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82-508: The Agena Target Vehicle ( / ə ˈ dʒ iː n ə / ; ATV ), also known as Gemini-Agena Target Vehicle ( GATV ), was an uncrewed spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques, and to perform large orbital changes , in preparation for the Apollo program lunar missions. The spacecraft was based on Lockheed Aircraft 's Agena-D upper stage rocket, fitted with

164-861: A docking adapter built by McDonnell Aircraft . The Agena was launched from Cape Kennedy 's Launch Complex 14 on top of an Atlas booster built by the Convair division of General Dynamics . The Agena first burn would occur shortly after shroud jettison and separation from the Atlas over the Atlantic Ocean . Over Ascension Island , a second burn would place the Agena into a low circular orbit. The McDonnell Gemini spacecraft would then be launched from Launch Complex 19 , as soon as 90 minutes later. Both countdowns would proceed in parallel and required close synchronization. The Gemini would rendezvous and dock with

246-588: A 58-centimeter (23 in) sphere which weighed 83.6 kilograms (184 lb). Explorer 1 carried sensors which confirmed the existence of the Van Allen belts, a major scientific discovery at the time, while Sputnik 1 carried no scientific sensors. On 17 March 1958, the US orbited its second satellite, Vanguard 1 , which was about the size of a grapefruit, and which remains in a 670-by-3,850-kilometre (360 by 2,080 nmi) orbit as of 2016 . The first attempted lunar probe

328-552: A backup: the Augmented Target Docking Adapter (ATDA), a smaller spacecraft consisting of the docking target with an attitude control propulsion system but without the Agena orbital change rocket. The ATDA was used once on Gemini 9A after a second ATV launch failure on May 17, 1966, but failed as a docking target because its launch shroud failed to separate. Each ATV consisted of an Agena-D -derivative upper rocket stage built by Lockheed Aircraft and

410-497: A cloudy sky, vanishing from view around T+50 seconds. Shortly before Booster Engine Cutoff (BECO), the guidance control officer announced that he had lost contact with the booster. Telemetry indicated that Agena staging had taken place on schedule at T+300 seconds. The Agena continued transmitting signals until T+436 seconds, when all telemetry ceased. Hidden behind clouds, the Atlas's B-2 engine gimbaled hard to right starting at T+120 seconds and remained fixed in that position, flipping

492-535: A considerable amount of time, is to follow a trajectory on the Interplanetary Transport Network . A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Space telescopes avoid the filtering and distortion of electromagnetic radiation which they observe, and avoid light pollution which ground-based observatories encounter. They are divided into two types: satellites which map

574-549: A descent through that atmosphere towards an intended/targeted region of scientific value, and a safe landing that guarantees the integrity of the instrumentation on the craft is preserved. While the robotic spacecraft is going through those parts, it must also be capable of estimating its position compared to the surface in order to ensure reliable control of itself and its ability to maneuver well. The robotic spacecraft must also efficiently perform hazard assessment and trajectory adjustments in real time to avoid hazards. To achieve this,

656-618: A docking target manufactured by McDonnell Aircraft . The name 'Agena' derived from the star Beta Centauri , also known as Agena. The combined spacecraft was a 26-foot (7.92 m)-long cylinder with a diameter of 5 feet (1.52 m), placed into low Earth orbit with the Atlas-Agena launch vehicle. It carried about 14,000 pounds (6,400 kg) of propellant and gas at launch, and had a gross mass at orbital insertion of about 7,200 pounds (3,300 kg). The ATV for Gemini 6 failed on launch on October 25, 1965, which led NASA to develop

738-471: A half. You remember the tragic fire we had at the Cape. (...) Jesus, with that fire going off and that, it would have burned the suits. Everything was soaked in oxygen. So thank God. That was another thing: NASA never tested it under the conditions that they would have had if they would have had to eject. They did have some tests at China Lake where they had a simulated mock-up of Gemini capsule, but what they did

820-585: A little off with the translational controller. And just like flying an aerial refueling, you did all this with just the old Mark-VIII eyeball. Once docked, the astronaut in the right seat could control Agena's thrusters and engine. They would fly the combined spacecraft in a stabilized mode and perform a number of experiments: After detaching from their respective Gemini capsules, Agena target vehicles continued to execute post-mission operations under ground control. For instance, GATV 5003, post-separation from Gemini 8, underwent extensive systems testing. Its main engine

902-563: A pad fallback still would not have occurred in this scenario and the astronauts would have been safe. The Titan's batteries were replaced and the fuel prevalves, which had opened, were removed and it was decided to launch without them. The second attempt to launch the 6A mission (third attempt for Gemini spacecraft No. 6) was successful on December 15 at 8:37:26 a.m. EST. All went well through launch and ascent; first stage cutoff occurred at T+160 seconds and second stage cutoff at T+341 seconds. Spacecraft separation occurred at T+361 seconds and

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984-412: A phase adjustment to put them on the same orbital inclination as Gemini 7. They now only trailed by 300 miles (483 km). The radar on Gemini 6A first made contact with Gemini 7 at three hours and fifteen minutes when they were 434 kilometers (270 mi) away. A third burn put them into a 168-by-170-mile (270 by 274 km) orbit. As they slowly gained, Schirra put Gemini 6A's computer in charge of

1066-433: A positively charged atom. The positively charged ions are guided to pass through positively charged grids that contains thousands of precise aligned holes are running at high voltages. Then, the aligned positively charged ions accelerates through a negative charged accelerator grid that further increases the speed of the ions up to 40 kilometres per second (90,000 mph). The momentum of these positively charged ions provides

1148-611: A pre-programmed list of operations that will be executed unless otherwise instructed. A robotic spacecraft for scientific measurements is often called a space probe or space observatory . Many space missions are more suited to telerobotic rather than crewed operation, due to lower cost and risk factors. In addition, some planetary destinations such as Venus or the vicinity of Jupiter are too hostile for human survival, given current technology. Outer planets such as Saturn , Uranus , and Neptune are too distant to reach with current crewed spaceflight technology, so telerobotic probes are

1230-433: A separation burn and slowly drifted more than 30 kilometers (19 mi) from Gemini 7. This ensured that there would not be any accidental collisions while the astronauts slept. The next day, before reentry, the crew of Gemini 6A had a surprise: ...this is Gemini VI. We have an object, looks like a satellite going from north to south, up in a polar orbit. He's in a very low trajectory traveling from north to south and has

1312-458: A tendency to leak oxidizer. While this would not be a problem for the Agena D with its single restart, the multi-restart GATV would eventually lose all of its oxidizer before the stage's operating life (which would last weeks instead of hours) could be completed. Unfortunately, pumping the fuel into the combustion chamber first caused the engine to backfire and rupture from mechanical shock. It was found out that Lockheed engineers did not properly test

1394-439: A very high climbing ratio. It looks like it might even be a ... Very low. Looks like he might be going to reenter soon. Stand by one ... You might just let me try to pick up that thing. At that point, the sound of " Jingle Bells " was heard played on an eight-note Hohner "Little Lady" harmonica and a handful of small bells. The Smithsonian Institution claims these were the first musical instruments played in space and keeps

1476-815: Is currently on display at the Stafford Air & Space Museum in Weatherford, Oklahoma , having previously been displayed at the Oklahoma History Center in Oklahoma City . The spacecraft had previously been on display at the Omniplex Science Museum elsewhere in the city. It is on a long-term loan from the Smithsonian Institution . Before being moved to Oklahoma, the spacecraft was displayed at

1558-500: Is fill it full of nitrogen. They didn't have it filled full of oxygen in the sled test they had. Even if the astronauts had not been injured or killed, ejection would ruin the spacecraft and delay the mission for months. After the Stage I engines ignited and shut down, fuel ( UDMH ) was leaking out of the PSV drain valve. The fuel had been ignited by the engine start, and the resulting fire

1640-441: Is increased fuel consumption or it is a physical hazard such as a poor landing spot in a crater or cliff side that would make landing very not ideal (hazard assessment). In planetary exploration missions involving robotic spacecraft, there are three key parts in the processes of landing on the surface of the planet to ensure a safe and successful landing. This process includes an entry into the planetary gravity field and atmosphere,

1722-457: Is not one universally used propulsion system: monopropellant, bipropellant, ion propulsion, etc. Each propulsion system generates thrust in slightly different ways with each system having its own advantages and disadvantages. But, most spacecraft propulsion today is based on rocket engines. The general idea behind rocket engines is that when an oxidizer meets the fuel source, there is explosive release of energy and heat at high speeds, which propels

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1804-419: Is the same as that of monopropellant propulsion system: very dangerous to manufacture, store, and transport. An ion propulsion system is a type of engine that generates thrust by the means of electron bombardment or the acceleration of ions. By shooting high-energy electrons to a propellant atom (neutrally charge), it removes electrons from the propellant atom and this results in the propellant atom becoming

1886-426: Is unique because it requires no ignition system, the two liquids would spontaneously combust as soon as they come into contact with each other and produces the propulsion to push the spacecraft forward. The main benefit for having this technology is because that these kinds of liquids have relatively high density, which allows the volume of the propellent tank to be small, therefore increasing space efficacy. The downside

1968-607: The Sun similar to the Earth's orbit. To reach another planet, the simplest practical method is a Hohmann transfer orbit . More complex techniques, such as gravitational slingshots , can be more fuel-efficient, though they may require the probe to spend more time in transit. Some high Delta-V missions (such as those with high inclination changes ) can only be performed, within the limits of modern propulsion, using gravitational slingshots. A technique using very little propulsion, but requiring

2050-818: The International Space Station (ISS), and the Tiangong space station . Currently, the ISS relies on three types of cargo spacecraft: the Russian Progress , along with the American Cargo Dragon 2 , and Cygnus . China's Tiangong space station is solely supplied by the Tianzhou . The American Dream Chaser and Japanese HTV-X are under development for future use with the ISS. The European Automated Transfer Vehicle

2132-480: The United States Air Force considers a vehicle to consist of the mission payload and the bus (or platform). The bus provides physical structure, thermal control, electrical power, attitude control and telemetry, tracking and commanding. JPL divides the "flight system" of a spacecraft into subsystems. These include: The physical backbone structure, which This is sometimes referred to as

2214-447: The telecommunications subsystem include radio antennas, transmitters and receivers. These may be used to communicate with ground stations on Earth, or with other spacecraft. The supply of electric power on spacecraft generally come from photovoltaic (solar) cells or from a radioisotope thermoelectric generator . Other components of the subsystem include batteries for storing power and distribution circuitry that connects components to

2296-429: The Agena as soon as Gemini's first orbit toward the end of the program. Gemini 11 's Richard F. Gordon, Jr. compared docking with the Agena to air-to-air refueling : You get yourself lined up, maybe five to ten feet out. And if everything looks all right and you look lined up with the docking cone, all you do is add a little thrust with the translational controller . And if it looks like you're going too fast you take

2378-727: The Agena featured in the short science fiction drama DARKSIDE produced by nrgpix as an entry to the London Sci Fi film festival 2020. [REDACTED]  This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration . Uncrewed spacecraft Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control , or remote guidance. They may also be autonomous , in which they have

2460-478: The GATV to root out this problem (it had been tested at a simulated altitude of 21 miles up when actual Agena engine start would occur at around 75 miles up). The solution to the problem was switching back to the normal oxidizer-first engine start and also testing the GATV in appropriate conditions. Bell Aerosystems, the manufacturer of the Agena's engine, were also instructed to perform further ground-level tests. After

2542-656: The Moon two years later. The first interstellar probe was Voyager 1 , launched 5 September 1977. It entered interstellar space on 25 August 2012, followed by its twin Voyager 2 on 5 November 2018. Nine other countries have successfully launched satellites using their own launch vehicles: France (1965), Japan and China (1970), the United Kingdom (1971), India (1980), Israel (1988), Iran (2009), North Korea (2012), and South Korea (2022). In spacecraft design,

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2624-406: The Moon; travel through interplanetary space; flyby, orbit, or land on other planetary bodies; or enter interstellar space. Space probes send collected data to Earth. Space probes can be orbiters, landers, and rovers. Space probes can also gather materials from its target and return it to Earth. Once a probe has left the vicinity of Earth, its trajectory will likely take it along an orbit around

2706-530: The Soviet Venera 4 was the first atmospheric probe to study Venus. Mariner 4 's 1965 Mars flyby snapped the first images of its cratered surface, which the Soviets responded to a few months later with images from on its surface from Luna 9 . In 1967, America's Surveyor 3 gathered information about the Moon's surface that would prove crucial to the Apollo 11 mission that landed humans on

2788-469: The base of the booster prematurely. This plug sent a lift-off signal to the spacecraft. Testing revealed that some plugs came out more easily than others, so they were replaced by different ones that would stay in place properly. However, the electrical plug turned out to not be the only problem with the booster. Examination of telemetry also showed that the Titan actually began experiencing thrust decay before

2870-564: The booster was assembled months earlier at the Martin-Marietta plant, blocking the flow of oxidizer. The cover was removed and the Titan II cleared for another launch attempt. Had the inadvertent electrical disconnect not occurred, the abort sensing system would have sent a shutoff command to the Titan at T+2.2 seconds due to the loss of Engine No. 2 chamber pressure. Since launcher release and liftoff would take place at T+3.2 seconds,

2952-450: The combustion of the fuel can only occur due to a presence of a catalyst . This is quite advantageous due to making the rocket engine lighter and cheaper, easy to control, and more reliable. But, the downfall is that the chemical is very dangerous to manufacture, store, and transport. A bipropellant propulsion system is a rocket engine that uses a liquid propellant. This means both the oxidizer and fuel line are in liquid states. This system

3034-453: The command and data subsystem. It is often responsible for: This system is mainly responsible for the correct spacecraft's orientation in space (attitude) despite external disturbance-gravity gradient effects, magnetic-field torques, solar radiation and aerodynamic drag; in addition it may be required to reposition movable parts, such as antennas and solar arrays. Integrated sensing incorporates an image transformation algorithm to interpret

3116-413: The commander of Gemini 7, Frank Borman , objected, pointing out that it would require Lovell to wear an uncomfortable EVA suit on a long-duration mission. The first attempt to launch the 6A mission (second attempt for Gemini spacecraft No. 6) was on December 12, 1965, at 9:54 a.m. EST. All went well right up to ignition; the engines ignited, but after about 1.5 seconds they abruptly shut down. Since

3198-510: The compatibility of the ATDA with the Atlas booster, since it had much lower mass than the GATV, potentially throwing off the launch vehicle's aerodynamics and calibrated settings. However, Convair assured McDonnell that it would pose no technical issues with the booster. A second GATV launch failure occurred on May 17, 1966, as Gemini 9 astronauts Tom Stafford and Eugene Cernan sat on their pad awaiting launch. The Atlas–Agena lifted smoothly into

3280-456: The crew entered a 100-by-161-mile (161 by 259 km) orbit. The plan called for the rendezvous to take place on the fourth orbit of Gemini 6. Their first burn came 94 minutes after launch when they increased their speed by 5 meters (16 1 ⁄ 2 feet) per second. Due to their lower orbit they were gaining on Gemini 7 and were only 730 miles, (or 1,175 kilometers), behind. The next burn was at two hours and eighteen minutes when Gemini 6A made

3362-435: The crew observed that the shroud of the ATDA had partially opened and was described by Stafford as "looking like an angry alligator". Docking was not possible, but the rendezvous maneuver was practiced instead. Gemini 8 's docking with the Agena was shown in episode 1 "Can We Do This?", of the 1998 HBO miniseries From the Earth to the Moon , and in the 2018 Neil Armstrong biopic First Man . Gemini 8 's docking with

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3444-459: The cryogenic leakage was not identified. The loss of the lock on the ground prevented normal engine cutoff signals from being transmitted to the Atlas; BECO was generated by the staging backup accelerometer, SECO at T+273 seconds due to LOX depletion, and VECO and Agena staging from a backup command generated by the missile programmer. Aside from the flight control system, all Atlas systems functioned properly. While Convair accepted responsibility for

3526-713: The entire sky ( astronomical survey ), and satellites which focus on selected astronomical objects or parts of the sky and beyond. Space telescopes are distinct from Earth imaging satellites , which point toward Earth for satellite imaging , applied for weather analysis , espionage , and other types of information gathering . Cargo or resupply spacecraft are robotic vehicles designed to transport supplies, such as food, propellant, and equipment, to space stations. This distinguishes them from space probes, which are primarily focused on scientific exploration. Automated cargo spacecraft have been servicing space stations since 1978, supporting missions like Salyut 6 , Salyut 7 , Mir ,

3608-423: The failure concluded that it was most likely caused by design modifications to the GATV versus a standard Agena D stage. The Agena D was designed to have its engine restarted just once while the GATV would need to be restarted five times. While a standard Agena D pumped oxidizer into the combustion chamber first and then followed with the fuel, the GATV was modified to do the reverse because the normal start method had

3690-712: The failure of the first GATV, NASA commissioned McDonnell to develop a backup docking target minus the Lockheed Agena rocket, the Augmented Target Docking Adapter (ATDA). This consisted of the Gemini docking collar and an attitude control propulsion system based on the Gemini Reentry Control System. The ATDA was 10.9 feet (3.3 m) long, with a mass of 1,750 pounds (794 kg). A few questions were raised about

3772-459: The fall of 1951. The first artificial satellite , Sputnik 1 , was put into a 215-by-939-kilometer (116 by 507 nmi) Earth orbit by the USSR on 4 October 1957. On 3 November 1957, the USSR orbited Sputnik 2 . Weighing 113 kilograms (249 lb), Sputnik 2 carried the first animal into orbit, the dog Laika . Since the satellite was not designed to detach from its launch vehicle 's upper stage,

3854-427: The following U.S. Department of Defense resources: 10,125 personnel, 125 aircraft and 16 ships. Walter Schirra explained the patch in the book All We Did Was Fly to the Moon : The Gemini 6 patch is hexagonal in shape, reflecting the mission number; and the spacecraft trajectory also traces out the number "6". The Gemini 6 spacecraft is shown superimposed on the "twin stars" Castor and Pollux, for "Gemini". I designed

3936-608: The ground. Increased autonomy is important for distant probes where the light travel time prevents rapid decision and control from Earth. Newer probes such as Cassini–Huygens and the Mars Exploration Rovers are highly autonomous and use on-board computers to operate independently for extended periods of time. A space probe is a robotic spacecraft that does not orbit Earth, but instead, explores further into outer space. Space probes have different sets of scientific instruments onboard. A space probe may approach

4018-521: The immediate imagery land data, perform a real-time detection and avoidance of terrain hazards that may impede safe landing, and increase the accuracy of landing at a desired site of interest using landmark localization techniques. Integrated sensing completes these tasks by relying on pre-recorded information and cameras to understand its location and determine its position and whether it is correct or needs to make any corrections (localization). The cameras are also used to detect any possible hazards whether it

4100-468: The instruments on display. Gemini 6A fired its retro-rockets and landed within 18 kilometers (11 miles) of the planned site in the Atlantic Ocean northeast of Turks and Caicos . It was the first recovery to be televised live, through a transportable satellite earth station developed by ITT on the deck of the recovery aircraft carrier USS Wasp . The Gemini 7 and 6A missions were supported by

4182-485: The launch failure, Lockheed engineers expressed concern about telemetry data that indicated a servo failure in the Agena, leading to doubts as to whether the stage would have still operated properly if the Atlas hadn't malfunctioned. However, the true cause of failure surfaced when the Air Force released film taken by tracking cameras at Melbourne Beach, Florida, which showed the Atlas pitching over and heading downward. It

