After a decades-long hiatus, we have finally restarted our exploration of the lunar surface using automated landers and rovers. While these missions almost make landing on the Moon look routine, it was not always this way and required the mastery of many new technologies and techniques. During the first half of the 1960s, the US and Soviet Union collectively made over a dozen attempts over the course of four years to land an instrumented payload on the surface of the Moon without success. The first American spacecraft to finally succeed was the premier mission of a series known simply as “Surveyor”.

Origins of Surveyor Program

NASA’s first lunar landing program was the Ranger project run by the Jet Propulsion Laboratory (JPL). This project was started in response to a directive in late December 1959 to launch five missions in 1961 and 1962 using the then new Atlas-Agena B rocket developed for the USAF. The first two Block I Ranger spacecraft were to serve as prototypes not only for the subsequent probes in the series but also the first generation of Mariner spacecraft to be sent to explore Venus and Mars (see “The Prototype That Conquered the Solar System”). The plan was for the subsequent three Block II Ranger missions to hard-land a simple 43-kilogram seismometer package on the lunar surface while the carrier took high-resolution television images of the cratered landscape during the final minutes of its descent (see “NASA’s First Moon Lander”).

But before the ink on the Ranger project authorization was even dry, NASA had plans for even more ambitious lunar missions in the works. In May of 1960, JPL’s Surveyor project was authorized. As originally envisioned, Surveyor was to consist of a single basic spacecraft design which could be outfitted for two different missions. Surveyor A would be designed to land on the lunar surface. It would have a mass of about 1,100 kilograms when launched and carry as much as 157 kilograms of instrumentation. Among these instruments were four television cameras: one would be used for approach imaging, a pair would be used for stereo imaging of the lading site and a fourth would be used to monitor a semi-automated drill designed to penetrate up to 1.5 meters below the lunar surface. Various instruments would be used to analyze samples extracted by the drill. Other instruments would include a seismometer, a magnetometer, along with sensors to measure lunar gravity, radiation, atmosphere, and surface mechanical properties.

The lander’s structure would consist of a simple tetrahedral frame upon which the various instruments and thermally controlled electronic compartments would be mounted. It would stand three meters from its three landing legs to the top of its mast mounted solar panel and planar high-gain antenna. After landing at a speed of three meters per second with the use of a solid rocket motor and a liquid propellant descent engines, it would have a mass of about 340 kilograms. The mission would last for a minimum of thirty days and hopefully as long as ninety. At this early stage, the first Surveyor flight was expected in 1963.

The second variant considered was designated Surveyor B. This spacecraft would use the same basic structure as the lander but instead would be placed into a 100-kilometer high lunar orbit to perform television reconnaissance of the Moon’s surface as well as perform other measurements of the lunar environment for a period of six months. On January 19, 1961, Hughes Aircraft (whose space division is now part of Boeing) received the contract to build Surveyor.

The launch vehicle for this new lunar spacecraft was to be the Atlas-Centaur then under development by NASA. The Centaur used liquid hydrogen and liquid oxygen (LOX) as propellants – the first rocket stage to do so. This combination provided up to half again as much thrust than a like mass of conventional propellants then in use. The Atlas booster to be used with the Centaur was to be a modified version of the Atlas D ICBM. The forward propellant tank was modified to accept the wider and heavier upper stage and a new MA-5 engine assembly providing ten percent more liftoff thrust than when the baseline MA-2 system was used.

Centaur development started officially on August 28, 1958, when the USAF received authorization to develop a high-energy upper stage for use with the USAF’s Atlas D and the ABMA’s Juno V (later to become NASA’s Saturn I). By October of that year, the Convair division of General Dynamics (whose space systems division is now part of the aerospace giant, Lockheed Martin) had received the contract to develop and build Centaur. Because of the political climate of the time, the Centaur development program was transferred to NASA in July of 1959 with the USAF relegated to an advisory role.

The development of a hydrogen fueled rocket proved to be fraught with difficulties. Insufficient funding and a series of technical problems delayed the launch of the first test article. Finally, on May 8, 1961, the first Atlas-Centaur was launched. After 44 seconds of flight, Centaur’s insulation panels started ripping off the ascending launch vehicle. Structural failure ensued and the hydrogen fueled Centaur exploded 55 seconds into the flight. The failure was studied and the stage’s design was modified. More redesign work added additional weight to this highly innovative upper stage and the expected performance dropped. As time wore on, it became clear that Centaur would not be available as soon as engineers and space planners would like.

