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79-565: In the United States, Discoverer II was a proposed military space-based radar program initiated in February 1998 as a joint Air Force, DARPA , and NRO program. The concept was to provide high-range-resolution ground moving target indication (GMTI), as well as SAR imaging and high-resolution digital mapping. This program was cancelled by Congress in 2007. SBR is a less-ambitious version of Discoverer II. Space-based radar ( SBR )

158-541: A mission module cabin separate from the command module (piloting and reentry cabin), and a propulsion and equipment module . On August 30, a feasibility study competition was announced, and on October 25, three study contracts were awarded to General Dynamics/Convair , General Electric , and the Glenn L. Martin Company . Meanwhile, NASA performed its own in-house spacecraft design studies led by Maxime Faget , to serve as

237-773: A 130-million-cubic-foot (3,700,000 m ) Vertical Assembly Building (VAB). in which the space vehicle (launch vehicle and spacecraft) would be assembled on a mobile launcher platform and then moved by a crawler-transporter to one of several launch pads. Although at least three pads were planned, only two, designated A   and   B, were completed in October 1965. The LOC also included an Operations and Checkout Building (OCB) to which Gemini and Apollo spacecraft were initially received prior to being mated to their launch vehicles. The Apollo spacecraft could be tested in two vacuum chambers capable of simulating atmospheric pressure at altitudes up to 250,000 feet (76 km), which

316-470: A commitment on America's response to the Soviets. On April 20, Kennedy sent a memo to Vice President Lyndon B. Johnson , asking Johnson to look into the status of America's space program, and into programs that could offer NASA the opportunity to catch up. Johnson responded approximately one week later, concluding that "we are neither making maximum effort nor achieving results necessary if this country

395-460: A gauge to judge and monitor the three industry designs. In November 1960, John F. Kennedy was elected president after a campaign that promised American superiority over the Soviet Union in the fields of space exploration and missile defense . Up to the election of 1960, Kennedy had been speaking out against the " missile gap " that he and many other senators said had developed between

474-471: A global scale. Data from radar altimeters are used for the accurate determination of the geoid, monitoring of tides, ocean currents and other large-scale ocean phenomena such as El Niño . SARs applications are many: they range from geology to crop monitoring, from measurement of sea ice to disaster monitoring to vessel traffic surveillance, not to forget the military applications (many civilian SAR satellites are, in fact, dual-use systems). SAR imaging offer

553-543: A great new American enterprise—time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on Earth. ...   I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important in

632-462: A limited Earth orbital mission, Apollo would carry three. Possible missions included ferrying crews to a space station , circumlunar flights , and eventual crewed lunar landings . In July 1960, NASA Deputy Administrator Hugh L. Dryden announced the Apollo program to industry representatives at a series of Space Task Group conferences. Preliminary specifications were laid out for a spacecraft with

711-459: A qualitative change in the systems architecture of the nation's reconnaissance assets... We see the opportunity to move towards an operational capability for the country, at least for imagery systems, that consists of an array of smaller, cheaper spacecraft in larger numbers which is at least as useful as those currently planned and to transport them to space with substantially smaller and less costly launch vehicles." The Defense Science Board (DSB)

790-404: A reaction control system. The initial LM model weighed approximately 33,300 pounds (15,100 kg), and allowed surface stays up to around 34 hours. An extended lunar module (ELM) weighed over 36,200 pounds (16,400 kg), and allowed surface stays of more than three days. The contract for design and construction of the lunar module was awarded to Grumman Aircraft Engineering Corporation , and

869-558: A spacecraft that could meet it while minimizing risk to human life, limiting cost, and not exceeding limits in possible technology and astronaut skill. Four possible mission modes were considered: In early 1961, direct ascent was generally the mission mode in favor at NASA. Many engineers feared that rendezvous and docking, maneuvers that had not been attempted in Earth orbit , would be nearly impossible in lunar orbit . LOR advocates including John Houbolt at Langley Research Center emphasized

