138-697: The SM-65E Atlas , or Atlas-E , was an operational variant of the Atlas missile. It first flew on October 11, 1960, and was deployed as an operational ICBM from September 1961 until April 1966. Following retirement as an ICBM, the Atlas-E, along with the Atlas-F , was refurbished for orbital launches as the Atlas E/F . The last Atlas E/F launch was conducted on March 24, 1995, using a rocket which had originally been built as an Atlas E. As fully operational ICBMs,
276-500: A W38 thermonuclear warhead with a yield of 3.75 Mt which was fuzed for either air burst or contact burst. The Mk 4 RV also deployed penetration aids in the form of mylar balloons which replicated the radar signature of the Mk 4 RV. The Mk 4 plus W-38 had a combined weight of 4,050 lb (1,840 kg). The Atlas missile's warhead was over 100 times more powerful than the bomb dropped over Nagasaki in 1945. The R-7 Semyorka
414-425: A 3 x 3 configuration: three launchers and one combined guidance control/launch facility constituted a launch complex, and three complexes comprised a squadron. At these later sites the combined guidance and control facility measured 107 by 121 ft (33 by 37 m) with a partial basement. A dispersal technique of spreading the launch complexes were 20 to 30 miles (30 to 50 km) apart was also employed to reduce
552-633: A continuous sweeping motion that is desirable for fields and particles instruments, as well as some optical scanning instruments, but they may require complicated systems to de-spin antennas or optical instruments that must be pointed at targets for science observations or communications with Earth. Three-axis controlled craft can point optical instruments and antennas without having to de-spin them, but they may have to carry out special rotating maneuvers to best utilize their fields and particle instruments. If thrusters are used for routine stabilization, optical observations such as imaging must be designed knowing that
690-461: A dry start (ignition coming before propellant injection) for an extremely rapid ignition that required no hold-down time on the pad to prevent combustion instability. The booster engines had separate gas generators unlike the Atlas D which had one gas generator for both engines. The launcher system used for the E and F series was also different from the D series, eliminating the hold-down arms in favor of
828-595: A dummy unit and the guidance program changed to fire the Atlas into the Pacific Ocean instead of over the North Pole into the Soviet Union. However, the project quickly met with opposition from Kansas governor John Anderson as well as politicians from neighboring states who protested the idea of a missile flying over populated areas, especially since on-duty ICBMs lacked any Range Safety destruct system in
966-402: A ground station. The attitude control algorithms are written and implemented based on requirement for a particular attitude maneuver. Asides the implementation of passive attitude control such as the gravity-gradient stabilization , most spacecraft make use of active control which exhibits a typical attitude control loop. The design of the control algorithm depends on the actuator to be used for
1104-649: A high-altitude explosion. The failure was attributed to corrosion in a piece of ducting that resulted in loss of lubricant to the B-1 turbopump. The ducting in the Atlas could have been easily replaced, but the Air Force elected not to do so on the grounds that the space shuttle would be replacing expendable launch vehicles soon. In addition, the converted Atlas missiles still had various ICBM hardware features which were unnecessary for space launches and added more complexity and failure points. These included attachment ducts so that
1242-514: A last-ditch weapon that would ensure a counterattack in the case the Soviets attempted a sneak attack on the US bomber bases. The initial versions were stored at ground level and thus subject to attack by Soviet bombers, which greatly reduced their suitability for this role. Starting with the F models they were stored in underground silos that offered some protection from air attack. New designs, especially
1380-440: A long-duration mission by producing control moments without fuel expenditure. For example, Mariner 10 adjusted its attitude using its solar cells and antennas as small solar sails. In orbit, a spacecraft with one axis much longer than the other two will spontaneously orient so that its long axis points at the planet's center of mass. This system has the virtue of needing no active control system or expenditure of fuel. The effect
1518-404: A mechanism that would immediately release the missile as thrust built up. Atlas-E launches were conducted from Cape Canaveral Air Force Station , at Launch Complexes 11 and 13 , and Vandenberg Air Force Base at OSTF-1 , LC-576 and SLC-3 . The Atlas E testing program commenced on October 11, 1960, when Missile 3E was launched from Cape Canaveral's LC-13. At around 40 seconds into launch,
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#17327874802991656-580: A mere 2.02% of the initial gross weight of the vehicle (still excluding payload). This very low dry weight gave Atlas D a range of up to 9,000 miles (14,500 km), or to orbit payloads without requiring an upper stage. It first flew on 14 April 1959. To provide the United States with an interim or emergency ICBM capability, in September 1959 the Air Force deployed three SM-65D Atlas missiles on open launch pads at Vandenberg AFB , California, under
1794-491: A minimum of three reaction wheels must be used, with additional units providing single failure protection. See Euler angles . These are rotors spun at constant speed, mounted on gimbals to provide attitude control. Although a CMG provides control about the two axes orthogonal to the gyro spin axis, triaxial control still requires two units. A CMG is a bit more expensive in terms of cost and mass, because gimbals and their drive motors must be provided. The maximum torque (but not
1932-562: A peak deployment level of 129 (30 D, 27 E, 72 F). Despite its relatively short life span, Atlas served as the proving ground for many new missile technologies. Perhaps more importantly, its development spawned the organization, policies, and procedures that paved the way for all of the later ICBM programs. After its retirement from operational ICBM service in 1965, the ICBMs were refurbished and used for close to forty years as space launch vehicle boosters. Eight flights of Atlas A occurred during
2070-426: A phenomenon known as Gimbal lock . A rotation matrix, on the other hand, provides a full description of the attitude at the expense of requiring nine values instead of three. The use of a rotation matrix can lead to increased computational expense and they can be more difficult to work with. Quaternions offer a decent compromise in that they do not suffer from gimbal lock and only require four values to fully describe
2208-502: A pressure transducer had accidentally been installed on the test port of the LOX regulator. This resulted in near-total LOX starvation of the sustainer engine. Strong vibration in the gas generator from the shutdown ruptured low-pressure ducting and started a propellant leak that led to a thrust section fire. The vernier engines never activated due to their startup timer being set to activate following sustainer start (which failed, thus preventing
2346-412: A squirrel monkey named Goliath ended in disaster as the Atlas's sustainer engine shut down almost immediately at liftoff, while the verniers failed to start at all. The booster engines managed to retain attitude control until a fire broke out in the thrust section and caused the B-1 engine to shut down at T+22 seconds. Telemetry data became erratic at this point. The Atlas began tumbling uncontrollably and
