A reusable launch system is a launch system that includes the recovery of some or all of the component stages. To date, several fully reusable suborbital systems and partially reusable orbital systems have been flown.
The first reusable launch vehicle to reach orbit was the Space Shuttle, which failed to accomplish the intended goal of reducing launch costs to below those of expendable launch systems. SpaceX CEO Elon Musk has said that if one can figure out how to reuse rockets like airplanes then the cost of access to space will be reduced by as much as a factor of a hundred.
During the 21st century, commercial interest in reusable launch systems has grown considerably, with several active launchers. The SpaceX's Falcon 9 rocket has a reusable first stage and capsule (for Dragon flights) and expendable second stage, The Spaceship Company has flown reusable suborbital spaceplanes, and the suborbital Blue Origin New Shepard rocket has recoverable first stages and crew capsules.
Most launch systms are rocket based, but there are also non-rocket spacelaunch systems, or combinations thereof.
Full reusable systems can be single stage to orbit (SSTO) as well as multiple (two or three) stage to orbit systems. Such systems are yet to be proven viable with particularly second stage designs not being reusable yet.
Partial reusable launch systems, in the form of multiple stage to orbit systems have been so far the only reusable configurations in use.
Launch systems can combine reusable space vehicles. The Space Shuttle for example was a reusable space vehicle (a spaceplane) as well as a part of its launch system.
Contemporary reusable orbital vehicles include the X-37, the Dream Chaser, the Dragon 2, the European Space Rider (successor to the IXV) and the Indian RLV Technology Demonstration Programme and Avatar.
As with launch vehicles, all pure spacecraft during the early decades of human capacity to achieve spaceflight were designed to be single-use items. This was true both for satellites and space probes intended to be left in space for a long time, as well as any object designed to return to Earth such as human-carrying space capsules or the sample return cannisters of space matter collection missions like Stardust (1999–2006) or Hayabusa (2005–2010). Exceptions to the general rule for space vehicles were the US Space Shuttle (mid-1970s-2011, with 135 flights between 1981 and 2011) and the Soviet Union Buran (1980-1988, with just one uncrewed test flight in 1988). Both of these spaceships were also an integral part of the launch system (providing launch acceleration) as well as operating as medium-duration spaceships in space. This began to change in the mid-2010s.
In the 2010s, the space transport cargo capsule from one of the suppliers resupplying the International Space Station was designed for reuse, and after 2017, NASA began to allow the reuse of the SpaceX Dragon cargo spacecraft on these NASA-contracted transport routes. This was the beginning of design and operation of a reusable space vehicle. As of 2020[update], SpaceX is currently building and testing the Starship spaceship to be capable of surviving multiple hypersonic reentries through the atmosphere so that they become truly reusable long-duration spaceships. But no Starship reuse flights have yet occurred.
Reusable stages weigh more than equivalent expendable stages. This is unavoidable due to the supplementary systems, landing gear and/or surplus propellant needed to land a stage. The actual mass penalty depends on the vehicle and the return mode chosen.
Conventional launch systems use rockets to liftoff predominantly vertically.
Other systems employ horizontal liftoff, as in the case of SpaceShipTwo which uses a carrier plane for liftoff.
With possible inflateable heat shields, as developed by the US (Low Earth Orbit Flight Test Inflatable Decelerator - LOFTID) and China, single-use rockets like the Space Launch System are considered to be retrofitted with such heat shields to salvage the expensive engines, possibly reducing the costs of launches significantly.
Launch systems like the Falcon 9 employ for their reusable stages not only at landing retrograde burns, but also at re-entry and even boostback burns.
Reusable systems can come in single or multiple (two or three) stages to orbit configurations. For some or all stages the following landing system types can be employed for partial or full recovery of the launch system.
These are landing systems which employ parachutes and bolstered hard landings, like in a splashdown at sea.
Single or main stages, as well as fly-back boosters can employ a horizontal landing system.
A variant is an in-air-capture tow back system, advocated by a company called EMBENTION with its FALCon project.
Expendable rockets air launched from aircraft can be considered partially reusable[according to whom?] if the aircraft is thought of as the first stage of the launch vehicle. An example of this configuration is the Northrop Grumman Pegasus.
Vehicles that land horizontally on a runway require wings and undercarriage. These typically consume about 9-12% of the landing vehicle mass, which either reduces the payload or increases the size of the vehicle. Concepts such as lifting bodies offer some reduction in wing mass, as does the delta wing shape of the Space Shuttle.
Systems like the McDonnell Douglas DC-X (Delta Clipper) and those by SpaceX are examples of a retrograde system. The boosters of Falcon 9 and Falcon Heavy land using one of their nine engines. The Falcon 9 rocket is the first orbital rocket to vertically land its first stage on the ground. Both stages of Starship are planned to land vertically.
Early ideas of a single-stage reusable spaceplane proved unrealistic and although even the first practical rocket vehicles (V-2) could reach the fringes of space, reusable technology was too heavy. In addition many early rockets were developed to deliver weapons, making reuse impossible by design. The problem of mass efficiency was overcome by using multiple expendable stages in a vertical-launch multistage rocket. The first reusable stages did not appear until the advent of the US Space Shuttle in 1981.
NASA started the Space Shuttle design process in the late 1960s, with the vision of creating a fully reusable spaceplane using a crewed fly-back booster for the 1970s. This design proved too expensive and complex to develop in time, therefore the design was scaled back to use reusable solid rocket boosters and an expendable external tank. The Shuttle proved much more expensive to operate over its 30 year lifetime than an expendable launch system would have been.
NASA proposed risky reusable concepts to replace the Shuttle technology, to be demonstrated under the X-33 and X-34 programs, which were both cancelled in the early 2000s due to rising costs and technical issues.
The Ansari X Prize contest was intended to develop private suborbital reusable vehicles. Many private companies competed, with the winner, Scaled Composites, reaching the Kármán line twice in a two-week period with their reusable SpaceShipOne.
On 23 November 2015 the New Shepard rocket became the first Vertical Take-off, Vertical Landing (VTVL) sub-orbital rocket to reach space by passing the Kármán line (100 km or 62 mi), reaching 329,839 ft (100,535 m) before returning for a propulsive landing.
The first Falcon 9 second flight of a first stage occurred on 30 March 2017. SpaceX now routinely recovers and reuses their first stages, with the intent of reusing fairings as well.
As of May 2020[update], the only operational reusable orbital-class launch systems are the Falcon 9 and Falcon Heavy, the latter of which is based upon the Falcon 9. SpaceX is also developing the fully-reusable Starship launch system, and Blue Origin is developing its own New Glenn partially-reusable orbital rocket, as it is intending to recover and reuse only the first stage.
|Blue Origin||New Shepard||US||Suborbital||Operational||Under development.|
|ISRO||RLV-TD||India||Suborbital||Project||Successful flight test|
|Virgin Galactic||SpaceShipTwo||US||Suborbital||Prototype||Designed for space tourism.|
|SpaceX||Falcon 9||US||Orbital||Operational||First stage and fairing reusable.|
|SpaceX||Falcon Heavy||US||Orbital||Operational||Core, side boosters and fairing reusable.|
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