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Why the U.S. Abandoned Nuclear-Powered Missiles More Than 50 Years Ago

Popular Mechanics logo Popular Mechanics 6 days ago Kyle Mizokami

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Last week’s mysterious nuclear accident in Russia became even more mysterious as the government admitted that a small nuclear reactor had exploded, killing seven people.

Evidence is piling up that the incident is somehow related to Russia’s development of a nuclear-powered cruise missile, and President Donald Trump took to Twitter to state that the U.S. has a similar system. One problem: the U.S. looked into nuclear-powered cruise missiles more than half a century ago before rejecting them as impractical.

a large truck © Globalsecurity.org Earlier reports of the August 8th incident stated that two individuals from Russia’s Defense Ministry were killed and six badly injured. Russia’s nuclear energy agency, has since admitted five of its employees were also killed in the explosion, with another three receiving injuries and burns. According to the Guardian, Rosatom said it was working on a number of experimental technologies, including “miniaturised sources of energy using [fissile] materials,” though a spokesperson did not explain how such research was related to the explosion.

After the incident, Greenpeace accused the Russian government of a coverup, using its own data to claim that radiation levels in the nearby city of Severodvinsk briefly spiked up to twenty times normal levels. The levels were not serious enough to warrant public health warnings.

a plane flying in the air: Artist’s depiction of SLAM. © Globalsecurity.org Artist’s depiction of SLAM. A consensus is emerging that the nuclear accident is in some way related to Russia’s development of the Burevestnik (“Storm Petrel”) nuclear-powered cruise missile, known by NATO as the SSC-X-9 Skyfall. One advantage of a nuclear-powered missile would be a nearly unlimited range, allowing the missile to fly much longer than conventionally powered cruise missiles. This would allow the missile to fly around U.S. air defenses, skirting entire continents if necessary. 

The United States tried to develop a nuclear-powered cruise missile in the 1950s and 1960s but abandoned the project as impractical. The weapon was known as Supersonic Low Altitude Missile, or SLAM, and it would have been the most dangerous nuclear weapon ever made.

SLAM, also known unofficially known as "The Big Stick," was designed as a low-flying cruise missile. A rocket booster would launch SLAM into the air and boost it to speeds where its nuclear-powered ramjet engine would kick in. Once activated, the engine would give SLAM a top speed of Mach 3.5. The YouTube channel Curious Droid has a great mini-history on this doomsday weapon:

The missile would fly unusually low for a missile of its time, just 1,000 feet, to avoid enemy radars. The supersonic shockwave was projected to leave a trail of devastation, flattening forests, buildings, and killing anyone in the missile's flight path.

SLAM, despite being advertised as a missile, was actually more like an unmanned bomber. Instead of a single warhead, it carried up to 26 hydrogen bombs, each hundreds of times more powerful than the bombs dropped on Hiroshima and Nagasaki. SLAM could fly a predetermined route over an enemy country or even continent, ejecting H-bombs on targets below. Once out of bombs SLAM would fly one last mission, running into a final target that would shower the target zone with lethal radioactivity.

a close up of a map: SLAM wartime flight profile. © Globalsecurity.org SLAM wartime flight profile. SLAM was never built because it was too dangerous to even test. The dangerous levels of radioactivity unleashed by the nuclear engine was a big plus in some apocalyptic wartime scenario, but it couldn't even be tested in the skies over the U.S. SLAM was also overtaken by intercontinental ballistic missile development, which could deliver a thermonuclear warhead against a target in Russia in half an hour. 

Whatever Russia was really testing last week in the arctic, it's likely something that should've remained an unused relic of the Cold War.

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