Instead of launching satellites with rockets, isn't it easier to fire them with a super-powerful cannon? It was this approach that the developers of the HARP project almost implemented in practice, and after them - and Saddam Hussein himself.
The idea of delivering cargo to orbit using a cannon was first proposed by Newton. His treatise Principia Matematica contains, among other things, the famous illustration of a cannon on top of a mountain, firing a cannonball parallel to the earth's surface. Explaining the principles of orbital mechanics, the scientist argued: if you give the nucleus the necessary acceleration, it will never fall to the Earth and will circle around it forever. This thought experiment formed the basis of the novel From the Earth to the Moon, written by Jules Verne in the 19th century: the writer sent his heroes to the moon with the help of a gigantic cannon. Of course, for a long time no one considered such projects other than a game of imagination.
Unlike a rocket, a projectile fired from a cannon constantly loses speed due to air resistance. This means that for launching into space, its initial velocity must be truly colossal, which is associated with a gigantic - in thousands of g - acceleration at the beginning of the journey, which threatens to turn the entire payload into a cake. In addition, the charge of gunpowder that would be required to give the projectile such acceleration would deform the barrel of even a very impressive thickness.
At the beginning of the 20th century, the capabilities of artillery began to grow. A smokeless gunpowder was invented that could burn gradually, accelerating the projectile along a flatter curve. In fact, this important discovery meant that the range of the shot could be increased almost indefinitely - by lengthening the barrel and increasing the powder charge. This opened the era of gigantic artillery mechanisms (and no less Cyclopean means of protection against them). The thirty-meter Paris Cannon, built by the Germans in 1918, fired a shell weighing more than 100 kg with an initial speed of 6 thousand km / h, and could fire at targets from a distance of 126 km. The flight itself lasted a full three minutes, while at the top of its trajectory the projectile reached an altitude of 42 km.
Ultra-long-range guns were also built during World War II, but even then it became clear that aircraft are much more effective as a means of delivering explosive charges over long distances. Therefore, the development of superguns stopped, coming close to the point at which the launch of shells into space became a feasible task.
In the early 1960s, the young American physicist Gerald Bull was captured by the idea of delivering cargo to orbit using cannons. Having managed to convince the American authorities of its prospects, he received several decommissioned 406-mm (16-inch) cannons at his disposal, as well as funds for the corresponding development. The project was designated HARP (High Altitude Research Project). For shooting, Gerald Bull's team used a specially designed sub-caliber (having a slightly smaller caliber than the barrel) Marlet projectile. In addition to the sealing device, or "shoe", dropped after exiting the barrel, the projectile had a cargo compartment and stabilizers. During the tests, one of the modifications of the projectile was launched to a maximum height of 180 km. That is, to come close to solving the problem of firing small objects into near-earth orbit.
As an experiment, mainly atmospheric probes, as well as various components of future satellites - sensors, batteries, modules of electronic and propulsion systems, etc. were placed in the cargo compartments of the projectiles. The project culminated in the development of the Martlet 2G-1 projectile equipped with a rocket booster. With its help, it would be possible to launch up to two kilograms of payload into orbit by means of a shot from a simple artillery gun. However, on the eve of the Martlet 2G-1 trials, research funding was suddenly cut off.
Nevertheless, it was HARP that became the first and, it seems, the only project in which a person almost managed to launch a payload into space by firing an ordinary cannon. And the project manager Gerald Bull went to work for Saddam Hussein and for several years worked on the creation of the colossal 1000mm Babylon cannon. As conceived by the creator, a 9-ton charge was supposed to deliver 600 kg of cargo at a distance of up to 1000 km, and a projectile with a jet accelerator would have doubled this distance. However, the work was not destined to end: in 1990, Gerald Bull, who had "got in touch with the bad guys," was killed. The huge 156-meter trunk of the Babylon project is still rusting in the middle of a pit specially dug in the Iraqi desert.
