Surveyor 1
Surveyor 1, an uncrewed NASA lunar lander, went into its mission against long odds. Justin Rennilson, formerly of the Jet Propulsion Laboratory, put it plainly: "We figured the probability of success at around 10 to 15 percent." How does a machine set itself down gently on another world? What did it send home from the surface? And what happened when the Sun went away for two weeks at a time?
A number of Ranger spacecraft had failed on their way to the Moon before Surveyor 1 flew. That record made the first Surveyor landing a real surprise to observers. Some television networks carried the landing live. Engineers faced hundreds of challenges, and an uninterrupted communication link for navigation and control was among the most critical.
The Jet Propulsion Laboratory, in Los Angeles County, California, managed the Surveyor program. The series was intended to make soft landings on the Moon, touching down intact rather than crashing. The Hughes Aircraft Company built the probe in El Segundo, California.
Surveyor 1 left Cape Canaveral Air Force Station in Florida on the 30th of May 1966. It flew straight toward the Moon with no parking orbit. The whole flight lasted about 63 hours and 30 minutes.
About 3.4 meters above the surface, the retrorockets were switched off. The probe fell freely the rest of the way. It came to rest on the 2nd of June 1966 on the Oceanus Procellarum, the Ocean of Storms. The site lies in the northeast part of a large crater called Flamsteed P, also known as the Flamsteed Ring. The crater Flamsteed itself sits inside Flamsteed P on its south side.
The Soviet probe Luna 9 had made the first soft Moon landing four months earlier. Surveyor 1 became the first American probe to land softly on any extraterrestrial body.
About 995.2 kilograms of spacecraft left Earth. The landing weight was about 294.3 kilograms, once the spent maneuvering propellant, the jettisoned solid-fueled retrorocket and the radar altimeter system were subtracted.
Over 100 engineering sensors rode on each Surveyor. Their purpose was to gather what planners of the crewed Apollo landings, which began in 1969, needed to know about the lunar surface. Television systems returned pictures of the spacecraft footpad and the surrounding terrain and surface materials. Other measurements covered how strongly the surface reflected radar, how much weight it could bear, and its temperatures.
Strain gauges rated for roughly 800 kgf, or 7.8 kN, sat on each leg shock absorber. They recorded the peak axial force at the moment of landing impact.
Soil chemistry came later. Probes beginning with Surveyor 3 carried instruments to measure the composition and mechanical properties of the lunar soil.
The camera's vidicon tube looked through a zoom lens that worked at either 25 millimeters or 100 millimeters. Those two settings gave fields of view of 25.3 and 6.43 degrees. A shutter, an iris, and clear, orange, green and blue filters completed the optics. Two cameras were carried, but the one meant for the approach was not used on this flight.
A movable mirror sat above the camera and swung in azimuth and elevation. Stepper motors moved it in fixed steps of 2.48 degrees in elevation and 3.0 degrees in azimuth, each with a tolerance of 0.1 degrees. Turning the mirror in azimuth also rotated the image in proportion to the angle. Those calibrated steps let engineers build large composite mosaics of the lunar surface. Readings from the iris and focus positions also allowed some photogrammetric measurements of lunar features.
Frame-by-frame coverage reached all 360 degrees in azimuth. In elevation it ran from 40 degrees above the plane normal to the camera's axis to 65 degrees below it. All of it waited on the proper radio commands from Earth.
The first 14 photographs used a 200-line mode sent through an omnidirectional antenna. One frame was scanned every 61.8 seconds. Each picture took 20 seconds to transmit and used a radio bandwidth of about 1.2 kilohertz.
Every later transmission used 600 lines over a directional antenna, with a frame scanned every 3.6 seconds. Reading one picture from the vidicon tube took about a second. Each demanded a bandwidth of about 220 kilohertz.
On Earth, the transmissions were converted into a standard TV signal for both closed-circuit and broadcast television. Images appeared on a slow-scan monitor coated with a long-persistence phosphor, chosen to match the maximum frame rate. A frame of TV identification arrived with each image and was displayed in real time. A video magnetic tape recorder kept the data.
Over 10,000 pictures were taken before the lunar sunset of the 14th of June 1966. They included wide-angle and narrow-angle panoramas, focus ranging surveys, photometric surveys, special area surveys and celestial photography.
The 14th of June 1966 brought the start of a two-week lunar night. Surveyor 1 was solar-powered, so it had no electricity to work with and went silent until the 7th of July.
Communication needed little juggling. The Moon always shows the same face to Earth, so line-of-sight radio contact only required changing ground stations as the Earth rotated. The Deep Space Network returned data from 1966 to 1967.
On the 7th of July the camera answered commands again. By the 14th of July 1966 it had returned nearly 1000 more pictures. That brought the total to 11,237 still photos, and video transmissions ended that day.
Engineering information, including temperatures, kept arriving through the 7th of January 1967, with several breaks during lunar nights. On the 6th of January 1967, the spacecraft was reactivated for 12 hours. It returned data on the motion of the Moon, which would help refine the map of the Moon's orbital path around the Earth and better fix the distance between the two worlds.
Updated
Common questions
What was Surveyor 1?
Surveyor 1 was the first lunar soft-lander in NASA's uncrewed Surveyor program. It gathered data about the lunar surface that was needed for the crewed Apollo landings, which began in 1969.
When did Surveyor 1 launch and land on the Moon?
Surveyor 1 launched from Cape Canaveral Air Force Station in Florida on the 30th of May 1966. It landed on the Moon on the 2nd of June 1966, after a flight of about 63 hours and 30 minutes.
Where did Surveyor 1 land on the Moon?
Surveyor 1 landed on the Oceanus Procellarum, the Ocean of Storms. The site is in the northeast part of the large crater Flamsteed P, also called the Flamsteed Ring.
How many pictures did Surveyor 1 send back from the Moon?
Surveyor 1 transmitted 11,237 still photos of the lunar surface. Over 10,000 were taken before the lunar sunset of the 14th of June 1966, and nearly 1000 more followed by the 14th of July 1966.
Who built and managed Surveyor 1?
The Jet Propulsion Laboratory, in Los Angeles County, California, managed the Surveyor program. The Hughes Aircraft Company built the spacecraft in El Segundo, California.
Was Surveyor 1 the first spacecraft to soft-land on the Moon?
No. The Soviet probe Luna 9 made the first soft Moon landing, four months before Surveyor 1. Surveyor 1 was the first American probe to land softly on any extraterrestrial body.
Why did Surveyor 1 stop working during the lunar night?
Surveyor 1 was solar-powered, so it had no electricity during the two-week lunar night. It did not operate from the 14th of June 1966 until the 7th of July 1966.
All sources
7 references cited across the entry
- 1Surveyor 1NASA's Solar System Exploration website — 27 December 2017
- 3Fifty Years of Moon Dust: Surveyor 1 was a Pathfinder for ApolloRod Pyle — 2 June 2016
- 4BookNASA SP-184 - SURVEYOR Program ResultsNASA — 1969
- 5Montgomery, Wolf The Surveyor lunar landing television system. IEEE Spectrum, August 1966, p. 55-56
- 7Surveyor 1NASA Space Science Data Coordinated Archive — 2014-08-26