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106-636: A range of applications were considered for Advanced Gemini missions, including military flights, space station 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 , which could propel the spacecraft to the Moon , to complete modifications of the Gemini to enable it to land on

212-526: A parasail or paraglider to guide it onto a runway or dry lake, such as the one at Edwards Air Force Base . It would have landed using skids derived from the North American X-15 . 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

318-571: A radar imaging system. MOL Launches would have been conducted from Launch Complex 40 at the Cape Canaveral Air Force Station , and Space Launch Complex 6 at Vandenberg Air Force Base . In 1966, a test flight was launched from LC-40, using a Titan IIIC . It consisted of the Gemini B spacecraft, built from the spacecraft used for the Gemini 2 test flight, atop OPS 0855 , a boilerplate MOL space station. Gemini B

424-413: A Gemini spacecraft, with all systems for crewed 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 crewed spacecraft. The spacecraft was equipped with a liquid propellant engine to perform rendezvous, and to reboost

530-518: A Titan II rocket, and would have been unable to maneuver in orbit. Another proposal saw the spacecraft being launched by a Titan IIIA or IIIC, using the Transtage for maneuvering. Once the mission was complete, the spacecraft would have been deorbited by means of five solid rocket motors . 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

636-723: A longer lifetime at the cost of requiring regular support launches. The ISS is divided into two main sections, the Russian Orbital Segment (ROS) and the US Orbital Segment (USOS). The first module of the ISS, Zarya , was launched in 1998. The Russian Orbital Segment's "second-generation" modules were able to launch on Proton , fly to the correct orbit, and dock themselves without human intervention. Connections are automatically made for power, data, gases, and propellants. The Russian autonomous approach allows

742-559: 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 , would have had a mass of no more than 4,372 kilograms (9,639 lb). Some of the proposals had a mass as low as 1,460 kilograms (3,220 lb), with cryogenic propellants being used in place of heavier hypergolic propellant . The proposal

848-542: A radar image, one can see only the energy that was reflected back towards the radar antenna. The radar moves along a flight path and the area illuminated by the radar, or footprint, is moved along the surface in a swath, building the image as it does so. Digital radar images are composed of many dots. Each pixel in the radar image represents the radar backscatter for that area on the ground ( terrain return ): brighter areas represent high backscatter, darker areas represents low backscatter. The traditional application of radar

954-462: A second crew to visit, bringing a new spacecraft with them; the Soyuz ferry could spend 90 days in space, at which point it needed to be replaced by a fresh Soyuz spacecraft. This allowed for a crew to man the station continually. The American Skylab (1973–1979) was also equipped with two docking ports, like second-generation stations, but the extra port was never used. The presence of a second port on

1060-424: 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

1166-414: A sharp beam. The sharpness of the beam defines the azimuth resolution. An airborne radar could collect data while flying this distance and process the data as if it came from a physically long antenna. The distance the aircraft flies in synthesizing the antenna is known as the synthetic aperture. A narrow synthetic beam width results from the relatively long synthetic aperture, which gets finer resolution than

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1272-524: A similar proposal. Space station A space station (or orbital station ) is a spacecraft which remains in orbit and hosts humans for extended periods of time. It therefore is an artificial satellite featuring habitation facilities . The purpose of maintaining a space station varies depending on the program. Most often space stations have been research stations , but they have also served military or commercial uses , such as hosting space tourists . Space stations have been hosting

1378-420: A smaller physical antenna. Inverse synthetic aperture radar (ISAR) is another kind of SAR system which can produce high-resolution on two- and three-dimensional images. An ISAR system consists of a stationary radar antenna and a target scene that is undergoing some motion. ISAR is theoretically equivalent to SAR in that high-azimuth resolution is achieved via relative motion between the sensor and object, yet

1484-451: 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 spacecraft was

1590-579: A space station occurred in Edward Everett Hale 's 1868 " The Brick Moon ". The first to give serious, scientifically grounded consideration to space stations were Konstantin Tsiolkovsky and Hermann Oberth about two decades apart in the early 20th century. In 1929, Herman Potočnik 's The Problem of Space Travel was published, the first to envision a "rotating wheel" space station to create artificial gravity . Conceptualized during

