Flightline: 99

[Skyfire77]

- An ASM-135 slung beneath an F-15A on a captive carry flight. | Photo USAF/Edwards Flight Test Center

FLIGHTLINE: 99
On 13 September 1985 F-15A 76-0084 launched an ASM-135 ASAT which destroyed a satellite in orbit.

Almost immediately after the launch of the USSR's Sputnik satellite, the US began to research anti-satellite weapons. On 13 October 1959, a USAF B-47 launched a modified Bold Orion ALBM which passed within 4 miles of the Explorer 6 satellite, orbiting at an altitude of 156 miles. Starting in 1962, modified Nike Zeus ABMs were tested as ASAT weapons under Project MUDFLAP, with mixed results. Intelligence reports of renewed Soviet interest in their own anti-satellite system pressured President Jimmy Carter into directing the USAF into developing a new ASAT missile. A 'crash' program initially designated the Prototype Miniature Air-Launched Segment (PMALS), then retitled the Air-Launched Miniature Vehicle (ALMV), resulted in a contact being awarded to LTV Aerospace for an air-launched, multi-stage missile.

-A CASM-135, used for captive carry trials, on display at the Smithsonian's Steven F. Udvar-Hazy Center. | Photo: G. Edward Johnson

-Cross section of the ASM-135's upper stage and MHV. | Illustration Sven's Space Place

-Cutaway view of the ASM-135's MHV. | Illustration: Sven's Space Place

The ASM-135 was mainly comprised of off-the-shelf components, allowing a rapid development and production. The first stage was a modified AGM-69 SRAM, while the second stage was an Altair 3, originally developed for the Scout launch vehicle. The third stage of the ASAT was the Miniature Homing Vehicle (MHV), which incorporated a Honeywell laser ring gyro and a Hughes-developed IR sensor. The seeker was eight strips of indium bismuth arranged in a precise formation to track targets as the MHV spun. Two liquid helium dewars, one in the F-15 (replacing the ammunition drum) and a second smaller tank in the MHV, cooled the sensor head. A ring of 56 solid rocket motors set around the MHV's circumference, controlled by a "bang-bang" system, guided the vehicle at the target, while 8 lower thrust "end-game" motors provided fine control just prior to impact. A group of four RCS motors at the back of the stage maintained a stable spin. The MHV did not include a warhead, the MHV's own momentum was sufficient to destroy the target in what is known as a kinetic kill.

A typical mission would see the ASM-135 mounted underneath an F-15. The fighter's computers would be programed with the target's orbital path, and the HUD would provide steering instructions to the pilot. The Eagle, flying at Mach 1.32, would then execute a 65° climb while the IR sensor scanned for the target. Upon acquisition, the missile would automatically launch at approximately forty thousand feet. Prior to release from the second stage, the ASAT would be spun up to 30rpm, then separated. This spinning motion allowed the IR seeker to see the target as it crossed the detector strips, providing course-correction data.

Five total test launches were carried out, in addition to an unknown number of captive-carry flights beforehand. The first test, on 21 January 1984, did not include an MHV, but proved that the rest of the missile worked. A second test on 13 November of that year was aimed a star, but the MHV failed to track. On 20 August 1985 President Ronal Reagan authorized a test against a satellite ahead of a Congressional ban on ASAT testing, expected later that year. In order to complete the test in so short a time, an existing satellite, the Solwind solar observatory, was designated as the target.

-The Solwind satellite, prior to launch. | Photo: NASA

On 13 September 1985, Maj. Wilbert D. "Doug" Pearson, flying F-15A, tail no. 76-0084 and nicknamed the "Celestial Eagle", launched an ASM-135 ASAT about 200 miles west of Vandenberg AFB. The 30lb MHV collided with the Solwind, which itself weighed a ton, at closing velocity of 15,000mph, destroying the satellite.

