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The Science Behind the Air Strikes
By Wagdy A. Sawahel, Ph.D., EurBiol 24/10/2001
The U.S. initiated a military campaign on Sunday October 7th, 2001 against
Afghanistan with the aim of hunting down Osama bin Laden - accused of organizing the September 11th attacks on the U.S. - and the Taliban who are sheltering him. For that purpose, the United States is using devastating weapons such as cruise missiles and smart bombs.
These destructive weapons are guided by TVs, infrared cameras, satellites, laser beams, or global positioning systems. However, despite this advanced technology, the missiles are not 100% reliable. American forces must deal with the unique challenges that each missile exhibits as it attempts to weaken the bin Laden network.
In addition, miserable winter weather with heavy rains, clouds and snow - as well as the Afghan mountain ranges - often hamper air strikes. As a result, Afghan cities, villages and civilians may suffer. Because of these circumstances, the United States must learn to overcome the unique challenges of each missile system and the inclement weather in order to minimize civilian losses and increase their military success rate. So what is the science behind these missiles and how is the United States working to minimize civilian losses?
Military Tactic:
What America is clearly hoping for is that a combination of external military pressure and internal defections or dissent will speed up the collapse of the Taliban regime. The stages the U.S.-led military campaign in Afghanistan might follow include:
1. Initial Stage:
The initial stage of attacks aims to destroy surface-to-air missile batteries belonging to the Taliban, to disrupt command and control centers and to destroy Taliban aircraft on the ground and/or render their runways unusable.
2. Stage Two:
Stage two has been focused on destroying the under-surface targets, such as networks of caves and bunkers thought to be used by the al-Qa'eda organization and the Taliban rulers. Any change in focus of the air operation to hit Taliban ground units and their foreign allies loyal to Osama Bin Laden could herald a ground offensive by the anti-Taliban forces.
3. Stage Three:
America has sent ground forces, supported by helicopters, into Afghanistan. However, the perils of this deployment are substantial and missiles and bombs are likely to remain the primary means of attack in the short term.
Types of Air Operations:
1. Military air strikes
The United States and the U.K. have begun using some of the vast range military hardware available to strike at targets in Afghanistan. Land and carrier-based aircraft and sea-launched cruise missiles have been in action. These military hardware include the following:
A. Bombs
In addition to regular bombs being used to destroy surface targets, more powerful bombs, capable of pile driving themselves through many meters of earth, concrete or rock before exploding, will be used.
B. Cruise Missiles
Cruise missiles are sophisticated flying bombs. Air-launched cruise missiles - with a 2,000-lb warhead - are dropped from B-52 long-range bombers. Sea-launched Tomahawks - with a 1,000-lb warhead - are launched using a rocket motor. They make their way to a pre-programmed target using GPS satellite navigation and other guidance systems.
C. Smart Bombs
"Smart Bomb" is an umbrella term for a varied range of bombs and missiles. Some have TV or infrared "seeker" devices in the nose of the weapon through which an attacking pilot can see and "lock onto" the target before launching the weapon. Laser-guided bombs track an inverted cone of reflected light from a laser beam shone onto the target.
D. Bunker Busting Bombs
The guided bomb unit GBU-28, often called a "bunker buster" was developed in a record time during the Gulf War in order to hit underground Iraqi command centers. It is fitted with a 2000 kg conventional warhead. These laser-guided bombs are dropped from F-15 fighter/bomber aircraft or B-2 stealth bombers, and can penetrate up to seven meters into concrete or 30 meters into the Earth.
E. Joint Direct Attack Munitions (JDAM)
The JDAM is a kit that can be fitted to conventional "dumb" deep-penetration bombs in order to turn them into precision weapons, guided by a combination of the global positioning satellite network and their own inertial guidance system. JDAMs have the advantage of working in any weather, unlike laser-guided weapons. They are also much cheaper. While a GBU-28 may cost $ 145,000, a JDAM is priced at only $ 10,000.
F. Vacuum Bomb
A thermobaric weapon typically comprises of a container of volatile gas or liquid and two relatively small explosive charges. The first bursts open the casing, producing a deadly explosive mist, which is ignited by the second. The resultant intense fireball is followed by an immense overpressure and shockwave moving at several thousand meters per second. Its destructive capability is such that it can be compared with a low yield nuclear device.
