The M55 rocket was a chemical weapon developed by the United States in the 1950s. The United States Army produced both Sarin and VX unitary warheads for the M55.
History
In 1951 the US Army Chemical Corps and Ordnance Corps initiated a joint program to develop a 115mm chemical rocket. The US Army Ordnance Corps designed the 115mm T238 and launcher in 1957 to provide the army a means to attack large area targets with chemical agents. Artillery and mortars are for small area targets; and due to different spin stabilities, warheads intended for explosives are not ideal for chemical delivery. The 115mm rocket was subsequently accepted as the M55 rocket with M91 launcher. Produced from 1959–1965, the M55s were manufactured at
Newport Army Ammunition Plant
The Newport Chemical Depot, previously known as the Wabash River Ordnance Works and the Newport Army Ammunition Plant, was a bulk chemical storage and destruction facility that was operated by the United States Army. It is located near Newpor ...
Sarin
Sarin (NATO designation GB G-series, "B"">Nerve_agent#G-series.html" ;"title="hort for Nerve agent#G-series">G-series, "B" is an extremely toxic synthetic organophosphorus compound.VXnerve agents for the M55.Croddy, Eric and Wirtz, James J. ''Weapons of Mass Destruction: An Encyclopedia of Worldwide Policy, Technology, and History'', Google Books , ABC-CLIO, 2005, p. 42, (), accessed November 8, 2008.
Okinawa
is a prefecture of Japan. Okinawa Prefecture is the southernmost and westernmost prefecture of Japan, has a population of 1,457,162 (as of 2 February 2020) and a geographic area of 2,281 km2 (880 sq mi).
Naha is the capital and largest city ...
Federation of American Scientists
The Federation of American Scientists (FAS) is an American nonprofit global policy think tank with the stated intent of using science and scientific analysis to attempt to make the world more secure. FAS was founded in 1946 by scientists who wo ...
'', updated June 15, 2000, accessed November 8, 2008. The rockets in Japan were moved to
Johnston Atoll
Johnston Atoll is an Unincorporated territories of the United States, unincorporated territory of the United States, currently administered by the United States Fish and Wildlife Service (USFWS). Johnston Atoll is a National Wildlife Refuge and ...
during
Operation Red Hat Operation Red Hat was a United States Department of Defense movement of chemical warfare munitions from Okinawa, Japan to Johnston Atoll in the North Pacific Ocean, which occurred in 1971.
Background
U.S. chemical weapons were brought into Okinawa ...
where they were destroyed during the 1990s.
Disposal issues
Disposal operations for the M55 are made more difficult because of the rocket's design.Noyes, Robert. ''Chemical Weapons Destruction and Explosive Waste: Unexploded Ordnance Remediation'', Google Books , William Andrew Inc., 1996, page 32, (). The rocket propellant was a double base composition
nitroglycerin
Nitroglycerin (NG), (alternative spelling of nitroglycerine) also known as trinitroglycerin (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless, oily, explosive liquid most commonly produced by nitrating g ...
(NG) and
nitrocellulose
Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...
(NC) propellant. Besides the NG and NC, M28 contains 2-nitrodiphenylamine (NDPA) as a stabilizer.The propellant is known by the military nomenclature M28 propellant. See: ''Effects of Degraded Agent and Munitions Anomalies on Chemical Stockpile Disposal Operations''. The rocket propellant cannot be removed from the warhead without cutting open the rocket.Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program,
U.S. National Research Council
The National Academies of Sciences, Engineering, and Medicine (also known as NASEM or the National Academies) are the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrell ...
. ''Review of Systematization of the Tooele Chemical Agent Disposal Facility'', Google Books , National Academies Press, 1996, p. 86, ().
The propellant itself presents a hazard, because it becomes unstable as it ages.Langford, Roland E. ''Introduction to Weapons of Mass Destruction'', Google Books , Wiley-IEEE, 2004, page 282, (). Specifically, the danger of
autoignition
The autoignition temperature or kindling point of a substance is the lowest temperature in which it spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to sup ...
is present as the stabilizer ages and becomes depleted.Peterson, Carl R.,
U.S. National Research Council
The National Academies of Sciences, Engineering, and Medicine (also known as NASEM or the National Academies) are the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrell ...
, et al. ''Recommendations for the Disposal of Chemical Agents and Munitions'', National Academies Press, 1994, Google Books , p. 46-48, (). The
U.S. National Research Council
The National Academies of Sciences, Engineering, and Medicine (also known as NASEM or the National Academies) are the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrell ...
and other sources called the M55 the most dangerous weapon in the American chemical arsenal because of this and other hazards.
Another danger is agent leakage. Army reports have indicated that nerve agent GB can corrode the metal casings of the munitions over time. As Sarin decomposes it forms acids which can corrode the aluminum casings found around the agent in the M55.Committee on Review of Army Planning for the Disposal of M55 Rockets at the Anniston Chemical Agent Disposal Facility, U.S. National Research Council, ''Assessment of Processing Gelled GB M55 Rockets at Anniston'', Google Books , National Academies Press, 2003, page 11, (). M55 rockets containing GB have accounted for the majority of leaking American chemical weapons. In mid-2002, over 4,000 munitions in the U.S. chemical stockpile were found to be leaking agent; of that number 2,102 were Sarin-containing M55s.
Specifications
The M55 is long and in diameter. The weapons can hold warheads filled with about of GB or VX. The warhead comprises about total, and consists of several components. The M34 and M36 Burster utilize
composition B
Composition B, colloquially Comp B, is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades and various other munitions. It was also use ...
or
tetrytol
Tetrytol is a high explosive, comprising a mixture of tetryl and TNT. Typically, the proportion of ingredients (by weight) is 65%, 70%, 75% or 80% tetryl to 35%, 30%, 25% or 20% TNT. Tetryl and TNT do form a eutectic with a setting point of 67.5 ...
and total about of the total weapon weight. The agent, as stated, comprises about ten pounds (4.5 kilograms) of the weight with the rest lying in the casing and M417
fuze
In military munitions, a fuze (sometimes fuse) is the part of the device that initiates function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The relative complexity of even the earliest fuze d ...
Anniston Chemical Activity
Anniston Chemical Activity was a U.S. Army chemical weapon storage site located in Alabama. The Army had stored approximately seven percent of the nation’s original chemical weapons stockpile at the Anniston Army Depot since the early 1960s. In ...
*
Johnston Atoll Chemical Agent Disposal System
Johnston Atoll Chemical Agent Disposal System (JACADS) was the U.S. Army's first chemical munitions disposal facility. It was located on Johnston Island, at Johnston Atoll and completed its mission and ceased operation in 2000.
Background
Prior ...
*
List of U.S. Army Rocket Launchers By Model Number
This is a list of U.S. Army rocket launchers by model number. Launchers can be either tube-type or rail-type.
M number
Launchers
* M1 rocket launcher, 2.36 inch, solid tube shoulder mount. Bazooka
** A1 Simplified design with improved el ...
(M91)
Notes
References
*Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program, Committee on Review and Evaluation of the Army Chemical Stockpile Disposal Program,
U.S. National Research Council
The National Academies of Sciences, Engineering, and Medicine (also known as NASEM or the National Academies) are the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrell ...
. ''Effects of Degraded Agent and Munitions Anomalies on Chemical Stockpile Disposal Operations'', Google Books , National Academies Press, 2004, p. 55, ()