|An air-to-air left side view of an F-15 Eagle aircraft releasing an anti-satellite (ASAT) missile during a test.jpeg|
|Place of origin||United States|
|In service||Not deployed|
|Weight||2600 lb (1,180 kg)|
|Length||18 ft (5.48 m)|
|Diameter||20 in (50.8 cm)|
|Warhead||Kinetic energy kill|
|403 miles (648 km)|
|Flight ceiling||350 miles (563 km)|
|Speed||>13,000ft/s, 8,860 mph (14,260 km/h)|
|Infrared homing seeker|
The ASM-135 ASAT is an air-launched anti-satellite multistage missile that was developed by Ling-Temco-Vought's LTV Aerospace division. The ASM-135 was carried exclusively by United States Air Force (USAF) F-15 Eagle fighter aircraft.
Development[edit | edit source]
Starting in the late 1950s, the United States began development of anti-satellite weapons. The first US anti-satellite weapon was the Bold Orion Weapon System 199B. Like the ASM-135, the Bold Orion missile was air-launched, but in this case from a B-47 Stratojet. The Bold Orion was tested on 19 October 1959 against the Explorer 6 satellite. The two-stage Bold Orion missile passed within 4 mi (6.4 km) of Explorer 6. From this distance, only a relatively large yield nuclear warhead would likely have destroyed the target.
Starting in 1960 the Department of Defense (DoD) started a program called SPIN (SPace INtercept). In 1962, the US Navy launched Caleb rockets as part of the Satellite Interceptor Program, with the objective of developing an anti-satellite weapon.
The United States developed direct ascent anti-satellite weapons. A United States Army Nike Zeus missile armed with a nuclear warhead destroyed an orbiting satellite in May 1963. One missile from this system known as Project MUDFLAP and later as Project 505 was available for launch from 1964 until 1967. A nuclear-armed Thor anti-satellite system deployed by the Air Force under Program 437 eventually replaced the Project 505 Nike Zeus in 1967. The Program 437 Thor missile system remained in limited deployment until 1975. One drawback of nuclear-armed anti-satellite weapons was that they could also damage United States reconnaissance satellites. As a result, the United States anti-satellite weapons development efforts were re-directed to develop systems that did not require the use of nuclear weapons.
In 1978, the USAF started a new program initially designated the Prototype Miniature Air-Launched Segment (PMALS) and Air Force Systems Command's Space Division established a system program office. The USAF issued a Request for Proposal for the Air-Launched Miniature Vehicle (ALMV). The requirement was for an air-launched missile that could be used against satellites in low Earth orbit.
Design[edit | edit source]
The LTV Aerospace Altair 3 was used as the second stage of the ASM-135. The Altair 3 used the Thiokol FW-4S solid propellant rocket engine. The Altair 3 stage was also used as the fourth stage for the Scout rocket  and had been previously used in both the Bold Orion and HiHo anti-satellite weapons efforts. The Altair was equipped with hydrazine fueled thrusters that could be used to point the missile towards the target satellite.
LTV Aerospace also provided the third stage for the ASM-135 ASAT. This stage was called Miniature Homing Vehicle (MHV) interceptor. Prior to being deployed the second stage was used to spin the MHV up to approximately 30 revolutions per second and point the MHV towards the target.
A Honeywell ring laser gyroscope was used for spin rate determination and to obtain an inertial timing reference before the MHV separated from the second stage. The infrared sensor was developed by Hughes Research Laboratories. The sensor used a strip detector where four strips of Indium Bismuth were arranged in a cross and four strips were arranged as logarithmic spirals. As the detector was spun, the infrared target's position could be measured as it crossed the strips in the sensor's field of view. The MHV infrared detector was cooled by liquid helium from a dewar installed in place of the F-15's gun ammunition drum and from a smaller dewar located in the second stage of the ASM-1