Ranger 6 was a lunar probe in the NASARanger program, a series of robotic spacecraft of the early and mid-1960s to obtain close-up images of the Moon's surface. It was launched on January 30, 1964 and was designed to transmit high-resolution photographs of the lunar terrain during the final minutes of flight until impacting the surface. The spacecraft carried six television vidicon cameras—two wide-angle (channel F, cameras A and B) and four narrow-angle (channel P)—to accomplish these objectives. The cameras were arranged in two separate chains, or channels, each self-contained with separate power supplies, timers, and transmitters so as to afford the greatest reliability and probability of obtaining high-quality television pictures. No other experiments were carried on the spacecraft. Due to a failure of the camera system, no images were returned.[2]
Rangers 6, 7, 8, and 9 were called Block 3 versions of the Ranger spacecraft. The spacecraft consisted of a hexagonal aluminum frame base 1.5m across on which was mounted the propulsion and power units, topped by a truncated conical tower that held the TV cameras. Two solar panel wings, each 739mm wide by 1537mm long, extended from opposite edges of the base with a full span of 4.6m, and a pointable high-gain dish antenna was hinge mounted at one of the corners of the base away from the solar panels. A cylindrical quasi omnidirectional antenna was seated on top of the conical tower. The overall height of the spacecraft was 3.6m.[2]
Propulsion for the mid-course trajectory correction was provided by a 224N thrust monopropellant hydrazine engine with four jet-vane vector control. Orientation and attitude control about three axes were enabled by twelve nitrogen gas jets coupled to a system of three gyros, four primary Sun sensors, two secondary Sun sensors, and an Earth sensor. Power was supplied by 9,792 silicon solar cells contained in the two solar panels, giving a total array area of 2.3 square meters and producing 200W. Two 1200 watt-hour AgZnO batteries rated at 26.5V with a capacity for 9 hours of operation provided power to each of the separate communication/TV camera chains. Two 1000 watt-hour AgZnO batteries stored power for spacecraft operations.[2]
Communications were through the quasi omnidirectional low-gain antenna and the parabolic high-gain antenna. Transmitters aboard the spacecraft included a 60W TV channel F at 959.52MHz, a 60W TV channel P at 960.05MHz, and a 3W transponder channel 8 at 960.58MHz. The telecommunications equipment converted the composite video signal from the camera transmitters into an RF signal for subsequent transmission through the spacecraft high-gain antenna. Sufficient video bandwidth was provided to allow for rapid framing sequences of both narrow- and wide-angle television pictures.[2]
Mission profile
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The Cuban Missile Crisis had momentarily diverted attention from the failure of Ranger 5, but that mission forced a wholesale review of the entire Ranger program. Numerous theories were put forward about the cause of the failures, including poor management at JPL, overly-ambitious spacecraft designs that were unworkable and unreliable with contemporary technology, and some lesser reasons such as heat sterilization of the probes.
NASA established a Ranger Board of Inquiry on October 29, 1962, headed by Albert J. Kelley, with the mission of establishing by November 30 the reasons for the continued program failures. The board's findings included the verdict that the Ranger design was "more complicated than necessary" for a lunar mission and also required a very high degree of engineering and workmanship, neither of which were being delivered. They also concluded that heat sterilization was damaging to the delicate spacecraft systems and should be abandoned at once. They also found that JPL's handling of the program was poor, the spacecraft lacked redundant systems in the event of a malfunction, NASA's deep-space tracking network crews were not trained adequately and had deficiencies in their equipment, and finally, the Atlas-Agena booster's reliability was poor, having malfunctioned on eight Air Force and NASA launches as November 1962 ended. If the Thor-Agena was also counted in, there had been a total of nine times that an Agena B stage had malfunctioned in flight.
The board's recommendations included improving the management of projects, abandoning heat sterilization and testing of components designed for future planetary missions on Ranger, outsourcing assembly of the probes to a subcontractor, and excluding JPL from involvement in procurement and launching of the Atlas-Agena. Moreover, it suggested that NASA needed to improve their prelaunch testing and preparation of launch vehicles.
