Advanced Gemini
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Advanced Gemini is a number of proposals that would have extended the
Gemini Gemini may refer to: Space * Gemini (constellation), one of the constellations of the zodiac ** Gemini in Chinese astronomy * Project Gemini, the second U.S. crewed spaceflight program * Gemini Observatory, consisting of telescopes in the Northern ...
program by the addition of various missions, including manned
low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...
,
circumlunar In orbital mechanics, a circumlunar trajectory, trans-lunar trajectory or lunar free return is a type of free return trajectory which takes a spacecraft from Earth, around the far side of the Moon, and back to Earth using only gravity once the ...
and
lunar landing A Moon landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959. The United S ...
missions. Gemini was the second manned spaceflight program operated by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
, and consisted of a two-seat spacecraft capable of maneuvering in orbit, docking with unmanned spacecraft such as Agena Target Vehicles, and allowing the crew to perform tethered
extra-vehicular activities Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable atmosphere of Earth, Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmen ...
. A range of applications were considered for Advanced Gemini missions, including military flights,
space station A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station i ...
crew and logistics delivery, and lunar flights. The Lunar proposals ranged from reusing the docking systems developed for the Agena target vehicle on more powerful upper stages such as the
Centaur A centaur ( ; grc, κένταυρος, kéntauros; ), or occasionally hippocentaur, is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse. Centaurs are thought of in many Greek myths as being ...
, which could propel the spacecraft to the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
, to complete modifications of the Gemini to enable it to land on the Lunar surface. Its applications would have ranged from manned lunar flybys before
Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label=Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label= ...
was ready, to providing emergency shelters or rescue for stranded Apollo crews, or even replacing the Apollo program. Some of the Advanced Gemini proposals used "off-the-shelf" Gemini spacecraft, unmodified from the original program, while others featured modifications to allow the spacecraft to carry more crew, dock with space stations, visit the Moon, and perform other mission objectives. Other modifications considered included the addition of wings or a
parasail Parasailing, also known as parascending, paraskiing or parakiting, is a recreational kiting activity where a person is towed behind a vehicle while attached to a specially designed canopy wing that resembles a parachute, known as a parasail w ...
to the spacecraft, in order to enable it to make a horizontal landing.


Background

Gemini was the second American manned orbital spaceflight program, after
Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...
. It was intended to demonstrate technologies and techniques required for the Apollo program, such as
extra-vehicular activities Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable atmosphere of Earth, Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmen ...
, rendezvous and docking, maneuvering in orbit and long duration flight. The
Gemini spacecraft Project Gemini () was NASA's second human spaceflight program. Conducted between projects Mercury and Apollo, Gemini started in 1961 and concluded in 1966. The Gemini spacecraft carried a two-astronaut crew. Ten Gemini crews and 16 individual ...
, which was built by
McDonnell Aircraft The McDonnell Aircraft Corporation was an American aerospace manufacturer based in St. Louis, Missouri. The company was founded on July 6, 1939, by James Smith McDonnell, and was best known for its military fighters, including the F-4 Phantom I ...
, was derived from the earlier
Mercury spacecraft Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbital spaceflight, orbit and return him safely, ideally ...
, but modified to accommodate two
astronaut An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...
s. It was also equipped with a larger equipment module, allowing it to support longer missions, and maneuver in orbit. It was launched by the
Titan II The Titan II was an intercontinental ballistic missile (ICBM) developed by the Glenn L. Martin Company from the earlier Titan I missile. Titan II was originally designed and used as an ICBM, but was later adapted as a medium-lift space l ...
rocket flying from
Launch Complex 19 Launch Complex 19 (LC-19) is a deactivated launch site on Cape Canaveral Space Force Station, Florida used by NASA to launch all of the Gemini crewed spaceflights. It was also used by uncrewed Titan I and Titan II missiles. LC-19 was in use fro ...
at the
Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the statio ...
. In total, twelve missions were launched, ten of which were manned. Following two unmanned test flights, the first manned flight,
Gemini 3 Gemini 3 was the first crewed mission in NASA's Project Gemini and was the first time two American astronauts flew together into space. On March 23, 1965, astronauts Gus Grissom and John Young flew three low Earth orbits in their spacecraft, ...
, was launched on 23 March 1965. The program concluded on 15 November 1966, with the successful recovery of
Gemini 12 Gemini 12 (officially Gemini XII) With Gemini IV, NASA changed to Roman numerals for Gemini mission designations. was a 1966 crewed spaceflight in NASA's Project Gemini. It was the 10th and final crewed Gemini flight ( Gemini 1 and Gemini 2 wer ...
. Many other applications were envisaged for the Gemini spacecraft at various stages before, during, and after the two years in which it was used by NASA for manned spaceflight. Although none of these proposals ever made it into operation, many were considered seriously, and in some cases flight hardware was constructed prior to cancellation. In the case of the
Manned Orbital Laboratory The Manned Orbiting Laboratory (MOL) was part of the United States Air Force (USAF) human spaceflight program in the 1960s. The project was developed from early USAF concepts of crewed space stations as reconnaissance satellites, and was a succ ...
, a Gemini spacecraft was launched on a suborbital demonstration flight in support of the program. In some cases technology developed in the Advanced Gemini program has been reintegrated into other programs, such as components from the
Titan IIIM The Titan IIIM was a planned American expendable launch system, intended to launch the Manned Orbiting Laboratory and other payloads. Development was cancelled in 1969. The stretched core stage was used on some versions of the Titan IIIB and the ...
, which was to have launched MOL, being used to upgrade other Titan rockets.


