Ranger 7

Last updated

Ranger 7
The Ranger Spacecraft GPN-2000-001979.jpg
Ranger 7
Mission type Lunar impactor
Operator NASA
COSPAR ID 1964-041A OOjs UI icon edit-ltr-progressive.svg
SATCAT no. 842
Mission duration65.5 hours
Spacecraft properties
Manufacturer Jet Propulsion Laboratory
Launch mass365.7 kilograms (806 lb)
Dimensions1.52 m × 2.51 m (5.0 ft × 8.2 ft)
Power200 W
Start of mission
Launch dateJuly 28, 1964, 16:50:00 (1964-07-28UTC16:50Z) UTC
Rocket Atlas LV-3 Agena-B 250D/AA9
Launch site Cape Canaveral LC-12
Lunar impactor
Impact dateJuly 31, 1964, 13:25:48.82 (1964-07-31UTC13:25:49Z) UTC
Impact site 10°38′02″S20°40′38″W / 10.6340°S 20.6771°W / -10.6340; -20.6771 [1]
(Between Mare Nubium and Oceanus Procellarum)
  Ranger 6
Ranger 8  
 

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.

Contents

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 video pictures. Ranger 7 transmitted over 4,300 photographs during the final 17 minutes of its flight. After 68.6 hours of flight, the spacecraft landed between Mare Nubium and Oceanus Procellarum. This landing site was later named Mare Cognitum. The velocity at impact was 1.62 miles per second, and the performance of the spacecraft exceeded hopes. [2] No other experiments were carried on the spacecraft. [3] [ unreliable source? ]

Aftermath of Ranger 6 and preparation for Ranger 7

Ranger 7 cameras system. Ranger 7 cameras.jpg
Ranger 7 cameras system.

Although NASA had attempted to put a positive spin on Ranger 6 on the grounds that everything except the camera system had worked well, William Coughlin, editor of the publication Missiles and Rockets, called it a "one hundred percent failure" and JPL's record thus far was "a disgrace". The mission had not been a complete failure, but Coughlin was not alone in his opinion that Jet Propulsion Laboratory in Pasadena, a nonprofit laboratory and extension of the California Institute of Technology (Caltech), was a "soft" academic environment without the drive or ambition needed to make the missions succeed. He considered Ranger a "loser" and for a while, anyone at NASA involved in the Ranger program tried to conceal it. It was also being said that sending probes up for the sole purpose of returning images was pointless and accomplished nothing that Apollo could not also achieve.

Shortly after Ranger 6's mission concluded, a review board was convened to resolve the cause of the TV camera failure. This was determined quickly; the inadvertent activation of the camera telemetry system during ascent had been caused by an electrical short that crippled the power supply for the cameras. But why it had happened was as yet a mystery, especially as telemetry data sent back from the probe could only provide a limited amount of information. On February 14, 1964, JPL released a report noting that an internal command switch could have activated prematurely or that arcing had occurred in the umbilical connector on the payload fairing. However, there was no evidence of the latter happening or any obvious way that it could occur and several modifications were proposed to the camera system and/or the payload fairing.

The NASA review board found that Ranger 6's systems were not as redundant as JPL had claimed, that prelaunch testing was inadequate, and there had been instances of the cameras turning themselves on at the RCA plant in New Jersey. If the cameras had to be completely redesigned from scratch, the next Ranger mission could be delayed almost a full year.

The full report as submitted to Congress came under criticism from several people at NASA, noting that, although the cameras lacked redundancy, any one of dozens of failure modes in the booster or spacecraft could also result in failure to return any TV images. In regards to the lack of adequate prelaunch testing, they brought up the incident back in 1961 with Ranger 1 deploying its solar panels during a ground test and that ground tests with full 60 W power had been discontinued on the Block II probes for fear of accidentally igniting the midcourse correction engine on the pad and destroying the entire launch vehicle in the process.

RCA also promised to look into workmanship standards at their main plant in Hightstown, New Jersey, when examination of a sealed Ranger module discovered a plastic bag with screws and washers inside. Although there was suspicion that this had been done by a disgruntled employee, it was far more probable that someone had done it by accident.

