Gerald Bull was not a man who thought small. Born in Ontario in 1928, he earned his PhD at the University of Toronto at age 22, making him the youngest person to receive a doctorate in Canada at the time. By the late 1950s, he was conducting launch experiments at Canada's Defence Research Establishment using guns as small as 76 millimeters, testing whether ballistic projectiles could gather atmospheric data more cheaply than sounding rockets. The U.S. Army's Ballistic Research Laboratory took notice. So did Lieutenant General Arthur Trudeau, the Army's Chief of Research and Development. Bull pitched them on something far more ambitious: a supergun capable of reaching orbit. The Army responded with two surplus 16-inch naval gun barrels, a heavy-duty crane, a $750,000 radar tracking system, and substantial financial backing. In 1961, Bull resigned from government research, joined McGill University, and began building his dream.

The choice of Barbados was strategic. Donald Mordell, McGill's Dean of Engineering and Bull's collaborator, argued that a launch site near the equator would harness Earth's rotation to give projectiles extra velocity. The island's Atlantic coastline provided a safe splashdown zone for anything that came back down. Barbados, still a British colony, welcomed the project enthusiastically -- at first. When the gun barrels arrived, they were too heavy to land at the chosen site. Instead, they were offloaded at Foul Bay, seven miles up the coast, and transported overland on temporary tracks. The assembled weapon eventually stretched to 120 feet and weighed nearly 200 tons, making it the largest operational artillery piece in the world. Each firing launched a Martlet projectile wrapped in a wooden sabot that split apart after leaving the barrel. The blasts shook houses for miles. Walls cracked. The Barbados government refused to recognize damage claims, and the initial excitement curdled into resentment among residents living within earshot of what amounted to the world's loudest science experiment.

The results were extraordinary. By the end of 1965, Project HARP had fired more than one hundred missiles above 80 kilometers, well into the ionosphere. The Martlets carried payloads of metallic chaff, chemical smoke canisters, and meteorological balloons to gather data on the upper atmosphere -- information that aircraft engineers desperately needed but found prohibitively expensive to collect by rocket. On November 19, 1966, the program's crowning achievement came not from Barbados but from a third HARP gun at Yuma Proving Ground in Arizona: a 185-pound Martlet projectile reached an altitude of 180 kilometers, soaring past the Karman line that marks the conventional boundary of outer space. That record for a gun-fired projectile has never been broken. Annual funding grew from $250,000 to $1.5 million, and by 1964, Canada's Department of Defence Production had committed $3 million per year to the joint program.

Politics killed what physics could not. Throughout 1966, critics in the Canadian government mounted fierce opposition, and bureaucratic pressures compounded funding delays. In November of that year, Canada announced it would pull all HARP funding after June 30, 1967. Without Canadian partnership, the U.S. Army withdrew its support as well. The Vietnam War was consuming military budgets, and NASA's preference for conventional rockets left little institutional appetite for a gun-launched alternative. Bull spent years trying to resurrect the concept. He eventually designed Project Babylon, an even larger supergun, for Saddam Hussein's Iraq -- a decision that ended when Bull was assassinated outside his Brussels apartment in March 1990, almost certainly by Israeli intelligence. Today, the original HARP gun sits rusting in the Barbadian undergrowth near the eastern coast, its barrel still angled toward the sky. It is a monument to an idea that worked but could not survive the world around it.