The timing could not have been worse. Within days of the failure of Atlas-Centaur 1, President John F. Kennedy threw down the gauntlet and committed the US to a manned lunar landing by the end of the decade. The Ranger and Surveyor program objectives were redirected to support this new effort and the U.S. Congress appropriated the needed funds in the months to follow.

But as the focus of NASA’s lunar programs were changing, problems with Surveyor were slowly building. In the first half of 1962, balloon-borne drop tests of retrorocket equipped models started over Holloman Air Force Base in New Mexico. The first test failed and subsequent tests had mixed results. Still, the tests did supply enough information to help fine tune Surveyor’s landing sequence and systems design.

Surveyor’s launch vehicle was having more than its share of difficulties as well. Throughout 1962, design changes were made to the Atlas-Centaur to correct various defects found during its first failed launch attempt as well as during ground testing. In October the entire development program was transferred from the Marshall Space Flight Center to NASA’s Lewis Research Center (now called the Glenn Research Center) due to the ever-increasing work on the Saturn rocket development and the lack of support for the Centaur with key people at Marshall like Wernher von Braun. At this stage, another test of the Atlas-Centaur was not expected until the middle of 1963.

Because of the Centaur design changes, Surveyor also had to shed some mass. The new design called for a somewhat lighter 950-kilogram lander carrying only 52 kilograms of instruments. Advanced design work continued and several new options were added to the lander’s design, including the use of a Martin-Marietta SNAP-11 nuclear generator to supply Surveyor A with 18.6 watts of power for ninety days. While this was only a fraction of what was needed to operate Surveyor, this generator would supply minimal power during the long lunar night when the solar panels would be useless. By the end of 1962, plans called for seven Surveyor A landing missions starting in late 1964 and five Surveyor B orbiters with the first launch expected in 1965. Options for five or more additional landers were also being considered.

Change of Direction

But as work progressed on Surveyor and it launch vehicle, JPL was experienced a frustrating string of problems with the failure of all three Ranger lunar landing missions launched during 1962. As a result of fears that JPL’s problems with Ranger could recur in its Surveyor program, and because of the continuing development issues with the Atlas-Centaur rocket, NASA Headquarters began to examine possible alternatives to Surveyor. Langley Research Center was quietly directed by Headquarters in 1962 to examine the possibility of using a lightweight lunar orbiter launched by the improved Atlas-Agena D to perform a photographic mapping mission in place of JPL’s Surveyor B orbiter. Any more major delays in either the Surveyor or its launch vehicle programs could severely impact the schedule of the all-important Apollo program. High resolution photographs of potential landing sites were urgently needed.

The studies conducted indicated that it was feasible to build a small lunar orbiter that would provide the needed lunar photographs. By March of 1963, the basic design for what came to be called Lunar Orbiter was completed and the project approved. On August 30, the newly created Lunar Orbiter Project Office at Langley issued a request for proposals for its new lunar project. The goal was to build an orbiter that could image potential Apollo landing sites 5° north and south of the equator between 45° east and west longitude with a resolution of one meter. The first flight was expected in 1966 (see “Lunar Orbiter 1: America’s First Lunar Satellite“).

NASA had similar concerns about the lander portion of the Surveyor program. In 1963, JPL began studies on a Block V Ranger to be launched using an Atlas-Agena D that would carry a small soft lander built by Northrop. This option, as it turned out, was never exercised and was dropped along with the advanced Block IV Ranger by the end of 1963, partially for budgetary reasons. There were also studies performed to switch Surveyor’s launch vehicle to the Titan IIIC being developed by the USAF but this option was not exercised as Atlas-Centaur development proceeded (see “The First Missions of the Titan IIIC”).

With its orbiter mission deleted, JPL’s Surveyor program continued by concentrating on building just the lunar lander variant. The program’s goals were also downsized and altered to support Apollo more directly. Now Surveyor would be used as an engineering tool to develop the techniques needed to land on the Moon. At the end of 1963, a total of seven flights were planned. The first four would be test flights, while the last three would be operational. The first Surveyor flight was still optimistically targeted for late 1964. Options for additional flights of heavier and more advanced Surveyor landers that would incorporate more of the originally planned experiments and possibly a small rover were still being considered. For this it would be required that the usable payload of the launch vehicle be increased.

