Friday 24 April 2009

How China Loses the Coming Space War (Pt. 3)

If China was to attack the strategically important deep-space satellites it would give the United States at least an indication of the impending attack two or more weeks prior to launch as it assembled its Long March rockets on their launch pads. There could be few other reasons for China to assemble so many rockets at its satellite launch centers for near-simultaneous launches. The US could, if it wished to initiate hostilities, destroy the rockets before they were launched using either stealth bombers or cruise missiles. Alternatively, it could wait and use its National Missile Defense interceptorswhich have an inherent ASAT capabilityto shoot down the first group of deep space ASATs as they wait for D-day in their parking orbit.

Once on their final trajectory, however, there is little or nothing the US could do to prevent them from striking their targets. It would be impossible, for instance, to move the targeted satellites out of the way in the final moments before the collision. The Chinese ASATs are known to be capable of very high speed maneuvers and trying to move a GPS or communications satellite to avoid a collision would require such dramatic changes in velocity as to shear off their solar cell panels and antennas. Having protector satellites in orbit near strategically important targets would also be counter productive. If such protectors raced out and destroyed an approaching ASAT they would simply create a shotgun blast of debris that would continue to circle the Earth and would every twelve (if attacking a GPS satellite) or 24 hours (for a communications satellite as the target) have another chance of colliding with its target. Time, in this case, is very much on the side of the attacker.Since China doesn't have enough deep-space ASATs to stop communications -- or even prevent GPS being used during most hours of the day -- Beijing might not even attempt to attack those targets. Which means the United States wouldn't have much of warning, to prepare for the onslaught. In that case, it is almost certain that China could destroy a number of surveillance and signals intelligence satellites in low Earth orbit before the US could take action.

If we assume that the US chain of command takes an hour, due to bureaucratic inertia, to react, China could destroy a total of nine such satellites before the US responds in the specific case examined here. This includes two out of the three functioning Keyhole high resolution photo-reconnaissance satellites, one of the three Lacrosse signals intelligence satellites in orbit, and six of the 15 NOSS satellites that the Navy uses to locate enemy ships at sea. This represents billions of dollars lost and, more important, a large fraction of the US space assets in low Earth orbit that could have been used in the subsequent conflict.

At that point, however, the United States could effectively stop Chinas attack simply by changing the remaining satellites orbital speeds by as little as 200 mph (they are typically moving at over 16,500 mph). This very small change will have a large effect in the position of the satellite the next time it crosses over China; effectively putting the satellite out of range of the pre-positioned ASAT launcher. This is not an excessive change in speed and, unless the satellite is very close to the end of its operational life, is well within the capability of its onboard fuel supply. Furthermore, it does not have to change its speed very rapidly the way a deep-space satellite would have to in order to avoid collision in its final moments. Instead, this relatively small velocity change has tens of minutes or even hours to change the position of the satellite before the next time it crosses over China. During this time, it is steadily moving away from its original position so that it could be hundreds of miles from where China thought it was going to be.

While it is possible that the pre-positioned ASAT missiles could still reach their target even after it had changed, they would not know where, exactly, to aim the missile. Instead, they would have to perform a radar search for the satellite in an ever expanding volume of space. This volume quickly becomes too large for even the most powerful of mobile radars. In fact, it would take a fairly large (perhaps 50 feet in diameter) to detect the satellite during its next pass and China does not have a lot of those radars. So most, if not all, of the satellites remaining after the first hour would be safe for the next 24. During that time, the United States could try to destroy all of Chinas fixed radars that are capable of tracking the satellites in their new orbits. (In other words, it does not matter how many additional ASATs China has to shoot at low Earth orbit satellites; a very different circumstance than the deep-space ASATs.)

This might, however, prove difficult; especially those facilities in the center of China that are out of reach of Tomahawk cruise missiles. Currently, only B-2 bombers could reach those sites with any chance of success and timing might prove difficult if they need to transit other countries during night time. A Global Strike capability, such as a conventionally armed Trident missile, might ease this task. Of course, even if all the radars are destroyed, China could still use optical telescopes to determine the new positions of the satellites but these methods are too slow to be used for aiming the ASAT missiles. And even then, China would have to spend days repositioning its mobile ASAT launchers, a task that would probably take several days and would extend the time the US could use for hunting down and destroying Chinese assets.

The short-term military consequences of an all attack by China on US space assets are limited, at most. Even under the worst-case scenario, China could only reduce the use of precision-guided munitions or satellite communications into and out of the theater of operations. They would not be stopped. China could destroy a large fraction of strategic intelligence gathering capabilities; but not all of it. With a greater than normal expenditure of fuel, the remaining US spy satellites could continue to survive their crosses over China and photograph Chinese troop movements, harbors, and strategic forces but, of course, at a reduced rate. The war would, however, quickly move into a tactical phase where the US gathers most of its operational photographs using airplanes, instead of satellites. US ships and unmanned vehicles might, theoretically, have difficulty coordinating, during certain hours of the day. Most of the time, they would be free to function normally. Chinas space strike would fail to achieve its war aims even if the United States failed to respond in any way other than moving its low Earth orbit satellites.

When it warned of a space Pearl Harbor, the Rumsfeld space commission was afraid that a lesser power could launch a surprise attack that would wipe out key US strategic assets and render the US impotent. This is what Japan tried, but failed, to do at the start of World War II. And much like Japans failure to destroy the US carrier fleet, a Chinese attack on US satellites would fail to cripple our military, Chinas strategic goal in launching a space war.

But if the short term military consequences to the United States are not that bad, the long term consequences to all space-faring nations would be devastating. The destruction of the nine satellites hit during the first hour of the attack considered here could put over 18,900 new pieces of debris over four inches in diameter into the most populated belt of satellites in low Earth orbit. Even more debris would be put into geostationary orbit if China launched an attack against communications satellites. In the immediate aftermath of the attack, the debris from each satellite would continue to clump together, much as the debris from last years test. However, over the next year or sowell after the terrestrial war with China had been resolvedthe debris fields would fan out and eventually strike another satellite.

These debris fields could easily cause a run-away chain of collisions that renders space unusable -- for thousands of years, and for everyone. Not only is this a quickly growing and important sector of the worlds economy (sales of GPS receivers alone reportedly exceeds $20 billion annually), but space is also used for humanitarian missions such as forecasting floods in Bangladesh or droughts in Africa. We cannot allow space to be forever barred to our use for what turns out to be a very minor military advantage. If the military utility of attacks in space are so minor; if the active defense of space assets is impractical, counterproductive, and unnecessary; and if the danger resulting from the consequent debris affects all space-faring nations for thousands of years to come, it is clear that diplomacy is in every country's interest.

The first step the United States should take is a simple declaration that we guarantee the continued flow of information to any country whose satellite is destroyed by an ASAT. We could do this using either our military or civilian-owned satellites. After all, if the space assets of the United States are not vulnerable to attacks because of the inherent redundancy, the same cannot be said of Chinas other potential regional competitors such as Australia, India, or Japan. Each of these countries has only a handful of satellites that could be quickly destroyed if China chooses to attack them. This declaration would effectively eliminate any military advantage that a country might get from attacking its neighbors limited fleet of satellites. After that, we should adopt the code of conduct that is being developed by the Stimson Center that establishes rules of the road for responsible space-faring nations. Finally, we should work toward a treaty banning the future testing of these most dangerous of anti-satellite weapons: the so-called "kinetic kill interceptors" that create such large amounts of debris. It'd be a first step towards containing the worst effects on war in space.

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