Surveyor 1, 2, 3, 4, 5, 6, 7

Surveyor 3 [NASA]

The Surveyor program consisted of seven uncrewed lunar missions that were launched between May 1966 and January 1968. Five of these spacecraft, Surveyor 1, 3, 5, 6, and 7 successfully soft-landed on the lunar surface. In addition to demonstrating the feasibility of lunar surface landings, the Surveyor missions obtained lunar and cislunar photographs and both scientific and technological information needed for the Apollo crewed landing program. Four spacecraft, Surveyor 1, 3, 5, and 6, returned data from selected mare sites from Apollo program support, and Surveyor 7 provided data from a contrasting rugged highland region.

Each spacecraft weighed 1000 kilograms at launch, was 3.3 meters high, and had a 4.5-meter diameter. The tripod structure of aluminum tubing provided mounting surfaces for scientific and engineering equipment. Onboard equipment consisted of a 3-meter-square solar panel that provided approximately 85 watt output, a main battery and 24-volt non-rechargeable battery that together yielded a 4090 watt total output, a planar array antenna, two omnidirectional antennas, and a radar altimeter. The spacecraft carried a Star-37 retro motor for breaking. After the Star-37 has burned out, it was separated and the Surveyor descended on its three hydrazine engines (Thiokol TD-339). The soft landing was achieved by the spacecraft free falling to the lunar surface after the engines were turned off at a 3.5-meter altitude to avoid contamination of the landing site. Operations began shortly after landing.

Four Surveyor spacecraft landed in the lunar maria near the equator. These sites were selected primarily because they were being considered for Apollo crewed lunar landings. Surveyor 7, the last in the series, landed in the highland region close to Tycho Crater, a site chosen primarily for its scientific interest. The suitability of each site for making a safe landing was also evaluated as part of the site selection process.

In addition to the objectives of developing and validating the technology for landing softly on the Moon and providing data on the compatibility of the Apollo spacecraft design with conditions on the lunar surface, the Surveyor program had the objective of adding to our scientific knowledge of the Moon. Toward that end, the following investigations were performed by the Surveyor spacecraft (note that not all investigations were carried out on every mission).

• Television Observations
  Each Surveyor spacecraft carried a television camera, and more than 86,000 70-millimeter pictures were obtained at very high resolution (to 1 millimeter). This photography provided information on the nature of the surface terrain in the immediate vicinity of the spacecraft as well as the number, distribution, and sizes of the craters and boulders in the area. In addition to lunar terrain studies, the photography supported investigations of soil mechanics, magnetic properties, and composition of the surface material.
• Lunar Surface Mechanical Properties
  Mechanical property estimates are the result of interpretations of landing telemetry data and television pictures as noted above. Measurements from strain gauges mounted on the spacecraft landing gear were analyzed. The surface sampler, flown on Surveyor 3 and Surveyor 7, also obtained data on mechanical properties. To study soil erosion effects and to determine soil properties, the vernier engines and attitude jets were operated after the landings and the results observed with the television camera.
• Lunar Surface Soil Mechanics
  The soil mechanics investigation was performed by the surface sampler carried on Surveyor 3 and 7. The sampler proved to be an extremely versatile and useful piece of equipment. Using this device, operators performed a number of bearing and impact tests and trenching operations. All these operations were monitored using the television camera, and photography of the results provided information for this investigation.
• Lunar Surface Temperature and Thermal Characteristics
  None of the Surveyor spacecraft carried any instruments, as such, to measure lunar surface temperatures or thermal characteristics. However, there were temperature sensors on the outer surfaces of two electronic compartments, on the solar panel, and on the planar array, which were highly dependent on the local thermal radiation environment.
• Lunar Surface Electromagnetic Properties
  Surveyor 5, 6, and 7 had a magnet attached to one of the spacecraft footpads to determine magnetic properties and composition of the soil. Surveyor 7 had additional magnets on a second footpad and the surface sampler. Photographs showing the amount of dust adhering to magnets indicated the amount of magnetic particles in the soil and allowed estimates of the lunar soil compositions when compared with premission experiment photographs of magnets in terrestrial soils of various compositions.
• Alpha-Scattering Chemical Analysis
  Composition of surface materials was also determined from data obtained by the alpha-scattering instrument. This instrument was carried by Surveyor 5, 6, and 7 to allow chemical analysis of the lunar surface material. The performance of the alpha-scattering equipment and operational system during the three missions was excellent. In all, six lunar samples were examined. The Surveyor 5, 6, and 7 missions provided the first chemical analysis of lunar surface material.