The Block III spacecraft would be stripped down to a minimum of instrumentation with the eight scientific instruments on Rangers 3-5 removed so that more space could be devoted to redundant systems hardware. This caused some protests from the scientific community that the gamma-ray and other measurements were far more valuable than simply returning photography of the Moon. Jet Propulsion Laboratory began more thorough testing of Ranger components and the second review board was put to work evaluating the reliability of the Atlas-Agena.
The booster problems would prove a particularly vexing one to solve because the U.S. Air Force, not NASA, was in charge of Atlas-Agena. Although NASA had hoped to launch planetary probes on Centaur, which was entirely under their control, that program was delayed by serious technical issues and would not be flight-ready for a long time. Having to share the booster with the U.S. Air Force and its Department of Defense missions on the West Coast created repeated mixups, delays, and technical problems. Therefore, it was recommended that NASA be given complete oversight in the procurement and launch of Atlas-Agena without the Air Force's involvement.
Launch of Ranger 6.
One of the important parts of the Ranger program was monitoring all Atlas and Thor-Agena launches to check for failures that could directly affect it. This job had been assigned to the Marshall Space Flight Center in Huntsville, Alabama, but was instead moved to the Lewis Research Center (LRC) in Cleveland, Ohio. LRC sent additional personnel to the Convair assembly plant in San Diego to monitor the construction of Atlas vehicles.
The review board focused on the malfunctions plaguing Atlas-Agena, in particular, the General Electric guidance system, both the Mod III-G variant used on East Coast Atlas Agenas and the Mod II-A used on West Coast vehicles, which had malfunctioned repeatedly. They recommended putting forward more detailed and stringent requirements for testing Atlas vehicles and making sure the guidance package could withstand in-flight vibration levels along with improved fabrication of wiring harnesses. Also, it was recommended that Convair establish one standardized booster configuration for all U.S. Air Force and NASA launches instead of custom modifications for each mission, replacing hardware with known design flaws with better substitutes, and improved testing of everything. Since the Air Force was in charge of Atlas-Agena, it followed that all these changes required their approval.
Finally, NASA for the first time would be given complete oversight of all its space launches. Air Force involvement in procuring, preparing, and flying launch vehicles, as well as drafting postflight mission reports for NASA missions, was to end, a step that would greatly streamline and improve program efficiency.
Problems continued, this time with getting the TV cameras for Ranger 6 in working order. The camera tubes, supplied by Radio Corporation of America, were of variable quality and it took some time to find one that matched JPL's standards.
During testing of Atlas guidance systems at General Electric, it was found that gold coating on diodes was flaking off and causing electrical shorts. Even worse, Ranger 6 had hundreds of the same diodes. This problem had easily eluded testing; moreover, ground tests could not simulate a "zero gravity" environment in space where the gold flakes would float around and form a short between the legs of the diode. In the end, there was no choice except to replace every one of the several hundred diodes inside Ranger 6's circuitry.
In April 1963, the United States Congress also decided to cut funding to the Ranger program by nearly 50% on the grounds that "no success had been achieved with any of the missions to date". This meant that plans for Ranger probes up to 13 were cancelled. Only Rangers 6-9 would be flown and they would carry little more than a TV camera.
The television cameras of the spacecraft Ranger 6.
One of Program Ranger's goals was looking for potential landing sites for crewed lunar missions. At this point, it was not clear exactly what the Moon's surface was like and widespread fears existed of there being bottomless quicksand that would swallow up spacecraft and astronauts. Since the basic design of the Apollo lunar module had already been finalized by 1963, landing on the Moon would only "confirm or deny that design". JPL decided to go for an impact point near the Moon's equator, in the Sea of Tranquility, partially because it was considered a prime Apollo landing spot, and also because the target had to match lighting conditions during the time of launch in January–February.
Ranger 6 and its launch vehicle (Atlas 199D and Agena 6008) arrived at Cape Canaveral in mid-December and, with the nation still mourning PresidentKennedy's assassination the previous month, began preflight tests.
Liftoff took place at 10:49 AM EST on January 30, 1964. The Atlas lifted smoothly into an overcast sky and disappeared from view. All went well during the boost phase and the launch vehicle's performance was excellent, indicating the hard-fought effort to improve booster reliability.
