Ranger program
The Ranger program was a series of unmanned space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of the Moon. The Ranger spacecraft were designed to take images of the lunar surface, transmitting those images to Earth until the spacecraft were destroyed upon impact. A series of mishaps, led to the failure of the first six flights. At one point, the program was called "shoot and hope". Congress launched an investigation into "problems of management" at NASA Headquarters and Jet Propulsion Laboratory. After two reorganizations of the agencies, Ranger 7 returned images in July 1964, followed by two more successful missions. Ranger was designed, beginning in 1959, in three distinct phases, called "blocks"; each block had progressively more advanced system design. The JPL mission designers planned multiple launches in each block, to maximize the engineering experience and scientific value of the mission and to assure at least one successful flight.
Total research, development and support costs for the Ranger series of spacecraft was $170 million. Each of the block III Ranger spacecraft had six cameras on board; the cameras were fundamentally the same with differences in exposure times, fields of view and scan rates. The camera system was divided into two channels, P and F; each channel was self-contained with separate power supplies and transmitters. The F-channel had two cameras: the narrow angle B-camera; the P-channel had four cameras: P1 and P2 and P3 and P4. The final F-channel image was taken between 2.5 and 5 seconds before impact and the last P-channel image 0.2 to 0.4 seconds before impact. The images provided better resolution than was available from Earth-based views by a factor of 1000; the design and construction of the cameras was led by Leonard R Malling. The Ranger program manager for the first six spacecraft was James D. Burke. Ranger 1, launched 23 August 1961, lunar prototype, launch failure Ranger 2, launched 18 November 1961, lunar prototype, launch failureBlock 1, consisting of two spacecraft launched into Earth orbit in 1961, was intended to test the Atlas-Agena launch vehicle and spacecraft equipment without attempting to reach the Moon.
Problems with the early version of the launch vehicle left Ranger 1 and Ranger 2 in short-lived, low-Earth orbits in which the spacecraft could not stabilize themselves, collect solar power, or survive for long. In 1962, JPL utilized the Ranger 1 and Ranger 2 design for the failed Mariner 1 and successful Mariner 2 deep-space probes to Venus. Ranger 3, launched 26 January 1962, lunar probe, spacecraft failed, missed Moon Ranger 4, launched 23 April 1962, lunar probe, spacecraft failed, impact Ranger 5, launched 18 October 1962, lunar probe, spacecraft failed, missedBlock 2 of the Ranger project launched three spacecraft to the Moon in 1962, carrying a TV camera, a radiation detector, a seismometer in a separate capsule slowed by a rocket motor and packaged to survive its low-speed impact on the Moon's surface; the three missions together demonstrated good performance of the Atlas/Agena B launch vehicle and the adequacy of the spacecraft design, but not both on the same attempt. Ranger 3 had problems with both the launch vehicle and the spacecraft, missed the Moon by about 36,800 km, has orbited the Sun since.
Ranger 4 had a perfect launch, but the spacecraft was disabled. The project team tracked the seismometer capsule to impact just out of sight on the lunar far side, validating the communications and navigation system. Ranger 5 was disabled. No significant science information was gleaned from these missions; the craft weighed 331 kg. Around the end of Block 2, it was discovered that a type of diode used in previous missions produced problematic gold-plate flaking in the conditions of space; this may have been responsible for some of the failures. Ranger 6, launched 30 January 1964, lunar probe, cameras failed Ranger 7 Launched 28 July 1964 Impacted Moon 31 July 1964 at 13:25:49 UT 10.35°S 20.58°W / -10.35. These spacecraft boasted a television instrument designed to observe the lunar surface during the approach; the first of the new series, Ranger 6, had a flawless flight, except that the television system was disabled by an in-flight accident and could take no pictures. The next three Rangers, with a redesigned television, were successful.
