 Artist's impression of Hermes | |||
| Designer | Centre National d'Études Spatiales | ||
|---|---|---|---|
| Country of origin | France | ||
| Specifications | |||
| Spacecraft type | Spaceplane | ||
| Launch mass | 21,000 kg (46,000 lb) | ||
| Payload capacity | 3,000 kg (6,600 lb) | ||
| Crew capacity | Three | ||
| Design life | 30 to 90 days | ||
| Production | |||
| Status | Cancelled | ||
| |||
Hermes was a proposedspaceplane designed by the FrenchCentre National d'Études Spatiales (CNES) in 1975, and later by theEuropean Space Agency (ESA). It was superficially similar to the AmericanBoeing X-20 Dyna-Soar and the largerSpace Shuttle.
In January 1985, CNES proposed to proceed with Hermes development under the auspices of the ESA.[1][2] Hermes was to have been a crewed spaceflight program launched by anAriane 5launch vehicle. In November 1987, the project was approved for pre-development from 1988 to 1990, after which authorisation for full development was required. However, the project experienced numerous delays and funding issues.
In 1992, Hermes was cancelled due to high cost and unachievable performance, as well as a partnership with theRussian Aviation and Space Agency (RKA) which reduced the need for an independent spaceplane. As a result, no Hermes shuttles were ever built. During the 2010s, it was proposed to resurrect the Hermes vehicle as apartially reusableair-launchedspaceplanelaunch system, known asSOAR.
During the 1960s and 1970s, there was increasing recognition by European nations that more international cooperation would be necessary for large space projects.[3] In 1973, theEuropean Space Research Organisation (ESRO) — a precursor to theEuropean Space Agency (ESA) — commenced development of a heavyexpendable launch system later named theAriane. The French space agencyCentre National D'études Spatiales (CNES), desired greater autonomy to avoid overreliance uponNASA, and envisaged a European-built human-capable space vehicle that would operate in conjunction with other ESA assets such as Ariane.[3]
In 1976, CNES commenced studies into a crewed version of Ariane.[4] Two different concepts included a capsule and a glider. In 1983, CNES opted to focus on a space plane that would deliver greater convenience, comfort, and cost-effectiveness.[4] A space plane would simplify recovery by having the necessary cross-range manoeuvrability to reach a given point on the Earth within a single day, while providing for a less challenging re-entry environment for the crew and payload. Reusability would also reduce the cost of successive missions.[4] Critical technologies identified includedthermal protection,environmental controls,life support systems,aerodynamics, and power.[5]
During the mid-1980s, in addition to theColumbus Man-Tended Free Flyer (an independent Europeanspace station) and theAriane 5 heavy launch vehicle,[6] CNES championed the development and production of theSpace Shuttle as a European initiative akin to the reusable space vehicle programs of the Soviet Union'sBuran and the USSpace Shuttle.[3]
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On 18 October 1985, CNES appointed Frenchaerospace companyAérospatiale as the primary contractor for Hermes, the name that had been given to the spacecraft. French aircraft manufacturerDassault-Breguet was awarded responsibility for the aerodynamic and aerothermal aspects of the design.[3]Arianespace was responsible for the Ariane 5 launcher and a strong candidate to manage operation of the infrastructure forHermes.[3]
On 25 October 1985, the proposal for Hermes was presented to the partner nations of the ESA.[3] A deadline of March 1987 was set for the 'Europeanisation' of the programme, under which portions of work for Hermes was assigned.[7] The work share was attributed 15% toWest Germany, 13% to Italy, 7% to Belgium, 5% to the Netherlands, 4% each to the United Kingdom, Spain, and Sweden, and 2% or less to Switzerland, Austria, Denmark and Ireland. Potential participation by Norway and Canada was mooted.[3] France held a 50 percent share of the work, although CNES was open to further redistribution of the work dependent upon individual partners increasing their stake in the programme. Early on, there was optimism that securing the funding from ESA members to proceed would not be difficult.[3]
In November 1987, the ESA issued its approval. As envisaged, by 1995 Hermes would enable the ESA to service the planned Columbus Man-Tended Free Flyer (MTFF)[8] (the MTFF was restructured and ultimately manufactured as theColumbus module of theInternational Space Station).[3] Development of Hermes was to proceed in two phases:[3]
Phase 1 was scheduled to end in 1990. Its plans called for the capability to lift 6 astronauts and 4,550 kg (10,030 lb) of cargo, but after theChallenger disaster, an ejection capacity was added to give astronauts at least a small chance of survival in case of catastrophe. Accordingly, the six seats were curtailed to three regularejection seats, which were chosen over an ejectable crewcapsule that would have offered an escape option at heights above 28 km (17 mi). The cargo capacity was reduced to 3,000 kg (6,600 lb).Hermes would not be able to place objects intoorbit because its cargo hold could not be opened; that option was abandoned due to weight concerns.[citation needed]
AlthoughHermes was originally viewed as fully reusable (up to 30 re-entries before major service), the limited capacity of the Ariane 5 launcher forced it to leave the Resource Module in orbit. A new resource module would be attached to theHermes and the entire structure would be launched again.
