Luna 9 (1966): The First Soft Landing on the Moon

Luna 9 was the Soviet space probe that made the first soft landing on the Moon on 3 February 1966. Touching down in the Ocean of Storms, it sent back the first photographs ever taken from the surface of another world. The pictures proved that the lunar ground was firm enough to support a spacecraft, a vital step towards human landings three years later.

Background: hitting the Moon versus landing on it

The Soviet Union had already achieved several lunar firsts. Shortly after Sputnik 1, Luna 2 became the first spacecraft to strike the Moon in September 1959, and Luna 3 photographed its far side a month later. Crashing into the Moon, however, was far easier than landing gently on it. The Moon has no atmosphere, so parachutes are useless and a probe must slow itself from more than 2.5 kilometres per second using rocket engines.

The engineering challenge was compounded by scientific uncertainty. Some scientists, notably the astronomer Thomas Gold, had suggested that the lunar plains might be covered with deep, fine dust in which a spacecraft could sink. Nobody could be sure until something landed.

A string of failures

Sergei Korolev’s design bureau began work on a lunar lander, the Ye-6 series, in the early 1960s. The programme suffered a long run of failures. Between 1963 and 1965, by most counts, eleven attempts were lost to launch failures, problems on the way, or crashes on the Moon, including the publicly announced Luna 5, Luna 7 and Luna 8 missions of 1965.

In 1965 Korolev, overloaded with crewed programmes, handed the project to the Lavochkin design bureau under its new chief designer, Georgy Babakin. Korolev died during surgery in January 1966, only weeks before the first success.

How Luna 9 landed

Luna 9 was launched from the Baikonur Cosmodrome on 31 January 1966 on a Molniya rocket, which first placed it in a parking orbit around the Earth and then sent it towards the Moon. The whole spacecraft weighed about 1,540 kilograms, but most of that was a retro-rocket stage and guidance equipment. The part designed to survive on the surface was a sphere of about 100 kilograms, roughly 58 centimetres across.

As the probe approached the Moon on 3 February, a radar altimeter triggered the main engine at a height of about 75 kilometres to brake its fall. Just before touchdown, a long probe touched the surface, the engine shut down and the capsule was thrown clear, cushioned by two inflated airbags. It bounced several times before coming to rest at 18:45 Universal Time in the Oceanus Procellarum, west of the craters Reiner and Marius.

A few minutes later the airbags were discarded and four petal-like covers opened. They tilted the capsule upright, steadied it on the uneven ground and exposed the radio antennas and a small camera.

Pictures from the Moon

The camera did not take snapshots. It used a rotating mirror to scan a full 360-degree panorama line by line, a process that took around 100 minutes for each picture. Over about three days the capsule transmitted during seven radio sessions, totalling roughly eight hours, sending several panoramas taken as the Sun rose higher in the lunar sky. Because the capsule had settled at a slight angle, which shifted during the mission, some images showed the scene from different viewpoints.

The pictures showed a gently undulating surface strewn with small rocks and pebbles, some casting long shadows, with shallow craters nearby. The capsule had not sunk into dust. Its batteries ran down, and the last signal was received on 6 February 1966.

The Jodrell Bank scoop

The Jodrell Bank radio observatory in Cheshire, England, directed by Bernard Lovell, had been tracking Soviet probes for years. Its staff noticed that Luna 9’s signals resembled the radio-facsimile system newspapers used to send photographs. They borrowed a suitable receiver from the Daily Express, decoded the signal and handed the pictures to the press.

British newspapers published the first images from the Moon within days of the landing, before the official Soviet release. Because Jodrell Bank did not know the correct proportions, the first versions were stretched horizontally. The episode caused some irritation in Moscow, though the Soviet Union soon published its own, accurate images.

Key people

• Sergei Korolev (1907-1966): chief designer of the Soviet space programme, whose bureau began the Ye-6 lander project and solved many of its early problems.
• Georgy Babakin (1914-1971): chief designer at the Lavochkin bureau, who took over the project in 1965 and led it to success; he later oversaw the Lunokhod rovers and Venus probes.
• Bernard Lovell (1913-2012): director of the Jodrell Bank observatory, whose team decoded and published the first Luna 9 images in the West.

Myths and facts

Myth: Luna 9 was the first spacecraft to reach the Moon. That distinction belongs to Luna 2, which crashed into the surface in 1959. Luna 9 was the first to land gently and keep working.

Myth: the Soviet Union hid the pictures. Soviet authorities did release the images, but Jodrell Bank decoded and published them first, so the earliest versions most people in the West saw were the stretched British prints.

Fact: Luna 9 did not land under engine power all the way down. Unlike later landers, it relied on its airbags to absorb the last part of the descent. The capsule was effectively dropped from a few metres up and bounced, a simple solution that worked for a light, rugged sphere.

Fact: it settled a real scientific debate. Before 1966 serious scientists argued over whether the lunar plains were firm or covered with deep, loose dust. Luna 9’s survival, and the clear shadows of rocks in its pictures, showed that the surface was solid enough for landers and, eventually, for astronauts.

Consequences

Luna 9 removed one of the biggest uncertainties facing Moon landing planners. Four months later, on 2 June 1966, the American Surveyor 1 made the first US soft landing and sent back thousands of detailed pictures. In December 1966 the Soviet Luna 13 landed with instruments that tested the soil directly.

The Soviet Union went on to land automated sample-return missions and the Lunokhod rovers in the 1970s, while the United States landed astronauts with Apollo 11 in July 1969. A similar airbag-cushioned landing approach was used decades later by NASA’s Mars Pathfinder mission in 1997.

By the numbers

Timeline

• 1959, 13 September: Luna 2 becomes the first spacecraft to hit the Moon.
• 1963-1965: By most counts eleven Soviet soft-landing attempts fail.
• 1966, 14 January: Sergei Korolev dies.
• 1966, 31 January: Luna 9 is launched from Baikonur.
• 1966, 3 February: Luna 9 lands in the Ocean of Storms and begins transmitting.
• 1966, early February: British newspapers publish Luna 9 images decoded at Jodrell Bank.
• 1966, 6 February: The last signal from Luna 9 is received.
• 1966, 2 June: Surveyor 1 makes the first American soft landing.

Why it matters

Luna 9 opened the era of exploring other worlds from their surfaces rather than from a distance. By showing that the Moon could bear the weight of a spacecraft and by sending the first views from its ground, it paved the way for robotic landers and, ultimately, for the astronauts who walked there.