A guidance system is a virtual or physical device, or a group of devices implementing a controlling the movement of a ship, aircraft, missile, rocket, satellite, or any other moving object. Guidance is the process of calculating the changes in position, velocity, altitude, and/or rotation rates of a moving object required to follow a certain trajectory and/or altitude profile based on information about the object's state of motion.[1][2][3]
A guidance system is usually part of a Guidance, navigation and control system, whereas navigation refers to the systems necessary to calculate the current position and orientation based on sensor data like those from compasses, GPS receivers, Loran-C, star trackers, inertial measurement units, altimeters, etc. The output of the navigation system, the navigation solution, is an input for the guidance system, among others like the environmental conditions (wind, water, temperature, etc.) and the vehicle's characteristics (i.e. mass, control system availability, control systems correlation to vector change, etc.). In general, the guidance system computes the instructions for the control system, which comprises the object's actuators (e.g., thrusters, reaction wheels, body flaps, etc.), which are able to manipulate the flight path and orientation of the object without direct or continuous human control.
One of the earliest examples of a true guidance system is that used in the German V-1 during World War II. The navigation system consisted of a simple gyroscope, an airspeed sensor, and an altimeter. The guidance instructions were target altitude, target velocity, cruise time, and engine cut off time.
A guidance system has three major sub-sections: Inputs, Processing, and Outputs. The input section includes sensors, course data, radio and satellite links, and other information sources. The processing section, composed of one or more CPUs, integrates this data and determines what actions, if any, are necessary to maintain or achieve a proper heading. This is then fed to the outputs which can directly affect the system's course. The outputs may control speed by interacting with devices such as turbines, and fuel pumps, or they may more directly alter course by actuating ailerons, rudders, or other devices.
Inertial guidance systems were originally developed for rockets. American rocket pioneer Robert Goddard experimented with rudimentary gyroscopic systems. Dr. Goddard's systems were of great interest to contemporary German pioneers including Wernher von Braun. The systems entered more widespread use with the advent of spacecraft, guided missiles, and commercial airliners.
US guidance history centers around 2 distinct communities. One driven out of Caltech and NASAJet Propulsion Laboratory, the other from the German scientists that developed the early V2 rocket guidance and MIT. The GN&C system for V2 provided many innovations and was the most sophisticated military weapon in 1942 using self-contained closed loop guidance. Early V2s leveraged 2 gyroscopes and lateral accelerometer with a simple analog computer to adjust the azimuth for the rocket in flight. Analog computer signals were used to drive 4 external rudders on the tail fins for flight control. Von Braun engineered the surrender of 500 of his top rocket scientists, along with plans and test vehicles, to the Americans. They arrived in Fort Bliss, Texas in 1945 and were subsequently moved to Huntsville, Alabama, in 1950 (aka Redstone arsenal).[4][5] Von Braun's passion was interplanetary space flight. However his tremendous leadership skills and experience with the V-2 program made him invaluable to the US military.[6] In 1955 the Redstone team was selected to put America's first satellite into orbit putting this group at the center of both military and commercial space.
The Jet Propulsion Laboratory traces its history from the 1930s, when Caltech professor Theodore von Karman conducted pioneering work in rocket propulsion. Funded by Army Ordnance in 1942, JPL's early efforts would eventually involve technologies beyond those of aerodynamics and propellant chemistry. The result of the Army Ordnance effort was JPL's answer to the German V-2 missile, named MGM-5 Corporal, first launched in May 1947. On December 3, 1958, two months after the National Aeronautics and Space Administration (NASA) was created by Congress, JPL was transferred from Army jurisdiction to that of this new civilian space agency. This shift was due to the creation of a military focused group derived from the German V2 team. Hence, beginning in 1958, NASA JPL and the Caltech crew became focused primarily on unmanned flight and shifted away from military applications with a few exceptions. The community surrounding JPL drove tremendous innovation in telecommunication, interplanetary exploration and earth monitoring (among other areas).[7]
In the early 1950s, the US government wanted to insulate itself against over dependency on the German team for military applications. Among the areas that were domestically "developed" was missile guidance. In the early 1950s the MIT Instrumentation Laboratory (later to become the Charles Stark Draper Laboratory, Inc.) was chosen by the Air Force Western Development Division to provide a self-contained guidance system backup to Convair in San Diego for the new Atlas intercontinental ballistic missile. The technical monitor for the MIT task was a young engineer named Jim Fletcher who later served as the NASA Administrator. The Atlas guidance system was to be a combination of an on-board autonomous system, and a ground-based tracking and command system. This was the beginning of a philosophic controversy, which, in some areas, remains unresolved. The self-contained system finally prevailed in ballistic missile applications for obvious reasons. In space exploration, a mixture of the two remains.
