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67-630: SECOR (Sequential Collation of Ranges) was a series of small United States Armed Forces satellites launched in the 1960s for geodesy measurements that precisely determined the locations of points on the Earth's surface, particularly of isolated islands in the Pacific Ocean. This data allowed for improved global mapping and precise positioning of ground stations for other satellites. Any SECOR satellite could be linked to four mobile ground stations: three were placed in accurately determined known locations, and

134-427: A detailed description is provided for Type I, and a differences-only summary for Type II. The Type 1 SECOR satellites were spherical, 50.8 cm (20.0 in) in diameter, in construction similar to Vanguard III and the early SOLRAD / Galactic Radiation and Background (GRAB) spacecraft. The satellites massed 16.8 kg (37 lb) in average, with most of it being batteries and voltage regulators. Their surface

201-408: A fourth one was placed in an unknown location. By measuring a satellite's distance from the three known stations, its position in space was determined. Then, the distance between the unknown ground station and the previously determined satellite's position was used to compute the unknown ground station's coordinates . This process was repeated many times, to enhance the accuracy of the measurement. Once

268-477: A large pool of professional volunteers . The U.S. has used military conscription , but not since 1973. The Selective Service System retains the power to conscript males, requiring the registration of all male citizens and residents of the U.S. between the ages of 18 and 25. The U.S. Armed Forces are considered the world's most powerful military, especially since the end of the Cold War . The military expenditure of

335-658: A single organization. The mission of Army Aviation is to find, fix and destroy any enemy through fire and maneuver and to provide combat support and combat service support in coordinated operations as an integral member of the combined arms team. Major aircraft include the AH-64 Apache , which serves as the Army's attack helicopter, the UH-60 Black Hawk , and the CH-47 Chinook for troop and cargo transport. Army Aviation also flies

402-453: A special operations force, Army Rangers are generally better equipped than standard infantry, utilizing the FN SCAR rifle. Army Special Forces , commonly known as Green Berets after their iconic headgear, are among the most elite soldiers in the Army. Special Forces conduct: Army Special Forces are trained in military free-fall parachuting and combat diver skillsets. They are considered

469-596: Is unique in that it is a military branch specializing in maritime operations and also a law enforcement agency. The United States Army (USA) is the United States Armed Forces' land force and is the largest and oldest service. Originally established in 1775 as the Continental Army , it consists of one million soldiers across the Regular Army, Army Reserve , and Army National Guard . The Army serves as

536-474: Is unique in that it specializes in maritime operations and is also a law enforcement agency. From their inception during the American Revolutionary War , the U.S. Armed Forces have played a decisive role in the country's history . They helped forge a sense of national unity and identity through victories in the early-19th-century First and Second Barbary Wars . They played a critical role in

603-700: The 10th Mountain Division , 11th Airborne Division , 25th Infantry Division , 82nd Airborne Division , 101st Airborne Division , and 173rd Airborne Brigade have a cavalry squadron equipped with the Joint Light Tactical Vehicle . The Field Artillery's mission is to destroy, suppress or neutralize the enemy by cannon, rocket or missile fire. Rocket systems include the M142 HIMARS and M270 multiple launch rocket system , which are corps-level assets found in field artillery brigades. Towed artillery includes

670-523: The 11th Airborne Division , 82nd Airborne Division , and 173rd Airborne Brigade are capable of airborne operations, in cooperation with the U.S. Air Force's transport aircraft. Finally, Infantry Brigade Combat Teams assigned to the 10th Mountain Division specialize in mountain warfare . Standard Infantry Brigade Combat Teams are assigned to the 25th Infantry Division , which offers additional training in jungle warfare . Armored Brigade Combat Teams comprise mechanized infantry battalions mounted in

737-400: The 4th Infantry Division . Each Armored Brigade Combat Team also possesses a cavalry squadron equipped with M2 Bradleys for scouting and security. Stryker Brigade Combat Teams from the 2nd Infantry Division , 4th Infantry Division , 11th Airborne Division , 2nd Cavalry Regiment , and 3rd Cavalry Regiment have a cavalry squadron equipped with Strykers . Infantry Brigade Combat Teams from