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948-515: A study phase, the project planned to launch two experimental satellites for demonstration and risk reduction. The project apparently suffered difficulties, and was canceled by Congress in 2000. Project Apollo The Apollo program , also known as Project Apollo , was the United States human spaceflight program carried out by the National Aeronautics and Space Administration (NASA), which succeeded in preparing and landing

1027-553: A very rapid revisit rate (about 15 minutes) to most areas of the earth for near-continuous surveillance of terrestrial and maritime vehicles, and could produce Interferometric SAR images for high-resolution terrain mapping. When needed, constellation tasking could be directed by a deployed Joint Task Force tactical commander. On February 22, 1999, three contractor teams were selected, led by Lockheed Martin Astronautics, Spectrum Astro , and TRW Defense Systems Division. After

1106-506: Is a nadir -looking radar with very high range resolution, which measures the ocean surface topography with an accuracy in the order of few centimeters. Additionally, analysis of the echo amplitude and shape can extract information about the wind speed and wave height, respectively. Some radar-altimeters (like CryoSat /SIRAL) employ synthetic aperture and/or interferometric techniques: their reduced footprint allows mapping of rougher surfaces like polar ices. A wind scatterometer observes

1185-592: Is a proposed constellation of active radar satellites for the United States Department of Defense . The SBR system would allow detection and tracking of aircraft , ocean-going vessels (similar to the Soviet US-A program), and potentially land vehicles from space. This information would then be relayed to regional and national command centers, as well as E-10 MC2A airborne command posts. Use of radar sensor for Earth observation purposes

1264-508: Is nearly a vacuum. Administrator Webb realized that in order to keep Apollo costs under control, he had to develop greater project management skills in his organization, so he recruited George E. Mueller for a high management job. Mueller accepted, on the condition that he have a say in NASA reorganization necessary to effectively administer Apollo. Webb then worked with Associate Administrator (later Deputy Administrator) Seamans to reorganize

1343-472: Is to reach a position of leadership." His memo concluded that a crewed Moon landing was far enough in the future that it was likely the United States would achieve it first. On May 25, 1961, twenty days after the first US crewed spaceflight Freedom 7 , Kennedy proposed the crewed Moon landing in a Special Message to the Congress on Urgent National Needs : Now it is time to take longer strides—time for

1422-668: The Apollo command and service module , succeeding the Mercury program . A lunar landing became the focus of the program only in 1961. Thereafter Project Gemini instead followed the Mercury program to test and study advanced crewed spaceflight technology. The Apollo program was conceived during the Eisenhower administration in early 1960, as a follow-up to Project Mercury. While the Mercury capsule could support only one astronaut on

1501-702: The European Space Agency 's Mars Express probe, and SHARAD (mars SHAllow RADar sounder) on JPL 's Mars Reconnaissance Orbiter (MRO). Both are currently operational. A radar sounder is also used on the Japanese Moon probe SELENE , launched September 14, 2007. A similar instrument (primarily devoted to ionospheric plasma probing) was embarked on the Japanese Martian mission Nozomi (launched in 1998 but lost). Discoverer II Discoverer II (initially known as STARLITE )

1580-522: The SPS ." Ironically, just such a failure happened on Apollo 13 when an oxygen tank explosion left the CSM without electrical power. The lunar module provided propulsion, electrical power and life support to get the crew home safely. Faget's preliminary Apollo design employed a cone-shaped command module, supported by one of several service modules providing propulsion and electrical power, sized appropriately for

1659-540: The Saturn V launch vehicle and LOR by forcing Shea, Seamans, and even Webb to defend themselves, delaying its formal announcement to the press on July 11, 1962, and forcing Webb to still hedge the decision as "tentative". Wiesner kept up the pressure, even making the disagreement public during a two-day September visit by the President to Marshall Space Flight Center . Wiesner blurted out "No, that's no good" in front of

