Jan. 11. And there have been no reports on Fengyun-1C since the time of the reported disintegration.
Rumors of an “energetic breakup” started circulating last weekend. A spokesman for the U.S. Strategic Command reported having no information about the breakup — but considering the hundreds of different pieces that are probably now being tracked, it can take a week or more to make sense of the radar returns.
Evidence of an actual missile launch would require tracking data from infrared observation satellites operated by the Pentagon. While that information would be highly classified, the obvious confidence among officials promoting this interpretation implies that they do, in fact, possess that sort of evidence.
It remains remotely possible that Fengyun blew up on its own, as many satellites and derelict rockets do when leftover fuel eventually mixes and ignites. But according to an expert who talked privately with MSNBC.com, the satellite “had little or no prop[ellant]; the only internal energy source might be batteries, which don't have that much energy. So it would be easy to rule out internal causes.”
Fengyun's loss also could be due to a massive meteoroid or orbital debris hit, occurring coincidentally within range of China’s main space launch base. But the odds of that are even smaller.
How big — and how high — a threat?
Why Fengyun became such an object of interest to U.S. military intelligence agencies in the days before the missile launch remains intriguing — and possibly of critical importance. Perhaps the retired satellite had been reactivated, and observers recognized this as an omen of the impending fireworks.
The last orbital data released by NORAD seem to show one end of the satellite's orbit being raised by about 20 miles (32 kilometers). Such tweaking is characteristic of a satellite lining up its orbital path for a rendezvous with a ground-launched visitor. The international space station does this in preparation for Russian spacecraft visits.
In fact, the reason the U.S. Air Force chose the air-launched anti-satellite system is that it does not have to have its target line up with a ground-based missile pad. Naturally, a real target in the real world would never make such a helpful maneuver.
Without the target’s maneuver to make itself easier to kill, a ground-based shot would likely have to be made from the side — or “out of plane,” in space navigation parlance. With such a geometry, the final approach for physical contact occurs under much higher rates of angular change, making terminal guidance much more difficult. It can be done, but with less reliability.
The geometry of this particular test (and also, whether this test was the first shot, or the fourth or fifth or more) remains classified. But further leaks and revelations can be expected.
How to avoid a space bullet
Also to be expected are suggested schemes for countermeasures. First of all, space is not under a uniform hazard from ground-based weapons. The higher you are, the less threatened you are. This is partly a matter of travel time: It could take a weapon four to six hours to reach a target in the 24-hour geosynchronous arc over the equator, where critical observation and applications satellites are located. But it's also a matter of accuracy and closing speed. Higher orbits pose much more of a challenge for weapons that depend on a fast relative closing speed for a “kill.”
Slideshow: Planetary pleasures In lower orbits, the best defense is a good pretense. That is, a potential target may survive by not allowing its hunters to know where it is accurately enough to get a warhead on a collision course. Either the target follows an adequately unpredictable orbit (often only a matter of being a few miles away from where the killer expects it to be), or it is accompanied by decoys in nearby orbits.
Deploying a larger number of smaller satellites is also an option. Being able to launch replacement satellites quickly has been considered, but producing and stockpiling enough spare payloads and boosters — and then getting the payload activated quickly enough once it arrives in space — has proven to be an operational and engineering nightmare.
The last-ditch defense — actually trying to stop an incoming impactor — remains a science-fiction dream. And that is largely because the “kill mechanism” of the weapon is so very, very simple.
It’s a throwback to the first weapons our remote ancestors used on the African savannah: Hit the sucker with a rock.
The physics of space killing
Experts tell MSNBC.com that after a space-to-space collision, a hypersonic shock wave goes through the satellite. The shock wave tears the structure apart from the inside out and reduces it to shrapnel.
The collision almost instantaneously results in two separate clouds of debris where once there were two separate objects. Those debris clouds fly approximately along the original paths of the objects, gradually spreading out over time.
If, as in last week's case, one of the high-speed objects was in a suborbital trajectory, its cloud would fall back into the atmosphere fairly quickly. Perhaps it produced a short-lived meteor storm that ground observers might have wondered about.
The original missile ascent might also have been visible over hundreds of miles. In the past — especially in secretive countries such as Russia and China — rocket launchings have led to widespread reports of UFOs. These might trickle in over the next few days, and would be extremely valuable to analyze with the knowledge of what really caused them.
