ANTI-SATELLITE WEAPONS (ASATS)
The following is a brief introduction for the non-space weapons expert by a layperson gleaned primarily from university-level library and Internet resources and will provide a brief history of negotiated treaties, describe the early U.S. and Russian ASAT systems, describe the ‘current’ ASAT systems being developed, and describe some of the future ASAT systems planners envision. Some novel ASAT systems will be described. Hardening techniques will be briefly described and finally, implications on future problems relating to the health of humans living in our atmosphere will be suggested.
ASATs or anti-satellite weapons are any object or process with the potential to destroy or make inoperable a satellite.
The following brief legal history is important given that international treaties will be either renegotiated, broken, or continually broken as presently researched systems and future systems are tested and deployed. The Partial Test-Ban Treaty, signed on August 5, 1963 bans nuclear weapons testing in the atmosphere, in outer space, and under water. The next international treaty, the Outer Space Treaty, was signed on January 27, 1967 and says this: "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..." (7). The ABM (Anti- Ballistic Missile) Treaty was signed May 26, 1972 and states: "Each Party undertakes to not develop, test, or deploy ABM systems or components which are sea-based, air-based, space-based, or mobile land-based" (7). The ABM treaty does not specifically prohibit research on and development of anti-satellite weapons, thus, this provides loopholes. ASATs and ABM weapons use the same technologies so that ABM weapons can be developed by developing ASATs, ..... treaties can be broken, disregarded, or euphemistically sidestepped. As an example of how our government will skirt the law, although treaties disallow testing of anti-satellite weapons against satellites in space, the U.S. recently tested a laser against an Air Force satellite in space. The government claimed it was not testing the laser as a weapon but, rather, was testing the ‘survivability’ of the satellite. Semantic quibbling to get around the law!
The U.S. and Russians have been developing ASATs since the late 50's. The first successful satellite intercept occurred May 24, 1962 and was launched by the U.S. from Kwajalein Atoll. It was reported as a "close intercept ". The first generation ASATs were either non-nuclear or nuclear ballistic missile launched weapons that were either direct hit-to-kill devices, or satellites that in close proximity to the target satellite would explode with the satellite debris as the shrapnel particles that destroy the target satellite. In the case of nuclear-tipped rocket used as an ASAT, the thermal blast, x-rays, or other radiation effects, or electro-magnetic effects would be the kill mechanism. An early Russian ASAT effort was a multi-staged rocket with a small ground controlled satellite with direct hit-to-kill capability. A self-guided homing vehicle was tried using infrared homing, but the system failed several times in testing, was not successful in the 60's, and was dropped.
The American developed and tested exoatmospheric (outside Earth’s atmosphere) nuclear ASATs using kiloton, and, a 1.4 megaton nuclear weapon was detonated at an altitude of 248 miles on July 9, 1962. The actual satellite kill mechanism for nuclear explosion results from thermal heating, through magnetic field effects on electronic components and semi-conductors. X-ray radiation hitting the satellite surface creates a very high surface electrical potential and high surface currents. These surface currents produce strong magnetic fields that penetrate the satellite metal skin and disrupt satellite electronics. At the time of these tests, designers were ‘plagued’ with a highly disruptive "electromagnetic pulse" that could and did destroy satellites that were unintended as targets. The Americans abandoned nuclear testing in space, but the "system generated electro-magnetic pulse" was seen as a potential energy source for latter generation ASAT designs. They are still on the weapons designer’s tables.
In the 1970s, the Americans pursued a two-tracked strategy of attempting to negotiate with the Soviets to eliminate ASAT systems of the future and simultaneously developing a new ASAT system, an air-launched missile with infrared homing capability. A two-staged rocket was launched from a Navy F-15 jet at high altitude. The rocket was tipped with a miniature homing vehicle, self-propelled with on-board guidance that was a direct hit-to-kill system. The homing system used infrared radiation (heat) to guide the kill vehicle to crash into the target satellite. That system was defunded in segments, from 100 or so launch vehicles at the start, 40+ F-15s, and then down to where it was eventually dropped during the Reagan administration. It was never operational as a system although tests confirmed that it could knock a satellite out of the sky.