Progress with the Atlas-Centaur continued at a steady pace during 1963. The second test launch, Atlas-Centaur 2, finally occurred during the afternoon of November 11 after months of delays. The goal of this flight was to simply get into orbit. No second burn of the Centaur’s advanced, hydrogen burning RL-10 engines was being considered on this flight. This time the Centaur successfully fired for 380 seconds to reach a 547 by 1,691-kilometer orbit gathering valuable engineering data on jettisoning its new insulation panels and nose cone. Much work remained to be done to perfect this fickle machine, but at last there seemed to be a light at the end of the tunnel.

While development of the Atlas-Centaur moved forward, substantial advances also continued to be made with the Surveyor program. Extensive testing of a prototype had been completed and testing of various systems was proceeding more or less on schedule. The mass estimate for the operational spacecraft was settling around 975 kilograms of which 30 kilograms would be instrumentation. At this stage of the program it was envisioned that on the three operational flights, an approach and two surface television cameras would be carried along with an alpha scattering instrument to measure soil composition, a seismograph, micrometeoroid detectors, and a soil dynamics experiment. Minimal instrumentation would be carried on the first four test flights now expected sometime in 1966.

Studies on the Surveyor follow on mission, known as Block II, were completed by late 1964. One of the payloads still under consideration for this 1,200 kilogram lander was a 70-kilogram rover that could make soil bearing and topographic studies up to three kilometers from the lander. In order to lift this much heavier payload, one study indicated that the Centaur stage would have to be upgraded and modified to use liquid oxygen/liquid fluorine mixture known as FLOX to replace the liquid oxygen (LOX) oxidizer that was normally used. The inclusion of highly reactive liquid fluorine in the oxidizer was expected to greatly increase the performance of the Centaur. Assuming the program was funded and the “FLOXed” Centaur was available, the first of as many as ten Block II Surveyor flights would take place around 1968.

But as these plans were being considered, the Atlas-Centaur test program was having mixed results. Atlas-Centaur 3, launched on June 30, 1964, failed to reach Earth orbit when a freak drive shaft failure in the stage’s hydraulic system caused the Centaur to spin out of control prematurely ending the flight. Atlas-Centaur 4 was launched on December 11 into a 163 by 172-kilometer parking orbit carrying a mass model of Surveyor in a flight to test the integrity of the total system. A secondary objective of this flight was to test the new upper stage’s restart capability for the first time. While the primary objectives were met, the Centaur failed to reignite and propel itself into a simulated lunar trajectory because of attitude control issues during its coast in orbit. The orbit of the now inert stage decayed the following day.

Because of the continued development problems with the Atlas-Centaur, the near-term goals of its development program were changed. Instead of making a short coast in an Earth parking orbit before a final burn of the Centaur propelled Surveyor to the Moon, a new option was adopted to provide a direct ascent capability for the initial Surveyor flights in 1966. While such a trajectory is less than optimum, it did have the advantage of requiring the Centaur to fire only once thus avoiding the problems encountered developing an in-flight restart capability. The initial flights of Surveyor would be light enough and the Atlas-Centaur accurate enough to make such a flight possible. A parking orbit capability would be available later in the year and an increased lift capability would follow in 1967.

The testing the direct-ascent option by placing a 640-kilogram dynamic mass model of Surveyor into a 160 by 800,000 kilometer orbit was the primary objective of the Atlas-Centaur 5 mission launched on March 2, 1965. Unfortunately, a valve failure caused the MA-5 engines of the Atlas to shutdown after only two seconds of flight. The fully fueled Atlas-Centaur fell back onto pad A at Launch Complex 36 (LC-36A) resulting in one of the most spectacular explosions at Cape Kennedy (see “The Launch of Atlas-Centaur 5”). Following the failure of Atlas-Centaur 5, Atlas-Centaur 6 was a welcome success. Launched on August 11 from the newly completed LC-36B, this test flight placed a 946-kilogram dynamic model of Surveyor directly into a its planned 169 by 820,315-kilometer orbit that simulated the direct ascent trajectory the first Surveyors would use to reach the Moon. With this successful flight, the first phase of Centaur development was completed and the Atlas-Centaur was deemed ready for service. Future test flights would be used to develop Centaur’s in-orbit restart capability.