Military applications

The
United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
intended to use the Gemini spacecraft to transport astronauts to its proposed
space stations A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station i ...
, the
Manned Orbital Development System The Military Orbital Development System was created by the US Air Force Space System Division (SSD) in June 1962. It was to begin plans to use Gemini hardware as the first step in a new US Air Force man-in-space program called MODS (Manned Orbital ...
and later the
Manned Orbital Laboratory The Manned Orbiting Laboratory (MOL) was part of the United States Air Force (USAF) human spaceflight program in the 1960s. The project was developed from early USAF concepts of crewed space stations as reconnaissance satellites, and was a succ ...
(MOL). These stations would have been launched by
Titan IIIM The Titan IIIM was a planned American expendable launch system, intended to launch the Manned Orbiting Laboratory and other payloads. Development was cancelled in 1969. The stretched core stage was used on some versions of the Titan IIIB and the ...
rockets, with a Gemini spacecraft atop, eliminating the need for rendezvous and docking maneuvers. For this purpose, several modifications were made to the Gemini capsule, including the installation of a hatch in the
heat shield In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...
to allow access to the space station. In order to give its astronauts experience before these programs started, the
Blue Gemini Blue Gemini was a United States Air Force (USAF) project first proposed in August 1962 for a series of seven flights of Gemini spacecraft to enable the Air Force to gain manned spaceflight experience prior to the launch of the Manned Orbital Develo ...
program was proposed, which would have seen USAF astronauts fly on NASA missions in order to practice various techniques required for their own missions. This would have first seen cooperative missions between NASA and the US Air Force, with two missions flying with crews composed of one astronaut from NASA, and one from the USAF, followed by two missions with all-USAF crews, but performing missions for NASA. After these flights, the US Air Force would have flown a number of missions of its own. Firstly, it would have flown a two-man Agena rendezvous and docking mission, followed by two one-man scientific or technology research missions. Other proposed missions included tests of the Astronaut Mobility Unit which was designed to assist with EVAs, inertial navigation systems, and flying a
radar imaging Imaging radar is an application of radar which is used to create two-dimensional images, typically of landscapes. Imaging radar provides its light to illuminate an area on the ground and take a picture at radio wavelengths. It uses an antenna and ...
system. MOL Launches would have been conducted from
Launch Complex 40 Space Launch Complex 40 (SLC-40), previously Launch Complex 40 (LC-40) is a launch pad for rockets located at the north end of Cape Canaveral Space Force Station, Florida. The launch pad was used by the United States Air Force for 55 Titan III a ...
at the
Cape Canaveral Air Force Station Cape Canaveral Space Force Station (CCSFS) is an installation of the United States Space Force's Space Launch Delta 45, located on Cape Canaveral in Brevard County, Florida. Headquartered at the nearby Patrick Space Force Base, the statio ...
, and Space Launch Complex 6 at
Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USS General Harry Taylor (AP-145), USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in K ...
. In 1966, a test flight was launched from LC-40, using a
Titan IIIC The Titan IIIC was an expendable launch system used by the United States Air Force from 1965 until 1982. It was the first Titan booster to feature large solid rocket motors and was planned to be used as a launcher for the Dyna-Soar, though the s ...
. It consisted of the
Gemini B The Manned Orbiting Laboratory (MOL) was part of the United States Air Force (USAF) human spaceflight program in the 1960s. The project was developed from early USAF concepts of crewed space stations as reconnaissance satellites, and was a s ...
spacecraft, built from the spacecraft used for the
Gemini 2 Gemini 2 (Gemini-Titan 2; GT-2) was the second spaceflight of the American human spaceflight program Project Gemini, and was launched and recovered on January 19, 1965. Gemini 2, like Gemini 1, was an uncrewed mission intended as a test fligh ...
test flight, atop
OPS 0855 OPS 0855, also designated OV4-3, was an American boilerplate Manned Orbiting Laboratory spacecraft launched in 1966. It was flown to demonstrate the launch configuration for future MOL missions. A number of research payloads, designated Manifold ...
, a boilerplate MOL space station. Gemini B was released on a suborbital trajectory, and descended to Earth to test modifications made to the heat shield, and ensure that the access hatch would not affect its performance. OPS 0855 continued on to orbit. Early MOL stations would have only been manned by a single crew, launched with the station. Later stations would have been designed to be resupplied, and support multiple crews, delivered by additional Gemini spacecraft, or derivatives. The MOL program was cancelled on 10 June 1969, in favor of unmanned reconnaissance satellites. Some systems developed for the program were later used on unmanned missions, while the
space suit A space suit or spacesuit is a garment worn to keep a human alive in the harsh environment of outer space, vacuum and temperature extremes. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, ...
s which were under development were transferred to NASA. The Titan IIIM rocket which was to launch MOL never flew, however some of the upgrades that were built into it were later used to upgrade other Titan rockets — the stretched first and second stages became the Titan 34, which was used as the core of some later
Titan IIIB Titan IIIB was the collective name for a number of derivatives of the Titan II ICBM and Titan III launch vehicle, modified by the addition of an Agena upper stage. It consisted of four separate rockets. The Titan 23B was a basic Titan II with an ...
flights, and on the
Titan 34D The Titan 34D was a United States expendable launch vehicle used to launch a number of satellites for military applications. Service history Derived from the Titan III, the Titan 34D featured Stage 1 and Stage 2 stretched with more powerful U ...
. The seven-segment
solid rocket booster A solid rocket booster (SRB) is a large solid propellant motor used to provide thrust in spacecraft launches from initial launch through the first ascent. Many launch vehicles, including the Atlas V, SLS and space shuttle, have used SRBs to give ...
s were later introduced on the
Titan IV Titan IV was a family of heavy-lift space launch vehicles developed by Martin Marietta and operated by the United States Air Force from 1989 to 2005. Launches were conducted from Cape Canaveral Air Force Station, Florida and Vandenberg Air For ...
-A.