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804-559: The 75th Ranger Regiment are an elite special operations infantry force in the United States Army Special Operations Command , specializing in air assault and airborne infiltration methods. The three primary missions of the 75th Ranger Regiment are special operations raids , forcible entry operations, such as an airfield seizure to enable the Air Force to bring in more forces, and special reconnaissance . As

871-722: The British Empire in the American Revolutionary War . These forces demobilized in 1784 after the Treaty of Paris ended the Revolutionary War. The Congress of the Confederation created the current United States Army on 3 June 1784. The United States Congress created the current United States Navy on 27 March 1794 and the current United States Marine Corps on 11 July 1798. All three services trace their origins to their respective Continental predecessors. The 1787 adoption of

938-636: The Constitution gave Congress the power to "raise and support armies," to "provide and maintain a navy", and to "make rules for the government and regulation of the land and naval forces", as well as the power to declare war . The President of the United States is the United States Armed Forces' commander-in-chief . The United States Coast Guard traces its origin to the formation of the Revenue Cutter Service on 4 August 1790, which merged with

1005-707: The Department of Homeland Security responsible for administering the United States Coast Guard . The military chain of command flows from the President of the United States to the secretary of defense (for services under the Defense Department) or secretary of homeland security (for services under the Department of Homeland Security), ensuring civilian control of the military . Within the Department of Defense,

1072-582: The Department of the Navy , which is a military department under the leadership of the secretary of the Navy and the under secretary of the Navy . The U.S. Marine Corps itself is led by the commandant of the Marine Corps and the assistant commandant of the Marine Corps , both generals who are advised by the sergeant major of the Marine Corps . The Marine Corps statutory mission is outlined in 10 U.S.C.   § 5063 and as originally introduced under

1139-683: The FIM-92 Stinger man-portable air-defense system , AN/TWQ-1 Avenger for short range air defense , and the counter rocket, artillery, and mortar 20mm gun system. The Iron Dome provides air defense against rockets, artillery, mortars, missiles, and unmanned aerial vehicles. The MIM-104 Patriot is capable of defeating a wide range of threats including aircraft, helicopters, UAVs, ballistic and cruise missiles, and Weapons of Mass Destruction. The Terminal High Altitude Area Defense protects strategic critical assets by conducting long-range endo-and-exo-atmospheric engagements of ballistic missiles using

1206-600: The M119 howitzer in infantry brigade combat teams and the M777 howitzer found in both infantry and Stryker brigade combat teams. The M109 self-propelled howitzer is utilized in armored brigade combat teams. During the Cold War, Army field artillery was responsible for the service's ballistic missile programs, including the PGM-11 Redstone , which was the first large ballistic missile in

1273-660: The M2 Bradley infantry fighting vehicle . Divisions with Armored Brigade Combat Teams include the 1st Infantry Division , 3rd Infantry Division , 4th Infantry Division , 1st Armored Division , and 1st Cavalry Division . Stryker Brigade Combat Teams are centered around Stryker infantry battalions operating out of the Stryker . Divisions with Stryker Brigade Combat Teams include the 2nd Infantry Division , 4th Infantry Division , 11th Airborne Division , 2nd Cavalry Regiment , and 3rd Cavalry Regiment . United States Army Rangers with

1340-681: The MQ-1C Gray Eagle drone. A specialized unit within Army Aviation, the 160th Special Operations Aviation Regiment (Airborne) serves as a special operations unit and operates modified variants of the MH-60 Black Hawk, MH-47 Chinook, and the MH-6 Little Bird . The U.S. Army is organized into four major Army Commands, nine Army Service Component Commands which serve as the Army component and joint force land component commanders for

1407-466: The Marine Corps Reserve . The Marine Corps maintains a very close relationship with the U.S. Navy, its sister service in the Department of the Navy. Although the Marine Corps has previously operated as an independent land force alongside the Army, its primary purpose is to serve as part of a unified naval service alongside the Navy in the maritime domain. The U.S. Marine Corps is organized under