Development of Surveyor itself was nearly completed at the same time. The last balloon-borne drop tests to verify the landing sequence were a success. The first flight article, called Surveyor A, had completed an extensive series of functional and environmental tests. The launch of this first spacecraft was expected in the early spring of 1966. Meanwhile, plans for future Surveyor missions were being restructured. After a thorough review, NASA decided to make use of the lighter 1000-kilogram stripped-down “engineering” model of Surveyor for all seven scheduled flights, instead of just for the first four missions as previously planned. It was felt that the lightly instrumented (and cheaper) lander was adequate to fulfill its primary objective of gathering information needed to verify the manned Apollo Lunar Module (LM) design. A decision to launch three or more follow-on missions using the more heavily instrumented Surveyor Block II model was deferred pending further study.

The Surveyor Spacecraft

In its final form, Surveyor was the most advanced lunar spacecraft of its day. The basic 2.4-meter tall structure consisted of a simple 27-kilogram tetrahedral frame made of tubular aluminum alloy members. In each of the three lower corners was a landing leg equipped with an aircraft-style shock absorber and a footpad of crushable honeycomb aluminum. The total span of the legs, once deployed, was 4.3 meters. Rising from the apex of the frame was a mast upon which was mounted a gimballed planar high-gain antenna and a solar panel supplying up to 85 watts of electrical power to the lander’s silver-zinc batteries. From the footpads to the top of its mast, Surveyor stood three meters tall.

Buried inside the spacecraft’s frame was a Morton Thiokol-built 91-centimeter diameter TE-M-364 solid propellant rocket motor that would provide between 35.5 to 44.5 kilonewtons of thrust, depending on the motor’s temperature at ignition. This 656-kilogram motor, which would later be used as the third stage in various Delta launch vehicles models flown in the 1970s and as the kick stage for the Pioneer and Voyager missions to the outer planets, would be used to negate most of Surveyor’s motion towards the Moon as the lander approached on a direct descent trajectory towards the lunar surface.

Surveyor also carried a second propulsion system for midcourse corrections and attitude control during the main retrorocket burn as well as for the final descent. This system consisted of three vernier engines fueled by monomethylhydrazine hydrate with MON-10 (a mixture of 90% nitrogen tetroxide and 10% nitric acid) serving as the oxidizer. These engines could be throttled by command of the spacecraft’s flight control subsystem producing between 130 and 460 newtons of thrust each. Yaw, pitch, and descent rate were controlled by selective throttling of the engines. Roll was controlled by a single gimballed vernier. During the trans-lunar coast, Surveyor’s attitude was controlled by a set of six nitrogen gas jets, each providing 270 millinewtons of thrust.

All the temperature sensitive electronics were carried in two thermal boxes. These compartments were covered with 75 layers of aluminized Mylar insulation and the tops were covered by mirrored glass thermal regulators. Compartment A, which maintained it internal temperature between +4° and +52° C, carried a redundant set of receivers and ten-watt radio transmitters, the batteries, their charge regulators, and some auxiliary equipment. The second box, Compartment B, was designed to maintain the temperature between -15° and +52° C. This compartment carried the computer “brains” of the spacecraft which controlled all aspects of the lander’s operation using a total of just 256 commands. Mounted elsewhere on the frame were star sensors, a pair of radar systems for landing, low-gain antennas, propellant, and helium pressurization tanks.

A total of 30 kilograms of instrumentation were carried by the first Surveyors. Most were engineering sensors such as strain gauges, accelerometers, rate gyros, temperature sensors, and so on to be used to make more than two hundred measurements of the spacecraft’s performance and condition. While not specifically designed for investigating the lunar environment, many of these measurements could be used to determine some of its basic properties.

The only true scientific instruments carried by the first Surveyors were a pair of slow-scan television cameras. One was pointed down to provide a view of the lunar surface and a footpad. These images would be transmitted during Surveyor’s final approach starting at an altitude of 1,600 kilometer to allow the landing site to be pinpointed, along with providing information on the surrounding terrain. As it turned out, however, this camera was never used on the first two flights after the requirement was deleted and the camera was removed altogether afterwards. It was felt that the upcoming Lunar Orbiter missions would provide the needed detailed images to help interpret the Surveyor findings and put them into a regional context.