2484-530: A success would send a needless provocation to the Soviet Union especially coming on the heels of the Cuban Missile Crisis. Atlas 65E was eventually launched on April 25, 1963, from OSTF-1 at Vandenberg, as a R&D flight carried out by a Convair team rather than the Walker missileers. The flight, which had a series of modifications designed to correct problems encountered on previous Atlas launches,
2622-547: A test launch of an Atlas missile to verify its operability. The serial numbers of all currently deployed Atlas missiles were written down on pieces of paper, placed inside a hat, and one would be pulled at random. The winner turned out to be Missile 65E, then located at Walker Air Force Base in Kansas. This would be the first launch of an active duty ICBM from an operational silo facility, the Mk IV nuclear warhead would be replaced with
2760-495: A weather satellite for the National Oceanic and Atmospheric Administration . The launch had been intended for the summer of 1985, but was delayed by more than a year due to endless technical problems and the need to use the Atlas pads at VAFB for DoD launches. After a frustrating series of problems with the Atlas's LOX tank and the booster turbopumps, liftoff took place at 7:52 AM PST. The launch went perfectly and inserted
2898-514: Is a device that senses the direction to the Sun . This can be as simple as some solar cells and shades, or as complex as a steerable telescope , depending on mission requirements. An Earth sensor is a device that senses the direction to Earth . It is usually an infrared camera ; nowadays the main method to detect attitude is the star tracker , but Earth sensors are still integrated in satellites for their low cost and reliability. A star tracker
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#17327874802993036-517: Is aerodynamic stabilization. This is achieved using a drag gradient, as demonstrated on the Get Away Special Passive Attitude Control Satellite (GASPACS) technology demonstration. In low Earth orbit, the force due to drag is many orders of magnitude more dominant than the force imparted due to gravity gradients. When a satellite is utilizing aerodynamic passive attitude control, air molecules from
3174-426: Is an optical device that measures the position(s) of star (s) using photocell (s) or a camera. It uses magnitude of brightness and spectral type to identify and then calculate the relative position of stars around it. A magnetometer is a device that senses magnetic field strength and, when used in a three-axis triad, magnetic field direction. As a spacecraft navigational aid, sensed field strength and direction
3312-506: Is based on the measurement of the rate of change of body-fixed magnetometer signals. where m {\displaystyle m} is the commanded magnetic dipole moment of the magnetic torquer and K {\displaystyle K} is the proportional gain and B ˙ {\displaystyle {\dot {B}}} is the rate of change of the Earth's magnetic field. Spacecraft attitude determination
3450-440: Is caused by a tidal force . The upper end of the vehicle feels less gravitational pull than the lower end. This provides a restoring torque whenever the long axis is not co-linear with the direction of gravity. Unless some means of damping is provided, the spacecraft will oscillate about the local vertical. Sometimes tethers are used to connect two parts of a satellite, to increase the stabilizing torque. A problem with such tethers
3588-401: Is compared to a map of Earth's magnetic field stored in the memory of an on-board or ground-based guidance computer. If spacecraft position is known then attitude can be inferred. Attitude cannot be measured directly by any single measurement, and so must be calculated (or estimated ) from a set of measurements (often using different sensors). This can be done either statically (calculating
3726-406: Is most common reacts to an error signal (deviation) based on attitude as follows where T c {\displaystyle T_{c}} is the control torque, e {\displaystyle e} is the attitude deviation signal, and K p , K i , K d {\displaystyle K_{\text{p}},K_{\text{i}},K_{\text{d}}} are
3864-483: Is placed in space. (For some applications such as in robotics and computer vision, it is customary to combine position and attitude together into a single description known as Pose .) Attitude can be described using a variety of methods; however, the most common are Rotation matrices , Quaternions , and Euler angles . While Euler angles are oftentimes the most straightforward representation to visualize, they can cause problems for highly-maneuverable systems because of
4002-418: Is that meteoroids as small as a grain of sand can part them. Coils or (on very small satellites) permanent magnets exert a moment against the local magnetic field. This method works only where there is a magnetic field against which to react. One classic field "coil" is actually in the form of a conductive tether in a planetary magnetic field. Such a conductive tether can also generate electrical power, at
4140-617: Is the process of determining the orientation of a spacecraft (vehicle or satellite). It is a pre-requisite for spacecraft attitude control. A variety of sensors are utilized for relative and absolute attitude determination. Many sensors generate outputs that reflect the rate of change in attitude. These require a known initial attitude, or external information to use them to determine attitude. Many of this class of sensor have some noise, leading to inaccuracies if not corrected by absolute attitude sensors. Gyroscopes are devices that sense rotation in three-dimensional space without reliance on
4278-704: The Cold War and intelligence showing the Soviet Union was working on an ICBM design led to it becoming a crash project in late 1952, along with the creation of several other missile projects to ensure one would enter service as soon as possible. The first test launch was carried out in June 1957, which failed. The first success of the Soviet R-7 Semyorka in August gave the program new urgency, leading to
SM-65E Atlas - Misplaced Pages Continue
4416-579: The Minuteman , rendered Atlas obsolete and it was retired from the ICBM role by 1965. These disadvantages had no bearing on its use for space launches, and Atlas-derived launch vehicles served a long history as launchers. Even before its ICBM use ended in 1965, Atlas had placed four Project Mercury astronauts in orbit and was becoming the foundation for a family of successful space launch vehicles, most notably Atlas Agena and Atlas Centaur . Mergers led to
4554-520: The celestial sphere , certain fields, and nearby objects, etc. Controlling vehicle attitude requires actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on the current attitude and specification of a desired attitude. Before and during attitude control can be performed, spacecraft attitude determination must be performed, which requires sensors for absolute or relative measurement. The broader integrated field that studies
4692-513: The 1990s, sometimes with solid-fueled upper stages, sometimes not. These Atlases should be not be confused with the Atlas H which flew five times during the 1980s and was a standard Atlas SLV-3 (descendant of the original Atlas D) flown with solid upper stages. During 1962–74, the Air Force conducted many dozens of test flights of reentry vehicles and Nike/Zeus target missiles. Most of these were on Atlas D or F missiles, however six of them used Atlas Es. After 1964, only three Atlas Es were flown during
4830-405: The 564th SMS consisted of six launchers grouped together, controlled by two launch operations buildings, and clustered around a central guidance control facility. This was called the 3 × 2 configuration: two launch complexes of three missiles each constituted a squadron. At the second Warren site for the 565th SMS and at Offutt AFB, Nebraska, for the 549th SMS, the missiles were based in
4968-513: The Atlas E and F, which differed only in guidance systems, had upgraded engines and inertial control instead of the Atlas D's radio ground guidance. The ignition system was also different from the one used on the D-series, which used a "wet" start, meaning that the propellants were injected into the combustion chamber prior to ignition, and a hypergolic igniter on the fully developed version. The Atlas E/F for comparison used pyrotechnic cartridges and
5106-542: The Atlas F to be launched in about ten minutes, a saving of about five minutes over the Atlas D and Atlas E, both of which were stored horizontally and had to be raised to a vertical position before being fueled. Atlas-F launches were conducted from Cape Canaveral Air Force Station, at Launch Complexes 11 and 13, and Vandenberg Air Force Base at OSTF-2 , Vandenberg AFB Launch Complex 576 and Vandenberg AFB Space Launch Complex 3. Strategic Air Command deployed 13 operational Atlas ICBM squadrons between 1959 and 1962. Each of
5244-401: The Atlas managed to fail at some point during test flights, from the engine combustion chambers to the tank pressurization system to the flight control system, but Convair engineers noted with some pride that there had never been a repeat of the same failure more than three times, and every component malfunction on an Atlas flight was figured out and resolved. Some of the repeat failures were also
5382-688: The Atlas missile, first flying on 11 June 1957. It was a test model designed to verify the structure and propulsion system, and had no sustainer engine or separable stages. The first three Atlas A launches used an early Rocketdyne engine design with conical thrust chambers and only 135,000 pounds of thrust. By the fourth Atlas test, they were replaced by an improved engine design that had bell-shaped thrust chambers and 150,000 pounds of thrust. There were eight Atlas A test flights, conducted in 1957–58, of which four were successful. All were launched from Cape Canaveral Air Force Station , at either Launch Complex 12 or Launch Complex 14 . The Convair X-12 / SM-65B
5520-448: The Atlas program, believed that the location of the propellant lines on the E/F missiles was causing LOX and RP-1 ejected from the spent booster engines following staging to mix and explode, possibly damaging valves or plumbing. As evidence of this, he pointed to telemetry data from flights indicating a momentary pitching motion of the missile after booster jettison, which could be the result of
5658-536: The CIA learning that the Soviet ICBM program was making progress, led to the project being dramatically accelerated. Project Atlas was assigned the highest Air Force development priority on 14 May 1954 by General Thomas D. White . A major development and test contract was awarded to Convair on 14 January 1955 for a 10-foot (3 m) diameter missile to weigh about 250,000 lb (113,400 kg). Atlas development
SM-65E Atlas - Misplaced Pages Continue
5796-437: The Earth's upper atmosphere strike the satellite in such a way that the center of pressure remains behind the center of mass, similar to how the feathers on an arrow stabilize the arrow. GASPACS utilized a 1 m inflatable 'AeroBoom', which extended behind the satellite, creating a stabilizing torque along the satellite's velocity vector. Control algorithms are computer programs that receive data from vehicle sensors and derive
5934-495: The LOX lines on the grounds that the RP-1 could not detonate without oxidizer. On December 6, Missile 6F suffered a leak in the sustainer hydraulic system at BECO, resulting in eventual loss of hydraulic pressure and failure to achieve the planned range. After this debacle, the Air Force relented and agreed to install cutoff valves for the RP-1 lines as well, and this failure mode did not repeat itself. The final Atlas E test from CCAS
6072-461: The PID controller parameters. A simple implementation of this can be the application of the proportional control for nadir pointing making use of either momentum or reaction wheels as actuators. Based on the change in momentum of the wheels, the control law can be defined in 3-axes x, y, z as This control algorithm also affects momentum dumping. Another important and common control algorithm involves
6210-535: The Range Safety system which sent a spurious manual cutoff command. The cause of them was unclear, and GD/A could not offer any solution except improved prelaunch checkout procedures. Atlas 70E launched from 576-C on July 30 and was successful, as was 72E, launched on August 24 from OSTF-1. Atlas 71E, the last flight of the year, launched from 576-C on September 25 and experienced a sustainer hydraulic line rupture at staging, leading to missile tumbling and failure of
6348-492: The Soviet R-5 first launched in 1953. Pressure in the tanks provides the structural rigidity required for flight. An Atlas rocket would collapse under its own weight if not kept pressurized, and had to have 5 psi (34 kPa) nitrogen in the tank even when not fueled. The rocket had two small thrust chambers on the sides of the tank called vernier rockets . These provided fine adjustment of velocity and steering after
6486-475: The Sun so they can provide electrical power to the spacecraft. Cassini ' s main engine nozzles were steerable. Knowing where to point a solar panel, or scan platform, or a nozzle — that is, how to articulate it — requires knowledge of the spacecraft's attitude. Because a single subsystem keeps track of the spacecraft's attitude, the Sun's location, and Earth's location, it can compute the proper direction to point
6624-540: The West Coast, but the first attempt ended ignominiously when Missile 27E lifted from OSTF-1 (Operational Silo Test Facility) on June 7. Almost immediately at liftoff, the B-1 engine experienced rough combustion, causing a fire in the thrust section that led to the explosion of the missile only four seconds after launch. The failure, a near-repeat of two Atlas D accidents the previous year, extensively damaged OSTF-1 and put it out of use for months. Postflight examination of
6762-693: The acquisition of the Atlas Centaur line by the United Launch Alliance . Today ULA supports the larger Atlas V , which combines the Centaur upper stage with a new booster. Until 1995, many retired Atlas ICBMs were refurbished and combined with upper stages to launch satellites. Atlas was the first US ICBM and one of the first large liquid-fueled rockets. As such, its early development was quite chaotic, with plans changing rapidly as flight tests revealed issues. Atlas began in 1946 with
6900-634: The aeronautical field, such as: This class of sensors sense the position or orientation of fields, objects or other phenomena outside the spacecraft. A horizon sensor is an optical instrument that detects light from the 'limb' of Earth's atmosphere, i.e., at the horizon. Thermal infrared sensing is often used, which senses the comparative warmth of the atmosphere, compared to the much colder cosmic background . This sensor provides orientation with respect to Earth about two orthogonal axes. It tends to be less precise than sensors based on stellar observation. Sometimes referred to as an Earth sensor. Similar to
7038-448: The angular rate is not estimated directly, but rather the measured angular rate from the gyro is used directly to propagate the rotational dynamics forward in time. This is valid for most applications as gyros are typically far more precise than one's knowledge of disturbance torques acting on the system (which is required for precise estimation of the angular rate). For some sensors and applications (such as spacecraft using magnetometers)
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#17327874802997176-463: The appendages. It logically falls to the same subsystem – the Attitude and Articulation Control Subsystem (AACS), then, to manage both attitude and articulation. The name AACS may even be carried over to a spacecraft even if it has no appendages to articulate. Attitude is part of the description of how an object is placed in the space it occupies. Attitude and position fully describe how an object
