Boussard interstellar ramjet, artwork. This is a theoretical spaceship that would be suitable for travel to the stars. Instead of carrying fuel, it uses the hydrogen gas found between the stars. Even though the interstellar hydrogen density is very low, a powerful magnetic field would be generated to 'scoop' hydrogen from a large volume of space. The hydrogen would pass into the fuel scoop at the nose, and then into a fusion reactor. Hot plasma from the reactor exits (lower right) through the exhaust nozzle, providing thrust. Such a ship could approach the speed of light, when relativity effects would lead to short journey times to the stars.