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77-428: The room where the flight controllers work was called the mission operations control room (MOCR, pronounced "moh-ker"), and now is called the flight control room (FCR, pronounced "ficker"). The controllers are experts in individual systems, and make recommendations to the flight director involving their areas of responsibility. Any controller may call for an abort if the circumstances require it. Before significant events,

154-409: A computer or data transmission system, to abort means to terminate , usually in a controlled manner, a processing activity because it is impossible or undesirable for the activity to proceed or in conjunction with an error. Such an action may be accompanied by diagnostic information on the aborted process. In addition to being a verb, abort also has two noun senses. In the most general case,

231-415: A cabin that housed the crew and carried equipment needed for atmospheric reentry and splashdown ; and the cylindrical service module which provided propulsion, electrical power and storage for various consumables required during a mission. An umbilical connection transferred power and consumables between the two modules. Just before reentry of the command module on the return home, the umbilical connection

308-500: A different person takes over the console. Flight controller responsibilities have changed over time, and continue to evolve. New controllers are added, and tasks are reassigned to other controllers to keep up with changing technical systems. For example, the EECOM handled command and service module communication systems through Apollo 10 , which was afterward assigned to a new position called INCO. Flight controllers are responsible for

385-515: A flashing rendezvous beacon visible from 54 nautical miles (100 km) away as a navigation aid for rendezvous with the LM. The SM was connected to the CM using three tension ties and six compression pads. The tension ties were stainless steel straps bolted to the CM's aft heat shield. It remained attached to the command module throughout most of the mission, until being jettisoned just prior to re-entry into

462-498: A large pressurized auxiliary orbital module where the crew would live and work for weeks at a time. They would perform space station-type activities in the module, while later versions would use the module to carry cargo to space stations. The spacecraft was to service the Project Olympus (LORL), a foldable rotating space station launched on a single Saturn V . Later versions would be used on circumlunar flights, and would be

539-480: A pore seal, a moisture barrier (a white reflective coating), and a silver Mylar thermal coating that looks like aluminum foil. The heat shield varied in thickness from 2 inches (5.1 cm) in the aft portion (the base of the capsule, which faced forward during reentry) to 0.5 inches (1.3 cm) in the crew compartment and forward portions. The Total weight of the shield was about 3,000 pounds (1,400 kg). The 1-foot-11-inch (0.58 m)-tall forward compartment

616-402: A so-called 'soft dock' state and enabled the pitch and yaw movements in the two vehicles to subside. Excess movement in the vehicles during the 'hard dock' process could cause damage to the docking ring and put stress on the upper tunnel. A depressed locking trigger link at each latch allowed a spring-loaded spool to move forward, maintaining the toggle linkage in an over-center locked position. In

693-463: Is there to help the flight director make those decisions that have no safety-of-flight consequences, but may have cost or public perception consequences. The FOD cannot overrule the flight director during a mission. The former mission operations directorate (MOD) position was renamed FOD when the flight crew operations directorate (FCOD) was merged back with MOD beginning in August 2014. Generally, only

770-441: The g -force experienced by the astronauts, permitted a reasonable amount of directional control and allowed the capsule's splashdown point to be targeted within a few miles. At 24,000 feet (7,300 m), the forward heat shield was jettisoned using four pressurized-gas compression springs. The drogue parachutes were then deployed, slowing the spacecraft to 125 miles per hour (201 kilometres per hour). At 10,700 feet (3,300 m)

847-567: The Aerojet-General company to start developing the engine, resulting in a thrust level twice what was needed to accomplish the lunar orbit rendezvous (LOR) mission mode officially chosen in July of that year. The engine was actually used for mid-course corrections between the Earth and Moon, and to place the spacecraft into and out of lunar orbit. It also served as a retrorocket to perform

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924-625: The Jet Propulsion Laboratory or the Johns Hopkins University Applied Physics Laboratory for deep-space missions or Goddard Space Flight Center for near-Earth missions. Each flight controller has a unique call sign , which describes the position's responsibilities. The call sign and responsibility refer to the particular console , not just the person, since missions are managed around the clock and with each shift change

