A replica of Luna 9 on display in the Museum of Air and Space Paris, Le Bourget
|Mission type||Lunar lander|
|Mission duration||6 days, 11 hours, 10 min.|
|Launch mass||1,580 kilograms (3,480 lb)|
|Landing mass||99 kilograms (218 lb)|
|Start of mission|
|Launch date||31 January 1966, 11:45:00UTC|
|Launch site||Baikonur 31/6|
|End of mission|
|Last contact||6 February 1966, 22:55UTC|
|Perigee||220 kilometres (140 mi)|
|Apogee||500,000 kilometres (310,000 mi)|
|Epoch||31 January 1966|
|Landing date||3 February 1966, 18:45:30 UTC|
Luna 9 (Луна-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.
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.
Launch and translunar coast
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).
Descent and landing
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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. From this moment the orientation of the spacecraft was supported by measurements of directions to the Sun and the Earth using an opto-mechanical system. At 74.885 kilometres (46.531 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. Approximately at 250 metres (820 ft) from the surface, the main retrorocket was turned off by the integrator of an acceleration having reached the planned velocity of the braking manoeuver. 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 was developed in the design bureau then known as OKB-1, under Chief Designer Sergei Korolev (who had died before the launch). The first 11 Luna missions were unsuccessful for a variety of reasons. At that time the project was transferred to Lavochkin design bureau since OKB-1 was busy with a manned expedition to the Moon. 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 with a total of 8 hours and 5 minutes were transmitted, as well as three series of 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 UTC on 6 February 1966.