ASATs (antisatellite weapons) have been used since the beginning of the space age. So far, thankfully, they have only been used against targets belonging to the same nation as the ASAT launch team. However, when used to destroy orbital targets, ASATs generate orbital debris, often large amounts of it. Attempts to reduce the amount of long lived debris by firing against a low orbit target are better than nothing, but in my view still unacceptable.

When a satellite in a circular orbit at height H is destroyed by an explosion or an orbital-velocity impact, energy is imparted to the resulting fragments, which typically orbit in the same orbital plane but in elliptical orbits where either the apogee or perigee is close to H, but the other apsis may be hundreds of kilometers lower or higher.

A traditional way to understand such events is the use of the Gabbard diagram, where each debris object in an orbit of perigee P and apogee A with orbital period T is mapped to a pair of points (T,P) and (T,A) in a period-height plot.

First, I summarize the various antisatellite programs which have resulted in test launches. Note that launches to test a launch vehicle which werenot aimed at a target, launches against imaginary `point in space' targets, and systems using a dummy nuclear warhead (which do not involve physically hitting the target) do not generate orbital debris.

A series of Russian satellites in the `Nivelir' program, including Kosmos-2535/2536, may also be antisatellite tests, but their status is unclear at the moment.

The US insists that the Burnt Frost operation, in which a failed NRO satellite was destroyed by an SM-3 missile just prior to reentry, was carried out for public safety (fears that the hydrazine on the satellite would be a health risk after impact). Nevertheless, it involved the destruction of a satellite and the generation of orbital debris, and in my view was seen by other nations as normalizing the use of antisatellite weapons (in the context of previous US ASAT programs and the continuing rhetoric of US space control and dominance). I therefore count it as an antisatellite weapon and include it within the scope of my condemnation of all such activities.

There are two broad trajectory types used:

• DA (Direct Ascent) suborbital launches, and
• CO (Co-Orbital) launches where the ASAT first goes into orbit and then maneuvers to intercept the target.

There are three basic types of warhead used, which I label:

• DN - Dummy Nuke. In this scenario a nuclear weapon is exploded near the target to destroy it. In all test flights of this system, no actual nuclear weapon was used - a dummy weapon and sensors to determine miss distance replaced the live warhead. No orbital debris is generated by such tests.
• HE - High Explosive, sometimes with an associated payload of shrapnel or ball bearings. Generates large amounts of orbital debris.
• KE - Kinetic Energy; the warhead does not explode, but is guided to hit the satellite. The destruction occurs simply due to the kinetic energy of the satellite smashing into the warhead. Large amounts of orbital debris may result.

---

Antisatellite projects
Agency	Program	Launch Vehicle	Trajectory	Warhead	Debris?	Period	Notes
US Air Force	High Virgo	B-58/High Virgo	DA	DN?	No	1959
US Air Force	Bold Orion	B-47/Bold Orion	DA	DN?	No	1959
US Army	Program 505	Nike Zeus	DA	DN	No	1962-1965
US Air Force	Program 437	Thor	DA	DN	No	1964-1970
OKB-52, SSSR	IS	Tsiklon-2	CO	HE	Yes	1968-1982
US Air Force	ASM-135	F-15A/ASAT	DA	KE	Yes	1984-1986
SDIO	Vector Sum	Delta 3920	CO	KE	Yes	1986
PKO MO RF	Kontakt	Mig-31D/79M6	DA	KE	(Yes)	1991	Not tested against target
Khrunichev, RF	Naryad	Rokot	CO	HE?	Yes	1990-1994	Not tested against target
PLA, China	Chinese ASAT	DF-21?	DA	KE	Yes	2005-2014?
US Navy/ABMDA	Burnt Frost	SM-3	DA	KE	Yes	2008
DRDO, India	PDV-II	PDV-II	DA	KE	Yes	2019-?
Almaz/MO RF	Nudol'	Nudol'	DA	HE or KE	Yes	2014-

See also:

The 2021 Russian test

Image: JCM