Gemini Ferry

Several Gemini Ferry spacecraft were proposed to provide transportation of crews and cargo to NASA and USAF space stations in low Earth orbit. NASA contracted McDonnell to conduct a study into what modifications would be needed to allow the Gemini spacecraft to support this. Three spacecraft were envisioned; a manned spacecraft to transport crew to the stations, a manned spacecraft with a cargo module for both crew and cargo delivery, and a dedicated unmanned spacecraft to resupply the station every three or four months. The studies looked at minimizing required modifications to the Gemini spacecraft. Three docking methods were considered. The first was use of the existing docking system used on Gemini-Agena missions. This would have allowed the mission to be accomplished with little modification to the Gemini spacecraft needed, however crew transfer could only have been accomplished by means of an
Extra-vehicular activity Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmental support. EVA inc ...
(EVA). Changes that would have been required included strengthening the nose, installing two solid rockets to be used for a separation burn, adding the necessary equipment to perform the transfer EVA, and providing provisions for flight to and from the station. The number of retro-rockets would have been increased from four to six. A second method would have seen the spacecraft dock in the same way, but after docking, the spacecraft would be swung round and attached to the side of the space station. A tunnel would then have been placed over the Gemini's hatches, allowing the crew to transfer to the station without performing an EVA. Some modifications to the hatches would have been required. The final proposed docking method was to use a port mounted on the rear of the equipment module, which would have allowed the crew to transfer directly between the spacecraft and space station, through the docking port. A modified version of the spacecraft was proposed, which would have included a cargo module attached to the back of a modified equipment module. The spacecraft would have approached the station, and docked backwards using a port on the rear of the cargo module. If one of the forward docking configurations had been used for the Gemini itself, the docking would have been controlled remotely from the station, with the Gemini then separating from the cargo module and flying around the station to dock normally on a different port. The rear-docking Gemini would have simply remained attached to the cargo module, with the crew boarding the station through it. Its docking would have been controlled by its own crew, from a station at the back of the cargo module. Two Gemini-derived spacecraft were considered for unmanned resupply flights. The first of these would have involved a Gemini spacecraft, with all systems for manned flight, re-entry and landing removed. The spacecraft would have docked using a port at the front of the spacecraft. Cargo would have been transferred through the nose of the spacecraft, where the re-entry attitude control system was located on the manned spacecraft. The spacecraft was equipped with a liquid propellant engine to perform rendezvous, and to reboost the space station. The other proposal was for a new spacecraft to be built for unmanned missions, but re-using as many Gemini systems as possible. It would have had a higher cargo capacity than the stripped-down version of the Gemini spacecraft. Crew-only or cargo-only supply missions would have been launched aboard a Titan II, and the
Saturn I The Saturn I was a rocket designed as the United States' first medium lift launch vehicle for up to low Earth orbit payloads.Terminology has changed since the 1960s; back then, 20,000 pounds was considered "heavy lift". The rocket's first stag ...
or
Saturn IB The Saturn IB (also known as the uprated Saturn I) was an American launch vehicle commissioned by the NASA, National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage (, ...
would have been used for the combined crew and cargo spacecraft. Because of the increased power of the Saturn I, the Gemini spacecraft's
ejection seat In aircraft, an ejection seat or ejector seat is a system designed to rescue the aircraft pilot, pilot or other aircrew, crew of an aircraft (usually military) in an emergency. In most designs, the seat is propelled out of the aircraft by an ex ...
s would not have been able to propel the crew far enough in the event of an explosion, so a launch escape tower was proposed, based on the one used on the
Mercury spacecraft Project Mercury was the first human spaceflight program of the United States, running from 1958 through 1963. An early highlight of the Space Race, its goal was to put a man into Earth orbital spaceflight, orbit and return him safely, ideally ...
. The Titan IIIM was also considered to launch the heavier spacecraft.