1696-416: A target with a laser and analyzing the reflected light. Laser radar is used for multi-dimensional imaging and information gathering. In all information gathering modes, lasers that transmit in the eye-safe region are required as well as sensitive receivers at these wavelengths. 3-D imaging requires the capacity to measure the range to the first scatter within every pixel. Hence, an array of range counters

1802-579: A variety of challenges to human habitability, including short-term problems such as the limited supplies of air, water, and food and the need to manage waste heat , and long-term ones such as weightlessness and relatively high levels of ionizing radiation . These conditions can create long-term health problems for space-station inhabitants, including muscle atrophy , bone deterioration , balance disorders , eyesight disorders , and elevated risk of cancer . Future space habitats may attempt to address these issues, and could be designed for occupation beyond

1908-481: A year, all aboard Mir . Many spacecraft are used to dock with the space stations. Soyuz flight T-15 in March to July 1986 was the first and as of 2016, only spacecraft to visit two different space stations, Mir and Salyut 7 . The International Space Station has been supported by many different spacecraft. The Tiangong space station is supported by the following spacecraft: The Tiangong program relied on

2014-562: Is a complex vehicle that must incorporate many interrelated subsystems, including structure, electrical power, thermal control, attitude determination and control , orbital navigation and propulsion, automation and robotics, computing and communications, environmental and life support, crew facilities, and crew and cargo transportation. Stations must serve a useful role, which drives the capabilities required. Space stations are made from durable materials that have to weather space radiation , internal pressure, micrometeoroids , thermal effects of

2120-419: Is a form of radar that transmits a narrow angle beam of pulse radio wave in the range direction at right angles to the flight direction and receives the backscattering from the targets which will be transformed to a radar image from the received signals. Usually the reflected pulse will be arranged in the order of return time from the targets, which corresponds to the range direction scanning. The resolution in

2226-413: Is a form of radar which moves a real aperture or antenna through a series of positions along the objects to provide distinctive long-term coherent-signal variations. This can be used to obtain higher resolution. SARs produce a two-dimensional (2-D) image. One dimension in the image is called range and is a measure of the "line-of-sight" distance from the radar to the object. Range is determined by measuring

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2332-507: Is needed. A monolithic approach to an array of range counters is being developed. This technology must be coupled with highly sensitive detectors of eye-safe wavelengths. To measure Doppler information requires a different type of detection scheme than is used for spatial imaging. The returned laser energy must be mixed with a local oscillator in a heterodyne system to allow extraction of the Doppler shift. Synthetic-aperture radar (SAR)

2438-551: Is not designed for disassembly and must be deorbited as one mass. The Axiom Orbital Segment is a planned commercial segment to be added to the ISS starting in the mid-2020s. Axiom Space gained NASA approval for the venture in January 2020. Up to three Axiom modules will attach to the International Space Station. The first module, Hab One, is expected to be launched at the end of 2026 and will be docked to

2544-402: Is often adequate to discriminate between various missiles, military aircraft, and civilian aircraft. Rolling is side to side. Pitching is forward and backwards, yawing is turning left or right. Monopulse radar 3-D imaging technique uses 1-D range image and monopulse angle measurement to get the real coordinates of each scatterer. Using this technique, the image doesn't vary with the change of

2650-456: Is then mapped onto a two-dimensional plane, with points with a higher reflectivity getting assigned usually a brighter color, thus creating an image. Several techniques have evolved to do this. Generally they take advantage of the Doppler effect caused by the rotation or other motion of the object and by the changing view of the object brought about by the relative motion between the object and

2756-452: Is to display the position and motion of typically highly reflective objects (such as aircraft or ships ) by sending out a radiowave signal, and then detecting the direction and delay of the reflected signal. Imaging radar on the other hand attempts to form an image of one object (e.g. a landscape) by furthermore registering the intensity of the reflected signal to determine the amount of scattering . The registered electromagnetic scattering