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1738-516: The Tropical Rainfall Measuring Mission , or cloud radars like the one used on Cloudsat . Like other Earth observation satellites , radar satellites often use Sun-synchronous orbits so that diurnal variations of vegetation are ignored, allowing long-term variations to be more accurately measured. Earth-observing radar satellites and satellite constellations include the following, with operational dates. Most of

1817-526: The U.S. Air Force , so he got Webb's permission to recruit General Samuel C. Phillips , who gained a reputation for his effective management of the Minuteman program, as OMSF program controller. Phillips's superior officer Bernard A. Schriever agreed to loan Phillips to NASA, along with a staff of officers under him, on the condition that Phillips be made Apollo Program Director. Mueller agreed, and Phillips managed Apollo from January 1964, until it achieved

1896-737: The White Sands Missile Range between May 1964 and January 1966. Saturn I, the first US heavy lift launch vehicle, was initially planned to launch partially equipped CSMs in low Earth orbit tests. The S-I first stage burned RP-1 with liquid oxygen (LOX) oxidizer in eight clustered Rocketdyne H-1 engines, to produce 1,500,000 pounds-force (6,670 kN) of thrust. The S-IV second stage used six liquid hydrogen-fueled Pratt & Whitney RL-10 engines with 90,000 pounds-force (400 kN) of thrust. The S-V third stage flew inactively on Saturn I four times. The first four Saturn I test flights were launched from LC-34, with only

1975-548: The command and service module (CSM), and all three landed safely on Earth in the Pacific Ocean on July 24. Five subsequent Apollo missions also landed astronauts on the Moon, the last, Apollo 17 , in December 1972. In these six spaceflights, twelve people walked on the Moon . Apollo ran from 1961 to 1972, with the first crewed flight in 1968. It encountered a major setback in 1967 when an Apollo 1 cabin fire killed

2054-450: The "5" indicating Saturn V. The three-stage Saturn V was designed to send a fully fueled CSM and LM to the Moon. It was 33 feet (10.1 m) in diameter and stood 363 feet (110.6 m) tall with its 96,800-pound (43,900 kg) lunar payload. Its capability grew to 103,600 pounds (47,000 kg) for the later advanced lunar landings. The S-IC first stage burned RP-1/LOX for a rated thrust of 7,500,000 pounds-force (33,400 kN), which

2133-451: The 1960s, President Kennedy's target date. The LOR method had the advantage of allowing the lander spacecraft to be used as a "lifeboat" in the event of a failure of the command ship. Some documents prove this theory was discussed before and after the method was chosen. In 1964 an MSC study concluded, "The LM [as lifeboat]   ... was finally dropped, because no single reasonable CSM failure could be identified that would prohibit use of

2212-520: The Air Force and the NRO established a joint program to undertake a "Space-based Radar Risk Reduction and Demonstration Program". The Discoverer II constellation was envisioned to be 24 satellites, each configured with Synthetic Aperture Radar (SAR) and Ground Moving Target Indication (GMTI) radar systems. Each satellite was envisioned to cost approximately $ 100 million. The constellation would allow for

2291-523: The CSM's role to the translunar ferry used to transport the crew, along with a new spacecraft, the Lunar Excursion Module (LEM, later shortened to LM (Lunar Module) but still pronounced / ˈ l ɛ m / ) which would take two individuals to the lunar surface and return them to the CSM. The command module (CM) was the conical crew cabin, designed to carry three astronauts from launch to lunar orbit and back to an Earth ocean landing. It

2370-630: The Canaveral launch facilities in Florida . The two newest launch complexes were already being built for the Saturn I and IB rockets at the northernmost end: LC-34 and LC-37 . But an even bigger facility would be needed for the mammoth rocket required for the crewed lunar mission, so land acquisition was started in July 1961 for a Launch Operations Center (LOC) immediately north of Canaveral at Merritt Island . The design, development and construction of