Big Gemini

Big Gemini Big Gemini (or "Big G") was proposed to NASA by McDonnell Douglas in August 1969 as an advanced version of the Gemini program, Gemini spacecraft system (albeit actually having little in common). It was intended to provide large-capacity, all-pu ...
, or Big G, grew out of a 1963 proposal called Gemini Transport, to develop an enlarged Gemini spacecraft with docking capability, which would take advantage of the increased capacity offered by the Saturn IB and Titan IIIM rockets. It was designed to transport between nine and twelve astronauts into space, and to be able to dock with space stations, in support of Apollo Applications and MOL missions. It would have been launched by a
Heavy lift launch vehicle A heavy-lift launch vehicle, HLV or HLLV, is an orbital launch vehicle capable of lifting between (by NASA classification) or between (by Russian classification) into low Earth orbit (LEO).50t payloads" , operational heavy-lift launch vehicl ...
; either a Titan IIIG or
Saturn INT-20 The Saturn INT-20 was a proposed intermediate-payload follow-on from the Apollo Saturn V launch vehicle. A conical-form interstage would be fitted on top of the S-IC stage to support the S-IVB stage, so it could be considered either a retrofitted ...
, the former being intended for use on US Air Force missions and the latter being intended for NASA missions. The Titan IIIM was also considered, which would have launched a smaller version of the spacecraft due to its lower capacity, to resupply MOL space stations later in the program. NASA also proposed several Saturn IB derivatives with solid first stages as alternatives to the INT-20, offering similar payload capacity. The shape and mass of the spacecraft would have varied depending on the rocket that was to launch it. The Saturn-launched version had a short, conical cargo module, and a total mass of whereas the Titan IIIG-launched version featured a longer, cylindrical module, with a total mass of . The Titan IIIM version would have been much shorter and lighter, with a mass of , as that rocket had less payload capacity than the Titan IIIG or Saturn. The IIIG variant would have carried twelve crew, while the others had a maximum capacity of nine. Use of the NASA variant with the Apollo Service Module was also considered. Once in orbit, Big G would have docked with space stations using an Apollo docking probe mounted on the rear of the cargo module, which was in turn mounted on the rear of the re-entry module. The re-entry module itself would have been enlarged to accommodate the larger crew, and the modifications made to the spacecraft for the MOL program would have been incorporated, including the hatch in the heat shield, which would have been used to provide access to the cargo module. In the event of a launch failure, the
launch escape system A launch escape system (LES) or launch abort system (LAS) is a crew-safety system connected to a space capsule that can be used to quickly separate the capsule from its launch vehicle in case of an emergency requiring the abort of the launch, suc ...
developed for the Apollo spacecraft would have been used to propel the re-entry module clear of the rocket. Big G would have made landings on land, using a
parasail Parasailing, also known as parascending, paraskiing or parakiting, is a recreational kiting activity where a person is towed behind a vehicle while attached to a specially designed canopy wing that resembles a parachute, known as a parasail w ...
or
paraglider Paragliding is the recreational and competitive adventure sport of flying paragliders: lightweight, free-flying, foot-launched glider aircraft with no rigid primary structure. The pilot sits in a harness or lies supine in a cocoon-like 'po ...