7314-448: The appropriate commands to the actuators to rotate the vehicle to the desired attitude. The algorithms range from very simple, e.g. proportional control , to complex nonlinear estimators or many in-between types, depending on mission requirements. Typically, the attitude control algorithms are part of the software running on the computer hardware, which receives commands from the ground and formats vehicle data telemetry for transmission to
7452-655: The attitude using only the measurements currently available), or through the use of a statistical filter (most commonly, the Kalman filter ) that statistically combine previous attitude estimates with current sensor measurements to obtain an optimal estimate of the current attitude. Static attitude estimation methods are solutions to Wahba's problem . Many solutions have been proposed, notably Davenport's q-method, QUEST, TRIAD, and singular value decomposition . Crassidis, John L., and John L. Junkins.. Chapman and Hall/CRC, 2004. Kalman filtering can be used to sequentially estimate
7590-555: The attitude, as well as the angular rate. Because attitude dynamics (combination of rigid body dynamics and attitude kinematics) are non-linear, a linear Kalman filter is not sufficient. Because attitude dynamics is not very non-linear, the Extended Kalman filter is usually sufficient (however Crassidis and Markely demonstrated that the Unscented Kalman filter could be used, and can provide benefits in cases where
7728-413: The attitude. Attitude control can be obtained by several mechanisms, including: Vernier thrusters are the most common actuators, as they may be used for station keeping as well. Thrusters must be organized as a system to provide stabilization about all three axes, and at least two thrusters are generally used in each axis to provide torque as a couple in order to prevent imparting a translation to
7866-416: The award of an Army Air Forces research contract to Convair for the study of a 1,500-to-5,000-mile (2,400 to 8,000 km) range missile that might at some future date carry a nuclear warhead. This MX-774 project was named for the Atlas of Greek mythology and the contractor's parent Atlas Corporation . At the time, the smallest atomic warheads were all larger than the maximum theoretical payloads of
8004-460: The booster engines would be shut off and a series of mechanical and hydraulic mechanisms would close the plumbing lines to them. The booster section would then be released by a series of hydraulic clamps (aside from the early test model Atlas B, which used explosive bolts) and slide off the missile on two tracks. From there on, the sustainer and verniers would operate by themselves. Booster staging took place at roughly two minutes into launch, although
8142-399: The cause of the problem; a botched repair job on a metal O-ring that caused sealant to plug up ventilation holes in the gas generator, which overpressurized and ruptured shortly after ignition. Escaping flames then burned through a LOX feed line, cutting off the flow of oxidizer to the gas generator and causing B-2 engine shutdown. On September 17, 1986, Atlas 52E successfully launched NOAA-G,
8280-538: The combination of sensors, actuators and algorithms is called guidance, navigation and control , which also involves non-attitude concepts, such as position determination and navigation . A spacecraft's attitude must typically be stabilized and controlled for a variety of reasons. It is often needed so that the spacecraft high-gain antenna may be accurately pointed to Earth for communications, so that onboard experiments may accomplish precise pointing for accurate collection and subsequent interpretation of data, so that
8418-582: The concept of detumbling, which is attenuating the angular momentum of the spacecraft. The need to detumble the spacecraft arises from the uncontrollable state after release from the launch vehicle. Most spacecraft in low Earth orbit (LEO) makes use of magnetic detumbling concept which utilizes the effect of the Earth's magnetic field . The control algorithm is called the B-Dot controller and relies on magnetic coils or torque rods as control actuators. The control law
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#17327874802998556-428: The direction opposite to that required to re-orient the vehicle. Because momentum wheels make up a small fraction of the spacecraft's mass and are computer controlled, they give precise control. Momentum wheels are generally suspended on magnetic bearings to avoid bearing friction and breakdown problems. Spacecraft Reaction wheels often use mechanical ball bearings. To maintain orientation in three dimensional space
8694-422: The early years. After watching Atlas Serial 7D explode shortly after its nighttime launch , Mercury astronaut Gus Grissom remarked "Are we really going to get on top of one of those things?" The numerous failures led to Atlas being dubbed an "Inter County Ballistic Missile" by missile technicians, but by 1965 most of the problems had been worked out and it was a reliable launch vehicle. Nearly every component in
8832-541: The energy generated by exploding propellant. The conclusion was that such an event had ruptured low pressure ducting on Missile 26E and caused loss of fuel flow to the sustainer gas generator, or else propellant residue had obstructed the ducting. Hujsak proposed that additional cutoff valves be added to the propellant lines in the booster engines that would be closed just before jettison. This upgrade had to be retrofitted to missiles that had already been shipped, but Air Force officials argued that they only needed to add valves to
8970-485: The event of a malfunction. Even if the Atlas flew perfectly, the booster section would still have a high chance of landing in a populated area. Secretary McNamara eventually agreed to transport Atlas 65E to Vandenberg and have the Walker AFB crew launch it there. Even with this change to a safer launching locale, Congress still argued over the geopolitical implications of such a test. A failure would damage US prestige,
9108-501: The event of a vernier failure. The sustainer engine on all Atlas variants consisted of a single thrust chamber with its own turbopump and gas generator, which also powered two small pressure-fed vernier engines. The verniers provided roll control and final velocity trim. The total sea level thrust of all five thrust chambers was 360,000 lb f (1,600 kN ) for a standard Atlas D. Atlas E/F had 375,000 pounds of thrust. Total sea level thrust for these three-engine Atlas Es and Fs
9246-503: The exact timing could vary considerably depending on the model of Atlas as well as the particular mission being flown. This "stage-and-a-half" design was made possible by the extremely light weight balloon tanks . The tanks made up such a small percentage of the total booster weight that the mass penalty of lifting them to orbit was less than the technical and mass penalty required to throw half of them away mid-flight. However, technology advanced quickly and not long after design work on Atlas
9384-561: The expense of orbital decay . Conversely, by inducing a counter-current, using solar cell power, the orbit may be raised. Due to massive variability in Earth's magnetic field from an ideal radial field, control laws based on torques coupling to this field will be highly non-linear. Moreover, only two-axis control is available at any given time meaning that a vehicle reorient may be necessary to null all rates. Three main types of passive attitude control exist for satellites. The first one uses gravity gradient, and it leads to four stable states with