2449-430: The Earth's atmosphere or return to Earth, its fuselage was designed totally without aerodynamic considerations and was of an extremely lightweight construction. It consisted of separate descent and ascent stages, each with its own engine. The descent stage contained storage for the descent propellant, surface stay consumables, and surface exploration equipment. The ascent stage contained the crew cabin, ascent propellant, and

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2528-570: The Earth, Gilruth had moved his organization to rented space in Houston, and construction of the MSC facility was under way, Kennedy visited Rice to reiterate his challenge in a famous speech : But why, some say, the Moon? Why choose this as our goal? And they may well ask, why climb the highest mountain ? Why, 35 years ago, fly the Atlantic ?   ... We choose to go to the Moon. We choose to go to

2607-613: The Moon by the end of 1969 required the most sudden burst of technological creativity, and the largest commitment of resources ($ 25 billion; $ 182 billion in 2023 US dollars) ever made by any nation in peacetime. At its peak, the Apollo program employed 400,000 people and required the support of over 20,000 industrial firms and universities. On July 1, 1960, NASA established the Marshall Space Flight Center (MSFC) in Huntsville, Alabama . MSFC designed

2686-628: The Moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills; because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win   ... The MSC was completed in September 1963. It was renamed by the US Congress in honor of Lyndon Johnson soon after his death in 1973. It also became clear that Apollo would outgrow

2765-676: The Moon, crippling the CSM. The crew barely managed a safe return to Earth by using the lunar module as a "lifeboat" on the return journey. Apollo used the Saturn family of rockets as launch vehicles, which were also used for an Apollo Applications Program , which consisted of Skylab , a space station that supported three crewed missions in 1973–1974, and the Apollo–Soyuz Test Project, a joint United States - Soviet Union low Earth orbit mission in 1975. Apollo set several major human spaceflight milestones . It stands alone in sending crewed missions beyond low Earth orbit . Apollo 8

2844-591: The October Cuban Missile Crisis , and fear of Kennedy's support for Webb. NASA announced the selection of Grumman as the LEM contractor in November 1962. Space historian James Hansen concludes that: Without NASA's adoption of this stubbornly held minority opinion in 1962, the United States may still have reached the Moon, but almost certainly it would not have been accomplished by the end of

2923-815: The Office of Manned Space Flight (OMSF). On July 23, 1963, Webb announced Mueller's appointment as Deputy Associate Administrator for Manned Space Flight, to replace then Associate Administrator D. Brainerd Holmes on his retirement effective September 1. Under Webb's reorganization, the directors of the Manned Spacecraft Center ( Gilruth ), Marshall Space Flight Center ( von Braun ), and the Launch Operations Center ( Debus ) reported to Mueller. Based on his industry experience on Air Force missile projects, Mueller realized some skilled managers could be found among high-ranking officers in

3002-555: The Saturn V. The Saturn IB could send over 40,000 pounds (18,100 kg) into low Earth orbit, sufficient for a partially fueled CSM or the LM. Saturn IB launch vehicles and flights were designated with an AS-200 series number, "AS" indicating "Apollo Saturn" and the "2" indicating the second member of the Saturn rocket family. Saturn V launch vehicles and flights were designated with an AS-500 series number, "AS" indicating "Apollo Saturn" and

3081-518: The Soviet Union and the United States due to the inaction of President Eisenhower. Beyond military power, Kennedy used aerospace technology as a symbol of national prestige, pledging to make the US not "first but, first and, first if, but first period". Despite Kennedy's rhetoric, he did not immediately come to a decision on the status of the Apollo program once he became president. He knew little about

3160-472: The center was conducted by Kurt H. Debus , a member of Wernher von Braun 's original V-2 rocket engineering team. Debus was named the LOC's first Director. Construction began in November 1962. Following Kennedy's death , President Johnson issued an executive order on November 29, 1963, to rename the LOC and Cape Canaveral in honor of Kennedy. The LOC included Launch Complex 39 , a Launch Control Center , and