2862-454: The Gemini program paved the way and achieved the first space rendezvous (undocked) with Gemini 6 and Gemini 7 in 1965. Subsequently in 1966 Neil Armstrong performed on Gemini 8 the first ever space docking, while in 1967 Kosmos 186 and Kosmos 188 were the first spacecrafts that docked automatically. In January 1969, Soyuz 4 and Soyuz 5 performed the first docked, but not internal, crew transfer, and in March, Apollo 9 performed

2968-678: The Salyut successor Mir . Uninterrupted occupation of stations has been achieved since the operational transition from the Mir to the ISS , with its first occupation in 2000. The ISS has hosted the highest number of people in orbit at the same time, reaching 13 for the first time during the eleven day docking of STS-127 in 2009. The duration record for a single spaceflight is 437.75 days, set by Valeri Polyakov aboard Mir from 1994 to 1995. As of 2021 , four cosmonauts have completed single missions of over

3074-565: The Second World War , the " sun gun " was a theoretical orbital weapon orbiting Earth at a height of 8,200 kilometres (5,100 mi). No further research was ever conducted. In 1951, Wernher von Braun published a concept for a rotating wheel space station in Collier's Weekly , referencing Potočnik's idea. However, development of a rotating station was never begun in the 20th century. The first human flew to space and concluded

3180-532: The Titan 34 , which was used as the core of some later Titan IIIB flights, and on the Titan 34D . The seven-segment solid rocket boosters were later introduced on the Titan IV -A. 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

3286-670: The Transtage , the second stage of a Titan II, four different types of Centaur , 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

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3392-828: The Apollo Lunar Module on the Moon, and the Apollo crew would have transferred to it by EVA. Following the Apollo 1 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

3498-565: 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

3604-406: 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

3710-478: 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 , before separating from the Gemini spacecraft. Some concerns were raised that

3816-418: The Gemini spacecraft on land. The spacecraft had originally been designed to land using a flexible Rogallo wing and a set of skis or wheels, however this was abandoned in favor of splashdowns 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

3922-408: The Gemini spacecraft to support this. Three spacecraft were envisioned; a spacecraft to transport crew to the stations, a spacecraft with a cargo module for both crew and cargo delivery, and a dedicated uncrewed 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

4028-572: The Gemini spacecraft to transport astronauts to its proposed space stations , the Manned Orbital Development System and later the Manned Orbital Laboratory (MOL). These stations would have been launched by Titan IIIM 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

4134-670: The Gemini spacecraft's heat shield would not have been able to protect it during the higher speed ballistic reentry 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 motors would have been added to allow this additional mass to be flown. The Gemini spacecraft would have rendezvoused with stacked Centaur and Agena upper stages in low Earth orbit. The Centaur would have placed

4240-412: 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

4346-544: The ISAR moving target scene is usually made up of non cooperative objects. Algorithms with more complex schemes for motion error correction are needed for ISAR imaging than those needed in SAR. ISAR technology uses the movement of the target rather than the emitter to make the synthetic aperture. ISAR radars are commonly used on vessels or aircraft and can provide a radar image of sufficient quality for target recognition. The ISAR image

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4452-461: The ISS and China 's Tiangong Space Station (TSS), which have been occupied since October 2000 with Expedition 1 and since June 2022 with Shenzhou 14 . The highest number of people at the same time on one space station has been 13, first achieved with the eleven day docking to the ISS of the 127th Space Shuttle mission in 2009. The record for most people on all space stations at the same time has been 17, first on May 30, 2023, with 11 people on

4558-470: The ISS and 6 on the TSS. Space stations are most often modular , featuring docking ports , through which they are built and maintained, allowing the joining or movement of modules and the docking of other spacecrafts for the exchange of people, supplies and tools. While space stations generally do not leave their orbit, they do feature thrusters for station keeping . The first mention of anything resembling

4664-587: The ISS on the SpaceX CRS-8 resupply mission. This module, based on NASA research in the 1990s, weighs 1,400 kilograms (3,100 lb) and was transported while compressed before being attached to the ISS by the space station arm and inflated to provide a 16 cubic metres (21 cu yd) volume. Whilst it was initially designed for a 2   year lifetime it was still attached and being used for storage in August 2022. The space station environment presents