Ranger 7 photographed its way down to target in a lunar plain, soon named Mare Cognitum, south of the crater Copernicus. It sent more than 4,300 pictures from six cameras to waiting engineers; the new images revealed that craters caused by impact were the dominant features of the Moon's surface in the smooth and empty plains. Great craters were marked by small ones, the small with tiny impact pockmarks, as far down in size as could be discerned—about 50 centimeters; the light-colored streaks radiating from Copernicus and a few other large craters turned out to be chains and nets of small crater
Exploration of the Moon
The physical exploration of the Moon began when Luna 2, a space probe launched by the Soviet Union, made an impact on the surface of the Moon on September 14, 1959. Prior to that the only available means of exploration had been observation from Earth; the invention of the optical telescope brought about the first leap in the quality of lunar observations. Galileo Galilei is credited as the first person to use a telescope for astronomical purposes. NASA's Apollo program was the first, to date only, mission to land humans on the Moon, which it did six times; the first landing took place in 1969, when astronauts placed scientific instruments and returned lunar samples to Earth. The ancient Greek philosopher Anaxagoras reasoned that the Sun and Moon were both giant spherical rocks, that the latter reflected the light of the former, his non-religious view of the heavens was one cause for eventual exile. In his little book On the Face in the Moon's Orb, Plutarch suggested that the Moon had deep recesses in which the light of the Sun did not reach and that the spots are nothing but the shadows of rivers or deep chasms.
He entertained the possibility that the Moon was inhabited. Aristarchus went a step further and computed the distance from Earth, together with its size, obtaining a value of 20 times the Earth radius for the distance. Although the Chinese of the Han Dynasty believed the Moon to be energy equated to qi, their'radiating influence' theory recognized that the light of the Moon was a reflection of the Sun; this was supported by mainstream thinkers such as Jing Fang. Shen Kuo of the Song Dynasty created an allegory equating the waxing and waning of the Moon to a round ball of reflective silver that, when doused with white powder and viewed from the side, would appear to be a crescent. By 499 AD, the Indian astronomer Aryabhata mentioned in his Aryabhatiya that reflected sunlight is the cause behind the shining of the Moon. Habash al-Hasib al-Marwazi, a Persian astronomer, conducted various observations at the Al-Shammisiyyah observatory in Baghdad between 825 and 835 AD. Using these observations, he estimated the Moon's diameter as 3,037 km and its distance from the Earth as 346,345 km, which come close to the accepted values.
In the 11th century, the Islamic physicist, investigated moonlight, which he proved through experimentation originates from sunlight and concluded that it "emits light from those portions of its surface which the sun's light strikes."By the Middle Ages, before the invention of the telescope, an increasing number of people began to recognise the Moon as a sphere, though many believed that it was "perfectly smooth". In 1609, Galileo Galilei drew one of the first telescopic drawings of the Moon in his book Sidereus Nuncius and noted that it was not smooth but had mountains and craters. In the 17th century, Giovanni Battista Riccioli and Francesco Maria Grimaldi drew a map of the Moon and gave many craters the names they still have today. On maps, the dark parts of the Moon's surface were called maria or seas, the light parts were called terrae or continents. Thomas Harriot, as well as Galilei, drew the first telescopic representation of the Moon and observed it for several years, his drawings, remained unpublished.
The first map of the Moon was made by the Belgian cosmographer and astronomer Michael Florent van Langren in 1645. Two years a much more influential effort was published by Johannes Hevelius. In 1647 Hevelius published Selenographia, the first treatise devoted to the Moon. Hevelius's nomenclature, although used in Protestant countries until the eighteenth century, was replaced by the system published in 1651 by the Jesuit astronomer Giovanni Battista Riccioli, who gave the large naked-eye spots the names of seas and the telescopic spots the name of philosophers and astronomers. In 1753 the Croatian Jesuit and astronomer Roger Joseph Boscovich discovered the absence of atmosphere on the Moon. In 1824 Franz von Gruithuisen explained the formation of craters as a result of meteorite strikes; the possibility that the Moon contains vegetation and is inhabited by selenites was considered by major astronomers into the first decades of the 19th century. In 1834–1836, Wilhelm Beer and Johann Heinrich Mädler published their four-volume Mappa Selenographica and the book Der Mond in 1837, which established the conclusion that the Moon has no bodies of water nor any appreciable atmosphere.