3239-426: The clear goal of a crewed landing replacing the more nebulous goals of space stations and circumlunar flights, NASA decided that, in order to make progress quickly, it would discard the feasibility study designs of Convair, GE, and Martin, and proceed with Faget's command and service module design. The mission module was determined to be useful only as an extra room, and therefore unnecessary. They used Faget's design as

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3318-449: The contract to build the CSM, and also the second stage of the Saturn V launch vehicle for NASA. Because the CSM design was started early before the selection of lunar orbit rendezvous, the service propulsion engine was sized to lift the CSM off the Moon, and thus was oversized to about twice the thrust required for translunar flight. Also, there was no provision for docking with the lunar module. A 1964 program definition study concluded that

3397-425: The entire crew during a prelaunch test. After the first successful landing, sufficient flight hardware remained for nine follow-on landings with a plan for extended lunar geological and astrophysical exploration. Budget cuts forced the cancellation of three of these. Five of the remaining six missions achieved successful landings, but the Apollo 13 landing had to be aborted after an oxygen tank exploded en route to

3476-463: The first human landing in July 1969, after which he returned to Air Force duty. Charles Fishman, in One Giant Leap , estimated the number of people and organizations involved into the Apollo program as "410,000 men and women at some 20,000 different companies contributed to the effort". Once Kennedy had defined a goal, the Apollo mission planners were faced with the challenge of designing

3555-441: The first men on the Moon in 1969. It was first conceived in 1960 during President Dwight D. Eisenhower's administration as a three-person spacecraft to follow the one-person Project Mercury , which put the first Americans in space. Apollo was later dedicated to President John F. Kennedy 's national goal for the 1960s of "landing a man on the Moon and returning him safely to the Earth" in an address to Congress on May 25, 1961. It

3634-485: The first person to fly in space, reinforcing American fears about being left behind in a technological competition with the Soviet Union. At a meeting of the US House Committee on Science and Astronautics one day after Gagarin's flight, many congressmen pledged their support for a crash program aimed at ensuring that America would catch up. Kennedy was circumspect in his response to the news, refusing to make

3713-421: The first stage live, carrying dummy upper stages filled with water. The first flight with a live S-IV was launched from LC-37. This was followed by five launches of boilerplate CSMs (designated AS-101 through AS-105 ) into orbit in 1964 and 1965. The last three of these further supported the Apollo program by also carrying Pegasus satellites, which verified the safety of the translunar environment by measuring

3792-445: The frequency and severity of micrometeorite impacts. In September 1962, NASA planned to launch four crewed CSM flights on the Saturn I from late 1965 through 1966, concurrent with Project Gemini. The 22,500-pound (10,200 kg) payload capacity would have severely limited the systems which could be included, so the decision was made in October 1963 to use the uprated Saturn IB for all crewed Earth orbital flights. The Saturn IB

3871-487: The great advantage, over its optical counterparts, of not being affected by meteorological conditions such as clouds, fog, etc., making it the sensor of choice when continuity of data must be ensured. Additionally, SAR interferometry (both dual-pass or single-pass, as used in the SRTM mission) allows accurate 3-D Reconstruction. Other types of radars have been flown for Earth observation missions: precipitation radars such as

3950-508: The heavy lift-class Saturn launch vehicles , which would be required for Apollo. It became clear that managing the Apollo program would exceed the capabilities of Robert R. Gilruth 's Space Task Group , which had been directing the nation's crewed space program from NASA's Langley Research Center . So Gilruth was given authority to grow his organization into a new NASA center, the Manned Spacecraft Center (MSC). A site