9522-551: The first successful Atlas A launch in December. Of the eight flights of the A model, only three were successful, but the later models demonstrated increasing reliability and the D model was cleared for use. Atlas C was declared operational in September 1959. Even at that time it was considered less than ideal as it had to be fuelled immediately before launch and thus had very slow reaction times. The Air Force still saw its strategic bombers as its primary force and considered Atlas as
9660-399: The flight continued, it's possible that the missile would not have achieved a proper trajectory. The next Atlas E test, from Cape Canaveral, was also a failure. Missile 17E on June 23 experienced a malfunction of the pitch gyro, which was apparently running at half speed. The missile began to oscillate in the pitch plane starting at T+15 seconds and eventually the excessive pitch rate exceeded
9798-419: The fuel management system. When stored, the missile sat atop an elevator. If placed on alert, it was fueled with RP-1 (kerosene) liquid fuel, which could be stored inside the missile for extended periods. If a decision was made to launch, it was fueled with liquid oxygen . Once the liquid oxygen fueling was complete, the elevator raised the missile to the surface for launching. This method of storage allowed
9936-598: The full-up engines delivering 303,000 pounds of thrust. On the Atlas E/F, each booster engine had a separate pump and gas generator. Later space launcher variants of the Atlas used the MA-5 propulsion system with twin turbopumps on each booster engine, driven by a common gas generator. The boosters were more powerful than the sustainer engine and did most of the lifting for the first two minutes of flight. In addition to pitch and yaw control, they could also perform roll control in
10074-406: The heating and cooling effects of sunlight and shadow may be used intelligently for thermal control, and also for guidance: short propulsive maneuvers must be executed in the right direction. Attitude control of spacecraft is maintained using one of two principal approaches: There are advantages and disadvantages to both spin stabilization and three-axis stabilization. Spin-stabilized craft provide
10212-402: The history of this variant. Ten flights of Atlas B occurred during the history of this variant. Six flights of Atlas C occurred during the history of this variant. Spacecraft attitude control Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as
10350-424: The hydraulic fluid to escape; they resulted in shielding being added to protect the rise-off disconnect. Missile 8E on January 24, 1961, lost roll control due to aerodynamic heating shorting the vernier pitch control servo, a problem that had not occurred since the early Atlas A tests. Missile 9E on February 4 experienced problems with the propellant utilization system and prematurely depleted its fuel supply, however
10488-496: The initial estimate is poor). Multiple methods have been proposed, however the Multiplicative Extended Kalman Filter (MEKF) is by far the most common approach. This approach utilizes the multiplicative formulation of the error quaternion, which allows for the unity constraint on the quaternion to be better handled. It is also common to use a technique known as dynamic model replacement, where
10626-501: The launchers could be dispersed more widely in what was called a 1 × 9 configuration, with one missile silo located at one launch site each for the nine missiles assigned to the squadron. Atlas-E launches were conducted from Cape Canaveral Air Force Station, at Launch Complexes 11 and 13, and Vandenberg Air Force Base at Vandenberg AFB Operational Silo Test Facility , Vandenberg AFB Launch Complex 576 and Vandenberg AFB Space Launch Complex 3 . The SM-65F Atlas , or Atlas-F ,
10764-453: The long axis (axis with smallest moment of inertia) pointing towards Earth. As this system has four stable states, if the satellite has a preferred orientation, e.g. a camera pointed at the planet, some way to flip the satellite and its tether end-for-end is needed. The second passive system orients the satellite along Earth's magnetic field thanks to a magnet. These purely passive attitude control systems have limited pointing accuracy, because
10902-411: The lubricant oil tank could be mounted either horizontally or vertically during preparation for a silo launch. As a result of the postflight investigation for Atlas 68E, it was decided to inspect all existing launch vehicles for corroded plumbing and also remove unneeded ICBM hardware. The last-ever failure of an Atlas caused by the booster itself, as opposed to the upper stages or other external factors,
11040-646: The maximum angular momentum change) exerted by a CMG is greater than for a momentum wheel, making it better suited to large spacecraft. A major drawback is the additional complexity, which increases the number of failure points. For this reason, the International Space Station uses a set of four CMGs to provide dual failure tolerance. Small solar sails (devices that produce thrust as a reaction force induced by reflecting incident light) may be used to make small attitude control and velocity adjustments. This application can save large amounts of fuel on
11178-455: The missile could not be kept in the state of flight readiness indefinitely and was largely useless for its intended purpose (military) and was similarly developed into a space launch vehicle, initially delivering Sputnik and Vostok into orbit. The Soyuz rocket is descended from the R-7 and remains in use today. The Convair X-11 / SM-65A Atlas / Atlas A was the first full-scale prototype of
11316-553: The missile hardware found extensive damage to the B-1 engine, particularly the injector head, which was almost completely destroyed. Afterwards, copper baffles were installed in all injector heads and the engine start sequence changed to wet start (an inert fluid kept in the engine tubes to reduce shock at ignition). The downside of this was adding 40 pounds (18 kg) of additional weight as well as slightly reduced engine performance. The ARMA guidance system on 27E also experienced erratic behavior due to an intermittently shorted diode; had
11454-637: The missile's structural limits. It broke up either from aerodynamic loads or heating 101 seconds after launch. After this debacle, all remaining Atlas E/F R&D flights had the SMRD (Spin Motor Rotation Detector) system installed. Atlas E tests at VAFB were curtailed until OSTF-1 could be repaired, and for the remainder of 1961 all testing took place from the Cape. Following two successive flights ending in explosions and an incinerated launch stand,
11592-427: The mission. Three Atlas Es were launched in 1964. The first of these was 48E on February 12, launched from 576-F. At approximately T+3 seconds, the guidance system issued inadvertent BECO and SECO/VECO cutoff discreets. Since however the programmer was set up to block cutoff commands during the first two minutes of flight in order to prevent a missile fallback on or around the pad area, nothing happened. The BECO command
11730-408: The observation of external objects. Classically, a gyroscope consists of a spinning mass, but there are also " ring laser gyros " utilizing coherent light reflected around a closed path. Another type of "gyro" is a hemispherical resonator gyro where a crystal cup shaped like a wine glass can be driven into oscillation just as a wine glass "sings" as a finger is rubbed around its rim. The orientation of
11868-483: The ocean rather than separation of the capsule from the booster. Had the flight succeeded, Goliath would have been sent on a 5,000 miles (8,000 km) suborbital lob and recovered in the South Atlantic. The capsule had no instrumentation or medical monitoring of the monkey, only a TV camera to record his actions during the flight. The sustainer engine was pulled from the ocean floor and examined, which found that
