To get astronauts into space, an incredible amount of fuel is needed (for example, the Saturn V rocket that launched the Apollo mission carried 770,000 liters of kerosene, as well as liquid oxygen as an oxidizer), So researchers have long been exploring alternatives to rockets — such as space elevators, kinetic launch systems (which spin a rocket to incredible speeds in a vacuum chamber and are not yet safe enough for humans), or a railgun (essentially a giant catapult).
The latter is currently being developed in China. The idea of the system is to launch the spacecraft along a giant electromagnetic launch track at Mach 1.6 (and in the future — up to Mach 5), and then it will start its own engines and leave the Earth’s atmosphere, accelerating to about 7 times the speed of sound.
The Aircraft Technology Research Institute of the China Aerospace Science and Industry Corporation (CASIC) has already built a two-kilometer test track in Datong, Shanxi Province.
A railgun that can accelerate a ship to Mach 1.6 with passengers on board must be at least 8 km long (and much longer, up to Mach 5). The problem is that this would require a large number of electromagnets that would need cryogenic cooling (and thus a giant vacuum chamber, which does not exist in nature), and a specific airlock to allow the vehicle to exit at supersonic speed (if the system does not work perfectly — a very nasty accident close to the energy of a tactical nuclear weapon could occur).
Another issue is that, for example, the railguns that launch fighters from the USS Gerald R. Ford, use 121 MJ to accelerate an aircraft to 241 km/h. To accelerate a vehicle of the same mass to Mach 5, a Chinese railgun would need a staggering 50,000 MJ (and the spaceplane that will be used in the future will weigh at least 10 times more).
Consequently, such an electromagnetic gun would require a nuclear power plant that would generate a gigajoule per second, and a completely new supercapacitor would be needed to store the energy. Dresden’s Hochfeld-Magnetlabor Dresden has a state-of-the-art capacitor battery that can withstand 50 MJ, which is a world record — the Chinese railgun would have to improve its achievements by a thousand.
The Chinese claim that if the railgun system is successful, it will reduce the cost of launching into orbit to $60/kg (SpaceX’s current cost is $3000/kg).
Source: South China Morning Post (via New Atlas)