two-stage-to-orbit (TSTO)Generally descriptive of a reusable launch vehicle that uses an air-breathing first stage and a separate or parallel, rocket-propelled second stage. Examples include Sanger's space plane and Boeing's Beta. An alternative TSTO concept is the Kistler K-1. Related entry single-stage-to-orbitRelated category ROCKETS, MISSILES, AND LAUNCH VEHICLESAlso on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |