First survivable landing on the Moon: Feb. 3, 1966
With this mission, the Soviets accomplished another spectacular first in the space race, the first survivable landing of a human-made object on another celestial body and the transmission of photographs from its surface.
Luna 9 was the 12th attempt at a soft-landing by the Soviets. It was also the first deep space probe built by the Lavochkin design bureau that would design and build all future Soviet (and Russian) lunar and interplanetary spacecraft.
All operations prior to landing occurred without fault. A 48-second mid-course correction at 19:29 UT on Feb. 1, 1966 some 145,000 miles (233,000 kilometers) from the Moon directed the probe to its target in the Ocean of Storms. About one hour before touchdown at a distance of 5,200 miles (8,300 kilometers), Luna 9 was put in proper attitude for retrofire. Just prior to engine ignition, two side compartments were jettisoned, followed by inflation of two shock-absorbing airbags covering the lander to a pressure of 1 atmosphere. Its main S5.5A engine ignited at an altitude of 46.5 miles (74.885 kilometers) above the surface and fired for 48 seconds until the probe was just 850 to 870 feet (260 to 265 meters) above ground, thus decelerating Luna 9 from 8,500 feet (2,600 meters) per second to a few feet per second.
Just above the surface, a long boom sensor made contact with the lunar surface, thus issuing a command to eject the 23-inch (58-centimeter) spheroid ALS capsule weighing 220 pounds (99.8 kilograms) from the main bus. The ALS (still enclosed in surrounded airbags) landed a few yards (meters) away. The impact time was recorded as 18:45:30 UT on Feb. 3, 1966 west of the Reiner and Marius craters in the Ocean of Storms (reported as 7 degrees 8 minutes north latitude and 64 degrees 32 minutes west longitude but closer to 8 degrees north latitude and 64 degrees west longitude).
About four minutes after landing, the airbags split open, and the petals covering the top of the ALS were deployed.
Precisely 4 minutes and 10 seconds after touchdown, Luna 9 began transmitting initial telemetry data back to Earth, although it would be another 7 hours (at 01:50 UT on Feb. 4, after the Sun climbed from 3 degrees to 7 degrees elevation) before the probe began sending back the first of nine images (including five panoramas) of the surface of the Moon.
The first panoramic images arrived very early in the morning in Moscow, and because officials were afraid to wake up Soviet space program curator Dmitriy Ustinov (1908-1984) (whose permission was required for publication in the Soviet media), the first panoramic images were actually published in the British media courtesy of Sir Bernard Lovell (1913-2012) at the Jodrell Bank Observatory who had intercepted and analyzed the same data.
The later images had the Sun much higher, up to 41 degrees, thus causing the shadow relief of the images to change. These were the first images sent back from the surface of another planetary body.
Controllers noticed at one point that Luna 9’s vantage point had slightly shifted over the sequence of images, possibly caused by the diminishing water supply of its thermal control system which changed its weight distribution. This change in perspective (of about 4 inches or 100 mm) opened up the possibility of stereo photography of the surface.
The KS-17M radiation detector measured a dosage of 30 millirads per day.
Perhaps the most important discovery from the mission was determining that a foreign object would not simply sink into the lunar dust, i.e., that the ground could support a heavy lander.
Mission controllers expected that the last communications session would be on Feb. 5, 1966 (from 16:00 to 17:41 UT) but were pleased to have an additional one, on Feb. 6, 1966 (from 20:37 to 22:55 UT). By the time contact was lost, controllers had communicated with Luna 9 over seven communications sessions lasting 8 hours and 5 minutes.
- Credit: NASA