In the summer of 1952, Dr. Richard Battin[8] and Dr. J. Halcombe ("Hal") Laning Jr., researched computational based solutions to guidance as computing began to step out of the analog approach. As computers of that time were very slow (and missiles very fast) it was extremely important to develop programs that were very efficient. Dr. J. Halcombe Laning, with the help of Phil Hankins and Charlie Werner, initiated work on MAC, an algebraic programming language for the IBM 650, which was completed by early spring of 1958. MAC became the work-horse of the MIT lab. MAC is an extremely readable language having a three-line format, vector-matrix notations and mnemonic and indexed subscripts. Today's Space Shuttle (STS) language called HAL, (developed by Intermetrics, Inc.) is a direct offshoot of MAC. Since the principal architect of HAL was Jim Miller, who co-authored with Hal Laning a report on the MAC system, it is a reasonable speculation that the space shuttle language is named for Jim's old mentor, and not, as some have suggested, for the electronic superstar of the Arthur Clarke movie "2001-A Space Odyssey." (Richard Battin, AIAA 82–4075, April 1982)
Hal Laning and Richard Battin undertook the initial analytical work on the Atlas inertial guidance in 1954. Other key figures at Convair were Charlie Bossart, the Chief Engineer, and Walter Schweidetzky, head of the guidance group. Walter had worked with Wernher von Braun at Peenemuende during World War II.
The initial "Delta" guidance system assessed the difference in position from a reference trajectory. A velocity to be gained (VGO) calculation is made to correct the current trajectory with the objective of driving VGO to Zero. The mathematics of this approach were fundamentally valid, but dropped because of the challenges in accurate inertial navigation (e.g. IMU Accuracy) and analog computing power. The challenges faced by the "Delta" efforts were overcome by the "Q system" of guidance. The "Q" system's revolution was to bind the challenges of missile guidance (and associated equations of motion) in the matrix Q. The Q matrix represents the partial derivatives of the velocity with respect to the position vector. A key feature of this approach allowed for the components of the vector cross product (v, xdv,/dt) to be used as the basic autopilot rate signals-a technique that became known as "cross-product steering." The Q-system was presented at the first Technical Symposium on Ballistic Missiles held at the Ramo-Wooldridge Corporation in Los Angeles on June 21 and 22, 1956. The "Q System" was classified information through the 1960s. Derivations of this guidance are used for today's military missiles. The CSDL team remains a leader in the military guidance and is involved in projects for most divisions of the US military.
On August 10 of 1961 NASA awarded MIT a contract for preliminary design study of a guidance and navigation system for Apollo program.[9] (see Apollo on-board guidance, navigation, and control system, Dave Hoag, International Space Hall of Fame Dedication Conference in Alamogordo, N.M., October 1976 [10]). Today's space shuttle guidance is named PEG4 (Powered Explicit Guidance). It takes into account both the Q system and the predictor-corrector attributes of the original "Delta" System (PEG Guidance). Although many updates to the shuttles navigation system have taken place over the last 30 years (ex. GPS in the OI-22 build), the guidance core of today's Shuttle GN&C system has evolved little. Within a manned system, there is a human interface needed for the guidance system. As Astronauts are the customer for the system, many new teams are formed that touch GN&C as it is a primary interface to "fly" the vehicle.[11] For the Apollo and STS (Shuttle system) CSDL "designed" the guidance, McDonnell Douglas wrote the requirements and IBM programmed the requirements.