Since no obvious reason for the malfunction could be found in the cameras themselves, investigation next shifted to the electrical umbilical on the payload fairing. This umbilical connector would normally be attached on the ground to permit testing of the Ranger's subsystems and only a thin hinged door covered it during launch. One of the pins on the connector was "hot" and could easily be bridged, transferring a voltage to the adjacent pins and activating the TV camera system during launch. As for the cause of it, one possibility was electrostatic discharge, the other was a shock wave of some sort.

Alexander Bratenahl, a physicist at JPL's Space Sciences Division, suggested that the electrical short was caused by venting propellant during Atlas booster section jettison. There was no tracking camera footage of this event on Ranger 6's launch, which had occurred on an overcast day, but film of other Atlas launches showed that a large white plume enveloped the launch vehicle after staging. Convair technicians confirmed that 112 pounds (51 kg) of LOX was vented from the Atlas after staging, but although the shock wave theory seemed tempting, James Kendall, another JPL physicist, dismissed it out of hand. The idea of an electrostatic discharge was also unlikely given the thinning air and high altitude of the Atlas when staging occurred.

Bratenahl persisted and studied more film of Atlas launches with the frames enlarged, which revealed light flashes in the post-staging plume. Another phone call to Convair revealed that 67 pounds (30 kg) of RP-1 were also dumped during staging and that the Atlas's sustainer engine exhaust ignited the propellant cloud, producing these flashes. Since the umbilical door on the payload shroud was only held in place with a thin latching mechanism, hot gases from igniting propellant could have contacted the electrical connector and caused a short. The inadvertent activation of the telemetry system during launch had occurred almost simultaneous with booster jettison at T+140 seconds. With that, the book could be closed on the cause of Ranger 6's failure.

Among the changes made for Ranger 7 included new procedures to apply full power testing to the spacecraft off of the launch pad, where there was no risk of the midcourse correction engine activating on top of a fully fueled Atlas-Agena.

Jet Propulsion Laboratory had originally wanted to have Ranger 7 impact in the same general area as Ranger 6 so the impact crater could be imaged, but lighting conditions during July would not be favorable so they instead decided to go for a little-known area 11 degrees south of the Moon's equator near the Sea of Storms. The probe was shipped to Cape Canaveral in mid-June along with Atlas 250D and Agena 6009.

Spacecraft design

Launch of Atlas Agena B with Ranger 7. Atlas Agena B with Ranger 7 (Jul. 28 1964).jpg
Launch of Atlas Agena B with Ranger 7.

Rangers 6, 7, 8, and 9 were called Block 3 versions of the Ranger spacecraft. The spacecraft consisted of a hexagonal aluminum frame base 1.5 metres (4 ft 11 in) across on which was mounted the propulsion and power units, topped by a truncated conical tower which held the TV cameras. Two solar panel wings, each 739 millimetres (29.1 in) wide by 1,537 millimetres (60.5 in) long, extended from opposite edges of the base with a full span of 4.6 metres (15 ft), 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 3.6 metres (12 ft). [3]

Propulsion for the mid-course trajectory correction was provided by a 224 N thrust monopropellant hydrazine engine with four jet-vane vector control. Orientation and attitude control about three axes was 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 metres (25 sq ft)and producing 200 W. Two 1200 watt-hour AgZnO batteries rated at 26.5 V 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. [3]

Communications were through the quasiomnidirectional low-gain antenna and the parabolic high-gain antenna. Transmitters aboard the spacecraft included a 60 W TV channel F at 959.52  MHz, a 60 W TV channel P at 960.05 MHz, and a 3 W transponder channel 8 at 960.58 MHz. 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. [3]

Mission profile

First image of the Moon taken by a U.S. spacecraft. The large crater at center right is Alphonsus Ranger7 PIA02975.jpg
First image of the Moon taken by a U.S. spacecraft. The large crater at center right is Alphonsus
Last picture by Ranger 7, taken about 488 m above the Moon, reveals features as small as 38 cm across. The noise pattern at right results from spacecraft impact while transmitting. NASA FACTS Volume 2 number 6 PROJECT RANGER image 04.jpg
Last picture by Ranger 7, taken about 488 m above the Moon, reveals features as small as 38 cm across. The noise pattern at right results from spacecraft impact while transmitting.