A radical shift in interest in ASATs, funding for ASATs, and development of ASATs took place in the Reagan presidency and continues to today. In 1965, Arthur Kantrowitz, the then-Director of AVCO Corporation, probably made the "first proposal for the use of particle beam weapons..." (6). In addition to the particle beams, the newer generation of ASATs includes another category of weapons referred to as ‘Directed Energy Weapons (DEWs). The distinction between the two is sometimes blurred. Particle beam weapons are a group of weapons that use electro-magnetic energy to accelerate particles, neutral atoms being likely candidates, to velocities close to the speed of light. A particle beam weapon called a ‘rail gun,’ is said to accelerate ‘charged’ particles to very high velocities. High-energy particle beams would, like nuclear explosions, either produce high surface temperatures, burning out the satellite electronics, produce high surface currents that would in turn produce electro-magnetic fields that would penetrate the skin of the satellite and disrupt sensitive electronics, or produce ions, electrically charged particles, that, depending on the particle type and energy, would disrupt satellite electronics by way of various radiation effects.
Lasers are part of a group of the DEWs that are, in fact, being built and tested. There are several types of lasers that can be used for ASAT weapons but all are devices that deliver highly focused energy as the "thing" that destroys. A wide spectrum of energy sources is available for use as the "stuff" that is moved, at the speed of light, carrying the destructive force. X-rays are the sources of an ‘eximer’ laser, where light is the source for LASER ASATs, and microwaves are the source for MASER ASATs. LASER is an acronym for the phrase-Light Amplification by Stimulated Emission of Radiation. MASER =Microwave Amplification by Stimulated Emission of Radiation. Directed energy weapons therefore will be streams of elementary particles, atoms, electrons, ions, light, microwaves, x-rays, gamma rays and even high powered plasmas that are accelerated to very high velocities that can ruin or destroy satellites.
There is a separate class of DEWS that, as a group, are planned to be spaced based; that is, as satellites themselves. They are called "nuclear pumped ASATs". These are weapons that will use a nuclear detonation in space which will produce x-rays, neutrons, gamma rays, or other parts of the electro-magnetic spectrum that will then be directed at the target satellite. These weapons will instantaneously destroy themselves in the nuclear detonation, are therefore one shot weapons that present danger to Earth’s inhabitants not only by contaminating the near outer space environment, but also as a threat during failed launches (as per the Challenger), and as failed satellites that can crash back to Earth’s atmosphere due to malfunction or collision with space debris. For those ASATs and anti-ballistic missile weapons using nuclear detonation as the source of energy for the weapon, the nuclear material on the space platform will itself be vulnerable to attack from adversary ASATs and further threaten Earth’s environment and inhabitants during conflict and thereafter, as that material could eventually crash back to Earth if dispersed because of satellite destruction.
Unfortunately this nuclear threat is not the only one associated with ASATs. The power for some of the directed energy weapons will come from nuclear reactors stationed in space, the weapon energized by a huge burst of nuclear material fissioning, like in a nuclear powered electric generating plant. This threat is further exacerbated by space-based ASATs, weapons satellites that will be powered by nuclear reactors for the day-to-day electrical needs, running the radar, the communications with the ground station and other satellites, on-board computers, and so forth. Satellites with these reactors will have to be launched, positioned in orbit, and maintained perfectly! Any mistake, however small, could have nuclear material, mostly Plutonium, a very chemically toxic and highly radioactive isotope, raining back down to Earth, polluting the Earth’s surface for generations. Note that this has happened with two Soviet spaced-based nuclear reactors. Malfunctions happened and these reactors crashed back to Earth, burned up in atmosphere, and spread nuclear materials over the face of Earth.
All future ASAT systems are not the very high tech Star Wars types of the Reagan era. Low(er) tech novel solutions are planned with some ready now. For example the Shuttle has satellite recovery ability evidenced by the Hubble repair effort. The captured Hubble could just as well have been an adversary’s spy satellite. Prepositioned space mines detonated when the offending satellite gets close are possible. A terrorist or military attack against a ground control station could disable a satellite just as effectively as an attack against the orbiting satellite. Unmanned satellite recovery is not beyond possibility. Recall that Mars was recently visited by robots.
Electronic signal manipulation is another major class of ASAT weapons effort. The signal to the satellite can be disrupted with a very loud, ‘electronic,’ competing signal. It is thus, ‘jammed.’ The signal to the satellite can be changed with incorrect information replacing the correct information. This is called "spoofing."