4770-437: The ISS, orbiting today. Each crew member stays aboard the station for weeks or months but rarely more than a year. Early stations were monolithic designs that were constructed and launched in one piece, generally containing all their supplies and experimental equipment. A crew would then be launched to join the station and perform research. After the supplies had been consumed, the station was abandoned. The first space station

4876-507: The Lunar surface. Its applications would have ranged from crewed lunar flybys before Apollo 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

4982-520: The Moon, and perform other mission objectives. Other modifications considered included the addition of wings or a parasail to the spacecraft, in order to enable it to make a horizontal landing. Gemini was the second American crewed orbital spaceflight program, after Mercury . It was intended to demonstrate technologies and techniques required for the Apollo program , such as extra-vehicular activities , rendezvous and docking, maneuvering in orbit and long duration flight. The Gemini spacecraft , which

5088-571: 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. Several missions were proposed to demonstrate methods of landing

5194-645: 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

5300-822: The South Pacific Ocean. The Tiangong Space Station ( Chinese : 天宫 ; pinyin : Tiāngōng ; lit. 'Heavenly Palace'), the first module of which was launched on 29 April 2021, is in low Earth orbit, 340 to 450 kilometres above the Earth at an orbital inclination of 42° to 43°. Its planned construction via 11 total launches across 2021–2022 was intended to extend the core module with two laboratory modules, capable of hosting up to six crew. These space stations have been announced by their host entity and are currently in planning, development or production. The launch date listed here may change as more information becomes available. (~23,548 cu ft) (~15892 cu ft) While originally Lockheed Martin

5406-643: 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

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5512-601: The US Air Force, with two missions flying with mixed crews, followed by two missions with all-USAF crews, but performing missions for NASA. After these flights, the US Air Force 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

5618-474: The areas of biology and biotech, technology development, educational activities, human research, physical science, and Earth and space science. 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 digital computer storage to record its images. In

5724-593: The assembly of space stations prior to the launch of crew. The Russian "second-generation" modules are able to be reconfigured to suit changing needs. As of 2009, RKK Energia was considering the removal and reuse of some modules of the ROS on the Orbital Piloted Assembly and Experiment Complex after the end of mission is reached for the ISS. However, in September 2017, the head of Roscosmos said that

5830-560: 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 , or from the Apollo Service Module , would have reduced

5936-568: The back-scatter that is perceived by the radar of the object (typically, a plane) flying over the earth. Through recent improvements of the techniques, radar imaging is getting more accurate. Imaging radar has been used to map the Earth, other planets, asteroids, other celestial objects and to categorize targets for military systems. An imaging radar is a kind of radar equipment which can be used for imaging. A typical radar technology includes emitting radio waves, receiving their reflection, and using this information to generate data. For an imaging radar,

6042-434: 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 uncrewed resupply flights. The first of these would have involved

6148-521: 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

6254-574: The crewed Shenzhou 10 in 2013. According to the China Manned Space Engineering Office , Tiangong-1 reentered over the South Pacific Ocean , northwest of Tahiti , on 2 April 2018 at 00:15 UTC. A second space laboratory Tiangong-2 was launched in September 2016, while a plan for Tiangong-3 was merged with Tiangong-2. The station made a controlled reentry on 19 July 2019 and burned up over

6360-499: The differential viability of the microbial cells, as a function of phylogenetic lineage, remain elusive. Like uncrewed spacecraft close to the Sun, space stations in the inner Solar System generally rely on solar panels to obtain power. Space station air and water is brought up in spacecraft from Earth before being recycled. Supplemental oxygen can be supplied by a solid fuel oxygen generator . The last military-use space station

6466-419: The direct ascent mission profile, and was intended to be cheaper, faster and safer than the Apollo lunar orbit rendezvous technique. Due to the risks associated with the Lunar landing, several 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