The Cold War-inspired "space race" and "Moon race" between the Soviet Union and the United States of America accelerated with a focus on the Moon. This included many scientifically important firsts, such as the first photographs of the then-unseen far side of the Moon in 1959 by the Soviet Union, culminated with the landing of the first humans on the Moon in 1969 seen around the world as one of the pivotal events of the 20th century, indeed of human history in general; the first man-made object to reach the Moon was the unmanned Soviet probe Luna 2, which made a hard landing on September 14, 1959, at 21:02:24 Z. The far side of the Moon was first photographed on October 7, 1959, by the Soviet probe Luna 3. Though vague by today's standards, the photos showed that the far side of the Moon completely lacked maria. In an effort to compete with these Soviet successes, U. S. President John F. Kennedy proposed th
THEMIS
The Time History of Events and Macroscale Interactions during Substorms mission began in February 2007 as a constellation of five NASA satellites to study energy releases from Earth's magnetosphere known as substorms, magnetic phenomena that intensify auroras near Earth's poles. The name of the mission is an acronym alluding to the Titan, Themis. Three of the satellites orbit the Earth within the magnetosphere, while two have been moved into orbit around the Moon; those two were renamed ARTEMIS for Acceleration, Reconnection and Electrodynamics of the Moon’s Interaction with the Sun. THEMIS B became ARTEMIS P1 and THEMIS C became ARTEMIS P2; the THEMIS satellites were launched February 17, 2007 from Cape Canaveral Air Force Station Space Launch Complex 17 aboard a Delta II rocket. Each satellite carries identical instrumentation, including a fluxgate magnetometer, an electrostatic analyzer, a solid state telescope, a search-coil magnetometer and an electric field instrument; each probe has a mass including 49 kg of hydrazine fuel.
THEMIS data can be accessed using the SPEDAS software. THEMIS was scheduled to launch on October 19, 2006. Owing to delays caused by workmanship problems with Delta II second stages—an issue that affected the previous mission, STEREO—the THEMIS launch was delayed to Thursday, February 15, 2007. Due to weather conditions occurring on Tuesday, February 13, fueling of the second stage was delayed, the launch pushed back 24 hours. On February 16, the launch was scrubbed in a hold at the T-4 minute point in the countdown due to the final weather balloon reporting a red, or nogo condition for upper level winds. A 24-hour turnaround procedure was initiated, targeting a new launch window between 23:01 and 23:17 UTC on February 17. Favorable weather conditions were observed on February 17, the countdown proceeded smoothly. THEMIS launched at 6:01 p.m. EST; the spacecraft separated from the launch vehicle 73 minutes after liftoff. By 8:07 p.m. EST, mission operators at the Space Sciences Laboratory of the University of California, Berkeley and received signals from all five spacecraft, confirming nominal separation status.
The launch service was provided by the United Launch Alliance through the NASA Launch Services Program. From February 15, 2007 until September 15, 2007 the five THEMIS satellites coasted in a string-of-pearls orbital configuration. From September 15, 2007 until December 4, 2007 the satellites were moved to more distant orbits in preparation for data collection in the magnetotail; this phase of the mission was called the "Dawn Phase" because the satellites' orbits were in apogee on the dawn side of the magnetosphere. On December 4, 2007 the first tail science phase of the mission began. In this segment of the mission scientists will collect data from the magnetotail of the Earth's magnetosphere. During this phase the satellites' orbits are in apogee inside the magnetotail; the scientists hope to observe magnetic reconnection events. During these events charged particles stored in the Earth's magnetosphere are discharged to form the aurora borealis. Tail science is performed in the winter of the northern hemisphere because the ground magnetometers that Themis scientists correlate the satellite data with have longer periods of night.
