Collection Item Summary:
This is an extendable scoop manufactured by the Hughes Aircraft Company in support of the Surveyor missions that explored the lunar surface. This particular soil mechanics/surface sampler (SSME) was used on the T-21 (Touchdown 21) engineering model. The scoop is a claw-like device at the end of a frame that extends several feet through a gear drive and electrical motor. Engineering model of the soil mechanics surface scoop (SMSS) carried on Surveyor Lunar Landers 3, 4 and 7. These spacecraft, launched starting in 1966, were used to survey the moon's surface to help select a safe landing site for the manned Apollo lunar landings. The scissors jack-like arm of the sampler was hinged to the frame of the spacecraft. The motor driven arm was extendible up to 5 feet and able to range over an area of 24 square feet. The scoop at the end of the arm was used to dig trenches in lunar soil. Images of the trenches sent back by the on-board TV camera, as well as strain gages on the arm provided data on the mechanical properties of the surface of the moon. The SMSS was manufactured by Hughes Aircraft. It was transferred to NASM by GSA in 1969.
Collection Item Long Description:
Soil Surface Sampler
The soil mechanics surface sampler's principal investigator for Surveyor 3 was Gene Shoemaker of the U.S. Geological Survey. The 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. It was mounted below the television camera and consisted primarily of a scoop approximately 12 cm long and 5 cm 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 3.2 cm diameter of solid lunar material and a maximum of 100 cc 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 sampler's arm could also be moved from an azimuth of +40 to -72 deg or be elevated 13 cm 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.
During Surveyor 3, the total operating time was 18 hr, 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 3.8 to 5 cm were obtained from the bearing tests, and a 17.5-cm depth was reached during trenching operations. The design of the mechanism and its electronic auxiliary was more than adequate for the lunar surface operations.
The second mission to use the soil sampler was Surveyor 4, whose principal investigator was Ronald F. Scott of the California Institute of Technology. During this mission the surface sampler performed seven bearing tests, four trench tests, and 13 impact tests. Due to the failure of the mission the surface sampler was never deployed.
In Surveyor 7, with Ronald Scott also the principal Investigator, this instrument performed 16 bearing tests, seven trenching tests, and two impact tests. It also freed the alpha-scattering instrument when it failed to deploy on the lunar surface, shaded this instrument, and moved this instrument for evaluation of other samples. Performance was flawless during 36 hr of operation between January 11 and January 23, 1968. The instrument responded to commands on February 14, 1968, which verified that it had survived the lunar night. The power system, however, was unable to support any operations.