On July 6, Ranger 7 completed its ground testing and was stacked atop the booster. On July 9, a NASA committee met and deemed the booster and spacecraft fully ready for launch, which was targeted for the 27th. [3]

The first countdown on July 27 failed due to a defective battery in the Atlas and a problem with the ground guidance equipment. The next day, all went smoothly and Ranger 7 lifted off from LC-12 at 12:50 PM EST. The weather was clear and cloudless on this launch and Atlas staging was observed by tracking cameras. The expected propellant cloud enveloped the booster, but no anomalous events occurred this time. Thirty minutes after liftoff, the Agena restarted to boost Ranger 7 on a trajectory towards the Moon.

The flight trajectory for Ranger 7 was quite accurate, but a short midcourse correction would still be needed to ensure impact in the Sea of Storms instead of the far side of the Moon, which was carried out early on the morning of July 29. The warmup period for the TV cameras would be performed earlier and made shorter than on Ranger 6. Out of fear of jeopardizing the mission, ground controllers decided that the probe's orientation was acceptable enough and they would not risk maneuvering with the attitude control thrusters to get into a better angle. At 6:09 AM PDT, the first video imagery reached Earth.

As Ranger 7 sped towards the surface of the Moon, TV camera performance remained normal. Images of the cratered lunar surface continued to filter back to JPL headquarters in Pasadena, California and finally, at 6:25, impact occurred and all signals from the probe ceased. In the JPL control room, there was "rapturous celebration". Ranger 7 had delivered the first close-distance imagery of the lunar surface and "more than anything, even the manned Mercury missions, had at last undone the sting Americans felt at Sputnik 1's launch".

The photographs returned from the probe found that the Moon was most likely "very craggy and rocky with debris everywhere". After speaking to the media, NASA officials were peppered with the obvious question – did the Moon have a surface solid enough that humans could safely land on it? Geologist Gerard Kuiper replied that, judging by the images, it seemed likely that at least some of the Moon was smooth enough to land a spacecraft on. However, the actual hardness of the surface couldn't be determined with certainty until a soft landing was made. Nonetheless, Ranger 7's images did seem to suggest that it was solid enough.

Ranger 7 reached the Moon on July 31. The F-channel began its one-minute warm-up 18 minutes before impact. The first image was taken at 13:08:45 UT at an altitude of 2110 km. Transmission of 4,308 photographs of excellent quality occurred over the final 17 minutes of flight. The final image taken before impact has a resolution of 0.5 meters. The spacecraft encountered the lunar surface in direct motion along a hyperbolic trajectory, with an incoming asymptotic direction at an angle of -5.57 degrees from the lunar equator. The orbit plane was inclined 26.84 degrees to the lunar equator. After 68.6 hours of flight, Ranger 7 impacted in an area between Mare Nubium and Oceanus Procellarum (subsequently named Mare Cognitum) at 10°38′02″S20°40′38″W / 10.6340°S 20.6771°W / -10.6340; -20.6771 . [1] (The impact site is listed as 10.63 S, 20.66 W in the initial report "Ranger 7 Photographs of the Moon".) Impact occurred at 13:25:48.82 UT at a velocity of 2.62 km/s. The spacecraft performance was excellent and the success of the mission finally brought a turnaround in NASA's fortunes after the endless string of lunar probe failures since 1958. [3]

Ranger 7 is credited for beginning the "peanut" tradition at NASA command stations. On the success of Ranger 7, someone in the control room was noticed eating peanuts. Since 1964 control rooms ceremonially open a container of peanuts for luck and tradition. [4]

Footnotes

  1. 1 2 Samuel Lawrence (September 24, 2013). "LROC Coordinates of Robotic Spacecraft - 2013 Update". lroc.sese.asu.edu. Archived from the original on May 9, 2015. Retrieved June 9, 2015.
  2. Calvin J. Hamilton. "Ranger 7". Views of the Solar System.
  3. 1 2 3 4 5 6 National Space Science Data Center, Ranger 7, NSSDC ID: 1964-041A
  4. Dina Spector (August 4, 2012). "NASA's Unlikely 'Good-Luck' Charm Comes In A Jar". Business Insider.

See also

Related Research Articles

<span class="mw-page-title-main">Mariner program</span> NASA space program from 1962 to 1973

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.