During the night, observations are not interrupted by charged particles from the Sun. In 2007, THEMIS "found evidence of magnetic ropes connecting Earth's upper atmosphere directly to the Sun," reconfirming the theory of solar-terrestrial electrical interaction proposed by Kristian Birkeland circa 1908. NASA likened the interaction to a "30 kiloVolt battery in space," noting the "flux rope pumps 650,000 Amp current into the Arctic!"On 26 February 2008, THEMIS probes were able to determine, for the first time, the triggering event for the onset of magnetospheric substorms. Two of the five probes, positioned one third the distance to the Moon, measured events suggesting a magnetic reconnection event 96 seconds prior to Auroral intensification. Dr. Vassilis Angelopoulos of the University of California, Los Angeles, the principal investigator for the THEMIS mission, claimed, "Our data show and for the first time that magnetic reconnection is the trigger." On May 19, 2008 the Space Sciences Laboratory at Berkeley announced NASA had extended the THEMIS mission to the year 2012.
NASA approved the movement of THEMIS B and THEMIS C into lunar orbit under the mission name ARTEMIS. In February 2017, THEMIS celebrated ten years of science operations; as of August 2017, the three THEMIS inner probes continue to collect valuable data on the Sun's interaction with the Earth's magnetosphere. In early 2010, ARTEMIS P1 performed two lunar flybys and one Earth flyby, approached insertion into a Lissajous orbit around a lunar Lagrange point. Lunar orbit insertion was targeted for April 2011. ARTEMIS P2 completed a lunar flyby and was on the inbound leg of the first of three deep space excursions on its way to a Lissajous orbit and was targeted for lunar orbit in April 2011. On June 22, 2011, ARTEMIS P1 began firing its thrusters to move out of its kidney-shaped libration orbit on one side of the Moon, where it had been since January. On July 2, 2011 12:30 p.m. EDT, ARTEMIS P1 entered lunar orbit; the second spacecraft, ARTEMIS P2, moved into lunar orbit on July 17, 2011. Along the way, the two spacecraft were the first to achieve orbit around the Moon's Lagrangian points.
As of August 2017, both lunar probes are in stabl
Apollo 11
Apollo 11 was the spaceflight that landed the first two people on the Moon. Commander Neil Armstrong and lunar module pilot Buzz Aldrin, both American, landed the Apollo Lunar Module Eagle on July 20, 1969, at 20:17 UTC. Armstrong became the first person to step onto the lunar surface six hours on July 21 at 02:56:15 UTC, they spent about two and a quarter hours together outside the spacecraft, collected 47.5 pounds of lunar material to bring back to Earth. Command module pilot Michael Collins flew the command module Columbia alone in lunar orbit while they were on the Moon's surface. Armstrong and Aldrin spent 21.5 hours on the lunar surface before rejoining Columbia in lunar orbit. Apollo 11 was launched by a Saturn V rocket from Kennedy Space Center on Merritt Island, Florida, on July 16 at 13:32 UTC, was the fifth crewed mission of NASA's Apollo program; the Apollo spacecraft had three parts: a command module with a cabin for the three astronauts, the only part that returned to Earth. After being sent to the Moon by the Saturn V's third stage, the astronauts separated the spacecraft from it and traveled for three days until they entered lunar orbit.
Armstrong and Aldrin moved into Eagle and landed in the Sea of Tranquillity. The astronauts used Eagle's ascent stage to lift off from the lunar surface and rejoin Collins in the command module, they jettisoned Eagle before they performed the maneuvers that blasted them out of lunar orbit on a trajectory back to Earth. They returned to Earth and splashed down in the Pacific Ocean on July 24 after more than eight days in space. Armstrong's first step onto the lunar surface was broadcast on live TV to a worldwide audience, he described the event as "one small step for man, one giant leap for mankind." Apollo 11 ended the Space Race and fulfilled a national goal proposed in 1961 by President John F. Kennedy: "before this decade is out, of landing a man on the Moon and returning him safely to the Earth." In the late 1950s and early 1960s, the United States was engaged in the Cold War, a geopolitical rivalry with the Soviet Union. On October 4, 1957, the Soviet Union launched the first artificial satellite.
