The Space Task Group was a working group of NASA engineers created in 1958, tasked with managing America's human spaceflight programs. Headed by Robert Gilruth and based at the Langley Research Center in Hampton, Virginia , it managed Project Mercury and follow-on plans. After President John F. Kennedy set the goal in 1961 for the Apollo Program to land a man on the Moon and bring him back safely to Earth, NASA decided a much larger organization and a new facility was required to perform the Task Group's function, and it was transformed into the Manned Spacecraft Center (now the Lyndon B. Johnson Space Center ), located in Houston, Texas .
178-588: In later years, the term Space Task Group was ambiguously reused to refer to an ad hoc committee appointed by the President to recommend human spaceflight programs, usually chaired by the Vice President . For instance, President Richard Nixon appointed such a group in February 1969 to outline a post-Apollo spaceflight strategy, chaired by Vice President Spiro T. Agnew . Created on November 5, 1958,
356-729: A perpetual union between the states in November 1777 and sent it to the states for ratification . Under the Articles, which took effect on March 1, 1781, the Congress of the Confederation was a central political authority without any legislative power. It could make its own resolutions, determinations, and regulations, but not any laws, and could not impose any taxes or enforce local commercial regulations upon its citizens. This institutional design reflected how Americans believed
534-1096: A president of the United States in Congress Assembled to preside over its deliberation as a neutral discussion moderator . Unrelated to and quite dissimilar from the later office of president of the United States, it was a largely ceremonial position without much influence. In 1783, the Treaty of Paris secured independence for each of the former colonies. With peace at hand, the states each turned toward their own internal affairs. By 1786, Americans found their continental borders besieged and weak and their respective economies in crises as neighboring states agitated trade rivalries with one another. They witnessed their hard currency pouring into foreign markets to pay for imports, their Mediterranean commerce preyed upon by North African pirates , and their foreign-financed Revolutionary War debts unpaid and accruing interest. Civil and political unrest loomed. Events such as
712-511: A "disruptive" erosion of his ability to govern. Ford failed to win election to a full term and his successor, Jimmy Carter , failed to win re-election. Ronald Reagan , who had been an actor before beginning his political career, used his talent as a communicator to help reshape the American agenda away from New Deal policies toward more conservative ideology. With the Cold War ending and
890-492: A NASA engineer who had worked to design the Mercury capsule, patented a design for a two-stage fully recoverable system with a straight-winged orbiter mounted on a larger straight-winged booster. The Air Force Flight Dynamics Laboratory argued that a straight-wing design would not be able to withstand the high thermal and aerodynamic stresses during reentry, and would not provide the required cross-range capability. Additionally,
1068-497: A crewed spaceflight engineer on both STS-51-C and STS-51-J to serve as a military representative for a National Reconnaissance Office payload. A Space Shuttle crew typically had seven astronauts, with STS-61-A flying with eight. The crew compartment comprised three decks and was the pressurized, habitable area on all Space Shuttle missions. The flight deck consisted of two seats for the commander and pilot, as well as an additional two to four seats for crew members. The mid-deck
1246-573: A delegate for Virginia. When the Constitutional Convention convened in May 1787, the 12 state delegations in attendance ( Rhode Island did not send delegates) brought with them an accumulated experience over a diverse set of institutional arrangements between legislative and executive branches from within their respective state governments. Most states maintained a weak executive without veto or appointment powers, elected annually by
1424-463: A dominant figure in American politics. Historians believe Roosevelt permanently changed the political system by strengthening the presidency, with some key accomplishments including breaking up trusts, conservationism, labor reforms, making personal character as important as the issues, and hand-picking his successor, William Howard Taft . The following decade, Woodrow Wilson led the nation to victory during World War I , although Wilson's proposal for
1602-467: A future reusable shuttle: Class I would have a reusable orbiter mounted on expendable boosters, Class II would use multiple expendable rocket engines and a single propellant tank (stage-and-a-half), and Class III would have both a reusable orbiter and a reusable booster. In September 1969, the Space Task Group, under the leadership of U.S. Vice President Spiro Agnew , issued a report calling for
1780-598: A glider. Its three-part fuselage provided support for the crew compartment, cargo bay, flight surfaces, and engines. The rear of the orbiter contained the Space Shuttle Main Engines (SSME), which provided thrust during launch, as well as the Orbital Maneuvering System (OMS), which allowed the orbiter to achieve, alter, and exit its orbit once in space. Its double- delta wings were 18 m (60 ft) long, and were swept 81° at
1958-545: A good deal of foreign and domestic policy without aid, interference or consent from Congress". Bill Wilson , board member of Americans for Limited Government , opined that the expanded presidency was "the greatest threat ever to individual freedom and democratic rule". Article I, Section 1 of the Constitution vests all lawmaking power in Congress's hands, and Article 1, Section 6, Clause 2 prevents
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#17327725250772136-482: A mobile platform for astronauts conducting an EVA. The RMS was built by the Canadian company Spar Aerospace and was controlled by an astronaut inside the orbiter's flight deck using their windows and closed-circuit television. The RMS allowed for six degrees of freedom and had six joints located at three points along the arm. The original RMS could deploy or retrieve payloads up to 29,000 kg (65,000 lb), which
2314-466: A month after taking office. Presidents often grant pardons shortly before leaving office, like when Bill Clinton pardoned Patty Hearst on his last day in office; this is often controversial . Two doctrines concerning executive power have developed that enable the president to exercise executive power with a degree of autonomy. The first is executive privilege , which allows the president to withhold from disclosure any communications made directly to
2492-484: A pair of recoverable solid rocket boosters (SRBs), and the expendable external tank (ET) containing liquid hydrogen and liquid oxygen . The Space Shuttle was launched vertically , like a conventional rocket, with the two SRBs operating in parallel with the orbiter's three main engines , which were fueled from the ET. The SRBs were jettisoned before the vehicle reached orbit, while the main engines continued to operate, and
2670-534: A partial-pressure version of the high-altitude pressure suits with a helmet. In 1994, the LES was replaced by the full-pressure Advanced Crew Escape Suit (ACES), which improved the safety of the astronauts in an emergency situation. Columbia originally had modified SR-71 zero-zero ejection seats installed for the ALT and first four missions, but these were disabled after STS-4 and removed after STS-9 . The flight deck
2848-530: A partially reusable system would be the most cost-effective solution. The head of the NASA Office of Manned Space Flight, George Mueller , announced the plan for a reusable shuttle on August 10, 1968. NASA issued a request for proposal (RFP) for designs of the Integral Launch and Reentry Vehicle (ILRV) on October 30, 1968. Rather than award a contract based upon initial proposals, NASA announced
3026-558: A phased approach for the Space Shuttle contracting and development; Phase A was a request for studies completed by competing aerospace companies, Phase B was a competition between two contractors for a specific contract, Phase C involved designing the details of the spacecraft components, and Phase D was the production of the spacecraft. In December 1968, NASA created the Space Shuttle Task Group to determine
3204-481: A port-side hatch that the crew used for entry and exit while on Earth. The airlock is a structure installed to allow movement between two spaces with different gas components, conditions, or pressures. Continuing on the mid-deck structure, each orbiter was originally installed with an internal airlock in the mid-deck. The internal airlock was installed as an external airlock in the payload bay on Discovery , Atlantis , and Endeavour to improve docking with Mir and
3382-431: A presidential veto, it requires a two-thirds vote of both houses, which is usually very difficult to achieve except for widely supported bipartisan legislation. The framers of the Constitution feared that Congress would seek to increase its power and enable a "tyranny of the majority", so giving the indirectly elected president a veto was viewed as an important check on the legislative power. While George Washington believed
3560-675: A result of an O-ring failing at low temperature, the SRBs were redesigned to provide a constant seal regardless of the ambient temperature. The Space Shuttle's operations were supported by vehicles and infrastructure that facilitated its transportation, construction, and crew access. The crawler-transporters carried the MLP and the Space Shuttle from the VAB to the launch site. The Shuttle Carrier Aircraft (SCA) were two modified Boeing 747s that could carry an orbiter on its back. The original SCA (N905NA)