Shortly after Atlas BECO and staging, an ominous development occurred when telemetry indicated that the telemetry for the TV camera on Ranger 6 had turned itself on and then back off again 67 seconds later. Telemetry data showed everything else appears to function normally and tensions at JPL eased. The Agena placed the probe into a parking orbit and then fired for translunar injection 25 minutes after launch. After separation of Ranger 6, the solar panels and high-gain antenna were extended and all appeared normal. The launch vehicle had placed the probe on an accurate enough flight path that only a short midcourse correction burn would be required. However, the activation of the TV camera telemetry during launch remained a cause for concern. JPL technicians wanted to turn the camera on to verify its operability, however, they were running the risk of not being able to turn it off again if an electrical short had indeed occurred somewhere. Since the camera had its own batteries and did not use the probe's main power bus, they would be depleted before it could get to the Moon and eliminate any chance of returning pictures. They decided that it was not worth compromising the mission and the camera would not be touched until descent to the Moon began.
Early on the morning of January 31, the command was sent to fire the midcourse correction engine, which performed flawlessly and set the probe on an impact course with the Sea of Tranquility. On February 2, JPL technicians prepared for the final phase of the mission. Ranger 6 began its descent and trajectory calculations determined that impact would occur close to the intended area. With the probe's angle suitable for taking images, the order was given to turn on the camera with 13 minutes and 10 seconds until impact. After an initial warm-up phase, the command to power them on was sent. However, no imagery or any sign of camera operation appeared. Two more commands were sent to turn on the camera, but still, nothing happened even though all other systems continued to operate normally. At 01:24 AM, impact with the Moon occurred and telemetry transmission from Ranger 6 ceased. The mission was over and for the 12th time in a row, a U.S. attempt to send a probe to the Moon had malfunctioned. Even worse, it had occurred one week before NASA officials were planning to announce to Congress their projected US$5.3 billion budget for FY 1965, a good deal of it related to crewed and uncrewed lunar missions. NASA attempted to put a positive spin on the mission by noting that, aside from the cameras, Ranger 6 and its Atlas-Agena booster had both functioned "extremely well".
Ranger 6 was launched into an Earth parking orbit and injected on a lunar trajectory by a second Agena burn. The midcourse trajectory correction was accomplished early in the flight by ground control. On February 2, 1964, 65.5 hours after launch, Ranger 6 impacted the Moon on the eastern edge of Mare Tranquillitatis (Sea of Tranquility in English). The orientation of the spacecraft to the surface during descent was correct, but no video signal was received and no camera data obtained. A review board determined the most likely cause of failure was due to an arc-over in the TV power system when it inadvertently turned on for 67 seconds approximately 2 minutes after launch during the period of booster-engine separation.[2]
This fourth American attempt at lunar impact was the closest success. The spacecraft, the first Block III type vehicle with a suite of six TV cameras, was sterilized to avoid contaminating the lunar surface. The series would also serve as a test bed for future interplanetary spacecraft by deploying systems (such as solar panels) that could be used for more ambitious missions. The Block III spacecraft carried a 173-kilogram TV unit (replacing the impact capsule carried on the Block II Ranger spacecraft). The six cameras included two full-scan and four partial-scan cameras. Ranger 6 flew to the Moon successfully and impacted precisely on schedule at 09:24:32 GMT on February 2. Unfortunately, the power supply for the TV camera package had short-circuited three days previously during Atlas booster separation and left the system inoperable. The cameras were to have transmitted high-resolution photos of the lunar approach from 1448 kilometers to 6.4 kilometers range in support of Project Apollo. Impact coordinates were 9°24' north latitude and 21°30' east longitude.[2]
The Mariner program was conducted by the American space agency NASA to explore other planets. Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the inner Solar System - visiting the planets Venus, Mars and Mercury for the first time, and returning to Venus and Mars for additional close observations.