This surprise success fired imaginations around the world. It demonstrated that the Soviet Union had the capability to deliver nuclear weapons over intercontinental distances, challenged American claims of military and technological superiority; this precipitated the Sputnik crisis, triggered the Space Race. President Dwight D. Eisenhower responded to the Sputnik challenge by creating the National Aeronautics and Space Administration, initiating Project Mercury, which aimed to launch a man into Earth orbit, but on April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first person in space, the first to orbit the Earth. It was another body blow to American pride. Nearly a month on May 5, 1961, Alan Shepard became the first American in space, completing a 15-minute suborbital journey. After being recovered from the Atlantic Ocean, he received a congratulatory telephone call from Eisenhower's successor, John F. Kennedy. Kennedy believed that it was in the national interest of the United States to be superior to other nations, that the perception of American power was at least as important as the actuality.
It was therefore intolerable that the Soviet Union was more advanced in the field of space exploration. He was determined that the United States should compete, sought a challenge that maximized its chances of winning. Since the Soviet Union had better booster rockets, he required a challenge, beyond the capacity of the existing generation of rocketry, one where the US and Soviet Union would be starting from a position of equality. Something spectacular if it could not be justified on military, economic or scientific grounds. After consulting with his experts and advisors, he chose such a project. On May 25, 1961, he addressed the United States Congress on "Urgent National Needs" and declared: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 for the long-range exploration of space. We propose to accelerate the development of the appropriate lunar space craft.
We propose to develop alternate liquid and solid fuel boosters, much larger than any now being developed, until certain, superior. We propose additional funds for other engine development and for unmanned explorations-explorations which are important for one purpose which this nation will never overlook: the survival of the man who first makes this daring flight, but in a real sense, it will not be one man going to the Moon-if we make this judgment affirmatively, it will be an entire nation. For all of us must work to put him there; the effort to land a man on the Moon had a name: Project Apollo. An early and crucial decision was choosing lunar orbit rendezvous over both direct ascent and Earth orbit rendezvous. A space rendezvous is an orbital maneuver in which two spacecraft navigate through space and meet up. On July 11, 1962, James Webb announced the decision to use lunar orbit rendezvous; this resulted in a much smaller launch vehicle, in the Apollo spacecraft being composed of three major parts: a command module with a cabin for the three astr
Moon
The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, the largest among planetary satellites relative to the size of the planet that it orbits; the Moon is after Jupiter's satellite Io the second-densest satellite in the Solar System among those whose densities are known. The Moon is thought to have formed not long after Earth; the most accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body called Theia. The Moon is in synchronous rotation with Earth, thus always shows the same side to Earth, the near side; the near side is marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters. After the Sun, the Moon is the second-brightest visible celestial object in Earth's sky, its surface is dark, although compared to the night sky it appears bright, with a reflectance just higher than that of worn asphalt.
Its gravitational influence produces the ocean tides, body tides, the slight lengthening of the day. The Moon's average orbital distance is 1.28 light-seconds. This is about thirty times the diameter of Earth; the Moon's apparent size in the sky is the same as that of the Sun, since the star is about 400 times the lunar distance and diameter. Therefore, the Moon covers the Sun nearly during a total solar eclipse; this matching of apparent visual size will not continue in the far future because the Moon's distance from Earth is increasing. The Moon was first reached in September 1959 by an unmanned spacecraft; the United States' NASA Apollo program achieved the only manned lunar missions to date, beginning with the first manned orbital mission by Apollo 8 in 1968, six manned landings between 1969 and 1972, with the first being Apollo 11. These missions returned lunar rocks which have been used to develop a geological understanding of the Moon's origin, internal structure, the Moon's history. Since the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft.