3738-615: A second orbiter. Later that month, Rockwell began converting STA-099 to OV-099, later named Challenger . On January 29, 1979, NASA ordered two additional orbiters, OV-103 and OV-104, which were named Discovery and Atlantis . Construction of OV-105, later named Endeavour , began in February 1982, but NASA decided to limit the Space Shuttle fleet to four orbiters in 1983. After the loss of Challenger , NASA resumed production of Endeavour in September 1987. After it arrived at Edwards AFB, Enterprise underwent flight testing with
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#17327725250773916-670: A separate central processing unit (CPU) and input/output processor (IOP), and non-volatile solid-state memory . From 1991 to 1993, the orbiter vehicles were upgraded to the AP-101S, which improved the memory and processing capabilities, and reduced the volume and weight of the computers by combining the CPU and IOP into a single unit. Four of the GPCs were loaded with the Primary Avionics Software System (PASS), which
4094-438: A sexual harassment suit could proceed without delay, even against a sitting president. The 2019 Mueller report on Russian interference in the 2016 presidential election detailed evidence of possible obstruction of justice , but investigators declined to refer Donald Trump for prosecution based on a United States Department of Justice policy against indicting an incumbent president. The report noted that impeachment by Congress
4272-612: A sitting American president led troops in the field", though James Madison briefly took control of artillery units in defense of Washington, D.C. , during the War of 1812 . Abraham Lincoln was deeply involved in overall strategy and in day-to-day operations during the American Civil War , 1861–1865; historians have given Lincoln high praise for his strategic sense and his ability to select and encourage commanders such as Ulysses S. Grant . The present-day operational command of
4450-410: A speech. After STS-4, NASA declared its Space Transportation System (STS) operational. The Space Shuttle was the first operational orbital spacecraft designed for reuse . Each Space Shuttle orbiter was designed for a projected lifespan of 100 launches or ten years of operational life, although this was later extended. At launch, it consisted of the orbiter , which contained the crew and payload,
4628-550: A state visit by a foreign head of state, the president typically hosts a State Arrival Ceremony held on the South Lawn , a custom begun by John F. Kennedy in 1961. This is followed by a state dinner given by the president which is held in the State Dining Room later in the evening. As a national leader, the president also fulfills many less formal ceremonial duties. For example, William Howard Taft started
4806-600: A system of reusable spacecraft where it was the only item funded for development. The first ( STS-1 ) of four orbital test flights occurred in 1981, leading to operational flights ( STS-5 ) beginning in 1982. Five complete Space Shuttle orbiter vehicles were built and flown on a total of 135 missions from 1981 to 2011. They launched from the Kennedy Space Center (KSC) in Florida . Operational missions launched numerous satellites , interplanetary probes , and
4984-404: A team to select a site for the new center. On September 19, Webb announced the new Manned Spacecraft Center (MSC) would be built on a Houston, Texas site donated by Rice University . Gilruth immediately began the transition of his Task Group into the new MSC, planning his increased staff organization and its move to Houston, using temporary leased office and test facility space on 12 sites while
5162-424: A third. In addition, nine vice presidents have become president by virtue of a president's intra-term death or resignation . In all, 45 individuals have served 46 presidencies spanning 58 four-year terms. Joe Biden is the 46th and current president, having assumed office on January 20, 2021. President-elect Donald Trump is scheduled to be inaugurated as the 47th president on January 20, 2025. During
5340-515: A total of 14 astronauts killed. A fifth operational (and sixth in total) orbiter, Endeavour , was built in 1991 to replace Challenger . The three surviving operational vehicles were retired from service following Atlantis ' s final flight on July 21, 2011. The U.S. relied on the Russian Soyuz spacecraft to transport astronauts to the ISS from the last Shuttle flight until the launch of
5518-428: A two-part drag parachute system to slow the orbiter after landing. The orbiter used retractable landing gear with a nose landing gear and two main landing gear, each containing two tires. The main landing gear contained two brake assemblies each, and the nose landing gear contained an electro-hydraulic steering mechanism. The Space Shuttle crew varied per mission. They underwent rigorous testing and training to meet
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5696-452: Is cooled by 1,080 interior lines carrying liquid hydrogen and is thermally protected by insulative and ablative material. The RS-25 engines had several improvements to enhance reliability and power. During the development program, Rocketdyne determined that the engine was capable of safe reliable operation at 104% of the originally specified thrust. To keep the engine thrust values consistent with previous documentation and software, NASA kept
5874-413: Is head of the executive branch of the federal government and is constitutionally obligated to "take care that the laws be faithfully executed". The executive branch has over four million employees, including the military. Presidents make political appointments . An incoming president may make up to 4,000 upon taking office, 1200 of which must be confirmed by the U.S. Senate . Ambassadors , members of
6052-571: Is to be commander-in-chief of the army and navy of the United States. ... It would amount to nothing more than the supreme command and direction of the military and naval forces ... while that [the power] of the British king extends to the DECLARING of war and to the RAISING and REGULATING of fleets and armies, all [of] which ... would appertain to the legislature. [Emphasis in
6230-513: The Columbia disaster . Beginning with STS-114 , the orbiter vehicles were equipped with the wing leading edge impact detection system to alert the crew to any potential damage. The entire underside of the orbiter vehicle, as well as the other hottest surfaces, were protected with tiles of high-temperature reusable surface insulation, made of borosilicate glass -coated silica fibers that trapped heat in air pockets and redirected it out. Areas on
6408-852: The American Revolutionary War , the Thirteen Colonies , represented by the Second Continental Congress in Philadelphia , declared themselves to be independent sovereign states and no longer under British rule. The affirmation was made in the Declaration of Independence , which was written predominantly by Thomas Jefferson and adopted unanimously on July 4, 1776, by the Second Continental Congress. Recognizing
6586-541: The Boy Scouts of America . Space Shuttle The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program . Its official program name was Space Transportation System (STS), taken from the 1969 plan led by U.S. Vice President Spiro Agnew for
6764-535: The Cabinet , and various officers , are among the positions filled by presidential appointment with Senate confirmation. The power of a president to fire executive officials has long been a contentious political issue. Generally, a president may remove executive officials at will. However, Congress can curtail and constrain a president's authority to fire commissioners of independent regulatory agencies and certain inferior executive officers by statute . To manage
6942-731: The Crew Dragon Demo-2 mission in May 2020. In the late 1930s, the German government launched the " Amerikabomber " project, and Eugen Sanger 's idea, together with mathematician Irene Bredt , was a winged rocket called the Silbervogel (German for "silver bird"). During the 1950s, the United States Air Force proposed using a reusable piloted glider to perform military operations such as reconnaissance, satellite attack, and air-to-ground weapons employment. In
7120-685: The Hubble Space Telescope (HST), conducted science experiments in orbit, participated in the Shuttle- Mir program with Russia, and participated in the construction and servicing of the International Space Station (ISS). The Space Shuttle fleet's total mission time was 1,323 days. Space Shuttle components include the Orbiter Vehicle (OV) with three clustered Rocketdyne RS-25 main engines,
7298-571: The ISS , along with the Orbiter Docking System . The airlock module can be fitted in the mid-bay, or connected to it but in the payload bay. With an internal cylindrical volume of 1.60 metres (5 feet 3 inches) diameter and 2.11 metres (6 feet 11 inches) in length, it can hold two suited astronauts. It has two D-shaped hatchways 1.02 m (40 in) long (diameter), and 0.91 m (36 in) wide. The orbiter
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7476-763: The League of Nations was rejected by the Senate. Warren Harding , while popular in office, would see his legacy tarnished by scandals, especially Teapot Dome , and Herbert Hoover quickly became very unpopular after failing to alleviate the Great Depression . The ascendancy of Franklin D. Roosevelt in 1933 led further toward what historians now describe as the Imperial presidency . Backed by enormous Democratic majorities in Congress and public support for major change, Roosevelt's New Deal dramatically increased
7654-610: The Martin Marietta X-24B . The program tested aerodynamic characteristics that would later be incorporated in design of the Space Shuttle, including unpowered landing from a high altitude and speed. On September 24, 1966, as the Apollo space program neared its design completion, NASA and the Air Force released a joint study concluding that a new vehicle was required to satisfy their respective future demands and that