1001-466: The fuel cell gauges and controls, the electrical and battery controls, and the communications controls. Flanking the sides of the main panel were sets of smaller control panels. On the left side were a circuit breaker panel, audio controls, and the SCS power controls. On the right were additional circuit breakers and a redundant audio control panel, along with the environmental control switches. In total,

1078-485: The spacecraft communicator communicates directly with the crew of a crewed space flight. The acronym dates back to Project Mercury when the spacecraft was originally termed a "capsule." NASA felt it important for all communication with the astronauts in space to pass through a single individual in the Mission Control Center . That role was first designated the capsule communicator or CAPCOM and

1155-452: The transposition, docking, and extraction maneuver at the beginning of the translunar coast. The docking mechanism was a non-androgynous system, consisting of a probe located in the nose of the CSM, which connected to the drogue , a truncated cone located on the lunar module. The probe was extended like a scissor jack to capture the drogue on initial contact, known as soft docking . Then

1232-619: The Apollo 204 Review Board, it was decided to terminate the crewed Block I phase and redefine Block II to incorporate the review board's recommendations . Block II incorporated a revised CM heat shield design, which was tested on the uncrewed Apollo 4 and Apollo 6 flights, so the first all-up Block II spacecraft flew on the first crewed mission, Apollo 7 . The two blocks were essentially similar in overall dimensions, but several design improvements resulted in weight reduction in Block II. Also,

1309-644: The Block I service module propellant tanks were slightly larger than in Block II. The Apollo 1 spacecraft weighed approximately 45,000 pounds (20,000 kg), while the Block II Apollo 7 weighed 36,400 lb (16,500 kg). (These two Earth orbital craft were lighter than the craft which later went to the Moon, as they carried propellant in only one set of tanks, and did not carry the high-gain S-band antenna.) In

1386-521: The CM and faster break-up on re-entry. The service propulsion system ( SPS ) engine was originally designed to lift the CSM off the surface of the Moon in the direct ascent mission mode, The engine selected was the AJ10-137 , which used Aerozine 50 as fuel and nitrogen tetroxide (N 2 O 4 ) as oxidizer to produce 20,500 lbf (91 kN) of thrust. A contract was signed in April 1962 for

1463-472: The CM reaction control subsystem; water tanks; the crushable ribs of the impact attenuation system; and a number of instruments. The CM-SM umbilical, the point where wiring and plumbing ran from one module to the other, was also in the aft compartment. The panels of the heat shield covering the aft compartment were removable for maintenance of the equipment before flight. The components of the ELS were housed around

1540-533: The CSM umbilical cables . The command module was built in North American's factory in Downey, California , and consisted of two basic structures joined together: the inner structure (pressure shell) and the outer structure. The inner structure was an aluminum sandwich construction consisting of a welded aluminum inner skin, adhesively bonded aluminum honeycomb core, and outer face sheet. The thickness of

1617-614: The Earth or the Moon, or the lunar landings. Controllers in MOCR/FCR are supported by the "backrooms", teams of flight controllers located in other parts of the building or even at remote facilities. The backroom was formerly called the staff support room (SSR), and is now called the multi-purpose support room (MPSR, pronounced "mipser"). Backroom flight controllers are responsible for the details of their assigned system and for making recommendations for actions needed for that system. "Frontroom" flight controllers are responsible for integrating

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1694-506: The Earth's atmosphere. At jettison, the CM umbilical connections were cut using a pyrotechnic-activated guillotine assembly. Following jettison, the SM aft translation thrusters automatically fired continuously to distance it from the CM, until either the RCS fuel or the fuel cell power was depleted. The roll thrusters were also fired for five seconds to make sure it followed a different trajectory from

1771-523: The FCR and MPSR are further supported by hardware and software designers, analysts and engineering specialists in other parts of the building or remote facilities. These extended support teams have more detailed analysis tools and access to development and test data that is not readily accessible to the flight control team. These support teams were referred to by the name of their room in Mission Control,