Much system complexity within manned systems is driven by "redundancy management" and the support of multiple "abort" scenarios that provide for crew safety. Manned US Lunar and Interplanetary guidance systems leverage many of the same guidance innovations (described above) developed in the 1950s. So while the core mathematical construct of guidance has remained fairly constant, the facilities surrounding GN&C continue to evolve to support new vehicles, new missions and new hardware. The center of excellence for the manned guidance remains at MIT (CSDL) as well as the former McDonnell Douglas Space Systems (in Houston).
Wernher Magnus Maximilian Freiherr von Braun was a German-American aerospace engineer and space architect. He was a member of the Nazi Party and Allgemeine SS and the leading figure in the development of rocket technology in Nazi Germany and later a pioneer of rocket and space technology in the United States.
The Jupiter-C was an American research and development vehicle developed from the Jupiter-A. Jupiter-C was used for three uncrewed sub-orbital spaceflights in 1956 and 1957 to test re-entry nosecones that were later to be deployed on the more advanced PGM-19 Jupiter mobile missile. The recovered nosecone was displayed in the Oval Office as part of President Dwight D. Eisenhower's televised speech on November 7, 1957.
The George C. Marshall Space Flight Center (MSFC), located in Redstone Arsenal, Alabama, is the U.S. government's civilian rocketry and spacecraft propulsion research center. As the largest NASA center, MSFC's first mission was developing the Saturn launch vehicles for the Apollo program. Marshall has been the lead center for the Space Shuttle main propulsion and external tank; payloads and related crew training; International Space Station (ISS) design and assembly; computers, networks, and information management; and the Space Launch System. Located on the Redstone Arsenal near Huntsville, MSFC is named in honor of General of the Army George C. Marshall.
Draper Laboratory is an American non-profit research and development organization, headquartered in Cambridge, Massachusetts; its official name is The Charles Stark Draper Laboratory, Inc. The laboratory specializes in the design, development, and deployment of advanced technology solutions to problems in national security, space exploration, health care and energy.
George Michael Low was an administrator at NASA and the 14th president of the Rensselaer Polytechnic Institute. Low was one of the senior NASA officials who made decisions as manager of the Apollo Spacecraft Program Office in the Apollo program of crewed missions to the Moon.
Joseph Francis Shea was an American aerospace engineer and NASA manager. Born in the New York City borough of the Bronx, he was educated at the University of Michigan, receiving a Ph.D. in Engineering Mechanics in 1955. After working for Bell Labs on the radio inertial guidance system of the Titan I intercontinental ballistic missile, he was hired by NASA in 1961. As Deputy Director of NASA's Office of Manned Space Flight, and later as head of the Apollo Spacecraft Program Office, Shea played a key role in shaping the course of the Apollo program, helping to lead NASA to the decision in favor of lunar orbit rendezvous and supporting "all up" testing of the Saturn V rocket. While sometimes causing controversy within the agency, Shea was remembered by his former colleague George Mueller as "one of the greatest systems engineers of our time".
Ernst Stuhlinger was a German-American atomic, electrical, and rocket scientist. After being brought to the United States as part of Operation Paperclip, he developed guidance systems with Wernher von Braun's team for the US Army, and later was a scientist with NASA. He was also instrumental in the development of the ion engine for long-endurance space flight, and a wide variety of scientific experiments.
George Edwin Mueller, was an American electrical engineer who was an associate administrator at NASA, heading the Office of Manned Space Flight from September 1963 until December 1969. Hailed as one of NASA's "most brilliant and fearless managers", he was instrumental in introducing the all-up testing philosophy for the Saturn V launch vehicle, which ensured the success of the Apollo program in landing a man on the Moon and returning him safely to the Earth by the end of 1969. Mueller also played a key part in the design of Skylab, and championed the Space Shuttle's development, which earned him the nickname, "the father of the Space Shuttle."