7832-660: The Newburgh Conspiracy and Shays' Rebellion demonstrated that the Articles of Confederation were not working. Following the successful resolution of commercial and fishing disputes between Virginia and Maryland at the Mount Vernon Conference in 1785, Virginia called for a trade conference between all the states, set for September 1786 in Annapolis, Maryland , with an aim toward resolving further-reaching interstate commercial antagonisms. When
8010-684: The Shuttle Carrier Aircraft , a Boeing 747 that had been modified to carry the orbiter. In February 1977, Enterprise began the Approach and Landing Tests (ALT) and underwent captive flights, where it remained attached to the Shuttle Carrier Aircraft for the duration of the flight. On August 12, 1977, Enterprise conducted its first glide test, where it detached from the Shuttle Carrier Aircraft and landed at Edwards AFB. After four additional flights, Enterprise
8188-853: The Shuttle Landing Facility at KSC, Florida, or to Rogers Dry Lake in Edwards Air Force Base , California. If the landing occurred at Edwards, the orbiter was flown back to the KSC atop the Shuttle Carrier Aircraft (SCA), a specially modified Boeing 747 designed to carry the shuttle above it. The first orbiter, Enterprise , was built in 1976 and used in Approach and Landing Tests (ALT), but had no orbital capability. Four fully operational orbiters were initially built: Columbia , Challenger , Discovery , and Atlantis . Of these, two were lost in mission accidents: Challenger in 1986 and Columbia in 2003 , with
8366-559: The Supreme Court of the United States . However, these nominations require Senate confirmation before they may take office. Securing Senate approval can provide a major obstacle for presidents who wish to orient the federal judiciary toward a particular ideological stance. When nominating judges to U.S. district courts , presidents often respect the long-standing tradition of senatorial courtesy . Presidents may also grant pardons and reprieves . Gerald Ford pardoned Richard Nixon
8544-633: The Tracking and Data Relay Satellite System and the Spacecraft Tracking and Data Acquisition Network ground stations to communicate with the orbiter throughout its orbit. Additionally, the orbiter deployed a high-bandwidth K u band radio out of the cargo bay, which could also be utilized as a rendezvous radar. The orbiter was also equipped with two UHF radios for communications with air traffic control and astronauts conducting EVA. The Space Shuttle's fly-by-wire control system
8722-588: The U.S. Constitution emerged. As the nation's first president, George Washington established many norms that would come to define the office. His decision to retire after two terms helped address fears that the nation would devolve into monarchy, and established a precedent that would not be broken until 1940 and would eventually be made permanent by the Twenty-Second Amendment . By the end of his presidency, political parties had developed, with John Adams defeating Thomas Jefferson in 1796,
8900-588: The United States of America . The president directs the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces . The power of the presidency has grown substantially since the first president, George Washington , took office in 1789. While presidential power has ebbed and flowed over time, the presidency has played an increasingly significant role in American political life since
9078-610: The Watergate scandal , Congress enacted a series of reforms intended to reassert itself. These included the War Powers Resolution , enacted over Nixon's veto in 1973, and the Congressional Budget and Impoundment Control Act of 1974 that sought to strengthen congressional fiscal powers. By 1976, Gerald Ford conceded that "the historic pendulum" had swung toward Congress, raising the possibility of
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#17327725250779256-636: The Watergate scandal , the Supreme Court ruled in United States v. Nixon , 418 U.S. 683 (1974), that executive privilege did not apply in cases where a president was attempting to avoid criminal prosecution. When Bill Clinton attempted to use executive privilege regarding the Lewinsky scandal , the Supreme Court ruled in Clinton v. Jones , 520 U.S. 681 (1997), that
9434-490: The convention failed for lack of attendance due to suspicions among most of the other states, Alexander Hamilton of New York led the Annapolis delegates in a call for a convention to offer revisions to the Articles, to be held the next spring in Philadelphia . Prospects for the next convention appeared bleak until James Madison and Edmund Randolph succeeded in securing George Washington 's attendance to Philadelphia as
9612-540: The external tank (ET), and the two solid rocket boosters (SRBs). Responsibility for the Space Shuttle components was spread among multiple NASA field centers. The KSC was responsible for launch, landing, and turnaround operations for equatorial orbits (the only orbit profile actually used in the program). The U.S. Air Force at the Vandenberg Air Force Base was responsible for launch, landing, and turnaround operations for polar orbits (though this
9790-484: The qualification requirements for their roles. The crew was divided into three categories: Pilots, Mission Specialists, and Payload Specialists. Pilots were further divided into two roles: Space Shuttle Commanders and Space Shuttle Pilots. The test flights only had two members each, the commander and pilot, who were both qualified pilots that could fly and land the orbiter. The on-orbit operations, such as experiments, payload deployment, and EVAs, were conducted primarily by
9968-585: The 1830s and 1840s until debates over slavery began pulling the nation apart in the 1850s. Abraham Lincoln 's leadership during the Civil War has led historians to regard him as one of the nation's greatest presidents. The circumstances of the war and Republican domination of Congress made the office very powerful, and Lincoln's re-election in 1864 was the first time a president had been re-elected since Jackson in 1832. After Lincoln's assassination, his successor Andrew Johnson lost all political support and
10146-524: The 20th century, especially during the Cold War , the U.S. president was often called "the leader of the free world". Article II of the Constitution establishes the executive branch of the federal government and vests executive power in the president. The power includes the execution and enforcement of federal law and the responsibility to appoint federal executive, diplomatic, regulatory, and judicial officers. Based on constitutional provisions empowering
10324-399: The 2195 aluminum-lithium alloy, which was 40% stronger and 10% less dense than its predecessor, 2219 aluminum-lithium alloy. The SLWT weighed 3,400 kg (7,500 lb) less than the LWT, which allowed the Space Shuttle to deliver heavy elements to ISS's high inclination orbit. The Solid Rocket Boosters (SRB) provided 71.4% of the Space Shuttle's thrust during liftoff and ascent, and were
10502-452: The Air Force required a larger payload capacity than Faget's design allowed. In January 1971, NASA and Air Force leadership decided that a reusable delta-wing orbiter mounted on an expendable propellant tank would be the optimal design for the Space Shuttle. After they established the need for a reusable, heavy-lift spacecraft, NASA and the Air Force determined the design requirements of their respective services. The Air Force expected to use
10680-418: The Armed Forces is delegated to the Department of Defense and is normally exercised through the secretary of defense . The chairman of the Joint Chiefs of Staff and the Combatant Commands assist with the operation as outlined in the presidentially approved Unified Command Plan (UCP). The president has the power to nominate federal judges , including members of the United States courts of appeals and
10858-415: The Constitution grants to the president as commander-in-chief has been the subject of much debate throughout history, with Congress at various times granting the president wide authority and at others attempting to restrict that authority. The framers of the Constitution took care to limit the president's powers regarding the military; Alexander Hamilton explained this in Federalist No. 69 : The President
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#173277252507711036-404: The ET was jettisoned after main engine cutoff and just before orbit insertion , which used the orbiter's two Orbital Maneuvering System (OMS) engines. At the conclusion of the mission, the orbiter fired its OMS to deorbit and reenter the atmosphere . The orbiter was protected during reentry by its thermal protection system tiles, and it glided as a spaceplane to a runway landing, usually to
11214-525: The IMU, INS, and TACAN systems, which first flew on STS-118 in August 2007. While in orbit, the crew primarily communicated using one of four S band radios, which provided both voice and data communications. Two of the S band radios were phase modulation transceivers , and could transmit and receive information. The other two S band radios were frequency modulation transmitters and were used to transmit data to NASA. As S band radios can operate only within their line of sight , NASA used
11392-419: The IMUs while in orbit. The star trackers are deployed while in orbit, and can automatically or manually align on a star. In 1991, NASA began upgrading the inertial measurement units with an inertial navigation system (INS), which provided more accurate location information. In 1993, NASA flew a GPS receiver for the first time aboard STS-51 . In 1997, Honeywell began developing an integrated GPS/INS to replace
11570-405: The KSC. The Space Shuttle was prepared for launch primarily in the VAB at the KSC. The SRBs were assembled and attached to the external tank on the MLP. The orbiter vehicle was prepared at the Orbiter Processing Facility (OPF) and transferred to the VAB, where a crane was used to rotate it to the vertical orientation and mate it to the external tank. Once the entire stack was assembled, the MLP
