In November 1966, a 180-kilogram dart named Martlet 2 shot out of a 16-inch naval gun barrel on the island of Barbados, punched through the atmosphere at Mach 10, and coasted to an altitude of 179 kilometers — 79 km above the Kármán line. It remains the highest altitude ever reached by a projectile fired from a gun. No rocket motor. No staging. Just chemistry, a very long tube, and a Canadian engineer named Gerald Bull who thought orbital access was fundamentally a ballistics problem, not a rocketry one.

Project HARP (High Altitude Research Project) started in 1961 as a partnership between McGill University and the U.S. Army's Ballistic Research Laboratory. The idea was elegantly cheap: surplus U.S. Navy 16-inch/50-caliber gun barrels — the kind that used to arm the Iowa-class battleships — were welded end-to-end into a 36-meter smoothbore tube, mounted at 85° elevation, and pointed at the sky. Instead of a shell, they fired a finned sub-caliber projectile called the Martlet, riding a discarding sabot. The gun consumed no propellant it hadn't already been built to burn. Each shot cost roughly $3,000 — against the $500,000 minimum for a sounding rocket in 1966 dollars.

Bull's team fired more than 200 rounds from Barbados, Yuma, and Highwater, Quebec. They measured upper-atmosphere winds, tested re-entry heating, and were within engineering distance of the Martlet 4, a rocket-assisted projectile designed to reach true orbital velocity by lighting a solid motor after gun-launch had already done the heavy lifting through the dense lower atmosphere — the part that eats 90% of a conventional rocket's energy budget.

Then it died. Not from technical failure. In 1967, the Canadian government withdrew funding. Ottawa was under mounting pressure to distance itself from U.S. military programs during Vietnam, and HARP's Army co-funding made it politically toxic. The U.S. Army lost interest the same year when its ballistic missile priorities shifted. The Barbados gun was abandoned on the beach where it still lies today, half-buried in sand and salt. Bull, embittered, took his expertise to Iraq to build the Project Babylon supergun for Saddam Hussein — and was assassinated on his Brussels doorstep in March 1990, most likely by Mossad.

Why it deserves a second look in 2026:

• Modern electronics survive 10,000 G. The Army's Excalibur artillery round proved gun-launched guidance packages work fine. CubeSats can be ruggedized to take the launch load.
• Light gas guns reach Mach 20+. Bull was limited to conventional powder. Hydrogen-driven two-stage guns — used routinely at NASA Ames since the 1990s — reach velocities that put circular orbit within one small motor burn.
• The economics work. Green Launch (2021) and SpinLaunch (raised $150M+) are both chasing HARP's core insight: chemical rockets are a terrible way to spend the first 30 seconds of flight. Green Launch specifically uses a hydrogen impulse launcher descended directly from Bull's work.
• The payload class is finally right. HARP made no sense when satellites weighed a ton. A modern 100 kg smallsat with electric propulsion is exactly what a Martlet 4 was sized for.

Bull was right about the physics. He was wrong about the diplomacy. Sixty years later, private companies are quietly rebuilding his gun — and pretending they invented it.