Luna 9, internal designation Ye-6 No.13, was an unmanned space mission of the Soviet Union's Luna programme. On 3 February 1966 the Luna 9 spacecraft became the first spacecraft to achieve a soft landing on the Moon, or any planetary body other than Earth, and to transmit photographic data to Earth from the surface of another planetary body.
The lander had a mass of 99 kilograms (218 lb). It used a landing bag to survive the impact speed of 22 kilometres per hour (6.1 m/s; 14 mph). It was a hermetically sealed container with radio equipment, a program timing device, heat control systems, scientific apparatus, power sources, and a television system.
Luna 9 was launched by a Molniya-M rocket, serial number 103-32, flying from Site 31/6 at the Baikonur Cosmodrome in the Kazakh Soviet Socialist Republic. Liftoff took place at 11:41:37 UTC on 31 January 1966. The first three stages of the four-stage carrier rocket injected the payload and fourth stage into low Earth orbit, at an altitude of 168 by 219 kilometres (104 by 136 mi) and 51.8 degrees inclination. The fourth stage, a Blok-L, then fired to raise the orbit's perigee to a new apogee approximately 500,000 kilometres (310,000 mi), before deploying Luna 9 into a highly elliptical geocentric orbit.
The spacecraft then spun itself up to 0.67 rpm using nitrogen jets. On 1 February at 19:29 UT, a mid-course correction took place involving a 48-second burn and resulting in a delta-V of 71.2 metres per second (234 ft/s).
At an altitude of 8,300 kilometres (5,200 mi) from the Moon, the spacecraft was oriented for the firing of its retrorockets and its spin was stopped in preparation for landing. At 25 kilometres (16 mi) above the lunar surface, the radar altimeter triggered the jettison of the side modules, the inflation of the air bags and the firing of the retro rockets. At 250 metres (820 ft) from the surface, the main retrorocket was turned off and the four outrigger engines were used to slow the craft. Approximately 5 metres (16 ft) above the lunar surface, a contact sensor touched the ground triggering the engines to be shut down and the landing capsule to be ejected. The craft landed at 22 kilometres per hour (6.1 m/s; 14 mph)
The spacecraft bounced several times before coming to rest in Oceanus Procellarum west of Reiner and Marius craters at approximately 7.08 N, 64.37 W on 3 February 1966 at 18:45:30 UT.
Luna 9 was the twelfth attempt at a soft-landing by the Soviet Union; it was also the first successful deep space probe built by the Lavochkin design bureau, which ultimately would design and build almost all Soviet (later Russian) lunar and interplanetary spacecraft. All operations prior to landing occurred without fault, and the 58-centimetre (23 in) spheroid ALS capsule landed on the Moon at 18:45:30 UT on 3 February 1966 west of the craters Reiner and Marius in the Ocean of Storms (at 7°8' north latitude and 64°22' west longitude). Approximately five minutes after touchdown, Luna 9 began transmitting data to Earth, but it was seven hours (after the Sun had climbed to 7° elevation) before the probe began sending the first of nine images (including five panoramas) of the surface of the Moon.
Approximately 250 seconds after landing in the Oceanus Procellarum, four petals which covered the top half of the spacecraft opened outward for increased stability. The television camera system began a photographic survey of the lunar environment. Seven radio sessions of 8 hours and 5 minutes, were transmitted, as well as a series of three TV pictures.
After assembly the photographs gave a panoramic view of the immediate lunar surface, comprising views of nearby rocks and of the horizon, 1.4 kilometres (0.87 mi) away.
The pictures from Luna 9 were not released immediately by the Soviet authorities, but scientists at Jodrell Bank Observatory in England, which was monitoring the craft, noticed that the signal format used was identical to the internationally agreed Radiofax system used by newspapers for transmitting pictures. The Daily Express rushed a suitable receiver to the Observatory and the pictures from Luna 9 were decoded and published worldwide. The BBC speculated that the spacecraft's designers deliberately fitted the probe with equipment conforming to the standard, to enable reception of the pictures by Jodrell Bank.
The radiation detector, the only scientific instrument on board, measured a dosage of 30 millirads (0.3 milligrays) per day. The mission also determined that a spacecraft would not sink into the lunar dust; that the ground could support a lander. Last contact with the spacecraft was at 22:55 UT on 6 February 1966.