Friday 24 April 2009

How China Loses the Coming Space War (Pt. 2)

If China and the US are going to come into armed conflict with each other in the next several decades, it will almost certainly be over the status of Taiwan. China has, for instance, indicated that it would be willing to use force if Taiwan took steps to formalize its independence from the main land or otherwise prevent its eventual reunification under the rule of the Peoples Republic. In such a scenario, it is entirely likely China could consider trying to negate or drastically reduce the US ability to use space at a tactical level.
But China could not launch the massive attack required to have anything like a significant effect on US ability to utilize space without months of careful planning and pre-positioning of special, ASAT carrying missiles around the country. It would also have to utilize its satellite launch facilities to attack any US assets in deep space: the GPS navigation satellites and communications satellites in geostationary orbit. Most importantly, it would have to time the attack so as to hit as many US satellites as simultaneously as possible. And, despite all that movement, Beijing would somehow have to keep the whole thing secret. Failure to do so would undoubtedly result in the US attacking the large, fixed facilities China needs to wage this kind of war before the full blow had been struck. Even if the United States failed to do so, China would undoubtedly plan for that contingency.

Based on the orbits of US military satellites determined by the worldwide network of amateur observers, there appears to be a large number of low Earth orbit military satellites over China several times each week. To hit them, China would have to preposition its ASAT-tipped missiles and their mobile launchers in remote areas of China, one position for each satellite. (If reports of low reliabilities for these missiles are correct, two or more missiles might be assigned to each satellite.) Furthermore, these positions are really only suitable for a particular day. If Chinas political and military planners have any uncertainty at all about which day to launch their space war, they would need to pre-position additional launchers around the country. Thus, attacking nine low Earth orbit satellites could require as many as 36 mobile launchersenough for two interceptors fired at each satellite with a contingency day if plans changemoved to remote areas of China; areas determined more by the satellite orbits than Chinas network of road. (As will be discussed below, nine is about the maximum they could reasonably expect to hit on the first day of the space war.)

Xslc_launch_pads At the same time that China would be trying to covertly move its mobile missile launchers around the country, it would also have to assemble a fleet of large rockets -- ones normally used for launching satellites. The more large rockets China uses for this task, the more deep-space satellites it can destroy. At present, however, China only has the facilities for assembling and launching a total for four such rockets nearly simultaneously. Two would have to be assembled out in the open where they could be observed by US spy satellites and two could be assembled inside a vertical assembly building during the 18 days it takes to stack and fuel the Long March rockets stages while preparing to launch. [See right.] Even the two assembled indoors would need to arrive by train and eventually would have to be moved, one after the other, to the launch pad. Each of these rockets, usually reserved for launching satellites into geostationary orbits, could carry three to four interceptors and their special orbital maneuver motors to attack either US navigation satellites, at about 12,000 miles altitude, or communications satellites at about 22,000 miles.

Four days prior to the attack, China would launch the first of its Long March rockets carrying deep-space attack ASATs; the same launch pad would have to be used for the second rocket stacked inside the vertical assembly building. As the technicians renovated that pad, the first rockets payload would circle the Earth in a parking orbit at about 200 miles altitude waiting to be joined by the other deep-space ASATs. This would appear to be a tell-tale sign of an impending strike. But China could explain the delay to the international community by claiming that the third stage, intended to take the payload it its final altitude, had failed to fire and that they were working on it. Roughly six hours before the first the attack on the USs low Earth orbit military satellites, the other three Long March rockets would have to be fired since it takes roughly that long to get their payloads up to their targets orbits. Delays or failures to launch any of these rockets would strand their interceptors on the launch pad and subject them to possible retaliatory bombing by the US.

If all goes as planned, China would have launched between 12 and 16 ASATs, each capable of destroying a strategically important deep-space satellite. However, the United States military has many, many more deep space satellites. There are, as of December 2007, 32 functioning GPS navigation satellites even though the original design calls for only 24. [See above, left] In addition, the US has 23 military communications satellites, six early warning satellites that observe missile launches, and six surveillance satellitesmost of which detect and monitor electronic transmissions of potential adversaries but one, apparently capable of photo-reconnaissancein geostationary orbit. These satellites are reinforced by a private network of 90 commercial communications satellites, owned and operated by US corporations, that presumably could be used to replace destroyed military communications satellites. (Eighty-four percent of the space communications to military forces in the Iraqi theater of operations during Operation Iraqi Freedom used commercial satellites.) On top of that, there are 75 civilian and the 64 military/civilian communications satellites in low Earth orbit although they do not have the same transmission capacity as the geostationary satellites. The United States may be the country most dependent on space for its military activities. But it is also the least vulnerable, because of the tremendous redundancy of its space assets.