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1474-484: The NOAA Commissioned Officer Corps . Each of the different military services is assigned a role and domain. The Army conducts land operations. The Navy and Marine Corps conduct maritime operations, the Marine Corps specializing in amphibious and maritime littoral operations primarily for supporting the Navy. The Air Force conducts air operations. The Space Force conducts space operations. The Coast Guard

1541-516: The National Security Act of 1947 , with its three primary areas of responsibility including: Solid-state electronics The term solid-state became popular at the beginning of the semiconductor era in the 1960s to distinguish this new technology. A semiconductor device works by controlling an electric current consisting of electrons or holes moving within a solid crystalline piece of semiconducting material such as silicon , while

1608-807: The United States Life-Saving Service on 28 January 1915 to establish the Coast Guard. The United States Air Force was established as an independent service on 18 September 1947; it traces its origin to the formation of the Aeronautical Division, U.S. Signal Corps , which was formed 1 August 1907 and was part of the Army Air Forces before being recognized as an independent service in the National Security Act of 1947. The United States Public Health Service Commissioned Corps

1675-488: The homeland security advisor , and the deputy national security advisor may also be members of the United States Armed Forces. The National Security Council Deputies Committee also includes the deputy secretary of defense , deputy secretary of homeland security , and vice chairman of the Joint Chiefs of Staff . Military leadership, including the secretary of defense, the secretary of Homeland Security, and chairman of

1742-603: The joint force land component , Navy components are typically dual-hatted as the joint force maritime component , and Air Force components are typically dual-hatted as the joint force air component , with the theater special operations command dual-hatted as the joint force special operations component, and Space Force component typically dual-hatted as the joint force space component. Combat support agencies are Department of Defense agencies with combat support missions that service operating forces planning or conducting military operations. This includes support during conflict or in

1809-410: The sergeant major of the Army . The Army's primary responsibility is to conduct prompt and sustained land combat as part of the joint force. Army landpower focuses on destroying an enemy's armed forces, occupying its territory, and breaking the will of an adversary. The five core competencies of the Army are: The thirteen specified functions of the Army are: The Infantry Branch forms the core of

1876-563: The territorial evolution of the U.S. , including the American Civil War . The National Security Act of 1947 created the modern U.S. military framework, establishing the National Military Establishment (later the Department of Defense or DoD) headed by the secretary of defense and creating both the U.S. Air Force and National Security Council ; in 1949, an amendment to the act merged the cabinet-level departments of

1943-435: The thermionic vacuum tubes it replaced worked by controlling a current of electrons or ions in a vacuum within a sealed tube. Although the first solid-state electronic device was the cat's whisker detector , a crude semiconductor diode invented around 1904, solid-state electronics started with the invention of the transistor in 1947. Before that, all electronic equipment used vacuum tubes , because vacuum tubes were

2010-508: The transistor radio , cassette tape player , walkie-talkie and quartz watch , as well as the first practical computers and mobile phones . Other examples of solid state electronic devices are the microprocessor chip, LED lamp, solar cell , charge coupled device (CCD) image sensor used in cameras, and semiconductor laser . Also during the 1960s and 1970s, television set manufacturers switched from vacuum tubes to semiconductors, and advertised sets as "100% solid state" even though

2077-523: The unified combatant commands , and thirteen direct reporting units. The United States Marine Corps (USMC) serves as the U.S. Armed Forces' naval land force, responsible for executing amphibious warfare and operating in the maritime littorals in support of the U.S. Navy. Originally established in 1775 as the Continental Marines , the Marine Corps consists of the Regular Marine Corps and

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2144-540: The Air Force through its Air and Missile Defense Commands and the Space Force through Army Space and Missile Defense Command, given their shared missile defense and space roles. In 1962, Air Defense Artillery achieved the first intercept of a ballistic missile with a nuclear-tipped Nike Zeus and operated the Nike Zeus as an anti-satellite weapon after completing a successful intercept in 1963. Army Aviation, distinct from

2211-471: The Armed Forces principal land service, responsible for conducting land warfare operations. The U.S. Army is organized under the Department of the Army , which is a military department under the leadership of the secretary of the Army and under secretary of the Army . The U.S. Army itself is led by the chief of staff of the Army and vice chief of staff of the Army , both generals who are advised by