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4264-530: The launch vehicle 216° around and sending it back towards Cape Kennedy. This rotation had made it impossible for ground guidance to lock on. Radar stations in the Bahamas tracked it heading north and descending. Vehicle stability was gradually regained following BECO, however it had pitched approximately 231° from its intended flight path. Both vehicles plunged into the Atlantic Ocean 107 nautical miles (198 km) downrange. The Agena's engine did not activate since

4346-523: The lift-off clock had started in the spacecraft, mission rules dictated that Wally Schirra, as the commander, had to immediately pull the D-ring between his knees and activate the ejection seats , carrying the astronauts away from the disaster that would be the result of a fully fueled Titan II falling back onto LC-19. However, Schirra did not feel any movement and knew that the booster had not lifted, so he decided not to abort. His quick thinking probably saved

4428-577: The mission as the reliability of the Gemini ejector seats was questionable; the astronauts could have been badly injured from high g-forces as the seats had to launch them at least 800 feet, which was deemed a safe distance from an exploding Titan II. In addition, the cabin interior had been soaking in pure oxygen for hours. Tom Stafford, in a NASA oral history in 1997, later recalled: So it turns out what we would have seen, had we had to do that, would have been two Roman candles going out, because we were 15 or 16 psi, pure oxygen, soaking in that for an hour and

4510-465: The mission. At 23 hours and 55 minutes into the mission, while the spacecraft passed over White Sands, New Mexico , the crew was to attempt to observe a laser beam originating from the ground. The retrorockets were scheduled to be fired at 46 hours and 10 minutes into the mission over the Pacific Ocean on the 29th orbit. Original mission plans also included the first live television coverage of

4592-427: The most powerful form of propulsion there is. For a propulsion system to work, there is usually an oxidizer line and a fuel line. This way, the spacecraft propulsion is controlled. But in a monopropellant propulsion, there is no need for an oxidizer line and only requires the fuel line. This works due to the oxidizer being chemically bonded into the fuel molecule itself. But for the propulsion system to be controlled,

4674-402: The only way to explore them. Telerobotics also allows exploration of regions that are vulnerable to contamination by Earth micro-organisms since spacecraft can be sterilized. Humans can not be sterilized in the same way as a spaceship, as they coexist with numerous micro-organisms, and these micro-organisms are also hard to contain within a spaceship or spacesuit. The first uncrewed space mission

4756-410: The patch to locate in the sixth hour of celestial right ascension. This was the predicted celestial area where the rendezvous should occur (in the constellation Orion). It finally did occur there. The original patch had called the flight GTA-6 (for Gemini-Titan-Agena) and showed the Gemini craft chasing an Agena. It was changed when the mission was altered to depict two Gemini spacecraft. The spacecraft

4838-431: The plug dropped out. Engine No. 1 was unaffected and nearly reached 100% thrust at shutdown, while Engine No. 2 never transitioned to in-flight performance levels. Engineers spent all night combing through the first stage, but failed to find any cause for the thrust decay. Eventually however, one technician identified the problem, which was a plastic dust cover inside the gas generator that had been carelessly left inside when

4920-408: The power sources. Spacecraft are often protected from temperature fluctuations with insulation. Some spacecraft use mirrors and sunshades for additional protection from solar heating. They also often need shielding from micrometeoroids and orbital debris. Spacecraft propulsion is a method that allows a spacecraft to travel through space by generating thrust to push it forward. However, there

5002-488: The proper altitude and velocity had not been attained, preventing the guidance system from sending the start command. While the exact cause of the engine gimbal control loss was not found, telemetry indicated that a short-to-ground occurred in the circuit for the servoamplifier output command signal, which may have been caused by cryogenic leakage in the thrust section. Substantiating this theory were abnormally low thrust section temperatures starting at T+65 seconds. The source of

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5084-419: The radio. At one stage the spacecraft were stationkeeping so well that neither crew had to make any burns for 20 minutes. Schirra said that because there is no turbulence in space, "I was amazed at my ability to maneuver. I did a fly-around inspection of Gemini 7, literally flying rings around it, and I could move to within inches of it in perfect confidence". As the crew sleep periods approached, Gemini 6A made