Of course, China does not have to destroy all these satellites to seriously hamper US military efforts in the Taiwan Straits. It would only have to destroy those satellites that have a direct line of sight to the conflict: this includes eight military and 22 US civilian communications satellites in geostationary orbits. Nevertheless, China would have to choose between attempts to destroy the satellites that guide US precision guided bombs and those satellites which relay the orders to drop those bombs. It simply cannot launch enough ASATs to destroy both systems.

But does China have enough to wipe out even a single set of American satellites? Lets examine the possibilities:

Attacking Navigation Satellites
You need a launch pad to attack a target in deep space, like an American GPS satellite. China has just three of these pads. This really restricts Chinas offensive capabilities in space. Assuming that China devotes all its deep-space ASATs on GPS satellites, it could destroy at most 16 satellites. At the current time, with 32 functioning navigation satellites, that would still leave 16 satellites still working. Over a period of years, the debris from those collisions would represent a significant threat to more than those satellites immediately attacked. They would pass, time and time again, through the belts of debris that resulted from the interceptions. However, it would probably take longer than the military conflict China initiated with these attacks before additional satellites were destroyed by subsequent collisions.

Usually, there are about nine GPS satellites over China at any given time. If China somehow managed to destroy all of these, it could eliminate America's use of precision-guided munitionsfor a few hours, until the orbits of other GPS satellites take them over the Taiwan Straits. Quite quickly, the constellations other 23 satellites would fill in the gap due to their normal orbital movement. Even if it destroyed 16 satellites, China could still only interrupt GPS over the Straits for about eight hours. During the other 16 hours there would be the four or more satellites present over the target area for bombing runs, unmanned aerial vehicle (UAV) flights, and ship tracking. This pattern of eight hours off followed by 16 hours when GPS could be used would be repeated every day until new satellites are launched. This outage would certainly cause difficulties; GPS not only guides American precision bombs it helps pilot UAV spy planes, and monitor ships. US casualties might increase , with air crews forced to fly missions during daylight hours and conduct some of the "dull, dirty, and dangerous" missions now flown by robotic planes. It's a situation no American commander would want to face. But it would not be a catastrophic one. And it would not eliminate precision weaponry, UAVs, or any other American activity that depends on GPS.

Keep in mind, this is the worst of the worst-case scenarios. It is highly unlikely that China could remove all the satellites over the conflict area at the same time. After all, attacking 16 satellites, all in different orbits with ASATs launched on just four different rockets involves some fairly complex orbital maneuvers. A much more likely scenario is that, at best, China could destroy four GPS satellites in the initial wave followed roughly seven hours later by four more, a third wave at roughly 45 minutes after that, and the final wave two hours later. Thus, the GPS attack is spread over ten hours and never eliminates all the satellites visible over the area of conflict at the same time. This Chinese attack on US navigation satellites would not eliminate or even significantly degrade the USs ability use precision-guided munitions..

Attacking Communications Satellites
While it is possible for China to eliminate the eight US military communications satellites in geostationary orbits that can broadcast to the Taiwan Straits, Beijing does not have enough the lauch capacity for as many ASATs as it would take to eliminate all 22 civilian communications satellites that could also be used. However, not all of these satellites have equal capacities for transmitting information; it might be possible for China to destroy enough of that capacity to limit the US military.

During the invasion of Iraq in 2003, US armed forces sent and received a tremendous amount of information via satellite. This included video conferencing between the Pentagon and the commanders in the field, satellite photographs downloaded to operations planners, orders directing jets where to drop their bombs, and soldiers emailing their families back home. At its peak, all of this added up to about three billion bits per second, a tremendous amount of information. Bandwidth was and continues to be a premium on the battlfield, particularly at the tactical level. And the appetite for information is only increasing. But the total amount of information transmitted over satellites is certain to increase by the next time we go to war; perhaps it could triple or even quadruple to twelve billion bits per second in the next ten years.