2278-485: The Army , commandant of the Marine Corps , chief of naval operations , chief of staff of the Air Force , chief of space operations , and the chief of the National Guard Bureau . The commandant of the Coast Guard is not an official member of the Joint Chiefs, but sometimes attends meetings as one of the military service chiefs. The senior enlisted advisor to the chairman is the most senior enlisted member in

2345-489: The Army, Navy, and Air Force into the DoD. The president of the U.S. is the commander-in-chief of the armed forces and forms military policy with the DoD and Department of Homeland Security (DHS), both federal executive departments , acting as the principal organs by which military policy is carried out. The U.S. Armed Forces are one of the world's largest military forces in terms of personnel. They draw their personnel from

2412-572: The Department of Defense's military departments. The United States Coast Guard is nominally under the Department of Homeland Security , but may be transferred to the Department of Defense's Department of the Navy (which is the civilian entity that oversees the coequal U.S. Marine Corps and U.S. Navy) at the direction of the President or Congress. With the exception of the Coast Guard, the military services only organize, train, and equip forces. The unified combatant commands are responsible for operational control of non-service retained forces. Each of

2479-726: The Joint Chiefs of Staff also sit on the National Space Council . Unified combatant commands are joint military commands consisting of forces from multiple military departments, with their chain of command flowing from the president, to the secretary of defense, to the commanders of the combatant commands. Each service organizes, trains, and equips forces that are then presented to the unified combatant commands through service component commands. Special Operations Command and Cyber Command also present theater special operations commands or joint force headquarters – cyber to other combatant commanders. Army components are typically dual-hatted as

2546-583: The SECOR satellites. United States Armed Forces The United States Armed Forces are the military forces of the United States . The armed forces consist of six service branches : the Army , Marine Corps , Navy , Air Force , Space Force , and Coast Guard . All six armed services are among the eight uniformed services of the United States , along with the U.S. Public Health Service Commissioned Corps and

2613-442: The U.S. The U.S. Air Force is the world's largest air force, followed by the U.S. Army Aviation Branch . The U.S. Naval Air Forces is the fourth-largest air arm in the world and is the largest naval aviation service, while U.S. Marine Corps Aviation is the world's seventh-largest air arm. The U.S. Navy is the world's largest navy by tonnage . The U.S. Coast Guard is the world's 12th-largest maritime force. The history of

2680-482: The U.S. Air Force and its predecessors, began as part of the field artillery in 1942. Small spotter planes were used to spot for artillery and naval bombardment, as well as to perform observation. These few aircraft formed the core of Army Aviation once the U.S. Air Force gained independence. In 1983, the Army created the Aviation Branch, for the first time since the Air Force's independence consolidating aviation under

2747-538: The U.S. Armed Forces dates back to 14 June 1775, with the creation of the Continental Army , even before the Declaration of Independence marked the establishment of the United States. The Continental Navy , established on 13 October 1775, and Continental Marines , established on 10 November 1775, were created in close succession by the Second Continental Congress in order to defend the new nation against

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2814-656: The U.S. Armed Forces is established in Article II in the Constitution whereby the president is named as the " Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States." The United States Armed Forces are split between two cabinet departments, with the Department of Defense serving as the primary cabinet department for military affairs and

2881-708: The U.S. arsenal, the MGM-31 Pershing , and the Pershing II . In 2023, the Army is intending to field the Long-Range Hypersonic Weapon and has reestablished larger artillery formations like the 56th Artillery Command . The Air Defense Artillery is responsible for defending geopolitical assets and providing maneuver forces with the freedom to move on the battlefield by deterring the enemy and destroying aerial threats, missile attacks, and surveillance platforms. Weapons employed by Air Defense Artillery include

2948-531: The U.S. military and the first new branch in 72 years. The origin of the Space Force can be traced back to the Air Force Space Command , which was formed 1 September 1982 and was a major command of the United States Air Force. The U.S. Congressional Research Office annually publishes a List of Notable Deployments of U.S. Military Forces Overseas since 1798. Presidential command over

3015-404: The U.S. was US$ 916 billion in 2023, the highest in the world, accounting for 37% of the world's defense expenditures . The U.S. Armed Forces has significant capabilities in both defense and power projection due to its large budget, resulting in advanced and powerful technologies which enable widespread deployment of the force around the world, including around 800 military bases outside