The second camera was mounted in a 1.65-meter tall mast attached to the spacecraft’s framework. The camera pointed up into a movable mirror that allowed the camera to view 360° of azimuth and from 60° below to 50° above the normal plane of the camera. The 7.3-kilogram camera package was canted at a 16° angle to offer a clear view of the surface between two of the footpads out to the lunar horizon 2½ kilometers away. The camera was fitted with a 25 to 100 mm zoom lens that offered a field of view of between 25.3° and 6.4°. The aperture could be set between f/4 and f/22 and the lens could be focused from 1.2 meters to infinity. A shutter was also included so that various integration times could be used to obtain the ideal exposure. While the nominal exposure time was 150 milliseconds, exposures as long as about thirty minutes could be accommodated. The typical resolution of the camera was one millimeter at a distance of four meters. By combining a series of images taken in a stepwise fashion at various azimuth and elevation angles, panoramic mosaics of the spacecraft and the surrounding terrain could be created.

The camera was also fitted with a filter wheel containing clear and three color filters. With the aid of calibration targets mounted at various points of the spacecraft, pictures taken through red, green, and blue spectral filters could be reconstructed back on Earth to yield full-color views of the lunar surface. The camera could only operate in real time via remote control from Earth using a total of 25 commands. The primary means of transmitting images was through the high-gain antenna. Using this powerful antenna, an image would be broken up into 600 scan lines and transmitted back to Earth in 3.6 seconds. The less powerful low-gain antennas, which served as a backup, would permit an image to be broken up into 200 lines and would require 61.8 seconds to transmit.

Like the Block II Ranger, Surveyor was designed to make a direct descent to the lunar surface from its translunar trajectory with no intermediate stop in lunar orbit. Surveyor was much more flexible than the Block II Ranger lander, however, since JPL’s new lander could approach the lunar surface at a substantial angle off the local vertical. This made most of the lunar hemisphere facing Earth accessible to Surveyor. Early flights, however, would be limited to the equatorial mare regions which, as a result of photography from Ranger’s successful Block III flights of 1964 and 1965, appeared to be the safest landing sites for the early Apollo missions (see “The Launch of Ranger 8”).

The Mission

As preparation of the hardware for the first Surveyor mission was being finished and the final Earth-based tests of the Surveyor systems were being performed, the Soviet Union once again beat the US to another space first. On February 3, 1966 Luna 9 became the first spacecraft to land successfully on the surface of the Moon and return data (see “Luna 9: The First Lunar Landing”). Although it had taken a dozen attempts over three years to finally achieve this success with a more modest lander design, the E-6 Luna spacecraft had beaten Surveyor to the Moon.

Since the first Surveyor mission was considered an engineering test, the primary objectives were very simple: demonstrate that Surveyor could be launched, communicate as well as be controlled from the Earth and successfully land on the surface of the Moon. Taking a single image of one of Surveyor’s three footpads after landing and transmitting it back to Earth was only a tertiary objective of the mission.

In preparation for the Surveyor A mission, Atlas 290D was erected on the pad at LC-36A on March 21, 1966. The Centaur was added ten days later to complete Atlas-Centaur 10 launch vehicle. The Surveyor A spacecraft with its launch fairing was added to the stack on April 17. After successfully completing a series of tests culminating with a final Combined Readiness Test on May 26, everything was set to go for a launch attempt on May 30 targeting a smooth area north of Flamsteed Crater in the mare known as Oceanus Procellarum. This landing site would allow a virtually vertical descent to the lunar surface after a flight of 63.6 hours with landing occurring just after local sunrise.

On May 30, 1966 at 10:41:01 EST (14:41:01 GMT), Atlas-Centaur 10 lifted off from Cape Kennedy and placed the 996-kilogram Surveyor 1 on a direct ascent trajectory towards the Moon. Once it separated from its launch vehicle 12 minutes and 37 seconds after liftoff, Surveyor deployed its landing gear as well as it low-gain antennas, locked its solar panel onto the Sun and then acquire its second celestial reference, the star Canopus. Early tracking showed that Surveyor 1 was only 400 kilometers off course. To maximize the chances of landing in a smooth area given its current trajectory, it was decided to retarget the lander about 30 kilometers north of its original aim point. A 21-second burn of Surveyor’s vernier engines 16 hours and 4 minutes after launch changed its velocity by 20.35 meters per second to place the receding spacecraft on target and optimize its approach trajectory. The only problem noted at this point was that one of the pair of low gain antennas did not fully deploy which was deemed not to be a major issue.