Phase 1 was not completed until the end of 1991 and by then the political climate had changed considerably. TheIron Curtain had been lifted and theCold War was ending. As a result, ESA commenced a year-long "reflection" period to determine whether it still made sense for Europe to build its own space shuttle and space station or if new partners could be found to share cost and development. Officially, Phase 1 completed at the end of 1992.
Phase 2 never began, after ESA and theRussian Aviation and Space Agency (RKA) agreed to cooperate on future launchers and a replacement space station forMir. Economic concerns prevented RKA from participating in a future launcher program, but at this point ESA's crew transport needs were reoriented towards the capsule system (as opposed to the glider system ofHermes) called for by the joint Russian/European designs.
When both Russia and ESA joined withNASA to build theInternational Space Station, the need for a European crew transport system was eliminated because Russian and American needs were already satisfied. Accordingly, ESA abandoned theHermes project.
Hermes was intended as areusable launch system to transportastronauts and moderate-size cargo payloads intolow Earth orbit (LEO) and back.[3] Hermes bears a resemblance to otherreusable launch vehicles such as theSpace Shuttle. However, unlike the Space Shuttle, Hermes could not carry heavy cargoes as that role was to be performed by the uncrewedAriane 5.[9] Hermes was envisioned to transport a maximum of three astronauts[10] along with a 3,000 kg (6,600 lb) pressurized payload. The launch weight would be up to 21,000 kg (46,000 lb), the practical upper limit of an extended Ariane 5 launcher.
Hermes was to be launched as the upper stage of the Ariane 5. Prior to the 1986 redesign,Hermes was a single spaceplane containing (front to back) a crew compartment for six, an airlock, an unpressurized cargo hold similar to Buran's and the Shuttle's, and a service module.[11] After the 1986Challenger accident it was substantially redesigned.[12] The crew cabin shrank to carry three astronauts, with the cargo hold pressurized and unable to carry or retrieve satellites.Hermes now consisted of two separate sections: the vehicle itself and a cone-shaped Resource Module having a docking mechanism attached to the vehicle's rear, which was detached and discarded prior tore-entry. Only the crewed vehicle would re-enter Earth's atmosphere and be re-used. The Resource Module and the launcher would be expended.[9] When launching the Hermes, the Ariane 5 would have had its upper stage replaced by the space plane and an adaptor to mate the vehicle to the maincryogenic stage. The equipment bay of the launcher would also be removed and the spaceplane would perform all guidance and control functions.[4] The development of the Ariane 5 was strongly influenced by the requirements ofHermes, such as the extra aerodynamic loads along with an increased reliability factor of 0.9999, while retaining minimal impact on the launcher's commercial competitiveness on non-Hermes missions.[4]
In comparison to the Space Shuttle,Hermes was substantially smaller.[4] It did not share theogival planform of the Shuttle, instead opting for a highly-sweptdelta wing complete withwingtip devices, similar to the proposedBoeing X-20 Dyna-Soar spacecraft. Like the Shuttle, the pressurised cabin could seat more than five people, two of whom would serve as pilots, while the unpressurised aft cargo bay would have been fitted with large doors spanning the length of the bay along the fuselage.[13] The vehicle would have been powered by a pair of 2,000N-thrust liquid propellantrocket motors identical to those used on the L4 low-energy upper stage of the Ariane 5.[4]