Both the Moon's natural prominence in the earthly sky and its regular cycle of phases as seen from Earth have provided cultural references and influences for human societies and cultures since time immemorial. Such cultural influences can be found in language, lunar calendar systems and mythology; the usual English proper name for Earth's natural satellite is "the Moon", which in nonscientific texts is not capitalized. The noun moon is derived from Old English mōna, which stems from Proto-Germanic *mēnô, which comes from Proto-Indo-European *mḗh₁n̥s "moon", "month", which comes from the Proto-Indo-European root *meh₁- "to measure", the month being the ancient unit of time measured by the Moon; the name "Luna" is used. In literature science fiction, "Luna" is used to distinguish it from other moons, while in poetry, the name has been used to denote personification of Earth's moon; the modern English adjective pertaining to the Moon is lunar, derived from the Latin word for the Moon, luna. The adjective selenic is so used to refer to the Moon that this meaning is not recorded in most major dictionaries.
It is derived from the Ancient Greek word for the Moon, σελήνη, from, however derived the prefix "seleno-", as in selenography, the study of the physical features of the Moon, as well as the element name selenium. Both the Greek goddess Selene and the Roman goddess Diana were alternatively called Cynthia; the names Luna and Selene are reflected in terminology for lunar orbits in words such as apolune and selenocentric. The name Diana comes from the Proto-Indo-European *diw-yo, "heavenly", which comes from the PIE root *dyeu- "to shine," which in many derivatives means "sky and god" and is the origin of Latin dies, "day"; the Moon formed 4.51 billion years ago, some 60 million years after the origin of the Solar System. Several forming mechanisms have been proposed, including the fission of the Moon from Earth's crust through centrifugal force, the gravitational capture of a pre-formed Moon, the co-formation of Earth and the Moon together in the primordial accretion disk; these hypotheses cannot account for the high angular momentum of the Earth–Moon system.
The prevailing hypothesis is that the Earth–Moon system formed after an impact of a Mars-sized body with the proto-Earth. The impact blasted material into Earth's orbit and the material accreted and formed the Moon; the Moon's far side has a crust, 30 mi thicker than that of the near side. This is thought to be; this hypothesis, although not perfect best explains the evidence. Eighteen months prior to an October 1984 conference on lunar origins, Bill Hartmann, Roger Phillips, Jeff Taylor challenged fellow lunar scientists: "You have eighteen months. Go back to your Apollo data, go back to your computer, do whatever you have to, but make up your mind. Don't come to our conference unless you have something to say about the Moon's birth." At the 1984 conference at Kona, the giant impact hypothesis emerged as the most consensual theory. Before the conference, there were parti
Lunar Orbiter program
The Lunar Orbiter program was a series of five unmanned lunar orbiter missions launched by the United States from 1966 through 1967. Intended to help select Apollo landing sites by mapping the Moon's surface, they provided the first photographs from lunar orbit and photographed both the Moon and Earth. All five missions were successful, 99 percent of surface of the Moon was mapped from photographs taken with a resolution of 60 meters or better; the first three missions were dedicated to imaging 20 potential manned lunar landing sites, selected based on Earth-based observations. These were flown at low-inclination orbits; the fourth and fifth missions were devoted to broader scientific objectives and were flown in high-altitude polar orbits. Lunar Orbiter 4 photographed the entire nearside and nine percent of the far side, Lunar Orbiter 5 completed the far side coverage and acquired medium and high resolution images of 36 preselected areas. All of the Lunar Orbiter spacecraft were launched by Atlas-Agena-D launch vehicles.