to guide it onto a runway or dry lake, such as the one at
Edwards Air Force Base Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is E ...
. It would have landed using skids derived from the
North American X-15 The North American X-15 is a hypersonic rocket-powered aircraft. It was operated by the United States Air Force and the National Aeronautics and Space Administration as part of the X-plane series of experimental aircraft. The X-15 set speed an ...
.


Lunar exploration


Circumlunar missions

A number of studies investigated sending a Gemini spacecraft onto a circumlunar trajectory. Many of the proposals made for this involved a double-launch architecture, with the Gemini spacecraft rendezvousing with an upper stage in orbit. Upper stages that were considered included the
Transtage Transtage, given the United States Air Force designation SSB-10A, was an American upper stage used on Titan III rockets, developed by Martin Marietta and Aerojet. History Transtage was developed in anticipation of a requirement to launch milita ...
, the second stage of a Titan II, four different types of
Centaur A centaur ( ; grc, κένταυρος, kéntauros; ), or occasionally hippocentaur, is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse. Centaurs are thought of in many Greek myths as being ...
, including the S-V variant developed for the Saturn I, the Agena-D, an enlarged Agena, and two Agenas burning in parallel. Either a Titan or Saturn IB would have been used to launch the upper stage, while the Gemini would launch on the Titan II, as it had in the Gemini program. Other proposals involved launching the Gemini spacecraft on a Titan IIIC, and refueling in low Earth orbit before proceeding to the Moon, and a single launch architecture using a three-stage variant of the Saturn IB. The Gemini-Centaur proposal was predicted to have been able to achieve a 72-hour circumlunar flight. The Centaur would have performed
trans-lunar injection A trans-lunar injection (TLI) is a propulsive maneuver used to set a spacecraft on a trajectory that will cause it to arrive at the Moon. History The first space probe to attempt TLI was the Soviet Union's Luna 1 on January 2, 1959 which wa ...
, before separating from the Gemini spacecraft. Some concerns were raised that the Gemini spacecraft's heat shield would not have been able to protect it during the higher speed
ballistic reentry Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet, or natural satellite. There are two main types of atmospheric entry: ''uncontrolled entry'', such as the ...
associated with the trajectory that would have been required. NASA proposed using a thicker heat shield and more insulation to protect the spacecraft. This and several other modifications made the spacecraft too heavy to be launched by the Titan II rocket which was used for the original twelve Gemini missions, so several
solid rocket motor A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder; they were used in warfare by the Arabs, Chinese, Persians ...
s would have been added to allow this additional mass to be flown.


Lunar orbit missions

The Gemini spacecraft would have rendezvoused with stacked Centaur and Agena upper stages in low Earth orbit. The Centaur would have placed the Gemini and Agena onto a circumlunar trajectory, along which they would coast until they reached the Moon. The Agena would then have been used to perform Lunar orbit insertion. Following the completion of activities in Lunar orbit, the Agena would have been fired again for trans-Earth injection. This architecture would have used a Titan II to launch the Gemini spacecraft, with a Saturn IB launching the upper stages.