G. B61-11 Nuclear Bomb
An unlikely but available option is the B61-11. The 350 kg weapon is designed to be delivered by a B-2 stealth bomber and to direct its explosive force downwards. A tail-mounted rocket accelerates the B61-11 downwards, allowing its hardened nose to penetrate up to 20 meters into the ground. The directed nuclear blast would cause extensive destruction to a depth of several hundred meters.
2. "Bombing" with Food
The U.S. has also started airdropping 37,500 humanitarian ration packets to refugees within Afghanistan. This was done from Air Force C-17 transport aircraft. They have four turbofan engines and can carry a load of 170,000 lbs (77,000 kgs). In spite of their size, these planes can operate from even a poorly prepared airfield. However, it has been reported that some Afghans were burning food parcels dropped by U.S. forces in protest to the attacks. One major concern is that the food parcels are being dropped in fields littered with un-detonated mines, left there by the Russians during their incursions.
3. "Bombing" with Radios
Psychological operations will play a key role in the war in Afghanistan. Leaflet drops and radio propaganda broadcasts are the chief weapons. Six EC-130E "Commando Solo" aircraft are known to be in the Afghanistan region. These planes operate as airborne radio stations, blocking local transmissions and broadcasting replacement propaganda programs. Only one third of people in Afghanistan are thought to be literate, so many of the U.S.-dropped leaflets will be printed with cartoons and illustrations and portable radios will become tuned into the U.S. military propaganda frequency.
Types of Launchers
1. Aircraft Carriers
The United States carriers, Carl Vinson and the Enterprise, are in the region. On board each are 70-80 planes used for attacks, defense, mid-air refueling, jamming enemy communications and radars and for airborne surveillance.
2. Fighters and Bomber Aircraft
A. B-1B Lancer
This is a long-range bomber capable of flying inter-continental missions without refueling. It has a crew of four and can fly at speeds in excess of 900 mph. It was originally intended to carry nuclear weapons to penetrate Soviet defenses and the swing-wing B-1 was first used in combat against Iraq during operation Desert Storm.
B. B-2 Spirit
These are the world's most costly aircrafts. Stealth features (technologies that make military machines less easy to detect with radar) account for its bizarre, triangular shape.
C. B-52 Stratofortress
This is a huge, heavy, intercontinental bomber regularly upgraded since the Cold War years. It has a crew of five and can carry up to 20 cruise missiles as well as dozens of conventional bombs.
D. F/A-18 Hornet
This is the U.S. Navy's main carrier-borne strike aircraft. It was designed from the outset to be capable of multiple roles - as a fighter or in ground attack and reconnaissance roles. Its range with a typical weapon load is limited to about 450 miles without mid-air refueling.
E. F-14 Tomcat
This big, two seat fighter is designed primarily for air defense above a carrier battle group. A11 can now carry the LANTERN navigation and targeting pods, allowing them to drop laser-guided bombs for precision strikes on ground targets. It has "variable geometry" wings, which sweep back at high speeds.
F. AWACS
These are flying command centers with various radar and communications systems. The E-3 sentry is a Boeing 707 derivative used to co-ordinate attacking aircraft over targets. It can fly for more than eight hours without refueling.
Accuracy of the Air Strikes
There are many natural factors which can affect the accuracy of the air strikes.
1. Weather
Miserable winter weather and lofty terrain can severely hamper air strikes. Cloud cover and snow will increasingly make laser-guided impossible and few aircrafts can work efficiently at the high altitudes of the Afghan mountain ranges.
Laser-guided bombs are not reliable unless the skies are clear, as they cannot work in bad weather. This is because rain and snow scatter the beams and keep them from passing through clouds. This could particularly affect operations around the southern city of Kandahar, where deep tunnels and nearby hills offered protection against the Russian air raids in the 1980s. Snowfall is more common here than around the capital, Kabul.
If the weather is too bad to use laser-guided bombs, an option is to use bombs fitted with global positioning systems (GPS). These are programmed with the target's coordinates and have a GPS receiver built into the tail. The GPS receiver checks the bomb's position with a GPS satellite and steers it towards the target. But GPS-guided bombs have drawbacks too, not least of which that they less accurate bombs. The programmer must have immensely detailed information of the area they want to target and if the target can move, they will most likely miss.
U.S. Special Forces in Afghanistan will now be trying to locate key targets from the ground, using laser range finders to record their exact coordinates. Their mission will contend with sub-zero temperatures. As winter draws closer in the capital city of Kabul, temperatures are likely to fall to around minus 10 oC by January. In some of the mountain valleys, conditions will get much worse. Temperatures go down as low as minus 30 oC in some of the high valleys.