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6572-478: The equipment module. The larger capsule would have been used to accommodate the crew of the spacecraft which required rescue. Another proposed mission would have seen a Gemini spacecraft rendezvous with a Pegasus 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

6678-461: The first crewed flight, Gemini 3 , was launched on 23 March 1965. The program concluded on 15 November 1966, with the successful recovery of Gemini 12 . 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 crewed spaceflight. Although none of these proposals ever made it into operation, many were considered seriously, and in some cases flight hardware

6784-477: The first ever internal transfer of astronauts between two docked spaceships. In 1971, the Soviet Union developed and launched the world's first space station, Salyut 1 . The Almaz and Salyut series were eventually joined by Skylab , Mir , and Tiangong-1 and Tiangong-2 . The hardware developed during the initial Soviet efforts remains in use, with evolved variants comprising a considerable part of

6890-477: The first orbit on April 12, 1961, with Vostok 1 . The Apollo program had in its early planning instead of a lunar landing a crewed lunar orbital flight and an orbital laboratory station in orbit of Earth, at times called Project Olympus , as two different possible program goals, until the Kennedy administration sped ahead and made the Apollo program focus on what was originally planned to come after it,

6996-450: The following spacecraft. The Mir space station was in orbit from 1986 to 2001 and was supported and visited by the following spacecraft: Research conducted on the Mir included the first long term space based ESA research project EUROMIR   95 which lasted 179   days and included 35 scientific experiments. During the first 20 years of operation of the International Space Station, there were around 3,000 scientific experiments in

7102-795: The forward port of Harmony , requiring relocation of the PMA-2 . Axiom Space plans to attach up to two additional modules to its first core module, and send private astronauts to inhabit the modules. The modules would later detach into the Axiom Station in a manner similar to Russia's proposed OPSEK. China's first space laboratory, Tiangong-1 was launched in September 2011. The uncrewed Shenzhou 8 then successfully performed an automatic rendezvous and docking in November 2011. The crewed Shenzhou 9 then docked with Tiangong-1 in June 2012, followed by

7208-446: The image obtained by monopulse radar 3-D imaging is the physical image which is consistent with the real size of the object. 4D imaging radar leverages a Multiple Input Multiple Output (MiMo) antenna array for high-resolution detection, mapping and tracking of multiple static and dynamic targets simultaneously. It combines 3D imaging with Doppler analysis to create the additional dimension – velocity. A 4D imaging radar system measures

7314-412: 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 ; either a Titan IIIG or Saturn INT-20 , the former being intended for use on US Air Force missions and

7420-552: The increased power of the Saturn I, the Gemini spacecraft's ejection seats 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 . The Titan IIIM was also considered to launch the heavier spacecraft. Big Gemini , 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

7526-617: The initial phases of powered descent. At an altitude of 1,800 metres (5,900 ft) 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

7632-458: The installation of a hatch in the heat shield to allow access to the space station. In order to give its astronauts experience before these programs started, the Blue Gemini 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

7738-483: 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 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

7844-484: 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

7950-401: The lunar landing. The Project Olympus space station, or orbiting laboratory of the Apollo program, was proposed as an in-space unfolded structure with the Apollo command and service module docking. While never realized, the Apollo command and service module would perform docking maneuvers and eventually become a lunar orbiting module which was used for station-like purposes. But before that

8056-403: The new stations allowed Progress supply vehicles to be docked to the station, meaning that fresh supplies could be brought to aid long-duration missions. This concept was expanded on Salyut 7, which "hard docked" with a TKS tug shortly before it was abandoned; this served as a proof of concept for the use of modular space stations. The later Salyuts may reasonably be seen as a transition between

8162-589: The only continuous presence of humans in space . The first space station was Salyut 1 (1971), hosting the first crew, of the ill-fated Soyuz 11 . Consecutively space stations have been operated since Skylab (1973) and occupied since 1987 with the Salyut successor Mir . Uninterrupted occupation has been sustained since the operational transition from the Mir to the International Space Station (ISS), with its first occupation in 2000. Currently there are two fully operational space stations –