11748-476: The RS-25 experienced multiple nozzle failures, as well as broken turbine blades. Despite the problems during testing, NASA ordered the nine RS-25 engines needed for its three orbiters under construction in May 1978. NASA experienced significant delays in the development of the Space Shuttle's thermal protection system . Previous NASA spacecraft had used ablative heat shields, but those could not be reused. NASA chose to use ceramic tiles for thermal protection, as
11926-505: The SRBs provided structural support for the orbiter vehicle and ET, as they were the only system that was connected to the mobile launcher platform (MLP). At the time of launch, the SRBs were armed at T−5 minutes, and could only be electrically ignited once the RS-25 engines had ignited and were without issue. They each provided 12,500 kN (2,800,000 lbf) of thrust, which was later improved to 13,300 kN (3,000,000 lbf) beginning on STS-8 . After expending their fuel,
12104-558: The SRBs were jettisoned approximately two minutes after launch at an altitude of approximately 46 km (150,000 ft). Following separation, they deployed drogue and main parachutes, landed in the ocean, and were recovered by the crews aboard the ships MV Freedom Star and MV Liberty Star . Once they were returned to Cape Canaveral, they were cleaned and disassembled. The rocket motor, igniter, and nozzle were then shipped to Thiokol to be refurbished and reused on subsequent flights. The SRBs underwent several redesigns throughout
12282-412: The Secretaries of State and Defense, the NASA Administrator, the Chairman of the Atomic Energy Commission, and any additional members that the president chose to appoint. This council was tasked with making recommendations on the direction of the US civilian and military space programs. Occasionally this council was referred to as a "Space Task Group". President John F. Kennedy persuaded Congress to modify
12460-399: The Space Shuttle through ascent, orbit, and reentry, but could not support an entire mission. The five GPCs were separated in three separate bays within the mid-deck to provide redundancy in the event of a cooling fan failure. After achieving orbit, the crew would switch some of the GPCs functions from guidance, navigation, and control (GNC) to systems management (SM) and payload (PL) to support
12638-426: The Space Shuttle to launch large satellites, and required it to be capable of lifting 29,000 kg (65,000 lb) to an eastward LEO or 18,000 kg (40,000 lb) into a polar orbit . The satellite designs also required that the Space Shuttle have a 4.6 by 18 m (15 by 60 ft) payload bay. NASA evaluated the F-1 and J-2 engines from the Saturn rockets , and determined that they were insufficient for
12816-636: The Space Task Group was headed by Robert Gilruth . Originally it consisted of 45 people, including eight secretaries and "computers", the occupational title for women who ran calculations on mechanical adding machines. Of its 37 engineers, 27 were from Langley Research Center , and 10 had been assigned from Lewis Research Center in Cleveland, Ohio . Original members of the group included Charles Donlan , Gilruth's deputy; Max Faget , head of engineering; Chuck Mathews, head of flight operations; Chris Kraft , also in flight operations; and Glynn Lunney , who at 21
12994-583: The Spacelab module through a 2.7 or 5.8 m (8.72 or 18.88 ft) tunnel that connected to the airlock. The Spacelab equipment was primarily stored in pallets, which provided storage for both experiments as well as computer and power equipment. Spacelab hardware was flown on 28 missions through 1999 and studied subjects including astronomy, microgravity, radar, and life sciences. Spacelab hardware also supported missions such as Hubble Space Telescope (HST) servicing and space station resupply. The Spacelab module
13172-474: The Supreme Court dismissed a case brought by a former Union spy. However, the privilege was not formally recognized by the U.S. Supreme Court until United States v. Reynolds 345 U.S. 1 (1953), where it was held to be a common law evidentiary privilege. Before the September 11 attacks , use of the privilege had been rare, but increasing in frequency. Since 2001, the government has asserted
13350-483: The United States and other countries. Such agreements, upon receiving the advice and consent of the U.S. Senate (by a two-thirds majority vote), become binding with the force of federal law. While foreign affairs has always been a significant element of presidential responsibilities, advances in technology since the Constitution's adoption have increased presidential power. Where formerly ambassadors were vested with significant power to independently negotiate on behalf of
13528-630: The United States becoming the world's undisputed leading power, Bill Clinton , George W. Bush , and Barack Obama each served two terms as president. Meanwhile, Congress and the nation gradually became more politically polarized, especially following the 1994 mid-term elections that saw Republicans control the House for the first time in 40 years, and the rise of routine filibusters in the Senate in recent decades. Recent presidents have thus increasingly focused on executive orders , agency regulations, and judicial appointments to implement major policies, at
13706-423: The United States, presidents now routinely meet directly with leaders of foreign countries. One of the most important of executive powers is the president's role as commander-in-chief of the United States Armed Forces . The power to declare war is constitutionally vested in Congress, but the president has ultimate responsibility for the direction and disposition of the military. The exact degree of authority that
13884-538: The White House". Presidents have been criticized for making signing statements when signing congressional legislation about how they understand a bill or plan to execute it. This practice has been criticized by the American Bar Association as unconstitutional. Conservative commentator George Will wrote of an "increasingly swollen executive branch" and "the eclipse of Congress". To allow
14062-585: The aft seating location, and also controlled the data on the HUD. In 1998, Atlantis was upgraded with the Multifunction Electronic Display System (MEDS), which was a glass cockpit upgrade to the flight instruments that replaced the eight MCDS display units with 11 multifunction colored digital screens. MEDS was flown for the first time in May 2000 on STS-101 , and the other orbiter vehicles were upgraded to it. The aft section of
14240-401: The associated propellant tanks. The AJ10 engines used monomethylhydrazine (MMH) oxidized by dinitrogen tetroxide (N 2 O 4 ). The pods carried a maximum of 2,140 kg (4,718 lb) of MMH and 3,526 kg (7,773 lb) of N 2 O 4 . The OMS engines were used after main engine cut-off (MECO) for orbital insertion. Throughout the flight, they were used for orbit changes, as well as
14418-488: The beginning of the 20th century, carrying over into the 21st century with notable expansions during the presidencies of Franklin D. Roosevelt and George W. Bush . In modern times, the president is one of the world's most powerful political figures and the leader of the world's only remaining superpower . As the leader of the nation with the largest economy by nominal GDP , the president possesses significant domestic and international hard and soft power . For much of
14596-562: The built-in hold at T−9 minutes, the countdown was automatically controlled by the Ground Launch Sequencer (GLS) at the LCC, which stopped the countdown if it sensed a critical problem with any of the Space Shuttle's onboard systems. At T−3 minutes 45 seconds, the engines began conducting gimbal tests, which were concluded at T−2 minutes 15 seconds. The ground Launch Processing System handed off
14774-461: The bulk of the ET, and was 29 m (96.7 ft) tall. The orbiter vehicle was attached to the ET at two umbilical plates, which contained five propellant and two electrical umbilicals, and forward and aft structural attachments. The exterior of the ET was covered in orange spray-on foam to allow it to survive the heat of ascent. The ET provided propellant to the Space Shuttle Main Engines from liftoff until main engine cutoff. The ET separated from
14952-494: The contract to build the orbiter to North American Rockwell. In August 1973, the external tank contract to Martin Marietta , and in November the solid-rocket booster contract to Morton Thiokol . On June 4, 1974, Rockwell began construction on the first orbiter, OV-101, dubbed Constitution, later to be renamed Enterprise . Enterprise was designed as a test vehicle, and did not include engines or heat shielding. Construction
15130-477: The control to the orbiter vehicle's GPCs at T−31 seconds. At T−16 seconds, the GPCs armed the SRBs, the sound suppression system (SPS) began to drench the MLP and SRB trenches with 1,100,000 L (300,000 U.S. gal) of water to protect the orbiter vehicle from damage by acoustical energy and rocket exhaust reflected from the flame trench and MLP during lift-off. At T−10 seconds, hydrogen igniters were activated under each engine bell to quell
15308-552: The death of William Henry Harrison and subsequent poor relations between John Tyler and Congress led to further weakening of the office. Including Van Buren, in the 24 years between 1837 and 1861, six presidential terms would be filled by eight different men, with none serving two terms. The Senate played an important role during this period, with the Great Triumvirate of Henry Clay , Daniel Webster , and John C. Calhoun playing key roles in shaping national policy in
15486-421: The deorbit burn prior to reentry. Each OMS engine produced 27,080 N (6,087 lbf) of thrust, and the entire system could provide 305 m/s (1,000 ft/s) of velocity change . The orbiter was protected from heat during reentry by the thermal protection system (TPS), a thermal soaking protective layer around the orbiter. In contrast with previous US spacecraft, which had used ablative heat shields,