Mariner 2, an American space probe to Venus, was the first robotic space probe to report successfully from a planetary encounter. The first successful spacecraft in the NASA Mariner program, it was a simplified version of the Block I spacecraft of the Ranger program and an exact copy of Mariner 1. The missions of the Mariner 1 and 2 spacecraft are sometimes known as the Mariner R missions. Original plans called for the probes to be launched on the Atlas-Centaur, but serious developmental problems with that vehicle forced a switch to the much smaller Agena B second stage. As such, the design of the Mariner R vehicles was greatly simplified. Far less instrumentation was carried than on the Soviet Venera probes of this period—for example, forgoing a TV camera—as the Atlas-Agena B had only half as much lift capacity as the Soviet 8K78 booster. The Mariner 2 spacecraft was launched from Cape Canaveral on August 27, 1962, and passed as close as 34,773 kilometers (21,607 mi) to Venus on December 14, 1962.
Mariner 1, built to conduct the first American planetary flyby of Venus, was the first spacecraft of NASA's interplanetary Mariner program. Developed by Jet Propulsion Laboratory, and originally planned to be a purpose-built probe launched summer 1962, Mariner 1's design was changed when the Centaur proved unavailable at that early date. Mariner 1, were then adapted from the lighter Ranger lunar spacecraft. Mariner 1 carried a suite of experiments to determine the temperature of Venus as well to measure magnetic fields and charged particles near the planet and in interplanetary space.
Mariner 3 was one of two identical deep-space probes designed and built by the Jet Propulsion Laboratory (JPL) for NASA's Mariner-Mars 1964 project that were intended to conduct close-up (flyby) scientific observations of the planet Mars and transmit information on interplanetary space and the space surrounding Mars, televised images of the Martian surface and radio occultation data of spacecraft signals as affected by the Martian atmosphere back to Earth.
Mariner 5 was a spacecraft of the Mariner program that carried a complement of experiments to probe Venus' atmosphere by radio occultation, measure the hydrogen Lyman-alpha spectrum, and sample the solar particles and magnetic field fluctuations above the planet. Its goals were to measure interplanetary and Venusian magnetic fields, charged particles, plasma, radio refractivity and UV emissions of the Venusian atmosphere.
Pioneer 4 was an American spin-stabilized uncrewed spacecraft launched as part of the Pioneer program on a lunar flyby trajectory and into a heliocentric orbit making it the first probe of the United States to escape from the Earth's gravity. Launched on March 3, 1959, it carried a payload similar to Pioneer 3: a lunar radiation environment experiment using a Geiger–Müller tube detector and a lunar photography experiment. It passed within 58,983 km (36,650 mi) of the Moon's surface. However, Pioneer 4 did not come close enough to trigger its photoelectric sensor. The spacecraft was still in solar orbit as of 1969. It was the only successful lunar probe launched by the U.S. in 12 attempts between 1958 and 1963; only in 1964 would Ranger 7 surpass its success by accomplishing all of its mission objectives.
Pioneer P-3 was intended to be a lunar orbiter probe, but the mission failed shortly after launch. The objectives were to place a highly instrumented probe in lunar orbit, to investigate the environment between the Earth and Moon, and to develop technology for controlling and maneuvering spacecraft from Earth. It was equipped to take images of the lunar surface with a television-like system, estimate the Moon's mass and topography of the poles, record the distribution and velocity of micrometeorites, and study radiation, magnetic fields, and low frequency electromagnetic waves in space. A mid-course propulsion system and injection rocket would have been the first United States self-contained propulsion system capable of operation many months after launch at great distances from Earth and the first U.S. tests of maneuvering a satellite in space.
Ranger 1 was a prototype spacecraft launched as part of the Ranger program of uncrewed space missions. Its primary mission was to test the performance of those functions and parts necessary for carrying out subsequent lunar and planetary missions; a secondary objective was to study the nature of particles and fields in the space environment. Due to a launch vehicle malfunction, the spacecraft could reach only Low Earth orbit, rather than the high Earth orbit that had been planned, and was only able to complete part of its mission.
Ranger 2 was a flight test of the Ranger spacecraft system of the NASA Ranger program designed for future lunar and interplanetary missions. Ranger 2 was designed to test various systems for future exploration and to conduct scientific observations of cosmic rays, magnetic fields, radiation, dust particles, and a possible hydrogen gas "tail" trailing the Earth.
