The British Skylon single-stage-to-orbit space plane would take off from a runway and fly on air-breathing hydrogen-fueled rocket engines for much of its ascent through the atmosphere. When the air becomes too thin, Skylon switches to onboard liquid oxygen.
The Skylon Personnel / Logistics Module (SPLM) could be installed in Skylon’s cargo bay for carrying a combination of passengers and supplies to orbital stations. If carrying passengers only, it could support up to 30 people.
From runway takeoff to an altitude of 17.4 miles (28 km), SABRE sucks in air to burn with its liquid hydrogen fuel. Once the air becomes too thin, Skylon switches to its onboard liquid oxygen tanks. This saves Skylon from having to carry more liquid oxygen than absolutely necessary.
The SABRE engine could be used in future commercial airliners capable of a cruising velocity of Mach 5 (3,806 mph, or 6,125 km/h) and a range of up to halfway around the world. This aircraft could carry 300 passengers from Brussels to Sydney in 4.6 hours.
A European Space Agency study undertaken in 2007 explored using Skylon space planes to assemble a Mars transfer vehicle in Earth orbit, for a launch opportunity in 2028. Three of the six crewmembers would land on Mars and spend about 30 days there. The entire mission would take two years and eight months.