15664-457: The deposed British system of Crown and Parliament ought to have functioned with respect to the royal dominion : a superintending body for matters that concerned the entire empire. The states were out from under any monarchy and assigned some formerly royal prerogatives (e.g., making war, receiving ambassadors, etc.) to Congress; the remaining prerogatives were lodged within their own respective state governments. The members of Congress elected
15842-516: The development of a space shuttle to bring people and cargo to low Earth orbit (LEO), as well as a space tug for transfers between orbits and the Moon, and a reusable nuclear upper stage for deep space travel. After the release of the Space Shuttle Task Group report, many aerospace engineers favored the Class III, fully reusable design because of perceived savings in hardware costs. Max Faget ,
16020-674: The ease of refurbishing them for reuse after they landed in the ocean. In January 1972, President Richard Nixon approved the Shuttle, and NASA decided on its final design in March. The development of the Space Shuttle Main Engine (SSME) remained the responsibility of Rocketdyne, and the contract was issued in July 1971, and updated SSME specifications were submitted to Rocketdyne in that April. That August, NASA awarded
16198-492: The effects of aerodynamic and thermal stresses during launch and reentry. The beginning of the development of the RS-25 Space Shuttle Main Engine was delayed for nine months while Pratt & Whitney challenged the contract that had been issued to Rocketdyne. The first engine was completed in March 1975, after issues with developing the first throttleable, reusable engine. During engine testing,
16376-512: The engines during powered flight and fly the orbiter during unpowered flight. Both seats also had rudder controls, to allow rudder movement in flight and nose-wheel steering on the ground. The orbiter vehicles were originally installed with the Multifunction CRT Display System (MCDS) to display and control flight information. The MCDS displayed the flight information at the commander and pilot seats, as well as at
16554-461: The executive branch may draft legislation and then ask senators or representatives to introduce these drafts into Congress. Additionally, the president may attempt to have Congress alter proposed legislation by threatening to veto that legislation unless requested changes are made. Many laws enacted by Congress do not address every possible detail, and either explicitly or implicitly delegate powers of implementation to an appropriate federal agency. As
16732-475: The expense of legislation and congressional power. Presidential elections in the 21st century have reflected this continuing polarization, with no candidate except Obama in 2008 winning by more than five percent of the popular vote and two, George W. Bush and Donald Trump , winning in the Electoral College while losing the popular vote. The nation's Founding Fathers expected the Congress , which
16910-605: The feasibility of reusable boosters. This became the basis for the aerospaceplane , a fully reusable spacecraft that was never developed beyond the initial design phase in 1962–1963. Beginning in the early 1950s, NASA and the Air Force collaborated on developing lifting bodies to test aircraft that primarily generated lift from their fuselages instead of wings, and tested the NASA M2-F1 , Northrop M2-F2 , Northrop M2-F3 , Northrop HL-10 , Martin Marietta X-24A , and
17088-504: The federal government by issuing various types of directives , such as presidential proclamation and executive orders . When the president is lawfully exercising one of the constitutionally conferred presidential responsibilities, the scope of this power is broad. Even so, these directives are subject to judicial review by U.S. federal courts, which can find them to be unconstitutional. Congress can overturn an executive order through legislation. Article II, Section 3, Clause 4 requires
17266-672: The final decision to scrub a launch was announced. In addition to the weather at the launch site, conditions had to be acceptable at one of the Transatlantic Abort Landing sites and the SRB recovery area. The mission crew and the Launch Control Center (LCC) personnel completed systems checks throughout the countdown. Two built-in holds at T−20 minutes and T−9 minutes provided scheduled breaks to address any issues and additional preparation. After
17444-539: The first U.S. president, firmly established military subordination under civilian authority . In 1794, Washington used his constitutional powers to assemble 12,000 militia to quell the Whiskey Rebellion , a conflict in Western Pennsylvania involving armed farmers and distillers who refused to pay an excise tax on spirits. According to historian Joseph Ellis , this was the "first and only time
17622-532: The first four Shuttle missions, astronauts wore modified U.S. Air Force high-altitude full-pressure suits, which included a full-pressure helmet during ascent and descent. From the fifth flight, STS-5 , until the loss of Challenger , the crew wore one-piece light blue nomex flight suits and partial-pressure helmets. After the Challenger disaster, the crew members wore the Launch Entry Suit (LES),
17800-481: The first time NASA performed a crewed first-flight of a spacecraft. On April 12, 1981, the Space Shuttle launched for the first time, and was piloted by John Young and Robert Crippen . During the two-day mission, Young and Crippen tested equipment on board the shuttle, and found several of the ceramic tiles had fallen off the top side of the Columbia . NASA coordinated with the Air Force to use satellites to image
17978-536: The first truly contested presidential election. After Jefferson defeated Adams in 1800, he and his fellow Virginians James Madison and James Monroe would each serve two terms, eventually dominating the nation's politics during the Era of Good Feelings until Adams' son John Quincy Adams won election in 1824 after the Democratic-Republican Party split. The election of Andrew Jackson in 1828
18156-635: The flight deck contained windows looking into the payload bay, as well as an RHC to control the Remote Manipulator System during cargo operations. Additionally, the aft flight deck had monitors for a closed-circuit television to view the cargo bay. The mid-deck contained the crew equipment storage, sleeping area, galley, medical equipment, and hygiene stations for the crew. The crew used modular lockers to store equipment that could be scaled depending on their needs, as well as permanently installed floor compartments. The mid-deck contained
18334-502: The forward separation motors and the parachute systems that were used during recovery. The rocket nozzles could gimbal up to 8° to allow for in-flight adjustments. The rocket motors were each filled with a total 500,000 kg (1,106,640 lb) of solid rocket propellant ( APCP + PBAN ), and joined in the Vehicle Assembly Building (VAB) at KSC. In addition to providing thrust during the first stage of launch,
18512-417: The government to act quickly in case of a major domestic or international crisis arising when Congress is not in session, the president is empowered by Article II, Section 3 of the Constitution to call a special session of one or both houses of Congress. Since John Adams first did so in 1797, the president has called the full Congress to convene for a special session on 27 occasions. Harry S. Truman
18690-661: The growing federal bureaucracy, presidents have gradually surrounded themselves with many layers of staff, who were eventually organized into the Executive Office of the President of the United States . Within the Executive Office, the president's innermost layer of aides, and their assistants, are located in the White House Office . The president also possesses the power to manage operations of
18868-474: The head of the executive branch, presidents control a vast array of agencies that can issue regulations with little oversight from Congress. In the 20th century, critics charged that too many legislative and budgetary powers that should have belonged to Congress had slid into the hands of presidents. One critic charged that presidents could appoint a "virtual army of 'czars'—each wholly unaccountable to Congress yet tasked with spearheading major policy efforts for
19046-402: The inner leading edge and 45° at the outer leading edge. Each wing had an inboard and outboard elevon to provide flight control during reentry, along with a flap located between the wings, below the engines to control pitch . The orbiter's vertical stabilizer was swept backwards at 45° and contained a rudder that could split to act as a speed brake . The vertical stabilizer also contained
19224-504: The largest solid-propellant motors ever flown. Each SRB was 45 m (149.2 ft) tall and 3.7 m (12.2 ft) wide, weighed 68,000 kg (150,000 lb), and had a steel exterior approximately 13 mm (.5 in) thick. The SRB's subcomponents were the solid-propellant motor, nose cone, and rocket nozzle. The solid-propellant motor comprised the majority of the SRB's structure. Its casing consisted of 11 steel sections which made up its four main segments. The nose cone housed
19402-575: The late 1950s, the Air Force began developing the partially reusable X-20 Dyna-Soar . The Air Force collaborated with NASA on the Dyna-Soar and began training six pilots in June 1961. The rising costs of development and the prioritization of Project Gemini led to the cancellation of the Dyna-Soar program in December 1963. In addition to the Dyna-Soar, the Air Force had conducted a study in 1957 to test
19580-543: The launch pad, the Space Shuttle was used to verify the proper positioning of the launch complex hardware. Enterprise was taken back to California in August 1979, and later served in the development of the SLC-6 at Vandenberg AFB in 1984. On November 24, 1980, Columbia was mated with its external tank and solid-rocket boosters, and was moved to LC-39 on December 29. The first Space Shuttle mission, STS-1 , would be
