Luna 20Courtesy of NASA's National Space Science Data Center
Launch Site/Country: Tyuratam (Baikonur Cosmodrome), U.S.S.R.
Launch Vehicle: Proton Booster Plus Upper Stage and Escape Stages
On-orbit dry mass: 5600.00 kg. (12,320 lb.)
DescriptionLuna 20 was placed in an intermediate earth parking orbit and, from this orbit, was sent towards the Moon. It entered lunar orbit on February 18, 1972. On February 21, 1972, Luna 20 soft landed on the Moon in a mountainous area near Mare Foecunditatis (Sea of Fertility), 120 kilometers (75 miles) from where Luna 16 had impacted. While on the lunar surface, the panoramic television system was operated. Lunar samples were obtained by means of an extendable drilling apparatus. Luna 20 was launched from the lunar surface on February 22, 1972, and landed in the Soviet Union on February 25, 1972. The lunar samples were recovered the following day.
The Luna 20 TV photography experiment used two special panoramic optico-mechanical TV cameras of the type used on the Lunokhod 1 moon rover in 1971. The cameras were placed on the landing stage under the module that returned to earth. They were positioned so that they were able to make circular scans of the area with a viewing angle of 30 degrees. To determine the position of the spacecraft relative to the meridian of the landing site, a panoramic picture containing an image of the earth was obtained. All operations of the drill experiment were photographed by the optico-mechanical TV cameras.
The Luna 20 drill was a thin-walled tube carrying helical threads on its outside surface and a crown on sharp teeth at its cutting end. The drill was equipped with two special mechanisms, one for capturing hard core samples and the other for holding loose material. It operated at 500 rpm, and it took 30 minutes for the entire length of the drill to penetrate any kind of soil. The drill was provided with thermal insulation and was hermetically sealed to avoid the sticking together of metallic surfaces in contact and the adhesion of lunar soil to it. It was opened only before drilling. This made it possible to lubricate working mechanisims during drilling by oil vapor, i.e., a substance that evaporates in a vacuum. Certain parts were covered with a lubricant that lowered friction in a vacuum. The rod was first put in a vertical position, and then was slowly moved counterclockwise through a 180-degree angle. It was then lowered to the surface. If progress was stopped, a standby motor was employed to overcome the obstacle. The drill penetrated to a depth of 250 millimeters (10 inches) in the lunar surface, and its contents were returned to earth on February 25, 1972. The sample was placed in a special ampule and was hermetically sealed on the moon.