1848-569: The base, and a height of 11 feet 5 inches (3.48 m) including the docking probe and dish-shaped aft heat shield. The forward compartment contained two reaction control system thrusters, the docking tunnel, and the Earth Landing System. The inner pressure vessel housed the crew accommodation, equipment bays, controls and displays, and many spacecraft systems. The aft compartment contained 10 reaction control engines and their related propellant tanks, freshwater tanks, and

1925-427: The basis for a direct ascent lunar spacecraft as well as used on interplanetary missions. In late 1960, NASA called on U.S. industry to propose designs for the vehicle. On May 25, 1961 President John F. Kennedy announced the Moon landing goal before 1970, which immediately rendered NASA's Olympus Station plans obsolete. When NASA awarded the initial Apollo contract to North American Aviation on November 28, 1961, it

2002-506: The center piston. In a temperature degraded condition, a single motor release operation was done manually in the lunar module by depressing the locking spool through an open hole in the probe heads, while release from the CSM was done by rotating a release handle at the back of the probe to rotate the motor torque shaft manually. When the command and lunar modules separated for the last time, the probe and forward docking ring were pyrotechnically separated, leaving all docking equipment attached to

2079-451: The command module panels included 24 instruments, 566 switches, 40 event indicators, and 71 lights. The three crew couches were constructed from hollow steel tubing and covered in a heavy, fireproof cloth known as Armalon. The leg pans of the two outer couches could be folded in a variety of positions, while the hip pan of the center couch could be disconnected and laid on the aft bulkhead. One rotation and one translation hand controller

2156-500: The conclusion of the Apollo program and during 1973–1974, three CSMs ferried astronauts to the orbital Skylab space station. Finally in 1975, the last flown CSM docked with the Soviet craft Soyuz 19 as part of the international Apollo–Soyuz Test Project . Concepts of an advanced crewed spacecraft started before the Moon landing goal was announced. The three-person vehicle was to be mainly for orbital use around Earth. It would include

2233-460: The decision to design two versions of the CSM: Block I was to be used for uncrewed missions and a single crewed Earth orbit flight ( Apollo 1 ), while the more advanced Block II was designed for use with the lunar module. The Apollo 1 flight was cancelled after a cabin fire killed the crew and destroyed their command module during a launch rehearsal test. Corrections of the problems which caused

2310-409: The deorbit burn for Earth orbital flights. The propellants were pressure-fed to the engine by 39.2 cubic feet (1.11 m ) of gaseous helium at 3,600 pounds per square inch (25 MPa), carried in two 40-inch (1.0 m) diameter spherical tanks. The exhaust nozzle measured 152.82 inches (3.882 m) long and 98.48 inches (2.501 m) wide at the base. It was mounted on two gimbals to keep

2387-441: The drogues were jettisoned and the pilot parachutes, which pulled out the mains, were deployed. These slowed the CM to 22 miles per hour (35 kilometres per hour) for splashdown. The portion of the capsule that first contacted the water surface contained four crushable ribs to further mitigate the force of impact. The command module could safely parachute to an ocean landing with only two parachutes deployed (as occurred on Apollo 15 ),

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2464-491: The environmental control system). On the flight of Apollo 13 , the EPS was disabled by an explosive rupture of one oxygen tank, which punctured the second tank and led to the loss of all oxygen. After the accident, a third oxygen tank was added to obviate operation below 50% tank capacity. That allowed the elimination of the tank's internal stirring-fan equipment, which had contributed to the failure. Also starting with Apollo 14 ,

2541-412: The event of aborting can be referred to as an abort. Sometimes the event of aborting can be given a special name, as in the case of an abort involving a Unix kernel where it is known as a kernel panic . Specifically in the context of data transmission , an abort is a function invoked by a sending station to cause the recipient to discard or ignore all bit sequences transmitted by the sender since

2618-403: The experts in the guidance backroom, especially Jack Garman , who told him that the problem was a computer overload, but could be ignored if it was intermittent. Bales called "Go!", Flight Director Gene Kranz accepted the call and the mission continued to success. Without the support of the backroom, a controller might make a bad call based on faulty memory or information not readily available to