4029-488: The important weight reductions that were offered by the LOR approach. Throughout 1960 and 1961, Houbolt campaigned for the recognition of LOR as a viable and practical option. Bypassing the NASA hierarchy, he sent a series of memos and reports on the issue to Associate Administrator Robert Seamans; while acknowledging that he spoke "somewhat as a voice in the wilderness", Houbolt pleaded that LOR should not be discounted in studies of

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4108-496: The initial design should be continued as Block I which would be used for early testing, while Block II, the actual lunar spacecraft, would incorporate the docking equipment and take advantage of the lessons learned in Block I development. The Apollo Lunar Module (LM) was designed to descend from lunar orbit to land two astronauts on the Moon and take them back to orbit to rendezvous with the command module. Not designed to fly through

4187-450: The long-range exploration of space; and none will be so difficult or expensive to accomplish. At the time of Kennedy's proposal, only one American had flown in space—less than a month earlier—and NASA had not yet sent an astronaut into orbit. Even some NASA employees doubted whether Kennedy's ambitious goal could be met. By 1963, Kennedy even came close to agreeing to a joint US-USSR Moon mission, to eliminate duplication of effort. With

4266-510: The lunar flights. On the extended lunar missions, an orbital scientific instrument package was carried. The service module was discarded just before reentry. The module was 24.6 feet (7.5 m) long and 12.83 feet (3.91 m) in diameter. The initial lunar flight version weighed approximately 51,300 pounds (23,300 kg) fully fueled, while a later version designed to carry a lunar orbit scientific instrument package weighed just over 54,000 pounds (24,000 kg). North American Aviation won

4345-434: The moon. The Cassini radar was a multimode system and could operate as Synthetic Aperture Radar , radar altimeter , scatterometer and radiometer . Sounding radars : these are low-frequency (normally, HF - 3 to 30 MHz - or lower) ground-penetrating Radars , used to acquire data about the planet sub-surface structure. Their low operating frequency allow them to penetrate hundreds of meters, or even kilometers, below

4424-459: The planet in 1983 and 1984 using SAR and Radar altimeters . The Magellan probe also imaged Venus in 1990 and 1994. The only other target of an imaging radar mission has been Titan , the largest moon of Saturn , in order to penetrate its opaque atmosphere. The radar of the Cassini probe , which orbited Saturn between 2004 and 2017, provided images of Titan's surface during each fly-by of

4503-483: The press, during a presentation by von Braun. Webb jumped in and defended von Braun, until Kennedy ended the squabble by stating that the matter was "still subject to final review". Webb held firm and issued a request for proposal to candidate Lunar Excursion Module (LEM) contractors. Wiesner finally relented, unwilling to settle the dispute once and for all in Kennedy's office, because of the President's involvement with

4582-556: The project was overseen by Thomas J. Kelly . Before the Apollo program began, Wernher von Braun and his team of rocket engineers had started work on plans for very large launch vehicles, the Saturn series , and the even larger Nova series. In the midst of these plans, von Braun was transferred from the Army to NASA and was made Director of the Marshall Space Flight Center. The initial direct ascent plan to send

4661-519: The question. Seamans's establishment of an ad hoc committee headed by his special technical assistant Nicholas E. Golovin in July 1961, to recommend a launch vehicle to be used in the Apollo program, represented a turning point in NASA's mission mode decision. This committee recognized that the chosen mode was an important part of the launch vehicle choice, and recommended in favor of a hybrid EOR-LOR mode. Its consideration of LOR—as well as Houbolt's ceaseless work—played an important role in publicizing

4740-457: The radars flown as payload in planetary missions (i.e., not considering avionics radar, such as docking and landing radars used in Apollo and LEM ) belong to two categories: imaging radars and sounders. Imaging radars : Synthetic aperture radars are the only instruments capable of penetrating heavy cloud cover around planets such as Venus , which was the first target for such missions. Two Soviet spacecraft ( Venera 15 and Venera 16 ) imaged