Lunar landing

Using the Gemini spacecraft for a manned Lunar landing was considered as early as the original Mercury Mark II proposal which led to the Gemini program. The initial proposal was for a
Lunar orbit rendezvous Lunar orbit rendezvous (LOR) is a process for landing humans on the Moon and returning them to Earth. It was utilized for the Apollo program missions in the 1960s and 1970s. In a LOR mission, a main spacecraft and a smaller lunar lander travel to ...
mission, using a Gemini spacecraft and a lightweight, open cockpit lander, launched by a
Saturn C-3 The Saturn C-3 was the third rocket in the Saturn C series studied from 1959 to 1962. The design was for a three-stage launch vehicle that could launch to low Earth orbit and send to the Moon via trans-lunar injection. U.S. President Kennedy's ...
rocket. It was the first time that Lunar orbit rendezvous was proposed as part of a lunar landing concept. The spacecraft would have been tested in Low Earth orbit before the Lunar missions, using two Titan II launches. The lander, which was designed by NASA's
Langley Research Center The Langley Research Center (LaRC or NASA Langley), located in Hampton, Virginia, United States of America, is the oldest of NASA's field centers. It directly borders Langley Air Force Base and the Back River on the Chesapeake Bay. LaRC has fo ...
, would have had a mass of no more than . Some of the proposals had a mass as low as , with
cryogenic propellant Cryogenic fuels are fuels that require storage at extremely low temperatures in order to maintain them in a liquid state. These fuels are used in machinery that operates in space (e.g. rockets and satellites) where ordinary fuel cannot be used, d ...
s being used in place of heavier
hypergolic propellant A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other. The two propellant components usually consist of a fuel and an oxidizer. Th ...
. The proposal was intended to provide a faster and lower-cost alternative to the Apollo program, which was at that time proposing a
direct ascent Direct ascent is a method of landing a spacecraft on the Moon or another planetary surface directly, without first assembling the vehicle in Earth orbit, or carrying a separate landing vehicle into orbit around the target body. It was proposed as ...
landing. Another proposal would have used a
Saturn V Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, with multistage rocket, three stages, and powered with liquid-propellant r ...
to achieve a direct ascent mission profile. The spacecraft consisted of four modules. The Retrograde Module would have been powered by an
RL10 The RL10 is a liquid-fuel cryogenic rocket engine built in the United States by Aerojet Rocketdyne that burns cryogenic liquid hydrogen and liquid oxygen propellants. Modern versions produce up to of thrust per engine in vacuum. Three RL10 ve ...
engine, and used to propel the spacecraft during the trans-lunar coast. During landing, it would be used for the initial phases of powered descent. At an altitude of above the Lunar surface, the RM would have been jettisoned, and a second module, the Terminal Landing Module, would have performed the final descent. After landing, the spacecraft would have stayed on the Moon for a day, before it was propelled back to Earth. Launch from the Lunar Surface and trans-Earth injection would have been performed by the Service Module, which would also have contained components of the life support system, and other systems which were located in the Equipment Module of the Earth orbit Gemini spacecraft. The Reentry Module was based on the Gemini capsule, but would have been modified to allow it to reenter the atmosphere at the higher velocity that would have been required by a Lunar flight. It was seen as the last effort by NASA managers and engineers who still advocated the direct ascent mission profile, and was intended to be cheaper, faster and safer than the Apollo lunar orbit rendezvous technique.