19758-673: The law to give him the authority to appoint the Vice President to chair the council in his place. As the Apollo program reached its climax in 1969, President Richard M. Nixon directed Vice President Spiro T. Agnew 's "Space Task Group" to recommend a future direction of the US human spaceflight program. Agnew enthusiastically supported an ambitious Space Transportation System program including reusable spacecraft, permanent Earth and Lunar stations, and human flight to Mars . However, Nixon knew
19936-422: The legislature to a single term only, sharing power with an executive council, and countered by a strong legislature. New York offered the greatest exception, having a strong, unitary governor with veto and appointment power elected to a three-year term, and eligible for reelection to an indefinite number of terms thereafter. It was through the closed-door negotiations at Philadelphia that the presidency framed in
20114-437: The mission specialists who were specifically trained for their intended missions and systems. Early in the Space Shuttle program, NASA flew with payload specialists, who were typically systems specialists who worked for the company paying for the payload's deployment or operations. The final payload specialist, Gregory B. Jarvis , flew on STS-51-L , and future non-pilots were designated as mission specialists. An astronaut flew as
20292-475: The mood in the US Congress would not continue to sustain funding at the level of Apollo, and cut these plans back to only the development of the Space Shuttle , with possible eventual establishment of an Earth orbital space station. President of the United States [REDACTED] [REDACTED] The president of the United States ( POTUS ) is the head of state and head of government of
20470-403: The national goal on May 25, 1961, of landing a man on the Moon by the end of the 1960s and bringing him back to Earth, it became clear to NASA administrator James E. Webb that Gilruth would need a much larger organization and facilities, in fact a new dedicated NASA center, to administer US human spaceflight programs. Webb got the approval of Kennedy, and the Congress, and in August 1961 appointed
20648-539: The necessity of closely coordinating their efforts against the British , the Continental Congress simultaneously began the process of drafting a constitution that would bind the states together. There were long debates on a number of issues, including representation and voting, and the exact powers to be given the central government. Congress finished work on the Articles of Confederation to establish
20826-571: The new facility was being built. By September 1962, his organization was moved to Houston and construction had begun, effectively marking the end of the Task Group. The MSC facility was completed in September 1963. The National Aeronautics and Space Act of 1958, which established NASA, also directed the President of the United States to chair a National Aeronautics and Space Council (later the National Space Council ), including
21004-512: The office as a position of global leadership. His successors, Harry Truman and Dwight D. Eisenhower , each served two terms as the Cold War led the presidency to be viewed as the " leader of the free world ", while John F. Kennedy was a youthful and popular leader who benefited from the rise of television in the 1960s. After Lyndon B. Johnson lost popular support due to the Vietnam War and Richard Nixon 's presidency collapsed in
21182-434: The operational mission. The Space Shuttle was not launched if its flight would run from December to January, as its flight software would have required the orbiter vehicle's computers to be reset at the year change. In 2007, NASA engineers devised a solution so Space Shuttle flights could cross the year-end boundary. Space Shuttle missions typically brought a portable general support computer (PGSC) that could integrate with
21360-424: The optimal design for a reusable spacecraft, and issued study contracts to General Dynamics , Lockheed , McDonnell Douglas , and North American Rockwell . In July 1969, the Space Shuttle Task Group issued a report that determined the Shuttle would support short-duration crewed missions and space station, as well as the capabilities to launch, service, and retrieve satellites. The report also created three classes of
21538-436: The orange foam itself was sufficiently protected, and the ET was no longer covered in latex paint beginning on STS-3. A light-weight tank (LWT) was first flown on STS-6, which reduced tank weight by 4,700 kg (10,300 lb). The LWT's weight was reduced by removing components from the hydrogen tank and reducing the thickness of some skin panels. In 1998, a super light-weight ET (SLWT) first flew on STS-91 . The SLWT used
21716-437: The orbiter vehicle 18 seconds after engine cutoff and could be triggered automatically or manually. At the time of separation, the orbiter vehicle retracted its umbilical plates, and the umbilical cords were sealed to prevent excess propellant from venting into the orbiter vehicle. After the bolts attached at the structural attachments were sheared, the ET separated from the orbiter vehicle. At the time of separation, gaseous oxygen
21894-467: The orbiter vehicle and would be removed and replaced in between flights. The RS-25 is a staged-combustion cycle cryogenic engine that used liquid oxygen and hydrogen and had a higher chamber pressure than any previous liquid-fueled rocket. The original main combustion chamber operated at a maximum pressure of 226.5 bar (3,285 psi). The engine nozzle is 287 cm (113 in) tall and has an interior diameter of 229 cm (90.3 in). The nozzle
22072-510: The orbiter vehicle's computers and communication suite, as well as monitor scientific and payload data. Early missions brought the Grid Compass , one of the first laptop computers, as the PGSC, but later missions brought Apple and Intel laptops. The payload bay comprised most of the orbiter vehicle's fuselage , and provided the cargo-carrying space for the Space Shuttle's payloads. It
22250-549: The orbiter vehicle's heat, and were opened upon reaching orbit for heat rejection. The orbiter could be used in conjunction with a variety of add-on components depending on the mission. This included orbital laboratories, boosters for launching payloads farther into space, the Remote Manipulator System (RMS), and optionally the EDO pallet to extend the mission duration. To limit the fuel consumption while
22428-528: The orbiter was docked at the ISS, the Station-to-Shuttle Power Transfer System (SSPTS) was developed to convert and transfer station power to the orbiter. The SSPTS was first used on STS-118, and was installed on Discovery and Endeavour . The Remote Manipulator System (RMS), also known as Canadarm, was a mechanical arm attached to the cargo bay. It could be used to grasp and manipulate payloads, as well as serve as
22606-423: The original.] In the modern era, pursuant to the War Powers Resolution , Congress must authorize any troop deployments longer than 60 days, although that process relies on triggering mechanisms that have never been employed, rendering it ineffectual. Additionally, Congress provides a check to presidential military power through its control over military spending and regulation. Presidents have historically initiated
22784-601: The originally specified thrust at 100%, but had the RS-25 operate at higher thrust. RS-25 upgrade versions were denoted as Block I and Block II. 109% thrust level was achieved with the Block II engines in 2001, which reduced the chamber pressure to 207.5 bars (3,010 psi), as it had a larger throat area. The normal maximum throttle was 104 percent, with 106% or 109% used for mission aborts. The Orbital Maneuvering System (OMS) consisted of two aft-mounted AJ10-190 engines and
22962-524: The president (and all other executive branch officers) from simultaneously being a member of Congress. Nevertheless, the modern presidency exerts significant power over legislation, both due to constitutional provisions and historical developments over time. The president's most significant legislative power derives from the Presentment Clause , which gives the president the power to veto any bill passed by Congress . While Congress can override
23140-406: The president believes are needed. Additionally, the president can attempt to shape legislation during the legislative process by exerting influence on individual members of Congress. Presidents possess this power because the Constitution is silent about who can write legislation, but the power is limited because only members of Congress can introduce legislation. The president or other officials of
23318-461: The president in the performance of executive duties. George Washington first claimed the privilege when Congress requested to see Chief Justice John Jay 's notes from an unpopular treaty negotiation with Great Britain . While not enshrined in the Constitution or any other law, Washington's action created the precedent for the privilege. When Nixon tried to use executive privilege as a reason for not turning over subpoenaed evidence to Congress during
23496-504: The president is authorized to adjourn Congress if the House and Senate cannot agree on the time of adjournment; no president has ever had to exercise this power. Suffice it to say that the President is made the sole repository of the executive powers of the United States, and the powers entrusted to him as well as the duties imposed upon him are awesome indeed. Nixon v. General Services Administration , 433 U.S. 425 (1977) ( Rehnquist, J. , dissenting ) The president
23674-422: The president personally has absolute immunity from court cases is contested and has been the subject of several Supreme Court decisions. Nixon v. Fitzgerald (1982) dismissed a civil lawsuit against by-then former president Richard Nixon based on his official actions. Clinton v. Jones (1997) decided that a president has no immunity against civil suits for actions taken before becoming president and ruled that