3082-487: The United States Armed Forces. Leadership of the Armed Forces, to include the president of the United States, the secretary of defense , the secretary of Homeland Security and chairman of the Joint Chiefs of Staff are members of the United States National Security Council , which advises the president on national security, military, and foreign policy matters. The national security advisor ,

3149-662: The conduct of other military activities related to countering threats to U.S. national security. This mission is focused on providing support to echelons at the CCMD level and below and may not encompass the full scope of the CSA's mission. The United States Armed Forces is composed of six coequal military service branches. Five of the branches, the United States Army , United States Marine Corps , United States Navy , United States Air Force , and United States Space Force , are organized under

3216-401: The different military services is assigned a role and domain. The U.S. Army conducts land operations, while the U.S. Navy and U.S. Marine Corps conduct maritime operations, with the Marine Corps specializing in amphibious and maritime littoral operations in support of the Navy. The U.S. Air Force conducts air operations, while the U.S. Space Force conducts space operations. The U.S. Coast Guard

3283-446: The electronic equipment were included. Lighter weight, solid-state electronics equipment was eventually developed to replace the initial units. The equipment was designed for all-weather operation. The data was recorded on magnetic tape and processed by a computer. First, the distances between each station and a satellite were obtained and recorded. The distances between the known positions and this satellite were used to determine

3350-454: The magnetic poles of Earth. The despin coils were simply large wire coils that were electrically shorted. Rotational movement within Earth's magnetic field induced current on the coils. The current in the coils generated a magnetic field of its own that opposed Earth's, thus slowing the satellite's rotation. As the coils were shorted, the electric current was converted to heat and dissipated to space. The initial braking took several days because of

3417-471: The military departments ( Department of the Army , United States Department of the Navy , and Department of the Air Force ) are civilian led entities that oversee the coequal military service branches organized within each department. The military departments and services are responsible for organizing, training, and equipping forces, with the actual chain of command flowing through the unified combatant commands . The Joint Chiefs of Staff , although outside

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3484-663: The most versatile special operations force in the entire world, operating as a multi-purpose force since 1952. The Armor Branch traces its history back to the United States Cavalry and are responsible for tank and cavalry reconnaissance operations. The U.S. Army fields the M1 Abrams main battle tank in Armored Battalions as part of Armored Brigade Combat Teams across the 1st Armored Division , 1st Cavalry Division , 1st Infantry Division , 3rd Infantry Division , and

3551-535: The only electronic components that could amplify —an essential capability in all electronics. The transistor, which was invented by John Bardeen and Walter Houser Brattain while working under William Shockley at Bell Laboratories in 1947, could also amplify, and replaced vacuum tubes. The first transistor hi-fi system was developed by engineers at GE and demonstrated at the University of Philadelphia in 1955. In terms of commercial production, The Fisher TR-1

3618-400: The operational chain of command, is the senior-most military body in the United States Armed Forces. It is led by the chairman of the Joint Chiefs of Staff , who is the military head of the armed forces and principal advisor to the president and secretary of defense on military matters. Their deputy is the vice chairman of the Joint Chiefs of Staff . Other members include the chief of staff of

3685-413: The satellite's location in space, and then, the previously measured distance from the fourth station and the calculated satellite position were used to calculate the coordinates of the fourth station with respect to the three known stations. The accuracy of the position calculations was enhanced by the great amount of data obtained in each satellite pass. At about 70 measurements per second, and considering

3752-762: The service's land combat power. U.S. Army infantry are generally equipped with the M4 carbine and M249 light machine gun , which will be replaced by the XM7 rifle and XM250 . Infantry is a core part of the Army's Brigade Combat Teams . The most numerous variant, the Infantry Brigade Combat Team, comprises light infantry battalions who fight on foot. Infantry Brigade Combat Teams of the 82nd Airborne Division are air assault capable, with infantry soldiers being transported by U.S. Army Aviation UH-60 Black Hawk and CH-47 Chinook helicopters. Infantry Brigade Combat Teams of