2695-457: The fire were applied to the Block II spacecraft, which was used for all crewed spaceflights. Nineteen CSMs were launched into space. Of these, nine flew humans to the Moon between 1968 and 1972, and another two performed crewed test flights in low Earth orbit , all as part of the Apollo program. Before these, another four CSMs had flown as uncrewed Apollo tests, of which two were suborbital flights and another two were orbital flights . Following

2772-445: The flight director will "go around the room", polling each controller for a go/no go decision, a procedure also known as a launch status check . If all factors are good, each controller calls for a "go" but if there is a problem requiring a hold or an abort, the call is "no go". Another form of this is stay/no stay, when the spacecraft has completed a maneuver and has now "parked" in relation to another body, including spacecraft, orbiting

2849-431: The forward docking tunnel. The forward compartment was separated from the central by a bulkhead and was divided into four 90-degree wedges. The ELS consisted of two drogue parachutes with mortars , three main parachutes , three pilot parachutes to deploy the mains, three inflation bags for uprighting the capsule if necessary, a sea recovery cable, a dye marker, and a swimmer umbilical. The command module's center of mass

2926-415: The forward heat shield was jettisoned to expose the Earth landing equipment and permit deployment of the parachutes. The 1-foot-8-inch (0.51 m)-tall aft compartment was located around the periphery of the command module at its widest part, just forward of (above) the aft heat shield. The compartment was divided into 24 bays containing 10 reaction control engines; the fuel, oxidizer, and helium tanks for

3003-404: The honeycomb varied from about 1.5 inches (3.8 cm) at the base to about 0.25 inches (0.64 cm) at the forward access tunnel. This inner structure was the pressurized crew compartment. The outer structure was made of stainless steel brazed-honeycomb brazed between steel alloy face sheets. It varied in thickness from 0.5 inch to 2.5 inches. Part of the area between the inner and outer shells

3080-452: The inside of an 8-by-2.75-foot (2.44 by 0.84 m) skin panel. The primary fuel (MMH) tank contained 69.1 pounds (31.3 kg); the secondary fuel tank contained 45.2 pounds (20.5 kg); the primary oxidizer tank contained 137.0 pounds (62.1 kg), and the secondary oxidizer tank contained 89.2 pounds (40.5 kg). The propellant tanks were pressurized from a single tank containing 1.35 pounds (0.61 kg) of liquid helium. Back flow

3157-461: The lunar module. In the event of an abort during launch from Earth, the same system would have explosively jettisoned the docking ring and probe from the CM as it separated from the boost protective cover. The central pressure vessel of the command module was its sole habitable compartment. It had an interior volume of 210 cubic feet (5.9 m ) and housed the main control panels, crew seats, guidance and navigation systems, food and equipment lockers,

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3234-512: The mission operations integration room (MOIR), and are now collectively referred to by the name of their current location, the mission evaluation room (MER). While the flight controllers and their backrooms are responsible for real-time decision making, the MOIR/MER provides the detailed data and history needed to solve longer-term issues. Uncrewed U.S. space missions also have flight controllers but are managed from separate organizations, either

3311-470: The module's pressure vessel. The fused silica outer pane served as both a debris shield and as part of the heat shield. Each pane had an anti-reflective coating and a blue-red reflective coating on the inner surface. Sources: The service module was an unpressurized cylindrical structure with a diameter of 12 feet 10 inches (3.91 m) and 14 feet 10 inches (4.52 m) long. The service propulsion engine nozzle and heat shield increased

3388-433: The most efficient way to keep the program on track was to proceed with the development in two versions: By January 1964, North American started presenting Block II design details to NASA. Block I spacecraft were used for all uncrewed Saturn 1B and Saturn V test flights. Initially two crewed flights were planned, but this was reduced to one in late 1966. This mission, designated AS-204 but named Apollo 1 by its flight crew,

3465-450: The needs of their system into the larger needs of the vehicle and working with the rest of the flight control team to develop a cohesive plan of action, even if that plan is not necessarily in the best interests of the system they are responsible for. Within the chain of command of the MCC, information and recommendations flow from the backroom to the frontroom to Flight, and then, potentially, to