8268-515: The paraglider in order to test the system before it would be required operationally. 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 , and would have seen a Gemini spacecraft attached to a set of wings developed during the ASSET program. This would have been launched by

8374-457: The range direction depends on the pulse width. The resolution in the azimuth direction is identical to the multiplication of beam width and the distance to a target. The AVTIS radar is a 94 GHz real aperture 3D imaging radar. It uses Frequency-Modulated Continuous-Wave modulation and employs a mechanically scanned monostatic with sub-metre range resolution. Laser radar is a remote sensing technology that measures distance by illuminating

8480-437: The returning waves are used to create an image. When the radio waves reflect off objects, this will make some changes in the radio waves and can provide data about the objects, including how far the waves traveled and what kind of objects they encountered. Using the acquired data, a computer can create a 3-D or 2-D image of the target. Imaging radar has several advantages. It can operate in the presence of obstacles that obscure

8586-519: The rocket that was to launch it. The Saturn-launched version had a short, conical cargo module, and a total mass of 47,300 kilograms (104,300 lb) whereas the Titan IIIG-launched version featured a longer, cylindrical module, with a total mass of 59,000 kilograms (130,000 lb). The Titan IIIM version would have been much shorter and lighter, with a mass of 15,600 kilograms (34,400 lb), as that rocket had less payload capacity than

8692-493: The space station. The other proposal was for a new spacecraft to be built for uncrewed 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 or Saturn IB would have been used for the combined crew and cargo spacecraft. Because of

8798-475: 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

8904-551: The sun and cold temperatures for long periods of time. They are typically made from stainless steel , titanium and high-quality aluminum alloys , with layers of insulation such as Kevlar as a ballistics shield protection. The International Space Station (ISS) has a single inflatable module, the Bigelow Expandable Activity Module , which was installed in April   2016 after being delivered to

9010-551: The target's movement. Monopulse radar 3-D imaging utilizes the ISAR techniques to separate scatterers in the Doppler domain and perform monopulse angle measurement. Monopulse radar 3-D imaging can obtain the 3 views of 3-D objects by using any two of the three parameters obtained from the azimuth difference beam, elevation difference beam and range measurement, which means the views of front, top and side can be azimuth-elevation, azimuth-range and elevation-range, respectively. Monopulse imaging generally adapts to near-range targets, and

9116-478: The target, and can penetrate ground (sand), water, or walls. Applications include: surface topography & coastal change; land use monitoring, agricultural monitoring, ice patrol, environmental monitoring ;weather radar- storm monitoring, wind shear warning;medical microwave tomography; through wall radar imaging; 3-D measurements, etc. Wall parameter estimation uses Ultra Wide-Band radar systems. The handle M-sequence UWB radar with horn and circular antennas

9222-591: The technical feasibility of separating the station to form OPSEK had been studied, and there were now no plans to separate the Russian segment from the ISS. In contrast, the main US modules launched on the Space Shuttle and were attached to the ISS by crews during EVAs . Connections for electrical power, data, propulsion, and cooling fluids are also made at this time, resulting in an integrated block of modules that

9328-437: The time from transmission of a pulse to receiving the echo from a target. Also, range resolution is determined by the transmitted pulse width. The other dimension is called azimuth and is perpendicular to range. The ability of SAR to produce relatively fine azimuth resolution makes it different from other radars. To obtain fine azimuth resolution, a physically large antenna is needed to focus the transmitted and received energy into

9434-451: The time of flight from each transmitting (Tx) antenna to a target and back to each receiving (Rx) antenna, processing data from the numerous ellipsoids formed. The point at which the ellipsoids intersect – known as a hot spot - reveals the exact position of a target at any given moment. Its versatility and reliability make 4D imaging radar ideal for smart home, automotive, retail, security, healthcare and many other environments. The technology

9540-519: The two groups. Unlike previous stations, the Soviet space station Mir had a modular design ; a core unit was launched, and additional modules, generally with a specific role, were later added. This method allows for greater flexibility in operation, as well as removing the need for a single immensely powerful launch vehicle . Modular stations are also designed from the outset to have their supplies provided by logistical support craft, which allows for

