broadcast satellites reside. The air force is currently tracking some 13,400 man-made objects in space, of which only a few hundred are active satellites. It acknowledges that there are more than 100,000 pieces of smaller, untrackable debris, each about the size of a marble (one centimeter) and millions of still smaller fragments. NASA officials have estimated that there may be about four million pounds of space junk in LEO alone.25 This debris includes dead or dying satellites, pieces of spent rocket boosters, all manner of metal shrouds and fairings, tools, nuts, bolts, and clamps of every size and description, lens caps, and even frozen sewage. In LEO they are traveling at the same speed as the space shuttle—17,500 miles per hour—or they would fall into the Earth’s atmosphere and be burned up.
Astronaut Sally Ride, the first woman in space aboard the Challenger space shuttle in 1983 and 1984, a member of the presidential commission that investigated the Challenger’s explosion in 1986, and a professor of physics at the University of California, San Diego, has been adamant that the use of antisatellite weapons would be “disastrous” because of the debris they would be likely to create. On her inaugural mission in June 1983, an incident fixed her opinion on this subject: “About halfway through the flight there was a small pit in the window of the space shuttle and we didn’t know what it was. An awful lot of analysis was done while we were in orbit to make sure that the strength of the window would sustain reentry. It did. We were all fine. But the analysis afterward showed that our window had been hit by an orbiting fleck of paint, and the relative velocities were enough that the paint actually made a small but visible gouge in the window. Well, a fleck of paint is not the same as a small piece of metal travelling at that same speed. So, as soon as you start increasing the amount of junk in a low Earth orbit, you have an unintended byproduct that starts putting some of your own quite valuable satellites at possible risk.”26
Joel Primack, a professor of physics at the University of California, Santa Cruz, agrees: “Weaponization of space would make the debris problem much worse, and even one war in space could encase the entire planet in a shell of whizzing debris that would thereafter make space near the Earth highly hazardous for peaceful as well as military purposes.... Every person who cares about the human future in space should also realize that weaponizing space will jeopardize the possibility of space exploration.”27 Primack observes that the density of debris is already so great at the 900-to 1,000-kilometer altitude (563 to 625 miles) and at the 1,500- to 1,700-kilometer altitude (938 to 1,063 miles) that pieces of junk colliding with each other could set off a chain reaction or cascade of collisions—the Kessler Effect, predicted mathematically in the 1970s by the NASA scientist Donald Kessler—that would make the zones useless.28 The Council on Foreign Relations Study Group on Space Weapons defines space debris as “unguided, hyper-velocity kinetic-energy weapon[s]” and concludes, “Because the United States owns a significant majority of the world’s satellites, it would suffer disproportionately from any increase in the amount of space debris.” Its overall conclusion is that “space weapons are not suited to the threats currently facing the United States in space or are outpaced by terrestrial alternatives.”29 All forms of space weapons, it noted, cost much more than terrestrial weapons systems, which of course do not have to be boosted into orbit, a cost that commercial operators put at between $300 million to $350 million per satellite.30 Earth-based weapons such as unmanned aerial vehicles (UAVs), cruise missiles, ICBMs, or submarine-launched intermediate-range ballistic missiles can do anything space-based weapons can, and a Tomahawk cruise missile costs a mere $600,000.
The air force has been conspicuously reluctant to discuss these issues. On September 15, 2004, the Pentagons Missile Defense Agency (MDA) said in a public statement that it was contemplating putting space-based missile interceptors in orbit by 2012 but acknowledged that such “kinetic kill vehicles,” in Pentagon jargon—weapons that destroy their targets simply by colliding with them at very high speeds—would create a great deal of space debris. It noted that a chunk of debris ten centimeters in diameter is likely to be as damaging to an orbiting spacecraft as twenty-five sticks of dynamite.31 Nonetheless, it planned to proceed with its antisatellite interceptors.
Some air force officers take the view, despite ample evidence to the contrary, that debris in low Earth orbit does not last long and quickly falls back into the atmosphere where it is burned up. The MDA report states, for instance, that in most cases debris that might be created by a missile-defense intercept would re-enter the atmosphere before completing a full orbit, and therefore would put satellites at risk only briefly. It advocates that vulnerable spacecraft such as the International Space Station and the Hubble Telescope be maneuvered out of the way to avoid collisions with debris. There is some evidence that debris resulting from missiles fired from the Earth might indeed quickly fall back into the atmosphere, but this would not be true of debris from space-based kinetic vehicles.32 Debris from satellites placed in the higher geosynchronous orbits will, of course, never descend into the atmosphere but go on spinning around the Earth forever. That is why much greater attention should be paid to moving spent communications satellites into “graveyard orbits ,” reserved for space junk and off- limits to voyagers and satellites.
Meanwhile, the
Despite air force propaganda, there is no way to protect our satellites by putting weapons in space. The only rational active defense would involve building redundancy into our space systems so that the loss of a particular spacecraft would not cripple us; the maintenance of replacement satellites ready to be launched into orbit whenever they are needed; the hardening of electronic components on particularly important satellites against microwave, laser, or other directed-energy attacks; and finally learning how better to disguise the laser, radar, visible, and infrared signatures of satellites, making them much harder to target in orbit.
Thirty years ago, during the period of Japan’s high-speed economic growth, I was in Tokyo talking with an official from that country’s trade ministry. Japan was then, as today, totally dependent on imported petroleum from the Middle East. I pointed out that Japan’s supertankers were highly vulnerable. What, I asked, would Japan do if a hostile power sank one of its tankers in the narrow straits around Singapore? His answer was straightforward: call Lloyd’s Insurance Company. It would be much cheaper to construct a new tanker than to defend the sea-lanes from Japan to the Persian Gulf by building a navy. There is a lesson in this for the United States. We cannot afford our air force’s plans to protect our space assets militarily, and the air force does not know how to do so in any case.
The missile-defense program is easily the most important place to examine the air force’s failures. There are potentially three ways to bring down an ICBM: first, in its boost phase, when the warhead and the rocket are still joined and both are heading up through the atmosphere to outer space; second, after the warhead has separated from the booster and is speeding through space toward its target; and finally, in its terminal phase, the extremely short period (measured in seconds) when the warhead reenters the atmosphere and plunges toward the Earth. The Clinton administration worked only on a midcourse interception by ground-based “kill vehicles.” The Bush administration took over this project and accelerated it but added brand-new and very expensive research objectives: downing a missile shortly after liftoff and during its final descent. Dubbed the “multi-tiered missile defense,” it aimed at giving the United States as many opportunities as possible to stop an incoming missile.