4819-557: The same portion of the ocean surface from different (at least 3) angles of view as the satellite passes by, measuring the echo amplitude and the corresponding surface reflectivity. Reflectivity being affected by the ocean surface "roughness", which in turn is affected by the wind and also dependent on its direction, this instrument can determine the wind speed and direction. These three types of radar are currently used on several satellites. Scatterometers are of high value for operational meteorology, allowing reconstruction of wind fields on

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4898-400: The space station, cislunar, and lunar landing missions. Once Kennedy's Moon landing goal became official, detailed design began of a command and service module (CSM) in which the crew would spend the entire direct-ascent mission and lift off from the lunar surface for the return trip, after being soft-landed by a larger landing propulsion module. The final choice of lunar orbit rendezvous changed

4977-452: The specification for another competition for spacecraft procurement bids in October 1961. On November 28, 1961, it was announced that North American Aviation had won the contract, although its bid was not rated as good as the Martin proposal. Webb, Dryden and Robert Seamans chose it in preference due to North American's longer association with NASA and its predecessor . Landing humans on

5056-514: The surface. Synthetic aperture techniques are normally exploited to reduce the ground footprint (due to the low operating frequency and the small allowable antenna dimensions, the beam is very wide) and, thus, the unwanted echo from other surface objects. The first radar sounder flown was ALSE (Apollo Lunar Sounder Experiment) on board Apollo 17 in 1972. Other sounder instruments flown (in this case around Mars ), are MARSIS (Mars Advanced Radar for SubSurface and Ionosphere Sounding) on board

5135-427: The technical details of the space program, and was put off by the massive financial commitment required by a crewed Moon landing. When Kennedy's newly appointed NASA Administrator James E. Webb requested a 30 percent budget increase for his agency, Kennedy supported an acceleration of NASA's large booster program but deferred a decision on the broader issue. On April 12, 1961, Soviet cosmonaut Yuri Gagarin became

5214-940: The three-person Apollo command and service module directly to the lunar surface, on top of a large descent rocket stage, would require a Nova-class launcher, with a lunar payload capability of over 180,000 pounds (82,000 kg). The June 11, 1962, decision to use lunar orbit rendezvous enabled the Saturn V to replace the Nova, and the MSFC proceeded to develop the Saturn rocket family for Apollo. Since Apollo, like Mercury, used more than one launch vehicle for space missions, NASA used spacecraft-launch vehicle combination series numbers: AS-10x for Saturn I, AS-20x for Saturn IB, and AS-50x for Saturn V (compare Mercury-Redstone 3 , Mercury-Atlas 6 ) to designate and plan all missions, rather than numbering them sequentially as in Project Gemini. This

5293-430: The workability of the approach. In late 1961 and early 1962, members of the Manned Spacecraft Center began to come around to support LOR, including the newly hired deputy director of the Office of Manned Space Flight, Joseph Shea , who became a champion of LOR. The engineers at Marshall Space Flight Center (MSFC), who were heavily invested in direct ascent, took longer to become convinced of its merits, but their conversion

5372-482: Was 11.42 feet (3.48 m) tall, 12.83 feet (3.91 m) in diameter, and weighed approximately 12,250 pounds (5,560 kg). A cylindrical service module (SM) supported the command module, with a service propulsion engine and an RCS with propellants, and a fuel cell power generation system with liquid hydrogen and liquid oxygen reactants. A high-gain S-band antenna was used for long-distance communications on

5451-463: Was a joint DARPA , Air Force, and National Reconnaissance Office project to build and launch a low Earth orbit (LEO) constellation for space-based radar . The project began in 1998 but was canceled by Congress in 2000. The Discoverer II concept dates back to June 1996, when the Director of Central Intelligence 's Small Satellite Review Panel concluded that: "...now is an appropriate time to make

