Getting anywhere in the world within four hours seems impossible, but a UK company, Reaction Engines Ltd., successfully completed testing of a new propulsion system that could one day make that possible.
The idea behind the REL system is similar to what we now see with current jetliners, but would function as a rocket.
Called SABRE, it burns hydrogen and oxygen but gets the oxygen from the atmosphere, much like a jet engine breathes fuel. The system would be affixed to a 275-foot Skylon spaceplane. Taking off and landing like a regular airbus, the vehicle would then burn its onboard fuel supply once it reaches speeds of about Mach 5.
Though roughly $400 million is still needed in funding, the company is confident funding from private investors will continue to come in as the project continues over the next four years.