At 5:35:46 GMT on June 2, 1966 when Surveyor was 1,600 kilometers from the lunar surface, it left its cruise attitude and aligned its retrorocket for its descent to the lunar surface. At 6:14:41 GMT at height of 320 kilometers, an altitude-marking radar mounted inside the molybdenum nozzle of the retrorocket was activated. At an altitude of 95.5 kilometers, the flight programmer started its countdown and then ignited the three vernier engines at 6:14:48 GMT, followed one second later by the main retrorocket as the spacecraft hit an altitude of 75.2 kilometers. During the forty-second burn of the solid propellant retrorocket, attitude was maintained by the verniers and the speed was cut from 2,610 meters per second to only 110 meters per second at an altitude of about 7.6 kilometers.

After the retrorocket burned out, the vernier engines were throttled to full and about eleven seconds later, the now empty retrorocket case was jettisoned as the Radar Altimeter and Doppler Velocity Sensor (RADVS) was activated. Using data from RADVS, the onboard computer controlled the thrust of the vernier engines to further reduce the speed of the lander to only 1.3 meters per second at an altitude of about 4.3 meters. At this point, the verniers were shutdown to avoid disturbing the lunar soil below and Surveyor dropped to the surface at a speed of 3 meters per second. After a short 6½ centimeter hop upon initial contact with the lunar surface, Surveyor had successfully landed on the Moon on the program’s first attempt at 6:17:36 GMT.

Tracking indicated that Surveyor 1 had come down at 2.45° S, 43.22° W only 14 kilometers from its aim point. After returning 36 minutes of engineering data to check on the lander’s condition (which indicated that the previously stuck low-gain antenna had snapped into place as a result of the landing impact), Surveyor 1 returned its first 200-line television image. This picture and the 10,731 others taken that first lunar day revealed that Surveyor had landed on fairly level rolling landscape inside of a 100-kilometer wide “ghost” crater that had been filled with molten rock eons earlier. A number of distinctive features in the rim of the ghost crater were visible to Surveyor in the distance and provided an independent check of the landing site location. Surveyor 1 was later spotted in images taken by Lunar Orbiter 3 the following year visually verifying the location.

Close examination of the images returned by Surveyor 1 showed that the landing site was littered with boulders ranging up to one meter across and craters of various sizes and states of preservation. The first color images of the lunar surface showed that it had a slightly brownish-gray color. The images and the engineering data from the landing indicated that the footpads had sunk only 2.5 centimeters into the granular lunar soil. This provided proof that the lunar surface was more than firm enough to hold the weight of the Apollo LM and its human occupants confirming similar observations made four months earlier by the Soviet Luna 9 lander.

As sunset approached at the Surveyor landing site, the camera was directed to take a series of images of bright stars in the sky using the camera’s long exposure mode. These first astronomical observations from the surface of another world helped to confirm the orientation of the lander and the calibration of the camera’s pointing system. As the Sun sank below the lunar horizon on June 14, 1966 at the end of Surveyor’s first lunar day, the camera was used to make a series of observations of the solar corona and sky glow associated with sunset. Afterwards, Surveyor 1 was placed into hibernation in hopes that the probe would survive the temperatures dipping to -160° C during the fourteen Earth day-long lunar night.

Although initial attempts at contact on June 28 failed, the lander responded to commands on July 6 returning another 618 images during its second lunar day of operations. On July 13, the battery voltage dropped dramatically as the Sun set once again. While intermittent contact was maintained with the spacecraft until January 7, 1967, the mission was effectively over at the end of the second lunar day due to the worsening condition of the spacecraft’s battery.

All together, Surveyor 1 responded to 297 commands enroute to the Moon, a total of 134,216 commands during its 219 Earth days on the lunar surface and returned 11,150 useful television images. The first Surveyor was an outstanding success and preparations were made to launch the second craft in the series (see “Surveyor 2: Things Don’t Always Go As Planned“).

Follow Drew Ex Machina on Facebook.

Related Video

Here is a video of live CBS News coverage of the Surveyor 1 landing as it happened in the early-morning hours of June 2, 1966.

Related Reading

“NASA’s First Moon Lander”, Drew Ex Machina, May 9, 2015 [Post]

“The Launch of Atlas-Centaur 5”, Drew Ex Machina, March 2, 2015 [Post]

“Luna 9: The First Lunar Landing”, Drew Ex Machina, February 3, 2016 [Post]

General References

J. Jason Wentworth, “A Survey of Surveyor”, Quest, Vol. 2, No. 4, pp 4-16, Winter 1993

Andrew Wilson, Solar System Log, Jane’s Publishing, 1987

First Surveyor Test Mission Set for May 30, NASA Press Release 66-127, May 26, 1966

Surveyor I: A Preliminary Report, NASA SP-126, June 1966