Blunt arrows: the limited utility of ASATs

Blunt arrows: the limited utility of ASATs

by Dwayne Day

Excerpt from The Space Review

Monday, June 6, 2005

Last week in The Space Review Mark Listner wrote about the Outer Space Treaty and anti-satellite weapons (ASATs): “Although technically the treaty does not allow these types of weapons (considering the ban on military activities), the fact is that these have been under development at times in the past, and may be so today.” (See “It’s time to rethink international space law”, May 31, 2005)

This is false. The Outer Space Treaty places no limits on anti-satellite weapons and never has. During the Cold War neither superpower actively sought an international treaty that would restrict their development of anti-satellite weapons. There were several reasons for this, but a primary one was the difficulty in verifying such a treaty, especially considering the nature of the Soviet ASAT system, which utilized rockets that were indistinguishable from active ICBMs unless they were physically inspected.

Many of the conditions that make ASAT weapons not very attractive remain in effect, and some of the conditions that led to their approval in the past do not exist today.

Despite the lack of ASAT arms control, the United States has not demonstrated much enthusiasm or interest in developing an ASAT weapon since the beginning of the space age. This was because ASAT weapons were expensive, limited in military utility, and provocative. In fact, it appears that the decisive factor in developing or not developing an American ASAT has often been the existence of an enemy ASAT capability. Given the high cost and limited utility of the weapon, multiple justifications were needed to make it possible, and the one that tipped the balance in favor of development was the existence of an enemy that needed to be deterred.

The international situation has changed significantly since the Cold War. However, many of the conditions that make ASAT weapons not very attractive remain in effect, and some of the conditions that led to their approval in the past do not exist today.

Banning WMDs, not ASATs

The Outer Space Treaty resulted from a long series of discussions within the United States government and eventually between the two superpowers. The most important section of the Outer Space Treaty is Article IV, which states:

“States Parties to the Treaty undertake not to place in orbit around the Earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner.

The Moon and other celestial bodies shall be used by all States Parties to the Treaty exclusively for peaceful purposes. The establishment of military bases, installations and fortifications, the testing of any type of weapons and the conduct of military maneuvers on celestial bodies shall be forbidden. The use of military personnel for scientific research or for any other peaceful purposes shall not be prohibited. The use of any equipment or facility necessary for peaceful exploration of the Moon and other celestial bodies shall also not be prohibited.”

Like most Cold War era treaties, this one essentially codified actions that the superpowers did not find attractive to pursue in the first place. Putting weapons of mass destruction such as nuclear bombs in orbit makes little sense. Orbital mechanics means that an orbiting weapon spends most of its time out of range of its target, unlike an ICBM that is always the same distance from its target. In addition, limited computing power also restricted the utility of an orbiting bomb, because it could not be programmed with a large target list. Finally, command and control of a weapon overhead was worrisome—what if the other side was able to jam or take over the weapon? Neither side therefore wanted to place weapons of mass destruction (WMDs) in orbit, making a treaty banning them possible.

Similarly, there is no logical reason to base weapons on other planets unless they are defending other installations there. If both superpowers had active moonbases they might take weapons to defend them. But neither had plans for moonbases and so it was an easy step to ban all weapons—not simply WMDs—from the moon, Mars, and other terrestrial bodies.

A State Department website explains the origins and significance of the Outer Space Treaty, noting that its two most important provisions are the ban on WMDs and the ban on weapons on other terrestrial bodies. Nowhere does it mention a ban on ASATs. The Outer Space Treaty mentions nothing about ASATs, and for good reason—both the United States and the Soviet Union already possessed them when they signed the treaty.

The Outer Space Treaty mentions nothing about ASATs, and for good reason—both the United States and the Soviet Union already possessed them when they signed the treaty.

The United States had Program 437, a system that utilized a Thor ballistic missile equipped with a 1.4 megaton nuclear warhead. It would launch from Johnston Island in the Pacific Ocean and fly essentially a ballistic trajectory. Program 437 operated from 1964 until the early 1970s, at which time the inefficiency, expense, and limited usefulness of the weapon led to its withdrawal from service. Notably the Program 437 ASATs were both ground-based and used a nuclear weapon (a weapon of mass destruction), but did not enter orbit. These facts did not prevent the United States from signing the Outer Space Treaty, nor did any other signatories charge that the Americans were in violation of a treaty that they were signing.

The Soviets possessed their own ASAT weapon. Known as the “satellite destroyer” (or “Istrebitel Sputnikov” in Russian), it was fitted atop a modified ballistic missile and used the co-orbital technique, meaning that it entered the same orbit as its target and essentially got close enough to it to fire a weapon, sort of like a Claymore directional mine or a shotgun blast. Work on the IS started in the early 1960s and it was tested through the early-1970s. The existence of the satellite destroyer also did not prevent the signing of the Outer Space Treaty.

The existence of both of these weapons did vastly complicate any effort to ban ASAT weapons, however. In order to verify such a ban, each side would have to inspect the payloads of the other side. During the early 1960s the United States held substantial internal discussions about this subject, particularly the concern that the Soviets would want to inspect American rockets carrying reconnaissance satellites. This was discussed in the NSAM 156 Committee, named after the National Security Action Memorandum that established it.

Over time, those concerned with ASAT arms control both inside the executive branch and in Congress determined that on-site verification was impossible, and so any ban would have to focus on testing which should be detectable under many circumstances. But the fact that the Soviet weapon had already been tested and was considered to be operational tended to complicate and nullify this debate.

For the full article, visit The Space Review