12006-627: The oil escaped until the pump ran out of lubricant and seized up, causing engine shutdown and loss of the missile. Improvements to the insulation boots and changes in preflight procedures to prevent pressure pulses from forming were implemented. Following the Cuban Missile Crisis in October 1962, several Congressmen voiced their concern about the reliability of the ICBM arsenal and whether it would actually work if called upon. Secretary of Defense Robert McNamara thus decided to carry out
12144-423: The operational control of the 576th Strategic Missile Squadron , 704th Strategic Missile Wing . Completely exposed to the elements, the three missiles were serviced by a gantry crane. One missile was on operational alert at all times. They remained on alert until 1 May 1964. The SM-65E Atlas , or Atlas-E , was the first 3-engine operational variant of the Atlas missile, the third engine resulting from splitting
12282-609: The opposing direction if a new orientation is to be held. Thruster systems have been used on most crewed space vehicles, including Vostok , Mercury , Gemini , Apollo , Soyuz , and the Space Shuttle . To minimize the fuel limitation on mission duration, auxiliary attitude control systems may be used to reduce vehicle rotation to lower levels, such as small ion thrusters that accelerate ionized gases electrically to extreme velocities, using power from solar cells. Momentum wheels are electric motor driven rotors made to spin in
12420-450: The oscillation is fixed in inertial space, so measuring the orientation of the oscillation relative to the spacecraft can be used to sense the motion of the spacecraft with respect to inertial space. Motion reference units are a kind of inertial measurement unit with single- or multi-axis motion sensors. They utilize MEMS gyroscopes . Some multi-axis MRUs are capable of measuring roll, pitch, yaw and heave . They have applications outside
12558-474: The other flight placed the SCORE satellite into orbit. All launches were conducted from Cape Canaveral Air Force Station , at Launch Complexes 11 , 13 and 14 . The SM-65C Atlas , or Atlas C was the third prototype Atlas version, a more refined model with improved, lighter-weight components. a bigger LOX tank, and a smaller fuel tank. First flown on 24 December 1958, it was the final development version. It
12696-483: The planned long range missiles, so the contract was canceled in 1947, but the Army Air Forces allowed Convair to launch the three almost-completed research vehicles using the remaining contract funds. The three flights were only partially successful, but did show that balloon tanks and gimbaled rocket engines were valid concepts. A second development contract was awarded to Convair on 23 January 1951 for what
12834-405: The remainder of the 1960s, all of them successful ABRES tests in 1968. No Atlas Es were launched between 1969 and 1979. On December 9, 1980, Missile 68E was used to launch a NOSS ELINT satellite from VABF's SLC-3W. Shortly before staging, the B-1 engine shut down, causing the booster to perform a 180-degree loop and plummet back towards Earth. The Range Safety destruct command was sent, resulting in
12972-435: The result of rushed launch schedules and could have been avoided. The last major design hurdle to overcome was unstable engine thrust, which caused three Atlas missiles (Serial 51D and 48D in 1960 and Serial 27E in 1961) to explode on their launching stands. Atlas was unusual in its use of balloon tanks for the propellants, made of very thin stainless steel with minimal or no rigid support structures, as already pioneered by
13110-416: The risk that one powerful nuclear warhead could destroy multiple launch sites. The SM-65E Atlas were based in horizontal "semi-hard" or "coffin" facilities that protected the missile against over-pressures up to 25 psi (170 kPa). In this arrangement the missile, its support facilities, and the launch operations building were housed in reinforced concrete structures that were buried underground; only
13248-410: The roofs protruded above ground level. These units were: The six SM-65F Atlas squadrons were the first ICBMs to be stored vertically in underground silos. Built of heavily reinforced concrete, the huge silos were designed to protect the missiles from over-pressures of up to 100 psi (690 kPa). These units were: The Atlas F's employment was dangerous due to the flammability of
13386-719: The spacecraft is always slowly rocking back and forth, and not always exactly predictably. Reaction wheels provide a much steadier spacecraft from which to make observations, but they add mass to the spacecraft, they have a limited mechanical lifetime, and they require frequent momentum desaturation maneuvers, which can perturb navigation solutions because of accelerations imparted by the use of thrusters. Many spacecraft have components that require articulation. Voyager and Galileo , for example, were designed with scan platforms for pointing optical instruments at their targets largely independently of spacecraft orientation. Many spacecraft, such as Mars orbiters, have solar panels that must track
13524-450: The spacecraft will oscillate around energy minima. This drawback is overcome by adding damper, which can be hysteretic materials or a viscous damper. The viscous damper is a small can or tank of fluid mounted in the spacecraft, possibly with internal baffles to increase internal friction. Friction within the damper will gradually convert oscillation energy into heat dissipated within the viscous damper. A third form of passive attitude control
13662-508: The specific attitude maneuver although using a simple proportional–integral–derivative controller ( PID controller ) satisfies most control needs. The appropriate commands to the actuators are obtained based on error signals described as the difference between the measured and desired attitude. The error signals are commonly measured as euler angles (Φ, θ, Ψ), however an alternative to this could be described in terms of direction cosine matrix or error quaternions . The PID controller which
13800-441: The staging sequence, but the exact reason for it was unclear, in part because of the normal momentary telemetry blackout that occurred at booster jettison due to ionized engine exhaust gases impinging on the telemetry antenna. When telemetry returned, the sustainer gas generator temperature was over 1,000 °F (538 °C), suggesting a LOX-rich shutdown. Ed Hujsak, assistant chief engineer of mechanical and propulsion systems for
13938-435: The start signal from being sent to the verniers). Despite these mishaps, the Atlas E was declared operational that month. The failure of Atlas 32E caused momentary concern over Project Mercury, but NASA reassured the public that the flight used a different model of booster and that the accident had no relevance to Mercury. The sustainer malfunction on Missile 26E had been traced to a gas generator failure which occurred during
14076-522: The stored liquid rocket fuels. Four sites and their missiles were destroyed during propellant loading exercises (known as PLXs) when liquid oxygen leaked and fires ensued. On 1 June 1963 Roswell's site 579-1 was destroyed by explosion and fire. On 13 February 1964 Roswell's site 579-5 was destroyed, and a month later on 9 March 1964 site 579-2 was also destroyed by explosion and fire. Finally, on 14 May 1964 an Altus AFB site, 577-6 in Frederick, Oklahoma,
14214-502: The successful flights of Missiles 22E and 21E during July, followed by the first Atlas F flight in August, came as a relief. On September 9, Missile 26E lost sustainer thrust following BECO and tumbled, falling into the Atlantic Ocean almost 2,000 miles (3,200 km) short of its target. Two E-series flights in October, 25E and 30E, were both successful. On November 10, an attempt to launch a biological mission (Missile 32E) with