<span class="mw-page-title-main">Mariner 6 and 7</span> Robotic spacecraft sent to Mars in 1969

Mariner 6 and Mariner 7 were two unmanned NASA robotic spacecraft that completed the first dual mission to Mars in 1969 as part of NASA's wider Mariner program. Mariner 6 was launched from Launch Complex 36B at Cape Canaveral Air Force Station and Mariner 7 from Launch Complex 36A. The two craft flew over the equator and south polar regions, analyzing the atmosphere and the surface with remote sensors, and recording and relaying hundreds of pictures. The mission's goals were to study the surface and atmosphere of Mars during close flybys, in order to establish the basis for future investigations, particularly those relevant to the search for extraterrestrial life, and to demonstrate and develop technologies required for future Mars missions. Mariner 6 also had the objective of providing experience and data which would be useful in programming the Mariner 7 encounter five days later.

<span class="mw-page-title-main">Mariner 1</span> 1962 NASA unmanned mission to fly by Venus

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.

<span class="mw-page-title-main">Mariner 3</span> Failed robotic deep-spacecraft to Mars

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.

<span class="mw-page-title-main">Surveyor program</span> 1960s NASA program to soft-land robotic probes on the Moon

The Surveyor program was a NASA program that, from June 1966 through January 1968, sent seven robotic spacecraft to the surface of the Moon. Its primary goal was to demonstrate the feasibility of soft landings on the Moon. The Surveyor craft were the first American spacecraft to achieve soft landing on an extraterrestrial body. The missions called for the craft to travel directly to the Moon on an impact trajectory, a journey that lasted 63 to 65 hours, and ended with a deceleration of just over three minutes to a soft landing.

<span class="mw-page-title-main">Surveyor 3</span> American lunar lander

Surveyor 3 was the third lander of the American uncrewed Surveyor program sent to explore the surface of the Moon in 1967. It was the first mission to carry a surface-soil sampling-scoop.

<span class="mw-page-title-main">Pioneer 4</span> NASA robotic spacecraft designed to study the Moon

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. 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 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-31

Pioneer P-31 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 midcourse 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.

<span class="mw-page-title-main">Ranger 1</span>

Ranger 1 was a prototype spacecraft launched as part of the Ranger program of unmanned 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.

<span class="mw-page-title-main">Ranger 3</span> 1962 robotic lunar exploration mission by NASA; malfunctioned

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.

<span class="mw-page-title-main">Ranger 4</span> 1962 American unmanned space flight intended to study the Moon

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.

<span class="mw-page-title-main">Ranger 5</span> US unmanned lunar space probe

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.

<span class="mw-page-title-main">Surveyor 1</span> Lunar lander spacecraft

Surveyor 1 was the first lunar soft-lander in the uncrewed Surveyor program of the National Aeronautics and Space Administration. This lunar soft-lander gathered data about the lunar surface that would be needed for the crewed Apollo Moon landings that began in 1969. The successful soft landing of Surveyor 1 on the Ocean of Storms was the first by an American space probe on any extraterrestrial body, occurring on the first attempt and just four months after the first soft Moon landing by the Soviet Union's Luna 9 probe.

<span class="mw-page-title-main">Ranger program</span> American unmanned lunar space missions in the 1960s

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, 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.

<span class="mw-page-title-main">Surveyor 2</span> Failed lunar lander launched in 1966

Surveyor 2 was to be the second lunar lander in the uncrewed American Surveyor program to explore the Moon. It was launched September 20, 1966 from Cape Kennedy, Florida aboard an Atlas-Centaur rocket. A mid-course correction failure resulted in the spacecraft losing control. Contact was lost with the spacecraft at 9:35 UTC, September 22.

<span class="mw-page-title-main">Ranger 6</span> United States lunar space probe

Ranger 6 was a lunar probe in the NASA Ranger program, a series of robotic spacecraft of the early and mid-1960s to obtain the first 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 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. No other experiments were carried on the spacecraft. Due to a failure of the camera system, no images were returned.

<span class="mw-page-title-main">Ranger 8</span> NASA spacecraft to explore the moon, 1965

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.

<span class="mw-page-title-main">Ranger 9</span> Lunar space probe launched in 1965 as part of NASAs Ranger program

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.

<span class="mw-page-title-main">Moon landing</span> Arrival of a spacecraft on the surface of the Moon

A Moon landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959.

<span class="mw-page-title-main">Atlas-Agena</span> American expendable launch system

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.

References