Guidance, navigation and control is a branch of engineering dealing with the design of systems to control the movement of vehicles, especially, automobiles, ships, aircraft, and spacecraft. In many cases these functions can be performed by trained humans. However, because of the speed of, for example, a rocket's dynamics, human reaction time is too slow to control this movement. Therefore, systems—now almost exclusively digital electronic—are used for such control. Even in cases where humans can perform these functions, it is often the case that GNC systems provide benefits such as alleviating operator work load, smoothing turbulence, fuel savings, etc. In addition, sophisticated applications of GNC enable automatic or remote control.
The Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, had three stages, and was powered with liquid fuel. Flown from 1967 to 1973, it was used for nine crewed flights to the Moon, and to launch Skylab, the first American space station.
Werner Karl Dahm was an early spaceflight scientist of the Peenemünde Future Projects Office who emigrated to the US under Operation Paperclip and was the Marshall Space Flight Center Chief Aerodynamicist.
J. Halcombe "Hal" Laning Jr. was a Massachusetts Institute of Technology computer pioneer who in 1952 invented an algebraic compiler called George that ran on the MIT Whirlwind, the first real-time computer. Laning designed George to be an easier-to-use alternative to assembly language for entering mathematical equations into a computer. He later became a key contributor to the 1960s race to the Moon, with pioneering work on space-based guidance systems for the Apollo Moon missions. From 1955 to 1980, he was deputy associate director of the MIT Instrumentation Laboratory.
An inertial navigation system is a navigation device that uses motion sensors (accelerometers), rotation sensors (gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity of a moving object without the need for external references. Often the inertial sensors are supplemented by a barometric altimeter and sometimes by magnetic sensors (magnetometers) and/or speed measuring devices. INSs are used on mobile robots and on vehicles such as ships, aircraft, submarines, guided missiles, and spacecraft. Older INS systems generally used an inertial platform as their mounting point to the vehicle and the terms are sometimes considered synonymous.
Eugene F. Lally was American aerospace engineer. He worked in the early 1960s on U.S. interplanetary space programs. Beside his space programs he was also an inventor and developed non-space products with his own company Dynamic Development Co. which he founded in the early 1960s. He later became an active amateur photographer and lubrication product entrepreneur. Lally contributed articles for popular space, astrobiology, photography, travel, and archaeology magazines. He was also a speaker at local space exploration and extraterrestrial intelligence (UFO) society meetings where he gave first-hand accounts of the early U.S. space program, commentaries on current U.S. space exploration activities and the search for extraterrestrial intelligence.
Walter Haeussermann was a German-American aerospace engineer and member of the "von Braun rocket group", both at Peenemünde and later at Marshall Space Flight Center, where he was the director of the guidance and control laboratory. He was awarded the Department of the Army Decoration for Exceptional Civilian Service in 1959 for his contributions to the US rocket program.
The Rocket City Space Pioneers (RCSP) was one of 29 teams from 17 different countries officially registered and in the competition for the Google Lunar X PRIZE (GLXP) during 2010–2012.
Robert J. "Bob" Parks was a US aerospace engineer and pioneer in the space program where he was intricately involved and/or directed for some of the most historic and important U.S. unmanned space missions. Over a 40-year tenure at the Jet Propulsion Laboratory (JPL/NASA), located in Pasadena, California, Parks’ impact was essential to helping the United States lead the world in space exploration. He served as Guidance Engineer for Explorer 1, the first successfully launched satellite by the United States. He directed the initial flyby missions to the Moon, the first soft landing on the Moon, Earth's first successful mission to another planet and initial missions to Mars, Saturn, Jupiter and Uranus.
Richard "Dick" Horace Battin was an American engineer, applied mathematician and educator who led the design of the Apollo guidance computer during the Apollo missions during the 1960s.
Swati Mohan is an Indian-American aerospace engineer and was the Guidance and Controls Operations Lead on the NASA Mars 2020 mission.
↑ Draper, C. S.; Wrigley, W.; Hoag, G.; Battin, R. H.; Miller, E.; Koso, A.; Hopkins, A. L.; Vander Velde, W. E. (June 1965). Apollo Guidance and Navigation(PDF) (Report). Massachusetts: Massachusetts Institute of Technology, Instrumentation Laboratory. pp.I-3 et seqq. Retrieved October 12, 2014.
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