ASAT weapons are being developed to destroy hostile satellites and ensure that a country’s own satellites are able to function without any interference. This trend is likely to pose a threat to any country, in hour of crisis
Space has been used for both civil and military purposes ever since the launch of the first satellite ‘Sputnik’ by the erstwhile Soviet Union way back in 1957. Since then exploitation of the sector has been dominated by military considerations as control of space is perceived to be the essence of ultimate command of Planet Earth. This is substantiated by the fact that the very first military satellite was launched in 1958, and in less than a year, the tests of anti-satellite (ASAT) weapons began. Thus from ‘militarisation’, by placing satellites in space to enhance terrestrial systems, we are seeing a graduation to ‘weaponisation’ of space with the development and deployment of ASAT weapons. Space-based assets are ‘force multipliers’, allowing traditional military missions to be conducted more efficiently. As the technology advanced, these assets became ‘force enablers’, opening up new mission possibilities. This perhaps is the irony dictating the development of both defensive and offensive weapon systems.
Not surprisingly, the advances in space technology have introduced a potential battleground that did not exist earlier. Space technology is entering a phase where systems are becoming complex and multipurpose, while the distinction between offensive and defensive is becoming extremely thin. In today’s world, with so many nuclear weapons dependant on satellites for their efficient use, any damage or disruption caused to the latter might lead to hostility between states and endanger international security.
Also, space-based systems are now being used to give early warning of missile launches or for target tracking, damage assessment and communications. The concern here is the ease with which satellites may be degraded and thus any threat to these systems will accelerate the arms race between nations.
Control of space is not only important to ensure access to satellites but also to support military operations on the earth. Any disruptions in these assets are likely to cause an imbalance in the strategic stability. The various systems orbiting the earth along with their applications are discussed in the subsequent paragraphs.
Reconnaissance craft are probably the most important type of military satellites since they are not only used for verifying certain arms control agreements but also are primarily used for pinpointing or acquiring military targets. These satellites can be divided into four kinds: photographic, electronic, ocean surveillance and early warning satellites.
- Photographic Reconnaissance Satellites: These detect, identify and pinpoint military targets. Sensors on board such satellites include television cameras, multi-spectral scanners and microwave radars. Most satellites broadcast a very wide signal which can be picked up in areas hundred of miles wide, but military satellites need to broadcast a narrow beam (as well as use encryption and frequency hopping).
- Electronic Reconnaissance Satellites: These are the ‘ears’ in space. They carry equipment designed to detect and monitor radio signals generated by activities on ground. Signals originating from military communications among bases, from early warning radars, air-defence and missile-defence radars or those used for missile control can be picked up by them. Not only do they locate systems producing electronic signals but also measure the characteristics of the signals so as to be able to plan penetration of defences. Satellites are also good surveillance devices and are involved in electronic countermeasures such as jamming an enemy’s signal, or revealing his activities which are intended to be undetectable.
- Ocean Surveillance and Oceanographic Satellites: These detect and track naval ships and determine sea conditions, which help in forecasting the weather. They can also detect submarines with equal ease.
- Early Warning Satellites: These give warning of a surprise attack by ballistic missiles. While the radars used earlier provided about 15 minutes of warning, the satellites have extended this warning time to 30 minutes.
Space-based sensors for surveillance of the earth, together with land-based surveillance systems, generate a considerable amount of data. The transmission of this and other data for military purposes need reliable and secure communication systems. Space is an area of vital interest as about 80 per cent of military communications are carried out using artificial earth satellites. Satellites also play a vital role in the command and control functions for the military forces of the big powers. Even communications between mobile forces such as aircraft, naval ships and soldiers on foot and their commanders is being conducted via satellites.
For many weapon systems, it is important to know the exact position and speed of a weapon. This is particularly so for missiles launched from sea-based platforms. Satellites are beginning to fulfil these requirements. Naval surface ships as well as submarines, aircraft and missiles determine their positions and velocities using signals emitted continuously by satellites. One of the more well-known programmes, the Global Positioning System (GPS), guides precision weapons such as joint direct attack munitions, conventional air-launched cruise missiles and Tomahawk land-attack missiles launched from aircraft and ships. GPS accuracy aids search and rescue, air refuelling, mapping, geodetic surveys, ground troop movements and other missions.
While the knowledge of cloud formation and movements is of importance in the photography of targets of military interest by reconnaissance satellites and in planning bombing missions, the amount of data collected is considerably more than this. These satellites have sensors which measure oxygen and nitrogen density of thermosphere, and which determine the temperature and water vapours at various altitudes. An immediate application of such data is for improving the accuracies of missiles.