Aerodynamic control would have been provided via a total of sevenflight control surfaces, the wingtiprudders,trailing edgeelevon/air brakes, and a body-mountedflap; these surfaces would have been controlled via quadruplex-redundantdigital flight controls and actuated via triplex-redundant hydraulics.[4] Mission management would have been performed via three general-purpose computers, a monitoring computer, and three digitaldatabuses. Electrical power was to be provided by amotor that would have usedliquid oxygen-liquid hydrogen along with ten US-builtfuel cells.[5] The environmental control and life support systems supplypressurisation of the cabin, along with air, water, and warmth, to support the crew for a maximum of 40 days, although may have been potentially extendable to enable 90 day missions.Hermes could have operated autonomously for up to one month, and would be able to remain docked with an orbiting space station for a maximum of 90 days.[5]
According to CNES,Hermes would have been subject to more extreme re-entry conditions than the Space Shuttle due to its smaller size exposing the vehicle to higher aerothermal pressures.[14] The baseline thermal protection,[15] was to withstand temperatures of 1,400-1,600 °C for a minimum of 20 minutes and studied by Dassault and SEP, would have consisted ofcarbon elements with an anti-oxidant coating applied to portions of the nose andleading edges of the wings, while thermal tiles were to have covered the underside of the wing and fuselage.[14] These tiles would have employed thin, reinforcedceramic-carbon honeycombcomposite insulating layers separated by thin sheets of metalalloy to reflect the heat; an alternative concept for the tiles would have employed higher metallic portions in place of ceramics. The upper surfaces of the vehicle would have been subject to less heat than the lower surfaces, and used flexible blanket-like low-density, glassfibre-ceramic layers.[14]
The shape of Hermes had been effectively frozen by November 1985.[14] It was refined by subsonicwind tunnel testing in the Onera, constrained by the requirements of subsonic flight. In order to gather valuable data in the face of Europe's lack of experience, Dassault proposed validating the aerodynamic properties of the vehicle by completing a 1.4-tonne, 1-scale aerothermal demonstrator, namedMaia, to be launched by anAriane 4 for re-entry studies.[16]
Four typical missions were projected forHermes:
After each mission, Hermes would be refurbished at a dedicated facility in Europe.[17] Around 40 days prior to a launch date, the vehicle would be transported on a specially-modifiedAirbus A300 airliner to its launch site inKourou,French Guiana, where it would be integrated with its payload and installed atop an Ariane 5 rocket prior to being transferred to the launch pad. Mission control was to be based atToulouse, France.[17] During a typical mission, communications and tracking would have been performed by a planned European network of data relay satellites with coverage across 75% of a Hermes mission at a 28.5° orbit at an altitude of 400 km (250 mi).
Following a mission, Hermes would land atIstres-Le Tubé Air Base nearIstres.[17] Other potential landing sites were mooted, includingGuiana Space Centre,Martinique Aimé Césaire International Airport on the island ofFort de France and unspecified airstrips inBermuda. In the event of an aborted launch during the first 84 seconds,Hermes would be able to return to Kourou. A later abort would likely necessitate a water landing in theAtlantic Ocean, after which the vehicle would need to be retrieved by a recovery ship. Other emergency landing strips were to be designated, dependent upon the specifics of each mission.[17]
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A full scale mockup was built in 1986,[18] and was shown in 1987 atLe Bourget in May, followed byMadrid in September andToulouse during October - November. In 1988 the mockup was shown atStrasbourg in Abril,Hanover in May, andBordeaux in December. With the end of the project in 1993, this mockup was transferred toENSICA (École nationale supérieures d'ingénieurs de construction aéronautique) in 1996. In 2005 it was brought toLe Bourget to await a possible restoration project.[18]
A 1/7 scale model built byEADS has been on display since 2002 at theBordeaux–Mérignac Airport.[18]
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