An Idea Too Far: The Orion spaceship

Many space programs have been proposed and canceled since the Space Age began 65 years ago.  None was more visionary - and probably more impossible - than Orion. 

The idea of Orion came out of the national laboratory at Los Alamos in 1957, caught on with the Advanced Research Projects Agency (ARPA), and was backed by the Air Force for several years.  General Atomics, a division of General Dynamics, also spent its own funds on the project, attracting leading physicist Freeman J. Dyson to assist with the design work.  Dyson predicted that “huge projects and whole empires” would come out of Orion.  Someone at ARPA must have thought so too, since the agency in 1958 put an initial $1M on contract to study the idea.

The basic concept was a spacecraft shaped like a short, squat artillery shell with a huge pusher plate and shock absorbers on the aft end.  The scale was enormous: the pusher plate alone would weigh 1,000 tons.  A magazine carrying hundreds of nuclear fission devices of yields up to five kilotons would spit them out into the center of the plate, where they would be ignited, vaporizing the propellant (which could be any inert matter available cheaply in large quantities, even such mundane items as ice or dirt).    Engineers estimated they could get up to 70% of the energy of the explosion converted into thrust against the pusher plate.  For versions with people aboard, crews of up to 150 people were considered.  The specific impulse (a measure of a rocket’s efficiency, abbreviated as Isp and stated in seconds) was estimated at anywhere from 2,000 (over five times what the best chemically-fueled engines could offer) to 50,000, depending on the design of the vehicle and the yield of the nuclear explosives.

Orion never got further than flying a three-foot-diameter model propelled by chemical explosives.  The unknowns confronting the project, as well as its potential costs, were staggering.  For a while in 1959, it was the only major space project left in ARPA after NASA had taken over civilian spaceflight and the military missions had been handed back to the Services.  At that point, no one outside ARPA wanted Orion.

In 1959, the Air Force took another look. Some Air Force officers liked the idea of putting our strategic deterrent on a space platform, out of range of any Soviet weapons.  One illustration showed no fewer than 500 ICBM warheads being dispensed by an Orion ship. 

At the Special Projects Office of the Air Force Special Weapons Center at Kirtland AFB, the overseer of the Orion contract was an Air Force officer and physicist named Lew Allen, later to become Air Force Chief of Staff.  In the late 1950s, the world had not yet grasped how dangerous atmospheric nuclear explosions were.  

In 1959, Air Force officers and physicists produced a study called “Military Implications of the Orion Vehicle.” It examined what, assuming the propulsion technology worked out, Orion-type ships could do for DoD in LEO, geosynchronous orbit (GEO), and deep space.  It was briefed to military audiences including the Air Staff, and a highly receptive General Thomas Power, then Commander in Chief, Strategic Air Command (CINCSAC). 

General Power was a solid believer in the importance of space to future Air Force plans.  He signed off on SAC Qualitative Operational Requirements (QORs) titled, “Strategic Aerospace Vehicle,” “Strategic Earth Orbital Base,” and “Strategic Space Command Post.” The concept of space-based nuclear deterrence was so intriguing that Power declared, “Whoever controls Orion controls the world."

Orion (image NASA)

In those days, what SAC wanted mattered a lot.  In the years before SLBMs and ICBMs arrived in significant numbers, SAC’s bombers made up the huge majority of the American nuclear deterrent.  In some years under Ike, SAC received over 40% of the US defense budget.  Power got Air Force funds to ensure continuation of Orion design studies, with the intent of launching a hardware R&D program when the design work was sufficiently mature.

When President Kennedy took office, though, his Defense Secretary, Robert McNamara, took a strongly negative view of Orion.  He limited its funding to studies only. 

There were plenty of reasons to be wary of Orion, even though the physics looked workable.  An Orion spaceship would take off from a pit on the Earth’s surface using small nuclear bombs all the way up through the atmosphere.  Even some officers who liked the idea of Orion eventually became wary of the fallout, literally and figuratively, of testing such a system in the United States.   With the October 1963 signing of the Limited Test Ban Treaty, prohibiting “any nuclear weapon test explosion, or any other nuclear explosion” in the atmosphere and space, Orion became all the more problematical.  

A late version of the idea was to put a scaled-down Orion on top of a Saturn V booster, lofting it into space without any nuclear explosions (although still with many nuclear devices on board.)  This spacecraft would have weighed about 100 tons and would join with a separately launched crew vehicle in orbit.  Orion briefings attracted some interest from Wernher von Braun, but, in December 1964, NASA notified the Air Force it was staying with chemical rockets.

The Air Force was unwilling to fight for Orion by itself, and the project quickly died.  About $11M had been spent.  Nuclear pulse propulsion, using either fission bombs like Orion or cleaner fusion bombs, has been studied several times since, but without attracting any significant military or NASA support.  Orion, while it still has a few believers today, was consigned to the dust bin of intriguing but ultimately impractical space programs.