-The ASM-135 separates from F-15A 76-0084 on its sole live mission. | Photo: Paul E. Reynolds (USAF)

-Seconds later, the 1st stage motor fired as the F-15 banked away. | Photo: Paul E. Reynolds (USAF)

In addition to proving that the ASAT worked, the test also provided NASA with data on the results of a hypervelocity impact in space, as well as changing thinking on orbital debris. It had been previously assumed that debris caused by a collision would be reflective and easily tracked, but the results of the test proved that, in fact, the pieces were so dark as to be almost undetectable visually, the result of soot from vaporized plastics and other compounds. Of 285 known pieces of Solwind, only two could be seen by optical tracking, the rest identified by USAF IR telescopes and a reentry radar deployed to Alaska. The rubble also did not persist in orbit for as long as predicted, with all but eight pieces having reentered by 1998, the result of increased heating and expansion of the atmosphere due to solar activity.

Two further tests were completed on 22 August and 29 September 1986, though both were directed against stars to comply with the prohibition against live tests. The USAF intended to procure 112 ASM-135s, with 20 F-15A fighters, from the 318th Fighter Interceptor Squadron based at McChord Air Force Base in Washington and the 48th Fighter-Interceptor Squadron based at Langley Air Force Base in Virginia, modified for the anti-satellite mission. However, the program was canceled in 1988, the result of increasing costs and push-back against the wider SDI program.

Fifteen ASM-135s and CASM-135 captive carry simulators were produced, and two of the CASM-135s are on display, one at the USAF Museum in Dayton Ohio, and the other at the Smithsonian's Steven F. Udvar-Hazy Center in Virginia.

The Celestial Eagle was restored to F-15A standards and remained in the USAF inventory, eventually assigned to the 125th Fighter Wing at Homestead AFB in Florida. Doug Pearson, now a retired Major General was reunited with -0084 on 13 September 2007 when he, along with his son (who is also an F-15 driver), visited the 125th as part of a USAF event to commemorate the mission. The aircraft was mothballed at AMARG in 2009 as the 125th transitioned to F-15Cs.

-Retired Maj. Gen. Doug Pearson (left) and Capt. Todd Pearson (right), 390th Fighter Squadron pilot from Mountain Home Air Force Base, Idaho, with the Celestial Eagle. | Photo: Senior Airman Erik Hofmeyer (USAF)

Though the USAF did not take the ASAT operational, the missile did play a part in the 1986 Tom Clancy novel Red Storm Rising, where it was used to destroy several Soviet satellites during a brief hot war between the USSR and NATO.

[Chariotoflove]

@skyfire77 This is the kind of great post series we want for the FP when we can get it set up. You write about complicated tech issues in an easy to digest way that doesn’t feel like dumbed-down USA Today news snippets.

[ForSweden]

strong Dad Energy

[ClassicDatsunDebate]

@forsweden Pleats will do that.

[Chariotoflove]

@forsweden @ClassicDatsunDebate said in Flightline: 99:

strong Dad Energy

Isn’t that Jake from State Farm?

[ForSweden]

@chariotoflove No, Jake is a good, decent man, so he flies the F-16.

[pyroholtz]

@skyfire77 this was a great read, I had no idea this ordnance existed, as launched from a fighter jet.

[Skyfire77]

@pyroholtz The Russians are even now working on a similar ASAT, the Izdeliye 293 Burevestnik, and there are one or two MiG-31s that have modified carry the missile.

[Chariotoflove]

@forsweden said in Flightline: 99:

@chariotoflove No, Jake is a good, decent man, so he flies the F-16.

Shots fired.

[Skyfire77]

@forsweden

[Highlander]

@skyfire77 I like how layered this joke is, you have to read the whole thread but it's brilliant.

[ttyymmnn]

@skyfire77 Good stuff. I remember when these tests were happening. Air and Space Magazine did a big write up about it in the last year or so. Maybe more, I'm way behind in my reading!

FYI: I'm not crazy about the new theme, particularly the way it handles captions. I've switched to make the captions quotations by putting a single caret in front of it. I think it looks better than the built-in captions.

Cheers!

[Skyfire77]

@ttyymmnn I actually just copied and pasted the captions from DT w/o changing anything. Might have to play with it some.