9646-414: The upper stages. Using the Gemini spacecraft for a crewed 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 mission, using a Gemini spacecraft and a lightweight, open cockpit lander, launched by a Saturn C-3 rocket. It was the first time that Lunar orbit rendezvous was proposed as part of

9752-606: The weeks or months that current missions typically last. Possible solutions include the creation of artificial gravity by a rotating structure , the inclusion of radiation shielding , and the development of on-site agricultural ecosystems. Some designs might even accommodate large numbers of people, becoming essentially "cities in space" where people would reside semi-permanently. Molds that develop aboard space stations can produce acids that degrade metal, glass, and rubber. Despite an expanding array of molecular approaches for detecting microorganisms, rapid and robust means of assessing

9858-402: Was Salyut 1 , which was launched by the Soviet Union on April 19, 1971. The early Soviet stations were all designated "Salyut", but among these, there were two distinct types: civilian and military. The military stations, Salyut 2 , Salyut 3 , and Salyut 5 , were also known as Almaz stations. The civilian stations Salyut 6 and Salyut 7 were built with two docking ports, which allowed

9964-465: 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 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

10070-522: Was built by McDonnell Aircraft , was derived from the earlier Mercury spacecraft , but modified to accommodate two astronauts . 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 rocket flying from Launch Complex 19 at the Cape Canaveral Air Force Station . In total, twelve missions were launched, ten of which were crewed. Following two uncrewed test flights,

10176-437: Was cancelled on 10 June 1969, in favor of uncrewed reconnaissance satellites. Some systems developed for the program were later used on uncrewed missions, while the space suits which were under development were transferred to NASA. The Titan IIIM rocket which was to launch MOL never flew, but some of the upgrades that were built into it were later used to upgrade other Titan rockets — the stretched first and second stages became

10282-515: Was constructed prior to cancellation. In the case of the Manned Orbital Laboratory , 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 , which was to have launched MOL, being used to upgrade other Titan rockets. The United States Air Force intended to use

10388-624: Was included in the project, as of 2024, it appears their primary role has been filled by Airbus , to provide the main habitat for the station. As of 2024, they are no longer listed as a partner on Starlab's website. (14,126 cu ft) (29,000 cu ft) Two types of space stations have been flown: monolithic and modular. Monolithic stations consist of a single vehicle and are launched by one rocket. Modular stations consist of two or more separate vehicles that are launched independently and docked on orbit. Modular stations are currently preferred due to lower costs and greater flexibility. A space station

10494-444: Was intended to provide a faster and lower-cost alternative to the Apollo program, which was at that time proposing a direct ascent landing. Another proposal would have used a Saturn V to achieve a direct ascent mission profile. The spacecraft consisted of four modules. The Retrograde Module would have been powered by an RL10 engine, and used to propel the spacecraft during the trans-lunar coast. During landing, it would be used for

10600-423: 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. The Manned Orbital Telescope was a proposal for a crewed spacecraft for astronomical or solar observation. It would have used the larger reentry module which

10706-409: 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

10812-465: 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 staffed 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

10918-706: Was the Soviet Salyut 5 , which was launched under the Almaz program and orbited between 1976 and 1977. Space stations have harboured so far the only long-duration direct human presence in space. After the first station, Salyut 1 (1971), and its tragic Soyuz 11 crew, space stations have been operated consecutively since Skylab (1973–1974), having allowed a progression of long-duration direct human presence in space. Long-duration resident crews have been joined by visiting crews since 1977 ( Salyut 6 ), and stations have been occupied by consecutive crews since 1987 with

11024-568: 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

11130-402: 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 (EVA). Changes that would have been required included strengthening the nose, installing two solid rockets to be used for

11236-507: Was used for data gathering and supporting the scanning method. 3-D measurements are supplied by amplitude-modulated laser radars—Erim sensor and Perceptron sensor. In terms of speed and reliability for median-range operations, 3-D measurements have superior performance. Current radar imaging techniques rely mainly on synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) imaging. Emerging technology utilizes monopulse radar 3-D imaging. Real aperture radar ( RAR )

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