In 1985, the U.S. Air Force fired a kinetic kill vehicle against a retired military satellite called Solwind. The satellite disintegrated into a swarm of fragments, almost 300 of which were big enough to be tracked by ground radars. The last of them took 15 years to re-enter the atmosphere and burn up.
Soviet tests of killer satellites between 1968 and 1982 showed a different pattern of debris, because the kill mechanism was not a head-on crash. Instead, it was a high-speed buckshot cloud created by firing a shaped charge after the interceptor maneuvered close to the target (presumably to inspect it and verify it was hostile). As a result, the target satellite remained essentially intact, although spinning, with its solar panels and camera ports presumably smashed and a few small pieces possibly breaking off. In contrast, the attacking satellite itself was usually fragmented by the force of the shaped charge’s detonation.
For a number of years, misled by fighter pilot memories, U.S. Air Force analysts believed that the object that did not disintegrate had to be the winner over the one that did — a good example of being fooled by past experience.
The diplomatic orbit
The most obvious reason for China’s test at this time would be to push the United States, and particularly the new Democrat-controlled Congress, into signing a formal treaty banning the use of anti-satellite weapons. Otherwise, any ground-based missile — in a silo, on a submarine, or even on a test range — would have to be considered a potential anti-satellite weapon.
The United States, while asserting that it does not possess and is not developing such a weapon, has become diplomatically isolated on this issue in recent years by proclaiming that such a treaty is undesirable because it isn’t needed — because there has not been any “arms race in space” that would require a formal agreement. The Chinese test trumps that excuse.
The political response has been predictable, and probably just what China intended. For example, Rep. Edward Markey, D-Mass., told The Washington Post that the Chinese action makes it essential that the administration begin negotiations to stop any possible space arms race.
However, there's a problem with relying on the proposed treaty to ban anti-satellite weapons. The treaty would mean only what each signatory thought it meant — except in the United States, where a ratified treaty would become subject to federal court enforcement and thus would mean whatever any crusading judge wanted it to mean.
A Russian-Chinese working paper on disarmament (PDF file) is not reassuring. The diplomats discuss definitions of concepts such as “Outer Space” or even “Space Weapons,” but they argue that a treaty might not really need specific definitions — for the reason that it is so difficult to reach agreement on them.
Another problem relates to enforcement, particularly with regard to dual-use systems. There are a dozen different projects to develop space rendezvous robots for repair, resupply or inspection in orbit (consider, for example, the Russian-German TECSAS project). The flick of a joystick during close approach is all it takes to convert a rescue mission into an attack. How could a piece of paper ward off that eventuality?
Is the genie out of the bottle?
Now that a ground-launched anti-satellite system has been demonstrated, getting that genie back into the bottle may prove a daunting challenge. Henceforth, any reasonably sized military missile could be a satellite-killer with the addition of a Volkswagen-sized warhead.
Such ambiguities underscore the criticality of credible inspection of all space-bound objects. Both the Russians and Chinese, who are pushing for a treaty, have acknowledged the difficulty of this issue and have proposed identical solutions to the impasse: Forget about inspections, just sign the treaty and trust each other.
At a recent disarmament conference, Chinese representatives said verification of a space treaty was "extremely difficult to negotiate."
"For the time being, to put on hold the verification issue until conditions are ripe, and to negotiate a treaty without verification provisions could be a practical alternative,” the Chinese statement said.
Russian negotiators concurred. “Elaborating the treaty without verification measures, which could be added at a later stage, might be a preferable option,” they said.
Such an approach would eliminate principles of treaty negotiation that go back to the days of Ronald Reagan and Mikhail Gorbachev: verifiability and enforceability. If it all comes down to blind trust of nonbinding, ambiguous promises, why bother signing anything at all?
For China’s long-range military strategy, the potential payoff from last week's bold move is high: to compel the United States into a treaty that will hamper its own space activities, while avoiding collateral consequences. It makes a whole lot more sense than steering onto an expensive new arms race, especially if you can win the race at the starting post.
NBC News space analyst James Oberg spent 22 years at NASA's Johnson Space Center as a Mission Control operator and an orbital designer. He is the author of several books on international space policy, including "Space Power Theory" and "Star-Crossed Orbits."