3542-565: The on board crew. Generally, a MOCR/FCR flight control team is made up of the more seasoned flight controllers than the SSR/MPSR, though senior flight controllers cycle back to support in the backroom periodically. One example of the usefulness of this system occurred during the descent of the Apollo 11 Lunar Module Eagle , when "1202" and "1201" program alarms came from the LM. GUIDO Steve Bales , not sure whether to call for an abort, trusted

3619-541: The person on the console. The nature of quiescent operations aboard the International Space Station (ISS) today is such that the full team is not required for 24/7/365 support. FCR flight controllers accept responsibility for operations without MPSR support most of the time, and the MPSR is only staffed for high-intensity periods of activity, such as joint Shuttle/ISS missions. The flight controllers in

3696-496: The preceding flag sequence . In the C programming language , abort() is a standard library function that terminates the current application and returns an error code to the host environment. Aborts are typically logged, especially in critical systems, to facilitate troubleshooting and improve future runs. This computing article is a stub . You can help Misplaced Pages by expanding it . Command and service module The Apollo command and service module ( CSM )

3773-419: The pressure between the tunnel and the CM so the hatch could be removed. The unified crew hatch (UCH) measured 29 inches (74 cm) high, 34 inches (86 cm) wide, and weighed 225 pounds (102 kg). It was operated by a pump handle, which drove a ratchet mechanism to open or close fifteen latches simultaneously. Apollo's mission required the LM to dock with the CSM on return from the Moon, and also in

3850-637: The primary flight controls, and the main FDAI (Flight Director Attitude Indicator). The CM pilot served as navigator, so his control panel (center) included the Guidance and Navigation computer controls, the caution and warning indicator panel, the event timer, the Service Propulsion System and RCS controls, and the environmental control system controls. The LM pilot served as systems engineer, so his control panel (right-hand side) included

3927-471: The probe cylinder body engaged and retained the probe center piston in the retracted position. Before vehicle separation in lunar orbit, manual cocking of the twelve ring latches was accomplished. The separating force from the internal pressure in the tunnel area was then transmitted from the ring latches to the probe and drogue. In undocking, the release of the capture latches was accomplished by electrically energizing tandem-mounted DC rotary solenoids located in

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4004-412: The probe was retracted to pull the vehicles together and establish a firm connection, known as "hard docking". The mechanism was specified by NASA to have the following functions: The probe head located in the CSM was self-centering and gimbal-mounted to the probe piston. As the probe head engaged in the opening of the drogue socket, three spring-loaded latches depressed and engaged. These latches allowed

4081-487: The radio call-sign Houston . When non-astronauts are communicating directly with the spacecraft, CAPCOM acts as the communications controller. As of 2011, due to the shrinking size of the astronaut corps at the end of the Shuttle program, fewer astronauts are available to perform CAPCOM duties, so non-astronauts from the space flight training and flight controller branches also function as CAPCOM during ISS missions, while

4158-488: The reaction control system (RCS) computer, power distribution block, ECS controller, separation controller, and components for the high-gain antenna, and included eight EPS radiators and the umbilical connection arm containing the main electrical and plumbing connections to the CM. The fairing externally contained a retractable forward-facing spotlight ; an EVA floodlight to aid the command module pilot in SIM film retrieval; and

4235-479: The role was filled solely by astronauts for the Apollo and Shuttle missions. Astronauts still take the CAPCOM position during critical events such as docking and EVA. In the context of potential crewed missions to Mars, NASA Ames Research Center has conducted field trials of advanced computer-support for astronaut and remote science teams, to test the possibilities for automating CAPCOM. Abort (computing) In

4312-426: The same thing and serve the same function. Leads the flight control team. Flight has overall operational responsibility for missions and payload operations and for all decisions regarding safe, expedient flight. This person monitors the other flight controllers, remaining in constant verbal communication with them via intercom channels called "loops". Is a representative of the senior management chain at JSC, and

4389-524: The specifications given below, unless otherwise noted, all weights given are for the Block II spacecraft. The total cost of the CSM for development and the units produced was $ 36.9  billion in 2016 dollars, adjusted from a nominal total of $ 3.7 billion using the NASA New Start Inflation Indices. The command module was a truncated cone ( frustum ) with a diameter of 12 feet 10 inches (3.91 m) across