Ranger 3 was a space exploration mission conducted by NASA to study the Moon. The Ranger 3 robotic spacecraft was launched January 26, 1962 as part of the Ranger program. Due to a series of malfunctions, the spacecraft missed the Moon by 22,000 mi (35,000 km) and entered a heliocentric orbit.
Ranger 4 was a spacecraft of the Ranger program, launched in 1962. It was designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to crashing upon the Moon, to rough-land a seismometer capsule on the Moon, to collect gamma-ray data in flight, to study radar reflectivity of the lunar surface, and to continue testing of the Ranger program for development of lunar and interplanetary spacecraft.
Ranger 5 was a spacecraft of the Ranger program designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to impacting on the Moon, to rough-land a seismometer capsule on the Moon, to collect gamma-ray data in flight, to study radar reflectivity of the lunar surface, and to continue testing of the Ranger program for development of lunar and interplanetary spacecraft. Due to an unknown malfunction, the spacecraft ran out of power and ceased operation. It passed within 725 km of the Moon.
The Ranger program was a series of uncrewed 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, however, 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 successfully returned images in July 1964, followed by two more successful missions.
The Agena Target Vehicle, also known as Gemini-Agena Target Vehicle (GATV), was an uncrewed spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques, and to perform large orbital changes, in preparation for the Apollo program lunar missions. The spacecraft was based on Lockheed Aircraft's Agena-D upper stage rocket, fitted with a docking target manufactured by McDonnell Aircraft. The name 'Agena' derived from the star Beta Centauri, also known as Agena. The combined spacecraft was a 26-foot (7.92 m)-long cylinder with a diameter of 5 feet (1.52 m), placed into low Earth orbit with the Atlas-Agena launch vehicle. It carried about 14,000 pounds (6,400 kg) of propellant and gas at launch, and had a gross mass at orbital insertion of about 7,200 pounds (3,300 kg).
Ranger 7 was the first space probe of the United States to successfully transmit close images of the lunar surface back to Earth. It was also the first completely successful flight of the Ranger program. Launched on July 28, 1964, Ranger 7 was designed to achieve a lunar-impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact.
The SAMOS or SAMOS-E program was a relatively short-lived series of reconnaissance satellites for the United States in the early 1960s, also used as a cover for the initial development of the KH-7 GAMBIT system. Reconnaissance was performed with film cameras and television surveillance from polar low Earth orbits with film canister returns and transmittals over the United States. SAMOS was first launched in 1960 from Vandenberg Air Force Base.
Ranger 8 was a lunar probe in the Ranger program, a robotic spacecraft series launched by NASA in the early-to-mid-1960s to obtain the first close-up images of the Moon's surface. These pictures helped select landing sites for Apollo missions and were used for scientific study. During its 1965 mission, Ranger 8 transmitted 7,137 lunar surface photographs before it crashed into the Moon as planned. This was the second successful mission in the Ranger series, following Ranger 7. Ranger 8's design and purpose were very similar to those of Ranger 7. It had six television vidicon cameras: two full-scan and four partial-scan. Its sole purpose was to document the Moon's surface.
Ranger 9 was a Lunar probe, launched in 1965 by NASA. It was designed to achieve a lunar impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact. The spacecraft carried six television vidicon cameras—two wide-angle and four narrow-angle —to accomplish these objectives. The cameras were arranged in two separate chains, or channels, each self-contained with separate power supplies, timers, and transmitters so as to afford the greatest reliability and probability of obtaining high-quality television pictures. These images were broadcast live on television to millions of viewers across the United States. No other experiments were carried on the spacecraft.
A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959.
The Atlas-Agena was an American expendable launch system derived from the SM-65 Atlas missile. It was a member of the Atlas family of rockets, and was launched 109 times between 1960 and 1978. It was used to launch the first five Mariner uncrewed probes to the planets Venus and Mars, and the Ranger and Lunar Orbiter uncrewed probes to the Moon. The upper stage was also used as an uncrewed orbital target vehicle for the Gemini crewed spacecraft to practice rendezvous and docking. However, the launch vehicle family was originally developed for the Air Force and most of its launches were classified DoD payloads.
Payloads are separated by bullets ( · ), launches by pipes ( | ). Crewed flights are indicated in underline. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in (brackets).
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