Apollo rescue

Due to the risks associated with the Lunar landing, a number of rescue spacecraft were proposed, to be used to allow the crew of an Apollo mission to return to Earth safely in the event of a problem. Many of these designs were based around the Gemini spacecraft. One of these proposals was the Gemini Lunar Orbit Rescue Vehicle, which was designed to retrieve the crew of an Apollo spacecraft stranded in orbit around the Moon. It was to have used a stretched reentry module to accommodate the three astronauts who would have been aboard the Apollo. This would have been attached to a modified Equipment Module. The Equipment Module contained engines which would be used for Lunar orbit insertion and trans-Earth injection, as well as life support equipment to keep the crew alive until they returned to Earth. Launch and trans-Lunar injection would have been performed by a Saturn V. Once the spacecraft was in Lunar orbit, the Apollo crew would have boarded it by means of an EVA. Another proposed spacecraft, the Gemini Lunar Surface Survival Shelter, was designed to be sent to the Moon ahead of an Apollo mission. It would have landed close to the planned Apollo landing site, and if the Apollo Lunar Module's ascent stage failed to ignite, the crew would have performed an EVA to transfer to the LSSS. The shelter was not designed to take off again after landing, so an LSRS or another Apollo mission would then be sent to collect the crew, while the Command Module Pilot of the original Apollo mission would have returned to Earth alone aboard his spacecraft. It consisted of a Gemini Reentry Module, which would have housed the astronauts while they awaited rescue, and a descent stage containing life support systems, consumables, and the engine and propellant used to land the spacecraft. The Gemini Lunar Surface Rescue Spacecraft was intended to fly a direct ascent mission, launched by a Saturn V. Descent stages, built from either the descent stage of the
Apollo Lunar Module The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed ...
, or from the
Apollo Service Module The Apollo command and service module (CSM) was one of two principal components of the United States Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functioned as a mother ship ...
, would have reduced the spacecraft's velocity as it approached the Moon. One configuration used two Service Modules and one LEM descent stage, with the LEM descent stage performing the final landing, and then being reused for ascent from the Lunar surface and trans-Earth injection. The other configuration used three LEM descent stages, with the second being used for landing and the third for ascent and TEI. The LSRS would have landed close to the Apollo Lunar Module on the Moon, and the Apollo crew would have transferred to it by EVA. Following the
Apollo 1 Apollo 1, initially designated AS-204, was intended to be the first crewed mission of the Apollo program, the American undertaking to land the first man on the Moon. It was planned to launch on February 21, 1967, as the first low Earth orbita ...
fire in January 1967, NASA conducted a safety review of the Apollo program. In response to this review, McDonnell proposed the Universal Lunar Rescue Vehicle, a repackaged version of the Lunar Surface Rescue Spacecraft with an enlarged capsule to make room for the three astronauts who were being rescued. It was intended to rescue an Apollo crew at almost any point while they were at the Moon, should an anomaly occur. Some ULRV designs included five seats, with two astronauts piloting it to the Moon. The proposal was considered, but rejected due to lack of funds.


Other proposals

A number of other applications were considered for the Gemini spacecraft.


Manned Orbital Telescope

The Manned Orbital Telescope was a proposal for a manned spacecraft for
astronomical Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies ...
or solar observation. It would have used the larger reentry module which was also proposed for the Big Gemini spacecraft, and would have been launched on a Saturn IB. The enlarged reentry module was also considered for a spacecraft proposed at the same time, which would have been used to rescue the crews of manned spacecraft that were stranded in low Earth orbit. It would have launched atop a Titan IIIC, once in orbit it would have maneuvered by means of a Transtage integrated into the equipment module. The larger capsule would have been used to accommodate the crew of the spacecraft which required rescuing.


Rendezvous with a Pegasus satellite

Another proposed mission would have seen a Gemini spacecraft rendezvous with a
Pegasus Pegasus ( grc-gre, Πήγασος, Pḗgasos; la, Pegasus, Pegasos) is one of the best known creatures in Greek mythology. He is a winged divine stallion usually depicted as pure white in color. He was sired by Poseidon, in his role as hor ...
satellite in low Earth orbit. The spacecraft would have either been launched directly into an orbit to rendezvous with the Pegasus, or into a lower orbit, subsequently docking with an Agena, and using that to raise its orbit. The Gemini would have flown around the Pegasus, and then one of the crew would have performed an EVA to recover a piece of one of the spacecraft's micrometeoroid detection panels. This mission would have been used to prove that rendezvous could be accomplished with any spacecraft, to collect data on the satellite's exposure to micrometeoroids — supporting data that the satellite had returned itself, and to demonstrate technology for military flights to inspect hostile satellites.