5530-619: Was an upgraded version of the Saturn I. The S-IB first stage increased the thrust to 1,600,000 pounds-force (7,120 kN) by uprating the H-1 engine. The second stage replaced the S-IV with the S-IVB-200 , powered by a single J-2 engine burning liquid hydrogen fuel with LOX, to produce 200,000 pounds-force (890  kN ) of thrust. A restartable version of the S-IVB was used as the third stage of

5609-497: Was announced by Wernher von Braun at a briefing on June 7, 1962. But even after NASA reached internal agreement, it was far from smooth sailing. Kennedy's science advisor Jerome Wiesner , who had expressed his opposition to human spaceflight to Kennedy before the President took office, and had opposed the decision to land people on the Moon, hired Golovin, who had left NASA, to chair his own "Space Vehicle Panel", ostensibly to monitor, but actually to second-guess NASA's decisions on

5688-606: Was changed by the time human flights began. Since Apollo, like Mercury, would require a launch escape system (LES) in case of a launch failure, a relatively small rocket was required for qualification flight testing of this system. A rocket bigger than the Little Joe used by Mercury would be required, so the Little Joe II was built by General Dynamics / Convair . After an August 1963 qualification test flight , four LES test flights ( A-001 through 004 ) were made at

5767-546: Was chosen in Houston , Texas, on land donated by Rice University , and Administrator Webb announced the conversion on September 19, 1961. It was also clear NASA would soon outgrow its practice of controlling missions from its Cape Canaveral Air Force Station launch facilities in Florida, so a new Mission Control Center would be included in the MSC. In September 1962, by which time two Project Mercury astronauts had orbited

5846-578: Was named after Apollo , the Greek god of light, music, and the Sun, by NASA manager Abe Silverstein , who later said, "I was naming the spacecraft like I'd name my baby." Silverstein chose the name at home one evening, early in 1960, because he felt "Apollo riding his chariot across the Sun was appropriate to the grand scale of the proposed program". The context of this was that the program focused at its beginning mainly on developing an advanced crewed spacecraft,

5925-503: Was started by NASA / JPL 's Seasat satellite, which carried three different radar sensors: After Seasat , SARs, altimeters and scatterometers have been flown on several other space missions. While the SAR, in principle, is similar to its airborne counterparts (with the advantage of the increased coverage and worldwide access offered by the satellite platform), the other two are specific to satellite operations. A satellite radar-altimeter

6004-662: Was the first crewed spacecraft to orbit another celestial body, and Apollo 11 was the first crewed spacecraft to land humans on one. Overall, the Apollo program returned 842 pounds (382 kg) of lunar rocks and soil to Earth, greatly contributing to the understanding of the Moon's composition and geological history. The program laid the foundation for NASA's subsequent human spaceflight capability and funded construction of its Johnson Space Center and Kennedy Space Center . Apollo also spurred advances in many areas of technology incidental to rocketry and human spaceflight, including avionics , telecommunications, and computers. The program

6083-403: Was the only component of the Apollo spacecraft to survive without major configuration changes as the program evolved from the early Apollo study designs. Its exterior was covered with an ablative heat shield , and had its own reaction control system (RCS) engines to control its attitude and steer its atmospheric entry path. Parachutes were carried to slow its descent to splashdown. The module

6162-423: Was the third US human spaceflight program to fly, preceded by the two-person Project Gemini conceived in 1961 to extend spaceflight capability in support of Apollo. Kennedy's goal was accomplished on the Apollo 11 mission when astronauts Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module (LM) on July 20, 1969, and walked on the lunar surface, while Michael Collins remained in lunar orbit in

6241-537: Was then asked to establish a Task Force on Satellite Reconnaissance (the so-called "Hermann Panel") to review all major aspects of such small satellite systems for defence. In its January 1998 report, the Task Force recommended that a modified STARLITE program be initiated, as a "Military Space Radar Surveillance Program," in an effort to achieve broad-area, all-weather, near-continuous radar access that could be integrated with military operations. In February 1998 DARPA,

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