What is Single-stage-to-orbit?
A '''single-stage-to-orbit''' (abbreviated as '''SSTO''') is a hypothetical spacecraft. It can reach [[Outer space|space]] from the surface of a [[planet]] without expending major pieces of the craft (such as engines, fuel tanks, or [[Wing|wings]]). As of November 2022, no SSTOs have successfully made it to space from [[Earth|Earth's]] surface; all space launches so far have been performed by [[Rocket|rockets]] with multiple stages. ==Advantages== SSTOs have been supposed to hold many advantages over rockets. The main one is their reusability. Most launch systems are expendable (meaning that they are used once and not reused or recovered), with some exception of partially reusable launch systems (such as [[NASA|NASA's]] [[Space Shuttle]] or [[SpaceX|SpaceX's]] [[Falcon Heavy]]). Such partially reusable launch systems have significantly reduced many peoples' interest in SSTOs, because they dramatically lower launch costs using already proven technology that doesn't need expensive development. == Challenges == === Technical issues === It is generally considered possible for a [[Rocket engine|rocket-powered]] SSTO to reach [[Low Earth orbit|Earth orbit]], so long as the many technical challenges with SSTOs can be solved sometime in the future. The main complications with SSTOs are: # Having to reach Earth orbital velocity (7,400 m/s; 27,000 km/h; 17,000 mph) # Having to overcome Earth's [[gravity]] (this may be particularly hard at the beginning of the flight, when the fuel tanks are fullest, the [[Atmosphere of Earth|atmosphere]] thickest, and Earth's gravity the most intense) # Having to fly within Earth's atmosphere (thus battling [[Drag (physics)|drag]] and engine inefficiencies caused by [[atmospheric pressure]]) All of these challenges have to be solved, made to work in a singular vehicle with little to no [[expenditure]] of hardware, and with some breathing room left over for the weight of the craft's payload. Doing so is a hard challenge. Scientists have been finding solutions for decades. === Costs ===