Assuming that the eight military communications satellites are destroyed first, that leaves at most eight ASATs to destroy the eight most capable civilian communications satellites. If these eight are removed, then there is still a total capacity of over 14 billion bits per second in US owned and operated civilian communications satellites. Thus, there should be enough transmission capacity for our military -- even if the demand for satellite communications increases by a factor of four. And the US military is used to using civilian satellites, as the 2003 invasion of Iraq showed. The vast majority (84%) of all military communications into and out of the theater of operations went through civilian satellites.

Attacking Early Warning Satellites
The United States has five satellites in geostationary orbit that detect missile launches using the heat released from their exhaust plumes. These satellites are primarily used to alert US nuclear forces to massive nuclear attacks on the homeland. However, in recent years, they have played an increasing role in conventional conflicts, such as both Gulf Wars, by cueing tactical missile defenses like the Patriot missile defense systems that gained fame in their engagements with Saddams SCUD missiles. Because of this new use, China might find it useful to attack them with ASATs. Since there are only five of them, China could destroy the entire constellation but at the cost of diverting some of the few available deep-space ASATs from other targets. Of course, China would not have to attack all five but could limit its attack to the three that simultaneously view the Taiwan Straits area.

If China did decide to destroy these early warning satellites, it would greatly reduce the area covered by US missile defenses in Taiwan against SCUD and longer range missiles. This is because the area covered by a theater missile defense system is highly dependent on the warning time it has; the greater the warning time, the more effective the missile defense systems radar is. Thus a Patriot battery, which might ordinarily cover the capital of Taiwan, could be reduced to just defending the military base it was stationed at. Some analysts believe that China would gain a tremendous propaganda coup by having a single missile make it through US defenses and thus might consider this use of its deep-space ASATs highly worthwhile even if it could not increase the probability of destroying military targets. On the other hand, China would run a tremendous risk of the US believing it was under a more general nuclear attack if China did destroy these early warning satellites.

Throughout the history of the Cold War, the US has had a policy of only launching a retaliatory nuclear strike if an incoming attack is detected by both early warning satellites and radars. Without the space leg of the early warning system, the odds of the US misinterpreting some missile launch that it detected with radar as a nuclear attack would be greatly increased even if the US did not view the satellite destruction as a sufficiently threatening attack all by themselves. Such a misinterpretation is not without precedent. In 1995, Russias early warning radars viewed a NASA sounding rocket launch off the coast of Norway and flagged it as a possible Trident missile launch. Many analysts believe that Russia was able to not respond only because it had a constellation of functioning early warning satellites. Any Chinese attacks on US early warning satellites would risk both intentional and mistaken escalation of the conflict into a nuclear war without a clear military goal.

Attacking Low Altitude Satellites
China would launch its first attack against a US electronic intelligence satellite in low Earth orbit minutes before the first wave of deep space ASATs hit their targets. The same type of ASAT used to target the deep-space satellites could also be launched on short range missiles from Transporter-Erector-Launchers (TELs). These are 22-wheeled vehicles that look very similar to tanker trucks. They're more sophisticated than the mobile launchers that Saddam used during the first Gulf War to launch SCUDs toward Israel and Saudi Arabia but would be no easier to find and destroy.

The exact order of attacks will depend upon the specific day and hour chosen but a typical attack might involve a first launch against a Lacrosse signals intelligence satellite followed within seconds by another, this time against a Keyhole 11 high-resolution spy satellite. Moments later, three ASATs would be launched against small groups of three NOSS satellites that the Navy uses to locate an adversarys ships at sea. These travel around the Earth in closely spaced groups of either two or three satellites and triangulate on the radio signals emitted by warships. During a span of about twenty minutes, China could attack and destroy a total of nine US military satellites in the scenario considered here. Inevitably, however, there would eventually be a lull in satellite crossings because of the random clumpings of satellites along their orbits.

If the United States does nothing to protect itself, such as change the orbits of its lower altitude satellites, China could continue to shoot down military satellites as they come over the horizon using pre-positioned ASATs. It is highly unlikely, however, that the United Sates would simply roll over while these attacks took place. Even today, with no formal satellite defenses, we could be fairly effective at stopping the destruction of our satellites.

Nevertheless, the loss of those satellites that were destroyed would be significant. It would increase the revisit times between spy satellites, which might not matter so much for reconnaissance satellites in a tactical setting. The loss of a significant fraction of the Navys enemy ship surveillance system, however, might be more important in battles around the Taiwan Straits. Without timely determination of enemy locations, the US would have to increase the number of aircraft devoted to scouting -- and subsequently
decrease the number of combat missions -- as these planes are diverted.

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