2. Altitude
If ground troops need close air support with heavy supplies being dropped off, altitude will be an issue. Afghanistan has mountain ranges over 6100 meters (20,000 feet) and the thinner air at higher altitudes makes it difficult for aircraft to operate. This is not a problem for B-52s, but helicopters will have a problem if they fly above 10,000 feet - or even lower than that if they are carrying a lot of troops or equipment.
Air Strikes Assessments
Knowing the challenges that face them due to varied missile accuracy and weather conditions, the Bush Administration has been very careful to order up detailed strike assessments of their targets in order to insure accuracy and minimal loss of civilian life.
1. International Satellites
Some data on the success of strikes can be obtained from satellites, and computers can compare and contrast images to spot changes. However, even the best satellites only pass over a particular spot twice a day, so they cannot reveal short-term changes. Also, images are impossible to obtain if it is cloudy.
2. U.S. Satellites
The U.S. military has about five satellites capable of producing images at its disposal: three photographic satellites and two radar satellites. A number of commercial companies can also provide satellite images of anywhere in the world on request. The best of these have a resolution of one meter. U.S. military satellites have a resolution of around 10 to 15 centimeters.
A National Reconnaissance Office (NRO) satellite launched on October 5, 2001 on a Titan IV rocket from Vandenberg air force base in California was believed to be a top-secret KH-11 spy satellite that could monitor Afghanistan. The satellite was likely to be equipped with a digital camera capable of picking out objects as small as 10 cm (4 inches) across on the ground. Orbiting hundred of miles above the Earth, the 15 ton KH-11 is capable of tracking small groups of people walking on the ground as well as vehicle and weapons movements. It can monitor conversations and even spot campfires at night using infrared technology.
On October 10, 2001 another "national security payload" was launched by NRO - a U.S. intelligence agency that designs, builds and maintains spy satellites - on an Atlas rocket from Cape Canaveral Air Force Station in Florida. This satellite would relay data such as imagery collected by other spy satellites to ground stations for use by intelligence experts. Spy satellites beam the information up to the relay satellite, in orbit about 25,000 miles (40,000 km) high, which in turn sends it back to intelligence analysts on the ground.
3. Spy Planes
Closer to Earth are high altitude spy planes such as the manned U2S or the unmanned RQ-4A Global Hawk. Both fly at around 20,000 meters (65,000 feet) and have high resolution, synthetic aperture radar systems that can produce photogenic quality images through clouds or at night. They also have optical and infrared cameras.
4. Fighter Aircrafts
At lower altitudes - about 7600 meters (25,000 feet) - the U.S. could use F18 fighters with real time video images beamed back to command centers or unmanned, slow-flying Predator spy planes. The Predator can also use lasers to "light-up" targets for bombers, however the Taliban shot one down in late September 2001.
Accuracy of Images from Analysis
The general accuracy of Tomahawk cruise missiles - being fired from the Arabian see 1000, kilometers
away - is uncertain. The U.S. measures them as 90% accurate but other experts estimate 80% is about the best that can be hoped for when trying to hit large targets and an accuracy a lot lower for small targets such as tanks or group of tents.
Although selected images taken from military satellites or reconnaissance aircraft showed successful air strikes on military and suspected targets in Afghanistan, other images revealed that a
misdirected missile killed some U.N. workers, hit a mosque, and a building belonging to the Afghan Technical Consultancy, the largest agency responsible for clearing mines left by Russian troops. The missiles are thought to have been aiming for a radio communications mast 50 meters away.
Despite the deployment of extensive hardware, mistakes have been made in the past. During the Gulf War, there were occasions when a target was believed to be destroyed. But when group troops arrived, they found it intact. Sometimes, a bomb landing beside a target can shower it with so much debris that it looks as if it has been destroyed.
Sources:
BBC News, 3 March 2002, “Guide
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Editorial. "Send In The Robots: Should We Let Machines With A Conscience Go To War ?"
New Scientist. October 13, 2001.
Eisman, Dale. "Air Force's B-2S Go To War. Some Ask: Overkill ?" The
Virginian-Pilot. October 13, 2001.
Mackler, Peter. "Special Ops: High-Tech Equipment, Methodical Tactics." Agence France Presse. October 14th, 2001.
Sander, Edmund. "Experts Say Photos Are Misleading." Los Angeles Times. October 13th, 2001.
Tang, Milson and Baker, Cumming. "A New Set of Blast Curves From Vapor Cloud Explosion."
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