23852-505: The president to "receive Ambassadors." This clause, known as the Reception Clause, has been interpreted to imply that the president possesses broad power over matters of foreign policy, and to provide support for the president's exclusive authority to grant recognition to a foreign government. The Constitution also empowers the president to appoint United States ambassadors, and to propose and chiefly negotiate agreements between
24030-457: The president to appoint and receive ambassadors and conclude treaties with foreign powers, and on subsequent laws enacted by Congress, the modern presidency has primary responsibility for conducting U.S. foreign policy. The role includes responsibility for directing the world's most expensive military , which has the second-largest nuclear arsenal . The president also plays a leading role in federal legislation and domestic policymaking. As part of
24208-516: The president to recommend such measures to Congress which the president deems "necessary and expedient". This is done through the constitutionally-based State of the Union address, which usually outlines the president's legislative proposals for the coming year, and through other formal and informal communications with Congress. The president can be involved in crafting legislation by suggesting, requesting, or even insisting that Congress enact laws that
24386-494: The president's veto power with the Line Item Veto Act . The legislation empowered the president to sign any spending bill into law while simultaneously striking certain spending items within the bill, particularly any new spending, any amount of discretionary spending, or any new limited tax benefit. Congress could then repass that particular item. If the president then vetoed the new legislation, Congress could override
24564-508: The president. The state secrets privilege allows the president and the executive branch to withhold information or documents from discovery in legal proceedings if such release would harm national security . Precedent for the privilege arose early in the 19th century when Thomas Jefferson refused to release military documents in the treason trial of Aaron Burr and again in Totten v. United States 92 U.S. 105 (1876), when
24742-568: The president. In recent decades, presidents have also made increasing use of executive orders , agency regulations, and judicial appointments to shape domestic policy. The president is elected indirectly through the Electoral College to a four-year term, along with the vice president . Under the Twenty-second Amendment , ratified in 1951, no person who has been elected to two presidential terms may be elected to
24920-404: The previous thirty years worked towards "undivided presidential control of the executive branch and its agencies". She criticized proponents of the unitary executive theory for expanding "the many existing uncheckable executive powers—such as executive orders, decrees, memorandums, proclamations, national security directives and legislative signing statements—that already allow presidents to enact
25098-424: The privilege also could not be used in civil suits. These cases established the legal precedent that executive privilege is valid, although the exact extent of the privilege has yet to be clearly defined. Additionally, federal courts have allowed this privilege to radiate outward and protect other executive branch employees but have weakened that protection for those executive branch communications that do not involve
25276-515: The privilege in more cases and at earlier stages of the litigation, thus in some instances causing dismissal of the suits before reaching the merits of the claims, as in the Ninth Circuit 's ruling in Mohamed v. Jeppesen Dataplan, Inc. Critics of the privilege claim its use has become a tool for the government to cover up illegal or embarrassing government actions. The degree to which
25454-500: The process for going to war, but critics have charged that there have been several conflicts in which presidents did not get official declarations, including Theodore Roosevelt 's military move into Panama in 1903, the Korean War , the Vietnam War , and the invasions of Grenada in 1983 and Panama in 1989. The amount of military detail handled personally by the president in wartime has varied greatly. George Washington,
25632-405: The program's lifetime. STS-6 and STS-7 used SRBs 2,300 kg (5,000 lb) lighter due to walls that were 0.10 mm (.004 in) thinner, but were determined to be too thin to fly safely. Subsequent flights until STS-26 used cases that were 0.076 mm (.003 in) thinner than the standard-weight cases, which reduced 1,800 kg (4,000 lb). After the Challenger disaster as
25810-400: The propellant for the Space Shuttle Main Engines, and connected the orbiter vehicle with the solid rocket boosters. The ET was 47 m (153.8 ft) tall and 8.4 m (27.6 ft) in diameter, and contained separate tanks for liquid oxygen and liquid hydrogen. The liquid oxygen tank was housed in the nose of the ET, and was 15 m (49.3 ft) tall. The liquid hydrogen tank comprised
25988-465: The requirements of the Space Shuttle; in July 1971, it issued a contract to Rocketdyne to begin development on the RS-25 engine. NASA reviewed 29 potential designs for the Space Shuttle and determined that a design with two side boosters should be used, and the boosters should be reusable to reduce costs. NASA and the Air Force elected to use solid-propellant boosters because of the lower costs and
26166-685: The reusability of the orbiter required a multi-use heat shield. During reentry, the TPS experienced temperatures up to 1,600 °C (3,000 °F), but had to keep the orbiter vehicle's aluminum skin temperature below 180 °C (350 °F). The TPS primarily consisted of four types of tiles. The nose cone and leading edges of the wings experienced temperatures above 1,300 °C (2,300 °F), and were protected by reinforced carbon-carbon tiles (RCC). Thicker RCC tiles were developed and installed in 1998 to prevent damage from micrometeoroid and orbital debris , and were further improved after RCC damage caused in
26344-529: The shuttle could then be constructed of lightweight aluminum , and the tiles could be individually replaced as needed. Construction began on Columbia on March 27, 1975, and it was delivered to the KSC on March 25, 1979. At the time of its arrival at the KSC, Columbia still had 6,000 of its 30,000 tiles remaining to be installed. However, many of the tiles that had been originally installed had to be replaced, requiring two years of installation before Columbia could fly. On January 5, 1979, NASA commissioned
26522-493: The size and scope of the federal government, including more executive agencies. The traditionally small presidential staff was greatly expanded, with the Executive Office of the President being created in 1939, none of whom require Senate confirmation. Roosevelt's unprecedented re-election to a third and fourth term, the victory of the United States in World War II , and the nation's growing economy all helped established
26700-462: The system of separation of powers , Article I, Section 7 of the Constitution gives the president the power to sign or veto federal legislation. Since modern presidents are typically viewed as leaders of their political parties, major policymaking is significantly shaped by the outcome of presidential elections, with presidents taking an active role in promoting their policy priorities to members of Congress who are often electorally dependent on
26878-622: The tradition of throwing out the ceremonial first pitch in 1910 at Griffith Stadium , Washington, D.C., on the Washington Senators's Opening Day . Every president since Taft, except for Jimmy Carter , threw out at least one ceremonial first ball or pitch for Opening Day, the All-Star Game , or the World Series , usually with much fanfare. Every president since Theodore Roosevelt has served as honorary president of
27056-418: The underside of Columbia , and determined there was no damage. Columbia reentered the atmosphere and landed at Edwards AFB on April 14. NASA conducted three additional test flights with Columbia in 1981 and 1982. On July 4, 1982, STS-4 , flown by Ken Mattingly and Henry Hartsfield , landed on a concrete runway at Edwards AFB. President Ronald Reagan and his wife Nancy met the crew, and delivered
27234-467: The upper parts of the orbiter vehicle were coated in tiles of white low-temperature reusable surface insulation with similar composition, which provided protection for temperatures below 650 °C (1,200 °F). The payload bay doors and parts of the upper wing surfaces were coated in reusable Nomex felt surface insulation or in beta cloth , as the temperature there remained below 370 °C (700 °F). The Space Shuttle external tank (ET) carried
27412-407: The veto by its ordinary means, a two-thirds vote in both houses. In Clinton v. City of New York , 524 U.S. 417 (1998), the U.S. Supreme Court ruled such a legislative alteration of the veto power to be unconstitutional. For most of American history, candidates for president have sought election on the basis of a promised legislative agenda. Article II, Section 3, Clause 2 requires
27590-528: The veto should only be used in cases where a bill was unconstitutional, it is now routinely used in cases where presidents have policy disagreements with a bill. The veto – or threat of a veto – has thus evolved to make the modern presidency a central part of the American legislative process. Specifically, under the Presentment Clause, once a bill has been presented by Congress, the president has three options: In 1996, Congress attempted to enhance
27768-462: Was 18 m (60 ft) long and 4.6 m (15 ft) wide, and could accommodate cylindrical payloads up to 4.6 m (15 ft) in diameter. Two payload bay doors hinged on either side of the bay, and provided a relatively airtight seal to protect payloads from heating during launch and reentry. Payloads were secured in the payload bay to the attachment points on the longerons . The payload bay doors served an additional function as radiators for
