Surveyor 3

Surveyor 3 was the third lander of the Surveyor program that explored the Moon. Launched on April 17, 1967, Surveyor 3 landed April 20, 1967 at the Mare Cognitium portion of the Oceanus Procellarum. A total of 6,315 images were transmitted to Earth.

As it was landing, highly reflective rocks confused Surveyor 3's descent radar. The engines failed to cut off at 14 ft (4.3 m) as per the planned flight profile. This spacecraft bounced twice. The first bounce reached an altitude of 35 ft (10 m). The second bounce reached 11 ft (3 m). On the third impact -- from an initial altitude of 11 feet (3 m) and velocity of zero which was under the original design target of 14 ft (4.3 m) slowly descending -- the spacecraft settled in a soft landing as per the design intentions.

This mission was the first carrying a surface soil sampling scoop. This was mounted on a motor driven arm and used to dig four trenches. The trenches were up to 7 in (180 mm) deep. Samples from the trenches were placed in front of the spacecraft's television cameras for image transmission back to Earth. When lunar nightfall came on May 3, 1967; the spacecraft was shut down to preserve battery power, upon the next lunar dawn (14 terrestrial days, or approximately 14 times 24 = 336 hours) the spacecraft could not be reactivated.

This site was subsequently selected for the Apollo 12 manned lunar mission. Several components of the Surveyor were collected and returned to Earth for study of the long term exposure effects of the harsh lunar environment on human artefacts.

Perhaps Surveyor 3's most remarkable finding, though, was a complete accident.
A common bacteria, Streptococcus mitis, was unintentionally present inside the spacecraft's camera at launch. Around 50 to 100 of these bacteria survived dormant in this harsh environment for three years, to be detected when Apollo 12 brought the camera back to Earth. The discovery, while paid comparatively little attention at the time, gave some credence to the idea of interplanetary panspermia, but more importantly, led NASA to adopt strict abiotic procedures for space probes to prevent contamination of Mars and other bodies suspected of having conditions suitable for life; most dramatically the Galileo spacecraft was deorbited to avoid impacting Europa.

Science instruments

Television

The TV camera consisted of a vidicon tube, 25 and 100 mm focal length lenses, shutters, filters, and iris mounted along an axis inclined approximately 16 deg to the central axis of the spacecraft. The camera was mounted under a mirror that could be moved in azimuth and elevation. Camera operation was totally dependent upon the receipt of the proper command structure from earth. Frame by frame coverage of the lunar surface was obtained over 360 deg in azimuth and from +40 deg above the plane normal to the camera Z axis to -65 deg below this plane. Both 600 line and 200 line modes of operation were used. The 200 line mode transmitted over an omnidirectional antenna and scanned one frame every 61.8 seconds. A complete video transmission of each 200 line picture required 20 seconds and utilized a bandwidth of 1.2 kHz. The 600 line pictures were transmitted over a directional antenna. These framed were scanned every 3.6 seconds. Each 600 line picture required nominally 1 second to be read from the vidicon and required a 220 kHz bandwidth for transmission. The data transmissions were converted to a standard television signal. The television images were displayed on earth on a slow scan monitor coated with a long persistency phosphor. The persistency was selected to optimally match the nominal maximum frame rate. One frame of TV identification was received for each incoming TV frame and was displayed in real time at a rate compatible with that of the incoming image. These data were recorded on a video magnetic tape recorder. The camera returned 6315 pictures between April 20 and May 3, 1967, including views of the spacecraft, lunar surveys, and views of the soil mechanics surface sampler and of the earth during solar eclipse.
The Apollo 12 Lunar Module landed near the Surveyor 3 spacecraft in November, 1969 and the astronauts examined the spacecraft and brought about 10 kg of parts back to Earth, including the Surveyor 3 camera, which is now on display in the Smithsonian Air and Space Museum in Washington, D.C.

Soil Mechanics Surface Sampler

The soil mechanics surface sampler was designed to dig, scrape, and trench the lunar surface and to transport lunar surface material while being photographed so that the properties of the lunar surface could be determined. The sampler was mounted below the television camera and consisted primarily of a scoop approximately 120 mm long and 50 mm wide. The scoop consisted of a container, a sharpened blade, and an electrical motor to open and close the container. A small footpad was attached to the scoop door to present a flat surface to the lunar surface. The scoop was capable of holding a maximum quantity of approximately 32 mm diameter of solid lunar material and a maximum of 100 cm³ of granular material. The scoop was mounted on a pantograph arm that could be extended about 1.5 m or retracted close to the spacecraft motor drive. The arm could also be moved from an azimuth of +40 to -72 deg or be elevated 130 mm by motor drives. It could also be dropped onto the lunar surface under force provided by gravity and a spring. The surface sampler performed seven bearing tests, four trench tests, and 13 impact tests. The total operating time was 18 h, 22 min on 10 separate occasions. Measurements of motor currents and forces applied to the surface were not obtained due to the state of the spacecraft telemetry following landing on the lunar surface. However, estimations were possible. The small spring constant of the torque spring precluded the determination of density from the impact tests. Penetrations of 38 to 50 mm were obtained from the bearing tests, and a 175 mm depth was reached during trenching operations. The design of the mechanism and its electronic auxiliary was more than adequate for the lunar surface operations.