Gemini Paraglider

Several missions were proposed to demonstrate methods of landing the Gemini spacecraft on land. The spacecraft had originally been designed to land using a flexible
Rogallo wing The Rogallo wing is a flexible type of wing. In 1948, Francis Rogallo, a NASA engineer, and his wife Gertrude Rogallo, invented a self-inflating flexible wing they called the Parawing, also known after them as the "Rogallo Wing" and flexible wing ...
and a set of skis or wheels, however this was abandoned in favor of
splashdown Splashdown is the method of landing a spacecraft by parachute in a body of water. It was used by crewed American space capsules prior to the Space Shuttle program, by SpaceX Dragon and Dragon 2 capsules and by NASA's Orion Multipurpose Crew ...
s under parachutes due to delays in development and failures during testing. As the proposed Big Gemini spacecraft would have landed this way, McDonnell Aircraft asked NASA to consider flying standard Gemini spacecraft with the paraglider in order to test the system before it would be required operationally.


Winged Gemini

Another alternative landing concept was the US Air Force's proposal to attach wings to the spacecraft. This proposal arose soon after the cancellation of the
X-20 Dyna-Soar The Boeing X-20 Dyna-Soar ("Dynamic Soarer") was a United States Air Force (USAF) program to develop a spaceplane that could be used for a variety of military missions, including aerial reconnaissance, bombing, space rescue, satellite mainten ...
, and would have seen a Gemini spacecraft attached to a set of wings developed during the
ASSET In financial accountancy, financial accounting, an asset is any resource owned or controlled by a business or an economic entity. It is anything (tangible or intangible) that can be used to produce positive economic value. Assets represent value ...
program. This would have been launched by a Titan II rocket, and would have been unable to maneuver in orbit. Another proposal saw the spacecraft being launched by a
Titan IIIA The Titan IIIA or Titan 3A was an American expendable launch system, launched four times in 1964 and 1965, to test the Transtage upper stage which was intended for use on the larger Titan IIIC. The Transtage was mounted atop two core stages deriv ...
or IIIC, using the Transtage for maneuvering. Once the mission was complete, the spacecraft would have been deorbited by means of five
solid rocket motor A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder; they were used in warfare by the Arabs, Chinese, Persians ...
s.


Long-duration missions

There were also proposals to use the Gemini spacecraft to conduct long-duration missions to small, purpose-built space stations in low-Earth orbit. One proposal saw a space station based on the Agena, which would have been used to provide propulsion and attitude control for the station. A pressurized module between the Agena and the docking adapter would have been used by the crew for accommodation and to conduct experiments. The crew would have boarded the Agena by means of an inflatable tunnel between the hatches and its airlock. The
Pecan The pecan (''Carya illinoinensis'') is a species of hickory native to the southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed in the southern United States, primarily in Georgia, ...
spacecraft was a similar proposal.


See also

*
Apollo Applications Program The Apollo Applications Program (AAP) was created as early as 1966 by NASA headquarters to develop science-based human spaceflight missions using hardware developed for the Apollo program. AAP was the ultimate development of a number of official ...
* Apollo program *
Big Gemini Big Gemini (or "Big G") was proposed to NASA by McDonnell Douglas in August 1969 as an advanced version of the Gemini program, Gemini spacecraft system (albeit actually having little in common). It was intended to provide large-capacity, all-pu ...
*
DIRECT Direct may refer to: Mathematics * Directed set, in order theory * Direct limit of (pre), sheaves * Direct sum of modules, a construction in abstract algebra which combines several vector spaces Computing * Direct access (disambiguation), a ...
*
Project Gemini Project Gemini () was NASA's second human spaceflight program. Conducted between projects Mercury and Apollo, Gemini started in 1961 and concluded in 1966. The Gemini spacecraft carried a two-astronaut crew. Ten Gemini crews and 16 individual ...
*
Manned Orbital Laboratory The Manned Orbiting Laboratory (MOL) was part of the United States Air Force (USAF) human spaceflight program in the 1960s. The project was developed from early USAF concepts of crewed space stations as reconnaissance satellites, and was a succ ...
*
Skylab Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three separate three-astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Major operations in ...
*
Soyuz program The Soyuz programme ( , ; russian: link=no, Союз , meaning "Union") is a human spaceflight programme initiated by the Soviet Union in the early 1960s. The Soyuz spacecraft was originally part of a Moon landing project intended to put a So ...


References

{{Use American English, date=January 2014 Abandoned military projects of the United States Cancelled American spacecraft Cancelled space missions Project Gemini