The Lunar Orbiters had an ingenious imaging system, which consisted of a dual-lens camera, a film processing unit, a readout scanner, a film handling apparatus. Both lenses, a 610 mm narrow angle high resolution lens and an 80 mm wide angle medium resolution lens, placed their frame exposures on a single roll of 70 mm film; the axes of the two cameras were coincident so the area imaged in the HR frames were centered within the MR frame areas. The film was moved during exposure to compensate for the spacecraft velocity, estimated by an electro-optical sensor; the film was processed and the images transmitted back to Earth. During the Lunar Orbiter missions, the first pictures of Earth as a whole were taken, beginning with Earth-rise over the lunar surface by Lunar Orbiter 1 in August, 1966; the first full picture of the whole Earth was taken by Lunar Orbiter 5 on 8 August 1967. A second photo of the whole Earth was taken by Lunar Orbiter 5 on 10 November 1967; the Boeing-Eastman Kodak proposal was announced by NASA on 20 December 1963.
The main bus of the Lunar Orbiter had the general shape of a truncated cone, 1.65 m tall and 1.5 m in diameter at the base. The spacecraft was composed of three decks supported by an arch; the equipment deck at the base of the craft held the battery, flight programmer, inertial reference unit, Canopus star tracker, command decoder, multiplex encoder, traveling-wave tube amplifier, the photographic system. Four solar panels were mounted to extend out from this deck with a total span across of 3.72 m. Extending out from the base of the spacecraft were a high gain antenna on a 1.32 m boom and a low-gain antenna on a 2.08 m boom. Above the equipment deck, the middle deck held the velocity control engine, propellant and pressurization tanks, Sun sensors, micrometeoroid detectors; the third deck consisted of a heat shield to protect the spacecraft from the firing of the velocity control engine. The nozzle of the engine protruded through the center of the shield. Mounted on the perimeter of the top deck were four attitude control thrusters.
Power of 375 W was provided by the four solar arrays containing 10,856 n/p solar cells which would directly run the spacecraft and charge the 12 A·h nickel-cadmium battery. The batteries were used during the brief periods of occultation. Propulsion for major maneuvers was provided by the gimballed velocity control engine, a hypergolic 100 pound-force thrust Marquardt Corp. rocket motor. Three axis stabilization and attitude control were provided by four one lb-force nitrogen gas jets. Navigational knowledge was provided by five sun sensors, the Canopus star sensor, the inertial navigation system. Communications were via a 10 W transmitter and the directional one meter diameter high-gain antenna for transmission of photographs, a 0.5 W transmitter and omnidirectional low-gain antenna for other communications. Both transmitters operated in the S band at about 2295 MHz. Thermal control was maintained by a multilayer aluminized Mylar and Dacron thermal blanket which enshrouded the main bus, special paint and small heaters.
The photographic system was provided by Eastman Kodak and it was derived from a system, provided by the National Reconnaissance Office, designed for the U-2 and SR-71 reconnaissance planes. The camera used two lenses to expose a wide-angle and a high-resolution image on the same film; the wide-angle, medium resolution mode used an 80 mm F 2.8 Xenotar lens manufactured by Schneider Kreuznach of West Germany. The high-resolution mode used a 610 mm F 5.6 Panoramic lens manufactured by the Pacific Optical Company. The photographic film was developed in-orbit with a semidry process, it was scanned by a photomultiplier for transmission to Earth; this system was adapted under permission of the NRO from the SAMOS E-1 reconnaissance camera, built by Kodak for a short-lived USAF near-realtime satellite imaging project. The Air Force had offered NASA several spare cameras from the KH-7 GAMBIT program, but authorities became concerned over security surrounding the classified cameras, including the possibility of images of the Moon giving away their resolution.
Some proposals were made that NASA not publish the orbital parameters of the Lunar Orbiter probes so that the resolution of the images could not be calculated through their altitude. In the end, NASA's existing camera systems, while lower resolution, proved to be adequate for the needs of the mission; as a backup for Lunar Orbiter program, NASA and the NRO cooperated on the Lunar Mapping and Survey Syst