4466-523: The success of the mission and for the lives of the astronauts under their watch. The Flight Controllers' Creed states that they must "always be aware that suddenly and unexpectedly we may find ourselves in a role where our performance has ultimate consequences." Well-known actions taken by flight controllers include: There are some positions that have and will serve the same function in every vehicle's flight control team. The group of individuals serving in those positions may be different, but they will be called

4543-543: The third parachute being a safety precaution. The command module attitude control system consisted of twelve 93-pound-force (410 N) attitude control thrusters, ten of which were located in the aft compartment, plus two in the forward compartment. These were supplied by four tanks storing 270 pounds (120 kg) of monomethylhydrazine fuel and nitrogen tetroxide oxidizer, and pressurized by 1.1 pounds (0.50 kg) of helium stored at 4,150 pounds per square inch (28.6 MPa) in two tanks. The forward docking hatch

4620-787: The thrust vector aligned with the spacecraft's center of mass during SPS firings. The combustion chamber and pressurant tanks were housed in the central tunnel. Four clusters of four reaction control system (RCS) thrusters (known as "quads") were installed around the upper section of the SM every 90°. The sixteen-thruster arrangement provided rotation and translation control in all three spacecraft axes. Each R-4D thruster measured 12 inches (30 cm) long by 6 inches (15 cm) diameter, generated 100 pounds-force (440 N) of thrust, and used helium-fed monomethylhydrazine (MMH) as fuel and nitrogen tetroxide (NTO) as oxidizer. Each quad assembly measured 2.2 by 2.7 feet (0.67 by 0.82 m) and had its own fuel, oxidizer, and helium tanks mounted on

4697-575: The total height to 24 feet 7 inches (7.49 m). The interior was a simple structure consisting of a central tunnel section 44 inches (1.1 m) in diameter, surrounded by six pie-shaped sectors. The sectors were topped by a forward bulkhead and fairing, separated by six radial beams, covered on the outside by four honeycomb panels, and supported by an aft bulkhead and engine heat shield. The sectors were not all equal 60° angles, but varied according to required size. The forward fairing measured 1 foot 11 inches (58 cm) long and housed

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4774-411: The upper end of the lunar module tunnel, the drogue, which was constructed of 1-inch-thick aluminum honeycomb core, bonded front and back to aluminum face sheets, was the receiving end of the probe head capture latches. After the initial capture and stabilization of the vehicles, the probe was capable of exerting a closing force of 1,000 pounds-force (4.4 kN) to draw the vehicles together. This force

4851-402: The waste management system, and the docking tunnel. Dominating the forward section of the cabin was the crescent-shaped main display panel measuring nearly 7 feet (2.1 m) wide and 3 feet (0.91 m) tall. It was arranged into three panels, each emphasizing the duties of each crew member. The mission commander's panel (left side) included the velocity , attitude, and altitude indicators,

4928-494: Was filled by another astronaut, often one of the backup- or support-crew members. NASA believes that an astronaut is most able to understand the situation in the spacecraft and pass information in the clearest way. For long-duration missions there is more than one CAPCOM, each assigned to a different shift team. After control of U.S. spaceflights moved to the Johnson Space Center in the early 1960s, each CAPCOM used

5005-451: Was filled with a layer of fiberglass insulation as additional heat protection. An ablative heat shield on the outside of the CM protected the capsule from the heat of reentry , which is sufficient to melt most metals. This heat shield was composed of phenolic formaldehyde resin . During reentry, this material charred and melted away, absorbing and carrying away the intense heat in the process. The heat shield has several outer coverings:

5082-451: Was generated by gas pressure acting on the center piston within the probe cylinder. Piston retraction compressed the probe and interface seals and actuated the 12 automatic ring latches which were located radially around the inner surface of the CSM docking ring. The latches were manually re-cocked in the docking tunnel by an astronaut after each hard docking event (lunar missions required two dockings). An automatic extension latch attached to