A significant and detailed argument about whether ASATs will work can be found in Stares, Space and National Security and The Fallacy of Star Wars by the Union of Concerned Scientists and revolves around the issue of increasing satellite survivability, the process of making a satellite less vulnerable to ASAT attack. An assessment of the argument requires one mentally consider satellites and ASATs in an all out go-for-broke, third world war, no-holds-barred scenario. ASATs will probably work, will be able to shoot down satellites. But, every shot will not result in a satellite kill, and to the extent that the designers have "hardened" their satellite, the satellite will last just that much longer, until, designs of the ASATs can be changed to overcome the hardening.
The methods used to "harden" or ‘increase the survivability of a satellite’ include some of the following:
- To begin, a satellite can be moved to a higher orbit. If, for example, the ASAT is a ground launched rocket with direct hit-to-kill capability, moving the satellite can add hours travel time to the satellite, time in which ground controllers could take evasive maneuvers.
- For satellite systems under attack by a ASAT with exoatmospheric nuclear warhead tipped capability spreading the satellites far enough apart could keep the nuclear detonation from taking out more than one satellite, hardening ‘the system’.
- Changing the satellite profile into one with a low radar cross-section would make it harder to see and therefore harder to knock out. {This method of hardening is particularly ominous. Satellites use large solar panels to generate the electricity to run the satellite. These panels will be eliminated and replaced with nuclear reactors (radioisotope thermal generators- RTGs). The satellite radar cross-section will be reduced but the danger to life on planet Earth will be immeasurably enlarged as these reactors with huge amounts of nuclear isotopes are launched, orbited around Earth, and disposed of. The threat is in the launch and in subsequent accidental reentry to Earth and its atmosphere.(See discussion of Cassini)}.
- Stealth technology using radar absorbing materials that can be applied to the satellite surfaces or construction of the satellite with radar absorbing materials is now possible.
- Radar and laser illumination sensors that warn the satellite of impending ASAT attack are now available and/or under development. These hardening systems will include filters and special shutters to protect sensors. Note here that an ASAT attack does not have to blow up or completely destroy the satellite but can ruin or make inoperable the satellite by ruining the sensors it employs.
- Infrared flares used to confuse a guidance system using infrared sensoring is a reality.
- Radar jamming devices would reduce the ability of the ASAT to ‘see’ the satellite.
- Radiation hardening includes construction of the satellite with metals that reduce the conductivity to the previously mentioned ‘system generated electro-magnetic pulse’ which arises from an ASAT nuclear explosion. Electrical components are now available, off the shelf, that are radiation hardened. Wrapping electrical components with materials that reduce electro-magnetic field penetration, Faraday cages, are evidently more than a theoretical possibility.
- Special materials that can withstand the thermal effects of laser heating are being researched and probably are now available.
- Satellites with the ability to ‘shoot back’ will bring the satellite hardening from the defensive phase to the active phase and Star Wars as active war in space will then become a reality.
- Redundancy, or having capability for whatever the satellite is positioned to do, in the form of other satellites pre-positioned, to continue the operation after an attack and loss of the original, ‘hardens’ the system, and ensures continued satellite system operation.
- Decoys can be employed confusing the ASAT with too many targets, obscuring the operative satellite and in the case of ASATs launched from Earth making destruction very costly.
Lasers using a variety of energy sources are currently being both developed and tested. Lasers can operate from the Earth, from the atmosphere, or from space. All three are being developed. The Mid-Infrared Advanced Chemical Laser (MIRACL) was tested in October, 1997. Reports on its success indicate that the operators were positive about the outcome. It was tested against an Air Force satellite and was said to have followed the satellite successfully for 30 km.. The test seems to really have been on the equipment that tracks and targets the satellite. This is a device called the SeaLite Beam Director (SLBD) and it is a the critical component of the laser. The laser makes the light. Getting it onto the target for the length of time required is the harder task. The satellite is moving very fast so that tracking and targeting the satellite successfully is vitally important. The SLBD is a large chunk of metal and electronics weighing 28,000 pounds! The MIRACL is itself a large structure. It is like a large combustion engine. It is a large combustion engine, also weighing tons and presently is rated at 2+ megawatt. Calculations, considering hardening techniques of new materials, indicate the power requirements may need to be raised by several orders of magnitude. This implies much larger chunks of equipment to be lifted into space, and most important, power sources, increasingly large nuclear reactors with large loads of radioactive isotopes that can fall back to Earth and contaminate the Earth and atmosphere.
The plan is to put a laser into a Boeing 747. When that effort is successful, size considerations will mean that the space-based laser will not be long in becoming a reality. Although part of the ballistic missile defense effort it will have satellite kill capacity and will therefore be a potential ASAT weapon as well.