Missions:

• Surveyor 1: Launched May 30, 1966; landed on Oceanus Procellarum, June 2, 1966; Surveyor 1 transmitted 11,237 still photos of the lunar surface to the Earth by using a television camera and a sophisticated radio-telemetry system. It transmitted video data from the Moon beginning shortly after its landing, through July 14, 1966 -- but with a period of no operations during the long lunar night of June 14, 1966, through July 7, 1966. The return of engineering information from Surveyor 1 continued through January 7, 1967
• Surveyor 2: Launched September 20, 1966; During the midcourse correction maneuver, one vernier engine failed to ignite, resulting in an unbalanced thrust that caused the spacecraft to tumble for its remaining 54 hours of the flight. Attempts to salvage the mission failed. Contact was lost with the spacecraft at 9:35 UTC, September 22. The spacecraft was targeted at Sinus Medii, but crashed near Copernicus crater. The spacecraft was calculated to have impacted the lunar surface at 03:18 UTC, September 23, 1966.
• Surveyor 3: Launched April 17, 1967; landed on Oceanus Procellarum, April 20, 1967; The spacecraft bounced twice on landing due to a late cut off of the landing engines. This Surveyor mission was the first one that carried a surface-soil sampling-scoop, which can be seen on its extendable arm in the pictures. This mechanism was mounted on an electric-motor-driven arm and was used to dig four trenches in the lunar soil. These trenches were up to 18 centimeters deep. Samples of soil from the trenches were placed in front of the Surveyor's television cameras to be photographed and the pictures radioed back to the Earth. When the first lunar nightfall came on May 3, 1967, it was shut down because its solar panels were no longer producing electricity. At the next lunar dawn (after 14 terrestrial days, or about 336 hours), Surveyor 3 could not be reactivated. It transmitted 6,300 still images. Surveyor 3 was visited by the crew of Apollo 12, which landed with the Lunar Module 'Intrepid' nearby. Some parts of the proobe were returned to earth.
• Surveyor 4: Launched July 14, 1967; crashed on Sinus Medii, July 17, 1967; After a flawless flight to the moon, radio signals from the spacecraft ceased during the terminal-descent phase, approximately 2.5 min. before touchdown. Contact with the spacecraft was never reestablished, and the mission was lost. The solid fuel retro rocket may have exploded near the end of its scheduled burn.
• Surveyor 5: Launched September 8, 1967; landed on Mare Tranquillitatis, September 11, 1967; Performed a successful landing, inspite of a helium leak. Data was received for 2 weeks after the landing. A miniature chemical analysis lab using an alpha particle backscatter device was used to determine the lunar surface soil consisted of basaltic rock. The objectives were to obtain postlanding television pictures of the lunar surface, conduct a Vernier engine erosion experiment, determine the relative abundance of the chemical elements in the lunar soil, obtain touchdown dynamics data, and obtain thermal and radar reflectivity data. The spacecraft transmitted excellent data for all experiments from shortly after touchdown until October 18, 1967, with an interval of no transmission from September 24 to October 15, 1967, during the first lunar night. Transmissions were received until November 1, 1967, when shutdown for the second lunar night occurred. Transmissions were resumed on the third and fourth lunar days, with the final transmission occurring on December 17, 1967. 19,000 pictures were transmitted during the first, second, and fourth lunar days.
• Surveyor 6: Launched November 7, 1967; landed on Sinus Medii, 10 November 1967; Virtually identical to Surveyor 5, this spacecraft carried a television camera, a small bar magnet attached to one footpad, and an alpha-scattering instrument as well as the necessary engineering equipment. Surveyor 6's engines were restarted and burned for 2.5 seconds on November 17 at 10:32 UTC in the first Lunar liftoff. The vehicle lifted off and was hovering 4 m above the Lunar surface. After moving west 2.5 m the spacecraft was once again successfully soft landed. The spacecraft continued functioning as designed. On November 24, 1967, the spacecraft was shut down for the 2 week lunar night. Contact was made on December 14, 1967, but no useful data were obtained. A total of 30,027 images were transmitted to Earth.
• Surveyor 7: Launched January 7, 1968; landed near Tycho crater, January 10, 1968; This spacecraft was similar in design to the previous Surveyors, but it carried more scientific equipment including a television camera with polarizing filters, a surface sampler, bar magnets on two footpads, two horseshoe magnets on the surface scoop, and auxiliary mirrors. Of the auxiliary mirrors, three were used to observe areas below the spacecraft, one to provide stereoscopic views of the surface sampler area, and seven to show lunar material deposited on the spacecraft. Operations of the spacecraft began shortly after the soft landing and were terminated on January 26, 1968, 80 hours after sunset. On Jan. 20, while the craft was still in daylight, the TV camera observed two laser beams aimed at it from the night side of the crescent Earth, one from Kitt Peak National Observatory, Tucson, Arizona, and the other at Table Mountain at Wrightwood, California. Operations on the second lunar day occurred from February 12 to 21, 1968.