Luna 9

Did You Know?

• Detailed Luna 9 models are on display at the Memorial Museum of Cosmonautics, Tsiolkovsky State Museum of the History of Cosmonautics, Museum of Cosmonautics and Rocket Technology, and Museum of Air and Space Paris.
• In early 2026, researchers published findings identifying a very probable candidate for the true landing site.

Spacecraft

The spacecraft and lander capsule together weighed 1538 kg and stood 2.7 meters tall. During descent, the main spacecraft ejected the lander capsule shortly before controlled impact. The lander, a spheroid Automatic Lunar Station (ALS) capsule measuring 58 cm, had a mass of 99 kg and used a landing bag to survive an impact speed exceeding 54 km/h. It was a hermetically sealed container housing radio equipment, a program timing device, heat control systems, scientific apparatus, power sources, and a television system. The spacecraft was developed at OKB-1 under Chief Designer Sergei Korolev, who died before launch. After the first 11 Luna missions failed, the project transferred to the Lavochkin design bureau, which built Luna 9 as its first successful deep space probe.

Launch and translunar coast

Luna 9 launched atop a Molniya-M rocket from Site 31/6 at Baikonur Cosmodrome at 11:41:37 GMT on 31 January 1966. The first three stages placed the payload and fourth stage into low Earth orbit at 168 by 219 km with an inclination of 51.8°. The Blok-L fourth stage then fired, raising the perigee to achieve a new apogee of approximately 500000 km, deploying Luna 9 into a highly elliptical geocentric orbit. The spacecraft spun up to 0.67 rpm using nitrogen jets for thermal control. A mid-course correction on 1 February at 19:29 GMT involved a 48-second burn delivering a delta-v of 71.2 m/s.

Descent and landing

At 8300 km from the Moon, the spacecraft oriented itself for retrorocket firing and stopped its spin. Orientation was maintained by an optomechanical system measuring directions to the Sun and Earth. At 75 km altitude, the radar altimeter triggered jettison of side modules, inflation of airbags, and retrorocket firing. At 250 m, the main retrorocket shut off when the integrator of acceleration reached the planned braking velocity; four outrigger engines then slowed the craft. About 5 m above the surface, a contact sensor triggered engine shutdown and ejection of the landing capsule with its inflated airbag. The capsule landed at 22 km/h, bounced several times, and came to rest in Oceanus Procellarum west of Reiner and Marius craters on 3 February 1966 at 18:45:30 GMT.

Surface operations

About 250 seconds after landing, four petals covering the top half of the spacecraft opened outward for stability. Seven hours later, once the Sun reached 7° elevation, the probe began transmitting the first of nine images, including five panoramas, of the lunar surface. Seven radio sessions totaling 8 hours and 5 minutes were sent, along with a series of three TV pictures. Assembled, the photographs provided a panoramic view of the immediate area, showing nearby rocks and the horizon 1.4 km away. Soviet authorities did not release the pictures immediately, but scientists at Jodrell Bank Observatory in England, monitoring the craft, recognized the signal format as the internationally agreed Radiofax system used by newspapers. The Daily Express rushed a receiver to the observatory, and the images were decoded and published worldwide. The BBC speculated that the designers deliberately used the standard to enable reception at Jodrell Bank. The only dedicated scientific instrument, a radiation detector, measured 30 millirads (0.3 milligrays) per day. The mission also confirmed that the lunar surface could support a lander without sinking. Last contact occurred at 22:55 GMT on 6 February 1966.