Project HARP originated as the brainchild of Gerald Bull, a renowned but controversial ballistic engineer who specialized in high velocity guns and gun propulsion systems. In the mid-1950s, Bull was working on Anti-Ballistic Missile (ABM) and Intercontinental Ballistic Missile (ICBM) research at the Canadian Armaments and Research Development Establishment (CARDE) when he formulated the idea to launch satellites into orbit using an enormous cannon. Bull believed that a large supergun would be significantly more cost-effective at sending objects into space than a conventional rocket, because in addition to not needing expensive rocket motors, firing a large gun wouldn't require the missile to throw away multiple rocket stages to break through the Earth's atmosphere to reach orbit. In theory, a sabot would protect the payload during firing and later fall away as the satellite inside emerges.