14352-653: The surface. By 1965, with the second-generation Titan II having reached operational status, the Atlas was obsolete as a missile system and had been phased out of military use. Many of the retired Atlas D, E, and F missiles were used for space launches into the 1990s. The penetrating lubricant WD-40 found its first use as a corrosion-inhibiting coating for the outer skin of the Atlas missile. The Atlas's complicated, unconventional design proved difficult to debug compared with rocket families such as Thor and Titan which used conventional aircraft-style structures and two stage setups and there were dozens of failed launches during
14490-420: The sustainer engine shut down. Atlas was informally classified as a "stage-and-a-half" rocket, with a central sustainer engine and set of two booster engines that were all started at launch, each drawing from a single set of propellant tanks. Most multistage rockets drop both engines and fuel tanks simultaneously before firing the next stage's engines. However, when the Atlas missile was being developed, there
14628-447: The sustainer engine was left dragging the dead weight of the booster section. This combined with the loss of roll control from vernier shutdown caused the missile to tumble and finally break up at T+295 seconds. The exact reason for the thrust section fire was not determined. In addition, an erroneous signal from a pad umbilical threw open the LOX boil-off valve at liftoff, causing a gradual decay in tank pressure during ascent, although this
14766-447: The sustainer hydraulic system lost pressure. After booster jettison, the missile lost attitude control, tumbled, and broke up at T+154 seconds. On November 30, the second attempt, Missile 4E, repeated the same failure except that the missile remained structurally intact until impact in the ocean. Both of these failures were traced to radiated heat that caused a failure of the sustainer hydraulic rise-off disconnect, which ruptured and allowed
14904-528: The sustainer propellant utilization system. This threw the main propellant valves to the sustainer full open at T+60 seconds and resulted in abnormally high thrust and premature sustainer cutoff. The open propellant valves resulted in an additional 43 seconds of residual thrust following SECO and the R/V missed its target by about 20 miles. Several modifications to the LOX feed system and the sustainer propellant valves were made afterwards. One other E-series flew during
15042-712: The three missile variants, the Atlas D, E, and F series, were deployed and based in progressively more secure launchers. The number of Atlas intercontinental ballistic missiles in service, at the end of each year: In September 1959 the first operational Atlas ICBM squadron went on operational alert at F.E. Warren AFB , Wyoming equipped with six SM-65D Atlas missiles based in above-ground launchers. Three additional Atlas D squadrons, two near F.E. Warren AFB, Wyoming, and one at Offutt AFB , Nebraska, were based in above-ground launchers that provided blast protection against over-pressures of only 5 pounds per square inch (34 kPa). These units were: The first site at Warren for
15180-407: The two booster thrust chambers into separate engines with independent sets of turbopumps. It first flew on 11 October 1960, and was deployed as an operational ICBM from September 1961 until March 1965. A major enhancement in the Atlas E was the new all-inertial system that obviated the need for ground control facilities. Since the missiles were no longer tied to a central guidance control facility,
15318-419: The vehicle. Their limitations are fuel usage, engine wear, and cycles of the control valves. The fuel efficiency of an attitude control system is determined by its specific impulse (proportional to exhaust velocity) and the smallest torque impulse it can provide (which determines how often the thrusters must fire to provide precise control). Thrusters must be fired in one direction to start rotation, and again in
15456-402: The warhead landed only a few miles short of the target, so the flight was considered a success. Missile 13E (March 14) experienced a similar problem, but with a much earlier sustainer cutoff and the warhead missed its target by almost 2,000 miles (3,200 km). Missile 16E (March 25) depleted its supply of helium control gas early, making it impossible to jettison the booster section. The missile
15594-460: The way that a terrestrial gyrocompass uses a pendulum to sense local gravity and force its gyro into alignment with Earth's spin vector, and therefore point north, an orbital gyrocompass uses a horizon sensor to sense the direction to Earth's center, and a gyro to sense rotation about an axis normal to the orbit plane. Thus, the horizon sensor provides pitch and roll measurements, and the gyro provides yaw. See Tait-Bryan angles . A Sun sensor
15732-889: The weather satellite into a 507 by 493 miles (816 km × 793 km) orbit; it was considered a "huge relief" after a year of multiple disasters for the US space program, and it orbited a badly needed satellite after the loss of GOES-G four months earlier. The final Atlas E launch (Missile 45E launched on March 24, 1995) successfully carried a weather satellite aloft for the Air Force. A total of 64 Atlas Es were launched between 1960 and 1995, thirty of them being space launches. Sixteen launches failed. SM-65 Atlas 1 × Rocketdyne LR-105 sustainer rocket engine, 2 × Rocketdyne XLR-89 booster rocket engines each 150,000 lbf (670 kN) sharing one turbopump (Atlas B, C) 1 × Rocketdyne LR-105 sustainer rocket engine, 2 × LR89 booster engines with independent turbopumps each 165,000 lbf (730 kN) (Atlas D, E, F, G) The SM-65 Atlas
15870-449: The year, when Missile 64E lifted from OSTF-1 on December 18 and self-destructed 40 seconds into launch when the B-2 engine shut down, resulting in a yaw maneuver that exceeded the missile's structural limits. The failure was traced to a pressure pulse at liftoff that caused the B-2 insulation boot to be jammed upward and snag on the drain valve for the turbopump lubricant oil tank. During ascent,
16008-433: Was 389,000 lb f (1,730 kN). Launcher variants of the Atlas often had performance enhancements to the engines. The Atlas missiles A through D used radio guidance : the missile sent information from its inertial system to a ground station by radio, and received course correction information in return. The Atlas E and F had completely autonomous inertial guidance systems. The ground based guidance computer
16146-442: Was Missile 40E on February 13, 1962. With OSTF-1 back in operation, Missile 66E launched on March 1. Shortly after liftoff, a thrust section fire started in the vicinity of the fuel fill/drain valve. It continued until approximately T+50 seconds and then disappeared, but apparently resulted in damage to the thrust section, as the helium control gas leaked and resulted in vernier engine shutdown as well as no booster jettison. After BECO,
16284-548: Was a key part of the missile system, until guidance computers were miniaturized enough to be installed inside the missile. Isaac L. Auerbach designed the Burroughs guidance computer for the Atlas ICBM missiles. The Burroughs guidance computer was one of the first transistor computers . It processed 24-bit data using 18-bit instructions. A total of 17 of these ground computers were delivered. These same ground computers
16422-419: Was a secondary failure that did not contribute to the eventual loss of the missile. The Atlas test program during 1962 mainly consisted of Atlas D and F flights. Just two more Atlas E tests were carried our during the year. On July 13, Missile 67E lifted from OSTF-1. A LOX leak, which apparently started at liftoff, resulted in abnormally cold thrust section temperatures and freezing of the helium control lines to
16560-483: Was also destroyed by explosion and fire during a PLX. Fortunately the crews all survived. None of the damaged sites were repaired or returned to service. After the solid-fuel LGM-30 Minuteman had become operational in early 1963, the Atlas became rapidly obsolete. By October 1964, all Atlas D missiles had been phased out, followed by the Atlas E/F in April 1965. About 350 Atlas ICBMs of all versions were built, with
