In one of the earliest missions of the space age, the Soviet Union’s Luna 3 probe photographed the far, or “hidden,” side of the Moon, revealing a surprising topography.
In the early days of space exploration, the successes of Soviet space missions were politically rewarding to Premier Nikita S. Khrushchev and personally and technically rewarding to chief designer Sergei Korolev. Korolev engineered many of these achievements, but did not receive wide acclaim, as Khrushchev (and his successors) kept Korolev’s identity a secret until after his death in 1966. In the meantime, Khrushchev instructed Korolev to continue to produce spectacular missions, and the chief designer enthusiastically complied, as he was given the resources to accomplish exciting goals faster than he had ever imagined possible. After three Sputniks impressed the world with their successes in Earth orbit, the Soviets set their sights on the Moon.
Following three launch failures in 1958, Luna 1 became the first spacecraft to fly by the Moon, passing within 6,000 kilometers in January, 1959. That accomplishment followed four failed efforts by the United States to send spacecraft to Earth’s celestial neighbor. After one more unsuccessful launch by the Soviet Union came the flight of Luna 2 in September. It succeeded in hitting the Moon on September 14, radioing data back to Earth throughout its flight. The Soviet Union’s next mission, Luna 3, was the most ambitious yet.
It was only the second anniversary of the launch of the first artificial satellite, Sputnik 1, when Luna 3 lifted off shortly before 7:00
The forces of nature have conspired to make the rate of the Moon’s revolution around Earth the same as its rotation on its own axis. The result is that residents of Earth see only one side of the Moon. (A slight wobbling of the Moon actually allows 59 percent of its surface to be seen from Earth.) The other side always points away, so it cannot be seen directly from Earth. The target of Luna 3 was this hidden side.
The spacecraft was cylindrical with hemispherical endcaps sporting a number of antennae. With a mass of 278.5 kilograms, its length was 1.32 meters and its diameter was 1.19 meters. This was the first of the Luna series to use solar cells (common on later spacecraft) to recharge batteries, rather than relying on batteries alone. The spacecraft spun for gyroscopic stability (the same phenomenon that stabilizes a spinning bullet or football) and to distribute the heat from the Sun uniformly over the exterior. Fans circulated air inside to keep the electronics between 25 degrees Celsius and 30 degrees Celsius, despite the extreme temperatures in the vacuum outside.
During its trip through space, sensors designed to detect micrometeoroids and cosmic rays relayed their measurements to Earth. Ground controllers received the scientific data and monitored the health and trajectory of the spacecraft.
Luna 3 coasted from Earth toward the space above the Moon’s south pole. The trajectory was selected so that as the spacecraft approached the Moon, gravity would bend its flight path to carry it over the south pole, behind the Moon, and then over the north pole to head back toward Earth.
At 5:16
Upon command from Earth, the spacecraft fired its tiny gas jets to stop its rotation. A sun sensor on one end guided Luna 3 so that its other end, containing the camera and a moon sensor, pointed roughly toward the Moon. A cover that had protected the camera during the trip through space was removed, and the moon sensor helped the jets adjust the spacecraft’s orientation to center the Moon for the camera. It was 6:30
For forty minutes, the camera recorded its unique views on a special film resistant to the cosmic rays impinging on the spacecraft during its flight. A telephoto lens picked up details of the lunar surface, and another lens captured wide-angle shots to aid in making a map and locating the detailed features. Luna 3 was equipped with a complete developing facility. The film was automatically drawn through a processor to develop and dry it. The negatives were then wound into a canister for storage until the time to radio the views to Earth. By the time the last photograph had been taken, Luna 3 had receded to 68,000 kilometers from the Moon. The spacecraft started its spinning again.
After the Moon’s gravity distorted its original orbit, Luna 3 was left in a large orbit that stretched to 480,000 kilometers from Earth. It reached that distance on October 10 and began the eight-day flight to the low point of its orbit, where it would be 47,500 kilometers away. During the fall back toward Earth, the pictures were scanned one-by-one with a narrow beam of light. The amount of light transmitted by each point on the negative revealed how dark or light that spot was. Luna 3 radioed to Earth the intensity of the light that shone through each part of the pictures, and eager scientists used that information to reconstruct the precious images. These fuzzy pictures revealed craters, mountains, dark areas, and bright areas and were the subject of much analysis long after the mission had concluded.
