The U.S. Navy recently asked Congress for $139 billion to update its fleet of nuclear-powered submarines. Unlike “conventional” submarines, which need to surface frequently, nuclear submarines can cruise below the sea at high speeds for decades without ever needing to refuel. Defense planners expect that the new submarines will run on one fueling for the entirety of deployment—up to a half century.
The advantages of nuclear submarines over their conventional cousins raise a question about another component of the military arsenal: Why don’t airplanes run on nuclear power?
The reasons are many. Making a nuclear reactor flightworthy is difficult. Shielding it from spewing dangerous radiation into the bodies of its crew might be impossible. During the Cold War, when the threat of nuclear apocalypse led to surprisingly pragmatic plans, engineers proposed to solve the problem by hiring elderly Air Force crews to pilot the hypothetical nuclear planes, because they would die before radiation exposure gave them fatal cancers.
The Italian American physicist Enrico Fermi had introduced the idea of nuclear flight as early as 1942, while serving on the Manhattan Project to build the atomic bomb. As World War II drew to a close, the United States began work to realize Fermi’s dream of nuclear-powered flight. From 1946 until 1961, vast teams of engineers, strategists, and administrators toiled in a whirl of blueprints, white papers, and green bills in an attempt to get the idea off the ground.
The advantages of nuclear-powered airplanes mirrored those of nuclear submarines. Nuclear submarines did not need to surface for fuel, and nuclear airplanes would not need to land. A 1945 proposal at the Department of War (now the Department of Defense) promised, “With nuclear propulsion, supersonic flight around the world becomes an immediate possibility.” A secret Atomic Energy Commission memorandum now held in the Eisenhower Presidential Library explained the promise of nuclear flight in a more measured tone. Nuclear energy “should make possible ranges of one or more times around the world with a single loading of the reactor.” The idea of a nuclear-powered bomber became a strategic dream for the military; it could stay aloft for days to cover any number of targets throughout the world, before returning to the United States without refueling.
The problem of refueling airplanes occupied many Cold War minds. Bombers would strain to reach their targets and strand in enemy territory with too little fuel to return home if they flew on only a single tank. Aerial refueling offered a solution, but a poor one. Planes caught in the act over enemy territory were prone to anti-aircraft fire. Evasive maneuvers would uncouple the two planes, prevent successful refueling, and endanger the mission.
To minimize the need for dangerous refueling, the United States relied on a global network of Air Force bases. Such bases—usually close to the U.S.S.R.—allowed planes to reach their targets and return on a single tank of fuel. Procuring the bases, however, proved expensive and unpopular. At one point, the United States offered $100 million in gold to purchase Greenland from Denmark and gain a new strategic location for bases. In the end, Denmark decided to keep Greenland, but the proposal illustrates the lengths the United States had to go to compensate for its planes’ limited range. A nuclear-powered airplane could avoid all of these issues.
But nuclear power came with its own problems. The reactor would have to be small enough to fit onto an aircraft, which meant it would release far more heat than a standard one. The heat could risk melting the reactor—and the plane along with it, sending a radioactive hunk of liquid metal careening toward Earth.
The problem of shielding pilots from the reactor’s radiation proved even more difficult. What good would a plane be that killed its own pilots?
To protect the crew from radioactivity, the reactor needed thick and heavy layers of shielding. But to take off, the plane needed to be as light as possible. Adequate shielding seemed incompatible with flight.
Still, engineers theorized that the weight saved from needing no fuel might be enough to offset the reactor and its shielding. The United States spent 16 years tinkering with the idea, to no avail. The Soviet Union pursued nuclear aircraft propulsion too, running up against the same problems. By 1958, an infamous article in Aviation Week, mostly made-up, claimed that the Soviets were already testing a functional nuclear airplane. Shortly after, President Dwight Eisenhower counseled calm and denounced the article as contrived. A representative of the Soviet program explained that “if we had flown an atomic-powered aircraft, we would be very proud of the achievement and would let everyone know about it.” Unfortunately for atomic-flight enthusiasts, both countries had little to brag about.
Neither program managed to overcome the problems of shielding and weight. The development of intercontinental ballistic missiles in the 1950s, moreover, weakened the case for developing nuclear-powered bombers. The nuclear airplane became redundant from a military point of view, as ICBMs avoided the problems of manned nuclear flight. They had only one-way missions, needed no refueling, and did not have pilots to shield. Without a military justification for atomic flight, funding withered away.
The nuclear airplane began to die a slow death. In the late 1950s, the Eisenhower administration cut the program’s budget. Nikita Khrushchev slashed funding for the Soviet equivalent. By 1961, both countries had dismantled their projects for manned nuclear-powered airplanes. Atomic flight seemed doomed.
In a last-ditch effort to keep the nuclear airplane on the table, military strategists considered a radical solution: They could use pilots closer to death. The Air Force would use crews old enough to die of natural causes before the harmful effects of radiation could show up and thus, the logic went, sidestep the shielding problem. As the nuclear-policy expert Leonard Weiss explained in an article for the Bulletin of the Atomic Scientists, the proposal would have made radiation shielding unnecessary and decreased the weight of the plane significantly. It might have let the nuclear airplane take flight.
The image of a corps of irradiated elderly pilots patrolling the world’s skies ready to unleash nuclear catastrophe drew on a form of ageism that pervaded Cold War apocalypse planning. In civil-defense plans for surviving a nuclear apocalypse, the old were always sacrificed first. Joe Martin at the University of Cambridge’s department of history and philosophy of science explained to me that Herman Kahn, one of the purported inspirations for Dr. Strangelove, made a ranking of food uses after nuclear catastrophe that reflected this Cold War age bias. The scale ranged from grade A (high-quality food reserved for pregnant women) to grade E (radioactive food only good for feeding animals). People over the age of 50 composed group D. Kahn put it bluntly in his book On Thermonuclear War: “Most of these people would die of other causes before they got cancer.”
Even that shocking proposal failed to save the nuclear airplane. The Eisenhower administration concluded that the program was unnecessary, dangerous, and too expensive. On March 28, 1961, the newly inaugurated President John F. Kennedy canceled the program. Proposals for nuclear-powered airplanes have popped up since then, but the fear of radiation and the lack of funding have kept all such ideas down.
The Air Force still maintains its affinity for older pilots. It has the highest enlistee age limit of any branch in the military, and it increased that limit to 39 years old in 2014. Some pilots could be much older. Last year, in response to a shortage of nearly 2,000 pilots, the Air Force beckoned back retired service members as part of the Voluntary Retired Return to Active Duty (VRRAD) program. VRRAD gives 1,000 former airmen and airwomen the option to return to active duty, possibly including combat duty. Referring to the placements of these retirees, an Air Force spokesperson said last year, “Everything is on the table.” Almost everything, at least: None of these pilots will ever fly a nuclear aircraft.