The knowledge of geophysics is continually being refined and increased. An important aspect of geophysics is geodesy, which includes determination of size and shape of the Earth, its gravitational field, detail maps and location of cities, towns and villages as well as the precise positions of military targets on the globe.
v This brief review of the space assets having military use indicates that the military satellites of the major powers are increasingly becoming part of the worldwide nuclear and conventional weapon systems that threaten the Earth’s future. Hence, space based systems could become targets in any major future conflict.
Reviewing the Threat Matrix
It is an established fact that the bulk of satellites, spaceships, stations and probes launched so far have performed military functions such as intelligence gathering, communication and navigation. Hence, it is too late to prevent militarisation of space. Also, the extensive use of spacecraft for auxiliary military purposes makes them tempting targets for attack. Weapons are bound to be developed to hit targets in space and from space, counter systems would be built against such weapons. Then, anti- counter systems would be devised to neutralise the latter, and so on. This is possible as space offers ample room for military rivalry.
To be able to draw significance of the space strike weapons, it needs to be understood that these are global in range and scope and virtually instantaneous in effect. These can also be employed to hit ground, air and sea targets making them extremely versatile weapons.
An important aspect of the threat to the space– based system emerges from the fact that these follow largely predictable orbits — sometimes for years — and are relatively fragile objects. The threat emerges from the complex systems deployed and employed on land, sea, air, and of course, space. These are currently confined to the fields of:-
- ASAT Weapons
- Kinetic energy weapons
- Directed energy weapons like lasers and particle beam weapons
Apart from satellites, space stations and space shuttles can be used as platforms for these weapons. The succeeding paragraphs will trace the complexities of the threat matrix emerging out of the numerous systems that have thus far been employed.
The ASAT weapon systems are being developed to destroy space-based systems which may pose a threat to any country in hours of crisis. The purpose of these weapons will be twofold: first, to destroy hostile satellites in space and second, to ensure that a country’s own satellites are able to function without any interference. Some of the systems employ nuclear-tipped missiles wherein the nuclear explosion affects the electronic and semi-conductor components of the system. Further, these weapons are not the only means of carrying out ASAT activities. The ground receiving stations linked to communications satellites and the space surveillance network are also vulnerable to attack. Thus, in any discussions involving ASAT systems, weapons capable of destroying such ground data-receiving stations and ground-based satellite command and control systems would also be considered. There are considerable similarities between the basic technologies used in ASAT and Ballistic Missile Defence (BMD) weapons. Hence, work on one can boost developments in the other area.
Since 1989, the US has been developing a programme featuring a hit-to-kill warhead, called the Kinetic Energy Anti-satellite (KEASAT) weapon, similar to that being developed for BMD. KEASAT uses a visible light optical seeker to find and track the target while a small computer-operated rocket motor guides the vehicle onto a collision course. It also has a shroud for the purpose of containing all the debris so as not to create space junk that would jeopardise US spacecraft. Electronic signal manipulation forms another major class of ASAT weapons. 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.
Kinetic Energy Weapons
Kinetic energy or impact weapons can be propelled either by chemical rockets or by electromagnetic forces. These normally employ rocket interceptors or rail guns, both using a Miniaturised Homing Vehicle (MHV) that homes in on the target and destroys it by direct impact. For rail guns, the homing vehicle is called a ‘guided projectile’. The corresponding device for interceptors is the Space-Based Kinetic Kill Vehicle (SBKKV). The rail gun’s guided projectile is launched alongwith a rail with tremendous acceleration by an electromagnetically generated force that acts on the projectile. According to current designs, this projectile would also have propulsion for guidance. The interceptor’s rocket is designed to accelerate its payload to maximum velocity in space, where it would be terminally guided. Limits on the velocity of space-based rocket interceptors do pose a few problems.
Interceptor rockets have an advantage. They can be fired in a salvo, that is, launched together to attack many targets at the same time. Thus, if they are within the range of a large number of space-based systems, they could destroy most of them simultaneously. On the other hand, rail guns do not have this advantage as their projectiles are fired sequentially. Despite producing higher velocities, they use energy less efficiently. This would imply that a defence constellation of rail guns would require a smaller number of battle stations, as the coverage varies inversely to the square of projectile velocity. The rate-of-fire limitations rule out the possibility of all projectiles being launched immediately. Given these limitations, if the Inter-Continental Ballistic Missiles (ICBMs) are launched simultaneously, it may not be possible for a single gun to attack all the ICBMs launched in the vicinity of the battle stations before the boost phase is completed.
Kinetic energy weapons are, however, well suited for attack during the post-boost and midcourse phases due to the advantage of lethality. As long as a direct hit is obtained, the target will be killed, since it is impossible to harden a booster, a bus, or a RV against kinetic energy weapons.