5166-464: The recovery of a U.S. spacecraft at sea from the recovery ship, the U.S. aircraft carrier Wasp . The Wasp was fitted with ground station equipment by ITT to relay live television, via the Intelsat I (nicknamed the "Early Bird") satellite. On October 25, 1965, Schirra and Stafford boarded their Gemini 6 craft to prepare for launch. Fifteen minutes later, the uncrewed Atlas-Agena target vehicle

5248-427: The rendezvous. At five hours and four minutes, he saw a bright star that he thought was Sirius, but this was in fact Gemini 7. After several more burns, the two spacecraft were only 130 feet (40 meters) apart. The burns had only used 112 lbs. (51 kilograms) of propellant on Gemini 6A, leaving plenty for some fly-arounds. During the next 270 minutes, the crews moved as close as one foot (30 centimeters), talking over

5330-536: The robotic spacecraft requires accurate knowledge of where the spacecraft is located relative to the surface (localization), what may pose as hazards from the terrain (hazard assessment), and where the spacecraft should presently be headed (hazard avoidance). Without the capability for operations for localization, hazard assessment, and avoidance, the robotic spacecraft becomes unsafe and can easily enter dangerous situations such as surface collisions, undesirable fuel consumption levels, and/or unsafe maneuvers. Components in

5412-539: The space stations Salyut 7 and Mir , and the International Space Station module Zarya , were capable of remote guided station-keeping and docking maneuvers with both resupply craft and new modules. Uncrewed resupply spacecraft are increasingly used for crewed space stations . The first robotic spacecraft was launched by the Soviet Union (USSR) on 22 July 1951, a suborbital flight carrying two dogs Dezik and Tsygan. Four other such flights were made through

5494-408: The spacecraft forward. This happens due to one basic principle known as Newton's Third Law . According to Newton, "to every action there is an equal and opposite reaction." As the energy and heat is being released from the back of the spacecraft, gas particles are being pushed around to allow the spacecraft to propel forward. The main reason behind the usage of rocket engine today is because rockets are

5576-414: The spacecraft is robotic. Robotic spacecraft use telemetry to radio back to Earth acquired data and vehicle status information. Although generally referred to as "remotely controlled" or "telerobotic", the earliest orbital spacecraft – such as Sputnik 1 and Explorer 1 – did not receive control signals from Earth. Soon after these first spacecraft, command systems were developed to allow remote control from

5658-423: The thrust to propel the spacecraft forward. The advantage of having this kind of propulsion is that it is incredibly efficient in maintaining constant velocity, which is needed for deep-space travel. However, the amount of thrust produced is extremely low and that it needs a lot of electrical power to operate. Mechanical components often need to be moved for deployment after launch or prior to landing. In addition to

5740-484: The total mass in orbit was 508.3 kilograms (1,121 lb). In a close race with the Soviets , the United States launched its first artificial satellite, Explorer 1 , into a 357-by-2,543-kilometre (193 by 1,373 nmi) orbit on 31 January 1958. Explorer I was an 205-centimetre (80.75 in) long by 15.2-centimetre (6.00 in) diameter cylinder weighing 14.0 kilograms (30.8 lb), compared to Sputnik 1,

5822-531: The use of motors, many one-time movements are controlled by pyrotechnic devices. Robotic spacecraft are specifically designed system for a specific hostile environment. Due to their specification for a particular environment, it varies greatly in complexity and capabilities. While an uncrewed spacecraft is a spacecraft without personnel or crew and is operated by automatic (proceeds with an action without human intervention) or remote control (with human intervention). The term 'uncrewed spacecraft' does not imply that

5904-437: Was Sputnik , launched October 4, 1957 to orbit the Earth. Nearly all satellites , landers and rovers are robotic spacecraft. Not every uncrewed spacecraft is a robotic spacecraft; for example, a reflector ball is a non-robotic uncrewed spacecraft. Space missions where other animals but no humans are on-board are called uncrewed missions. Many habitable spacecraft also have varying levels of robotic features. For example,