16698-419: Was an attempted launch of the military GPS satellite Navstar 7 on December 19, 1981, using Missile 76E. The B-2 engine shut down seconds after liftoff, causing the Atlas to pitch over and nosedive into the ground. The Range Safety officer sent the destruct command moments before impact, leaving a burnt crater only a few hundred feet from Launch Complex SLC3E. Investigation of the booster debris quickly pinpointed
16836-461: Was completed, Convair rival Martin proposed a solution to the air-starting problem. Their Titan I missile, developed as an Atlas backup, had a conventional two stage design. The booster engine consisted of two large thrust chambers. The Atlas A/B/C/D had a single turbopump assembly and gas generator driving both booster engines; the A/B/C had an interim engine with lower thrust while the D-series had
16974-471: Was completely successful and the missile flew 6,000 miles (9,700 km) downrange, missing the target point by only a few hundred meters. It was also the first completely successful launch from OSTF-1 after five failed attempts. Seven Atlas E flights took place during 1963. The first three, including 65E, were entirely successful. Atlas 24E, launched from OSTF-1 on July 26, experienced an accidental sustainer shutdown at T+143 seconds due to electrical shorts in
17112-404: Was destroyed by Range Safety at T+35 seconds, the B-2 engine continuing to operate until missile destruction. The nose cone impacted in the ocean about 20 seconds later. Goliath, who was in a padded container with no restraints, was recovered from the Atlantic Ocean three days later. A postmortem examination of the monkey found that he had died of multiple head injuries probably caused by impact with
17250-400: Was doubt as to whether a rocket engine could be air-started. Therefore, the decision was made to ignite all of the Atlas' engines at launch; the booster engines would be discarded, while the sustainer continued to burn. A stage of a liquid propellant rocket normally consists of both propellant tanks and engines, so jettisoning one or more engines only is equivalent to "half a stage". At staging,
17388-430: Was dragged down by the weight of the spent booster engines and fell short of its intended range, also the propellant utilization system malfunctioned again and caused the engines to run fuel rich. The failure was traced to two mistakenly transposed wires which caused spurious venting of the control helium out the vernier engines. Missile 12E (May 13) and Missile 18E (May 26) both performed well. Testing now began at VAFB on
17526-437: Was later used for Atlas-Able , Project Mercury , and other early spacecraft. The warhead of the Atlas D was originally the G.E. Mk 2 "heat sink" re-entry vehicle (RV) with a W49 thermonuclear weapon , combined weight 3,700 lb (1,680 kg) and yield of 1.44 megatons (Mt). The W49 was later placed in a Mk 3 ablative RV, combined weight 2,420 lb (1,100 kg). The Atlas E and F had an AVCO Mk 4 RV containing
17664-467: Was originally designated as the XB-65 experimental bomber; in 1955 it was redesignated SM-65 ("Strategic Missile 65") and, from 1962, it became CGM-16. This letter "C" stood for "coffin" or "Container", the rocket being stored in a semi-hardened container; it was prepared for launch by being raised and fueled in the open. The Atlas-F (HGM-16) was stored vertically underground, but launched after being lifted to
17802-504: Was originally planned to be used as the first stage of the Atlas-Able rocket, but following an explosion during a static test on 24 September 1959, this was abandoned in favor of the Atlas D. Six flights were made, all sub-orbital ballistic test flights of the Atlas, with three tests succeeding, and three failing. All launches were conducted from Cape Canaveral Air Force Station, at Launch Complex 12. The SM-65D Atlas , or Atlas D ,
17940-465: Was successful. Missile 57E on August 27 fell 70 miles (110 km) short of its planned range when a malfunction of the guidance system accelerometer caused the sustainer and vernier cutoff signals to be issued four seconds early. The Atlas E and F were phased out of use as operational ICBMs in 1965 and replaced by the hypergolically-fueled Titan II . Decommissioned Atlas missiles were then used for military satellite launches from Vandenberg AFB well into
18078-462: Was the final operational variant of the Atlas missile. It first flew on 8 August 1961, and was deployed as an operational ICBM between September 1962 and April 1965. The Atlas F was essentially a quick-firing version of the Atlas E, modified to be stored in a vertical position inside underground concrete and steel silos. It was nearly identical to the E version except for interfaces associated with their different basing modes (underground silo for F) and
18216-407: Was the first Soviet ICBM and similarly started all engines before launch to avoid igniting a large liquid fuel engine at high altitudes. However, the R-7 had a central sustainer section, with four boosters attached to its sides. The large side boosters required use of an expensive launch pad and prevented launching the rocket from a silo. Like the Atlas, the use of cryogenic liquid oxygen meant that
18354-556: Was the first operational intercontinental ballistic missile (ICBM) developed by the United States and the first member of the Atlas rocket family . It was built for the U.S. Air Force by the Convair Division of General Dynamics at an assembly plant located in Kearny Mesa , San Diego . Development dates to 1946, but over the next few years the project underwent several cancellations and re-starts. The deepening of
18492-411: Was the first operational version of the Atlas missile and the basis for all Atlas space launchers, debuting in 1959. Atlas D weighed 255,950 lb (116,100 kg) (without payload) and had an empty weight of only 11,894 lb (5,395 kg); the other 95.35% was propellant. Dropping the 6,720 lb (3,048 kg) booster engine and fairing reduced the dry weight to 5,174 lb (2,347 kg),
18630-494: Was the second prototype version, introducing the stage and a half system that was a hallmark of the Atlas rocket program. This version was the first American rocket to achieve a flight distance that could be considered intercontinental when it flew 6,325 miles (10,180 km). The Atlas B was first flown on 19 July 1958. Of ten total flights, nine were sub-orbital test flights of the Atlas as an Intercontinental Ballistic Missile , with five successful missions and four failures;
18768-436: Was then called MX-1593, with a relatively low priority. The initial design completed by Convair in 1953 was larger than the missile that eventually entered service. Estimated warhead weight was lowered from 8,000 lb (3,630 kg) to 3,000 lb (1,360 kg) based on highly favorable U.S. nuclear warhead tests in early 1954. This, in addition to the Soviet Union 's 1953 Joe 4 dry fuel thermonuclear weapon test and
18906-506: Was tightly controlled by the Air Force's Western Development Division, WDD, later part of the Air Force Ballistic Missile Division. Contracts for warhead, guidance and propulsion were handled separately by WDD. The first successful flight of a highly instrumented Atlas missile to full range occurred 28 November 1958. Atlas ICBMs were deployed operationally from 31 October 1959 to 12 April 1965. The missile
19044-486: Was unblocked at T+120 seconds and the SECO/VECO command at T+200 seconds, causing the missile to impact only 685 miles (1,102 km) downrange. This was the first outright malfunction of the guidance computer on an E-series Atlas and the eventual solution to this problem involved equipping the guidance system with acoustic padding and anti-shock mounts to protect it from liftoff-induced vibration. Missile 5E on February 25
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