3819-487: The solar panels.{{}} SECOR transponders were also attached to a number of satellites. While the specific implementation was done on a case-by-case basis, the general idea was to place a transponder either outside/inside of a host satellite, sharing power, antennas, and telemetry with other experiments. The ground stations were transportable. They consisted of three shelters, one for radio equipment, one for data handling, and one for storage. Generators and air conditioning for

3886-421: The surface, providing 17 volts. Within the sphere, a vertically aligned cylinder housed the batteries and voltage regulators. A stable voltage was essential for accurate transponder operation, and, in addition to the voltage regulators, each battery cell in the battery was matched to within 0.03 volts in their discharge curves. The transponder was placed on a framework within the remaining space. Each satellite

3953-445: The time the satellite was visible from the ground station, a typical satellite pass yielded approximately 48,000 measurements. Because depending on the exact angle between the satellite and a ground station, the precision could have variation, data was collected during several passes. This allowed data from the best passes to be selected, while still conserving a great amount of redundancy. Once enough measurements had been made to ensure

4020-419: The unknown position was precisely established, one of the stations was moved to a different place and became the new unknown position. In this way, former measurements helped establish new positions. Sources differ in details such as names and launch dates. When there are inconsistencies, sources are provided for both. EGRS (Engineer Geodetic Research Satellite) was the U.S. Army Corps of Engineers acronym for

4087-565: The unknown station's position was accurately determined, it became a known station. Then one of the four stations was moved to a new unknown point, and the process began again. SECOR was a predecessor to navigational satellite systems such as Timation and Navstar-GPS (Global Positioning System). Fifteen dedicated SECOR satellites were made, and eight SECOR transponders flew as a subsystem of other satellites. Two versions of SECOR satellites were built, Type I and Type II. They had several differences, but they also shared many features. Therefore,

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4154-570: The weak magnetic field at the typical SECOR orbital altitudes. These later satellites were made in the shape of a rectangular prism, measuring 25.3 × 29.8 × 34.9 cm (10.0 × 11.7 × 13.7 in). They were almost fully covered in solar cells, and the antennas were made of flexible steel tape. They were much more compact, and thus worked better as secondary payloads. They were designed to avoid removing covers and panels during satellite pre-launch checks. Their antennas were perforated, to diminish antenna shadow over

4221-506: The world's largest air-transportable X-band radar. The Ground-Based Midcourse Defense is an anti-ballistic missile system operated by Army Space and Missile Defense Command to defend the United States homeland against an intercontinental ballistic missile attack. Major Air Defense Artillery units include the 32nd Army Air and Missile Defense Command and Army Space and Missile Defense Command's 100th Missile Defense Brigade . Air Defense Artillery has an extremely close relationship with

4288-488: Was equipped to transmit data such as battery charge, voltages, temperature of equipment inside the satellite, etc. Later satellites had more telemetry channels. On the inner side of the skin, a magnetic rod was placed. It aligned itself with Earth's magnetic field , thus keeping the satellite in a constant orientation. Also inside the skin, many despin coils were placed. These devices were used to stop undesired rotation induced by launch vehicle separation, and by passing near

4355-405: Was formerly considered to be a branch of the United States Armed Forces from 29 July 1945 until 3 July 1952, and is now one of the eight uniformed services of the United States. Should it be called into active duty again, it would constitute a seventh branch of the Armed Forces. The United States Space Force was established as an independent service on 20 December 2019. It is the sixth branch of

4422-448: Was made of polished aluminium covered with a thin layer of silicon monoxide to help with thermal regulation. There were nine collapsible antennas, eight around the equator for distance measurement and one atop the sphere for telemetry and command. A hollow cone connected the upper stage of the launch vehicle to the base of the satellite. Expected lifespan was one year. Six sets of 160 solar cells were mounted on aluminium plates around

4489-465: Was the first "all transistor" preamplifier , which became available mid-1956. In 1961, a company named Transis-tronics released a solid-state amplifier, the TEC S-15. The replacement of bulky, fragile, energy-hungry vacuum tubes by transistors in the 1960s and 1970s created a revolution not just in technology but in people's habits, making possible the first truly portable consumer electronics such as

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