5986-541: Was canceled. After reviewing the situation, NASA decided to launch an alternate Gemini 6A mission, eight days after the launch of Gemini 7 , which was scheduled as a 14-day long-duration mission in December. Gemini 6A would perform the first rendezvous of two spacecraft in orbit, using Gemini 7 as the target, though they would not dock. The crews also discussed the possibility of Stafford performing an EVA from 6A to 7, swapping places with Gemini 7 pilot Jim Lovell , but

6068-485: Was discovered when the Pad Crew inspected the engine compartment. Water spray was initiated and a cap was installed on the drain line. About 60 minutes after the aborted launch, the booster and spacecraft had been made safe and the service tower raised up to it. After removing the propellants from the Titan II, the booster was checked out and they quickly uncovered one culprit, which was an umbilical plug that dropped out of

6150-610: Was fired nine times, and it executed 5,000 commands, surpassing the contractual requirement of 1,000. This allowed a detailed assessment of its command and communication systems. The vehicle was eventually placed in a 220 nmi (410 km; 250 mi) circular decay orbit, facilitating its observation during the Gemini 10 mission. Similarly, GATV 5005 performed three orbital maneuvers post-Gemini 10 separation, including adjustments to study temperature effects in varying orbits and executing 1,700 commands, some of which were relayed from Gemini 10. The first Gemini-Agena Target Vehicle (GATV)

6232-419: Was launched on October 25, 1965, while the Gemini 6 astronauts were waiting on the pad. While the Atlas performed normally, the Agena's engine exploded during orbital injection. Since the rendezvous and docking was the primary objective, the Gemini 6 mission was scrubbed, and replaced with the alternate mission Gemini 6A , which rendezvoused (but could not dock) with Gemini 7 in December. An investigation into

6314-413: Was launched. After a successful burn of the Atlas booster, the Agena's engine fired to separate it from the Atlas. But immediately after the Agena's engine fired at the six-minute mark in the flight, telemetry was lost. A catastrophic failure apparently caused the vehicle to explode, as Range Safety was tracking multiple pieces of debris falling into the Atlantic Ocean. After 50 minutes, the Gemini launch

6396-480: Was previously used between 2008 and 2015. Solar System   → Local Interstellar Cloud   → Local Bubble   → Gould Belt   → Orion Arm   → Milky Way   → Milky Way subgroup   → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster   → Local Hole   → Observable universe   → Universe Each arrow ( → ) may be read as "within" or "part of". Gemini 6A Gemini 6A

6478-550: Was the Luna E-1 No.1 , launched on 23 September 1958. The goal of a lunar probe repeatedly failed until 4 January 1959 when Luna 1 orbited around the Moon and then the Sun. The success of these early missions began a race between the US and the USSR to outdo each other with increasingly ambitious probes. Mariner 2 was the first probe to study another planet, revealing Venus' extremely hot temperature to scientists in 1962, while

6560-441: Was the fifth crewed Gemini flight, the 13th crewed American flight, and the 21st crewed spaceflight of all time (including two X-15 flights over 100 kilometers (54 nautical miles)). The original Gemini 6 mission, scheduled for launch on October 25, 1965, at 12:41 pm EDT, had a planned mission duration of 46 hours 47 minutes, completing a total of 29 orbits. It was to land in the western Atlantic Ocean south of Bermuda. The mission

6642-415: Was then determined that the Agena's servo malfunction was caused by passing through the Atlas's ionized exhaust trail. The Gemini 9A modified mission launch was rescheduled for June 1, 1966, using the ATDA. However, the shroud that protected the docking adapter during launch failed to separate, due to lanyards being incorrectly secured with adhesive tape. Gemini 9A was launched on June 3, and when in orbit,

6724-473: Was to include four dockings with the Agena Target Vehicle . The first docking was scheduled for five hours and forty minutes into the mission. The second was scheduled for seven hours and forty-five minutes, the third at nine hours and forty minutes, and the fourth and final docking at ten hours and five minutes into the mission. The final undocking would take place at 18 hours and 20 minutes into

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