5159-529: Was installed on the armrests of the left-hand couch. The translation controller was used by the crew member performing the transposition, docking, and extraction maneuver with the LM, usually the CM Pilot. The center and right-hand couches had duplicate rotational controllers. The couches were supported by eight shock-attenuating struts, designed to ease the impact of touchdown on water or, in case of an emergency landing, on solid ground. The contiguous cabin space

5236-431: Was mounted at the top of the docking tunnel. It was 30 inches (76 cm) in diameter and weighed 80 pounds (36 kg), constructed from two machined rings that were weld-joined to a brazed honeycomb panel. The exterior side was covered with 0.5-inch (13 mm) of insulation and a layer of aluminum foil. It was latched in six places and operated by a pump handle. The hatch contained a valve in its center, used to equalize

5313-410: Was offset a foot or so from the center of pressure (along the symmetry axis). This provided a rotational moment during reentry, angling the capsule and providing some lift (a lift to drag ratio of about 0.368 ). The capsule was then steered by rotating the capsule using thrusters; when no steering was required, the capsule was spun slowly, and the lift effects cancelled out. This system greatly reduced

5390-615: 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 , which carried a crew of three astronauts and the second Apollo spacecraft, the Apollo Lunar Module , to lunar orbit, and brought the astronauts back to Earth. It consisted of two parts: the conical command module,

5467-551: Was organized into six equipment bays: The CM had five windows. The two side windows measured 9 inches (23 cm) square next to the left and right-hand couches. Two forward-facing triangular rendezvous windows measured 8 by 9 inches (20 by 23 cm), used to aid in rendezvous and docking with the LM. The circular hatch window was 9 inches (23 cm) in diameter located directly over the center couch. Each window assembly consisted of three thick panes of glass. The inner two panes, which were made of aluminosilicate , made up part of

5544-409: Was planned for launch on February 21, 1967. During a dress rehearsal for the launch on January 27, all three astronauts ( Gus Grissom , Ed White and Roger Chaffee ) were killed in a cabin fire, which revealed serious design, construction and maintenance shortcomings in Block I, many of which had been carried over into Block II command modules being built at the time. After a thorough investigation by

5621-530: Was prevented by a series of check valves, and back flow and ullage requirements were resolved by containing the fuel and oxidizer in Teflon bladders which separated the propellants from the helium pressurant. The four completely independent RCS clusters provided redundancy; only two adjacent functioning units were needed to allow complete attitude control. The lunar module used a similar four-quad arrangement of R-4D thruster engines for its RCS. Electrical power

5698-552: Was produced by three fuel cells , each measuring 44 inches (1.1 m) tall by 22 inches (0.56 m) in diameter and weighing 245 pounds (111 kg). These combined hydrogen and oxygen to generate electrical power, and produced drinkable water as a byproduct. The cells were fed by two hemispherical-cylindrical 31.75-inch (0.806 m) diameter tanks, each holding 29 pounds (13 kg) of liquid hydrogen , and two spherical 26-inch (0.66 m) diameter tanks, each holding 326 pounds (148 kg) of liquid oxygen (which also supplied

5775-540: Was severed and the service module was cast off and allowed to burn up in the atmosphere. The CSM was developed and built for NASA by North American Aviation starting in November 1961. It was initially designed to land on the Moon atop a landing rocket stage and return all three astronauts on a direct-ascent mission, which would not use a separate lunar module, and thus had no provisions for docking with another spacecraft. This, plus other required design changes, led to

5852-450: Was still assumed the lunar landing would be achieved by direct ascent rather than by lunar orbit rendezvous . Therefore, design proceeded without a means of docking the command module to a lunar excursion module (LEM) . But the change to lunar orbit rendezvous, plus several technical obstacles encountered in some subsystems (such as environmental control), soon made it clear that substantial redesign would be required. In 1963, NASA decided

5929-466: Was the area outside the inner pressure shell in the nose of the capsule, located around the forward docking tunnel and covered by the forward heat shield. The compartment was divided into four 90-degree segments that contained Earth landing equipment (all the parachutes, recovery antennas and beacon light, and sea recovery sling), two reaction control thrusters, and the forward heat shield release mechanism. At about 25,000 feet (7,600 m) during reentry,

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