Directed Energy Weapons
Lasers: It is an acronym for ‘light amplification by simulated emission of radiation’. It is a device that produces an intense, narrow beam of electromagnetic radiation which is capable of destroying a missile by damaging the skin or outer casing of the missile. The feature that makes a laser particularly attractive for destruction of space systems is its potential to deliver a narrow beam at a great distance at the speed of light. This makes it faster than any kinetic energy weapon, by over a thousand times.
From early 1990s, lasers have demonstrated the capability to be developed as potential weapons against space based assets. High-energy lasers based either in space or on the ground with relay mirrors could be very potent weapons when used against a relatively soft target such as satellites, boosters or a bus. The problem is that lasers can only kill boosters at a certain rate. The laser beam must ‘dwell’ on the target for a certain length of time before the laser spot will burn through the skin of the booster and destroy it. This ‘dwell time’ is directly proportional to the laser spot area and the target hardness, and inversely proportional to the average power of the laser.
The US is developing an Airborne Laser (ABL) programme, which is designed to acquire, track and destroy theatre ballistic missiles. This may be the first step towards building a spacebased laser weapon system. In addition to the ABL, another programme is underway to demonstrate the feasibility of a high-energy laser weapon in space. The underlying assumption is that the entire weapon platform must be deployed in space as this is the most technologically feasible and cost-effective approach. An alternative architecture involves placing the laser device on the ground and employing optical systems, which are basically large mirrors, to relay the laser beam to the target. While another option entails using a combination of space-based lasers and optical relay mirrors in order to reduce the number of costly laser platforms. With its tremendous speed, lack of recoil and extremely long range, laser offers the potential to destroy missiles and other space based systems.
The four major types of high energy laser systems that are being considered for space-based and ground-based laser weapons are:-
- Chemical lasers powered by a reaction between hydrogen and fluorine, oxygen and iodine, and deuterium and fluoride
- Excimer lasers using krypton fluoride
- Free electron lasers
- X-ray lasers
Particle Beam Weapons
These fall into two categories, neutral and charged particle beams. All particle beams start out as charged beams, accelerated up to speed and steered by magnetic or electric fields. To create a neutral beam, the charge is then removed by stripping one of the electrons from each particle. These do get absorbed by the atmosphere and can be used up to about 600 kilometres.
Threat from Emerging Technologies
The use of orbiting rods of depleted uranium equipped with small boost rockets and GPS guidance electronics could be ordered by ground controllers to plunge from orbit, travelling at hypersonic velocity as they neared Earth. They could penetrate hundreds of feet into the earth, overcoming all attempts to harden underground command bunkers. They might even be effective against high-value airborne targets, such as Airborne Warning and Control System aircraft.
Electromagnetic radiation weapons might be another technology that is close to coming into its own. Development of large thin-film antennas could enable spacecraft to project narrow beams of Radio Frequency (RF) energy over long distances to either space or ground targets.
There are some rendezvous space weapons, for instance small satellites that gradually edge closer to target space assets. They might quietly spray paint onto an adversary’s sensors or solar panels or nudge the craft gently to send it out of orbit. Rendezvous weapon’s effects might be difficult to distinguish from simple malfunctions. Some of the weapons that could be used against satellites, such as aircraft-launched kinetic anti-satellite interceptors are relatively inexpensive compared with the cost of the satellites themselves. Decoys might be one defensive solution. Lightweight fake satellites attached to the real thing with long tethers might be able to deceive some anti-satellite weapons. Furthermore, development of space ‘mines’ may soon be within the reach of a number of nations. Mines are quite awkward to negate, as it is not clear if they would be detectable from the ground.
The next step up the escalator is likely to be the electronic jamming of an adversary’s space assets. The act of ‘uplink jamming’— or interfering with satellites themselves via brute-force noise or other selected wavelength interference — is an attractive option but requires large amounts of electric power. That means uplink jamming systems are likely to be large and complex. Downlink jamming — blocking ground-system reception of space transmissions — might be a simpler technological task. The dedicated jamming aircraft and helicopters now used to perform conventional airborne jamming missions could be modified for use in this role.
Finally, the world needs to consider how to clear space debris. Such an activity might be analogous to clearing sea lanes of mines or dangerous flotsam. Today, Earth is orbited by more than 150,000 pieces of debris which are large enough to damage or destroy any space system. The amount of such debris is likely to mushroom in years to come, when there will be hundreds or even thousands of small to medium-size satellites in orbit.
The security of assets in space is critical to confidence in strategic planning. If strategies in this environment are to include possible conventional war and limited nuclear conflicts, the utility of space assets rises dramatically.