27946-499: Was Space Shuttle-specific software that provided control through all phases of flight. During ascent, maneuvering, reentry, and landing, the four PASS GPCs functioned identically to produce quadruple redundancy and would error check their results. In case of a software error that would cause erroneous reports from the four PASS GPCs, a fifth GPC ran the Backup Flight System, which used a different program and could control
28124-641: Was a modified airport jet bridge that was used to assist astronauts to egress from the orbiter after landing, where they would undergo their post-mission medical checkups. The Astrovan transported astronauts from the crew quarters in the Operations and Checkout Building to the launch pad on launch day. The NASA Railroad comprised three locomotives that transported SRB segments from the Florida East Coast Railway in Titusville to
28302-569: Was a significant milestone, as Jackson was not part of the Virginia and Massachusetts elite that had held the presidency for its first 40 years. Jacksonian democracy sought to strengthen the presidency at the expense of Congress, while broadening public participation as the nation rapidly expanded westward. However, his successor, Martin Van Buren , became unpopular after the Panic of 1837 , and
28480-517: Was available as a remedy. As of October 2019, a case was pending in the federal courts regarding access to personal tax returns in a criminal case brought against Donald Trump by the New York County District Attorney alleging violations of New York state law. As head of state , the president represents the United States government to its own people and represents the nation to the rest of the world. For example, during
28658-466: Was carried for 5.6 km (3.5 mi) to Launch Complex 39 by one of the crawler-transporters . After the Space Shuttle arrived at one of the two launchpads, it would connect to the Fixed and Rotation Service Structures, which provided servicing capabilities, payload insertion, and crew transportation. The crew was transported to the launch pad at T−3 hours and entered the orbiter vehicle, which
28836-565: Was closed at T−2 hours. Liquid oxygen and hydrogen were loaded into the external tank via umbilicals that attached to the orbiter vehicle, which began at T−5 hours 35 minutes. At T−3 hours 45 minutes, the hydrogen fast-fill was complete, followed 15 minutes later by the oxygen tank fill. Both tanks were slowly filled up until the launch as the oxygen and hydrogen evaporated. The launch commit criteria considered precipitation, temperatures, cloud cover, lightning forecast, wind, and humidity. The Space Shuttle
29014-686: Was completed on September 17, 1976, and Enterprise was moved to the Edwards Air Force Base to begin testing. Rockwell constructed the Main Propulsion Test Article (MPTA)-098 , which was a structural truss mounted to the ET with three RS-25 engines attached. It was tested at the National Space Technology Laboratory (NSTL) to ensure that the engines could safely run through the launch profile. Rockwell conducted mechanical and thermal stress tests on Structural Test Article (STA)-099 to determine
29192-551: Was entirely reliant on its main computer, the Data Processing System (DPS). The DPS controlled the flight controls and thrusters on the orbiter, as well as the ET and SRBs during launch. The DPS consisted of five general-purpose computers (GPC), two magnetic tape mass memory units (MMUs), and the associated sensors to monitor the Space Shuttle components. The original GPC used was the IBM AP-101B , which used
29370-657: Was equipped with an avionics system to provide information and control during atmospheric flight. Its avionics suite contained three microwave scanning beam landing systems , three gyroscopes , three TACANs , three accelerometers , two radar altimeters , two barometric altimeters , three attitude indicators , two Mach indicators , and two Mode C transponders . During reentry, the crew deployed two air data probes once they were traveling slower than Mach 5. The orbiter had three inertial measuring units (IMU) that it used for guidance and navigation during all phases of flight. The orbiter contains two star trackers to align
29548-653: Was first flown in 1975, and was used for the ALT and ferrying the orbiter from Edwards AFB to the KSC on all missions prior to 1991. A second SCA (N911NA) was acquired in 1988, and was first used to transport Endeavour from the factory to the KSC. Following the retirement of the Space Shuttle, N905NA was put on display at the JSC, and N911NA was put on display at the Joe Davies Heritage Airpark in Palmdale, California . The Crew Transport Vehicle (CTV)
29726-403: Was later improved to 270,000 kg (586,000 lb). The Spacelab module was a European-funded pressurized laboratory that was carried within the payload bay and allowed for scientific research while in orbit. The Spacelab module contained two 2.7 m (9 ft) segments that were mounted in the aft end of the payload bay to maintain the center of gravity during flight. Astronauts entered
29904-406: Was located below the flight deck and was where the galley and crew bunks were set up, as well as three or four crew member seats. The mid-deck contained the airlock, which could support two astronauts on an extravehicular activity (EVA), as well as access to pressurized research modules. An equipment bay was below the mid-deck, which stored environmental control and waste management systems. On
30082-617: Was moved to the Marshall Space Flight Center (MSFC) on March 13, 1978. Enterprise underwent shake tests in the Mated Vertical Ground Vibration Test, where it was attached to an external tank and solid rocket boosters, and underwent vibrations to simulate the stresses of launch. In April 1979, Enterprise was taken to the KSC, where it was attached to an external tank and solid rocket boosters, and moved to LC-39 . Once installed at
30260-539: Was nearly removed from office, with Congress remaining powerful during the two-term presidency of Civil War general Ulysses S. Grant . After the end of Reconstruction , Grover Cleveland would eventually become the first Democratic president elected since before the war, running in three consecutive elections (1884, 1888, 1892) and winning twice. In 1900, William McKinley became the first incumbent to win re-election since Grant in 1872. After McKinley's assassination by Leon Czolgosz in 1901, Theodore Roosevelt became
30438-602: Was never used). The Johnson Space Center (JSC) served as the central point for all Shuttle operations and the MSFC was responsible for the main engines, external tank, and solid rocket boosters. The John C. Stennis Space Center handled main engine testing, and the Goddard Space Flight Center managed the global tracking network. The orbiter had design elements and capabilities of both a rocket and an aircraft to allow it to launch vertically and then land as
30616-422: Was not launched under conditions where it could have been struck by lightning , as its exhaust plume could have triggered lightning by providing a current path to ground after launch, which occurred on Apollo 12 . The NASA Anvil Rule for a Shuttle launch stated that an anvil cloud could not appear within a distance of 19 km (10 nmi). The Shuttle Launch Weather Officer monitored conditions until
30794-418: Was tested on STS-2 and STS-3, and the first full mission was on STS-9. Three RS-25 engines, also known as the Space Shuttle Main Engines (SSME), were mounted on the orbiter's aft fuselage in a triangular pattern. The engine nozzles could gimbal ±10.5° in pitch, and ±8.5° in yaw during ascent to change the direction of their thrust to steer the Shuttle. The titanium alloy reusable engines were independent of
30972-489: Was the first branch of government described in the Constitution , to be the dominant branch of government; however, they did not expect a strong executive department. However, presidential power has shifted over time, which has resulted in claims that the modern presidency has become too powerful, unchecked, unbalanced, and "monarchist" in nature. In 2008 professor Dana D. Nelson expressed belief that presidents over
31150-701: Was the most recent to do so in July 1948, known as the Turnip Day Session . In addition, prior to ratification of the Twentieth Amendment in 1933, which brought forward the date on which Congress convenes from December to January, newly inaugurated presidents would routinely call the Senate to meet to confirm nominations or ratify treaties. In practice, the power has fallen into disuse in the modern era as Congress now formally remains in session year-round, convening pro forma sessions every three days even when ostensibly in recess. Correspondingly,
31328-444: Was the top level of the crew compartment and contained the flight controls for the orbiter. The commander sat in the front left seat, and the pilot sat in the front right seat, with two to four additional seats set up for additional crew members. The instrument panels contained over 2,100 displays and controls, and the commander and pilot were both equipped with a heads-up display (HUD) and a Rotational Hand Controller (RHC) to gimbal
31506-440: Was the youngest member of the group. The head of the public affairs office was John "Shorty" Powers . In 1959, the group was expanded by the addition of 32 engineers from Canada, who had been left without jobs when the Avro Arrow project was cancelled. These new engineers included Jim Chamberlin , George Harris , John Hodge , Owen Maynard , Bryan Erb , Rodney Rose , and Tecwyn Roberts . After President John F. Kennedy set
31684-498: Was vented from the nose to cause the ET to tumble, ensuring that it would break up upon reentry. The ET was the only major component of the Space Shuttle system that was not reused, and it would travel along a ballistic trajectory into the Indian or Pacific Ocean. For the first two missions, STS-1 and STS-2 , the ET was covered in 270 kg (595 lb) of white fire-retardant latex paint to provide protection against damage from ultraviolet radiation. Further research determined that
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