An undated computer generated image made available by Reaction Engines SKYLON on November 28, 2012 showing the SKYLON unpiloted, reusable spaceplane intended to provide reliable, responsive and cost effective access to space. SKYLON reports that Reaction Engines Ltd., of Oxfordshire, England, announced on 28 November 2012 the biggest breakthrough in aerospace propulsion technology since the invention of the jet engine. Critical tests have been successfully completed on the key technology for SABRE, an engine which will enable aircraft to reach the opposite side of the world in under four hours, or to fly directly into orbit and return in a single stage, taking off and landing on a runway.