About 40 percent of the side seen from Earth is covered by vast smooth regions known as mare. Early astronomers thought these dark expanses were seas (hence the Latin mare, which means sea); they were later thought to be the remains of enormous lava flows. These regions have since been determined to be areas sculpted by the impacts of meteors, asteroids, and comets. For researchers, the greatest surprise waiting on the other side of the Moon was the paucity of these features. Luna 3 had imaged 70 percent of the far side, and less than 10 percent was covered by what had been called lunar maria, or lunar seas (plural for mare). Instead, the terrain was dominated by craters and mountains.
Some of the features located on the visible side near the Moon’s rim were included in Luna 3’s photography, allowing these areas to be viewed without the foreshortening distortion that occurs when they are seen nearly edge-on from Earth. In addition, because their locations already were known, their appearances on the photographs allowed scientists to establish the positions of new features on the far side with great reliability. They also aided in estimating the quality of the images and in testing the scientists’ abilities to interpret the pictures.
Luna 3 continued looping around Earth even after its job was completed. In November, its radio transmissions ceased, and its orbit eventually took it back to Earth’s atmosphere in April, 1960. No one took notice when it burned up; but by then, the secrets it had uncovered already were well-known to the world.
Luna 3’s views of the Moon were exciting to scientists and nonscientists alike. The startling asymmetry between the near and far sides of the Moon remains a significant scientific mystery and is still accepted as the most important discovery of Luna 3. No theory for why the two sides should be so different has gained wide acceptance, despite many attempted explanations. Even after spacecraft orbited the Moon, landed on it, and returned samples from its surface, the answer remains unknown.
The Soviet Union used the stunning results of Luna 3 to bolster its global prestige. Claiming the rights to name its discoveries, the Soviet Union gave many of the new features names of national importance, such as the Sea of Moscow, the Gulf of Cosmonauts, Tsiolkovsky Crater, and the Soviet Mountain Range. Khrushchev enjoyed the growing impression, at home and throughout the world, of the Soviet Union as a rapidly advancing socialist nation, with him as the efficient and progressive leader.
Yuri Gagarin, who later became the first person in space and one of his country’s most beloved heroes, has said that the pride and excitement elicited by these images provided the final inspiration for him to apply to the cosmonaut program. Many Soviet scientists, engineers, and officials predicted that, with the Soviet Union’s clear lead in space, their spacecraft soon would visit other planets and conduct many other bold missions throughout the solar system and beyond. Some politicians in the United States claimed the pictures were counterfeits, but that did little to mitigate the admiration and envy of the Soviet Union’s accomplishment.
The early triumphs of the Soviet Union in exploring the Moon stood in stark contrast to the efforts of its competitor. After twelve complete or partial failures, the first fully successful probe by the United States was Ranger 7 in July, 1964, and the first photographs the United States took of the hidden side were made in 1966 by Lunar Orbiter 1.
After Luna 3’s spectacular success in 1959, there was no doubt that the Soviet Union held a substantial lead in lunar exploration. For reasons unknown in the West, however, Luna 4 was not launched until 1963, and Lunas 4 through 8 all failed. In a related program, Zond (“probe”) 3 did image the remaining unseen portion of the far side in July, 1965. Following the five disappointments in the Luna series, the Soviet Union took the lead again in the use of unpiloted spacecraft to study the Moon, with Luna 9 making the first soft landing in February, 1966, and Luna 10 being the first to enter orbit about the Moon in April.
After American astronauts landed on the Moon in July and November of 1969, Luna 16 succeeded in retrieving 101 grams of lunar soil in September, 1970. Luna 17 delivered the first remote-controlled rover to the Moon two months later. That same year, a crater 360 kilometers in diameter—one of the largest on the far side of the Moon—was named Korolev, honoring Korolev’s work with the Soviet missions in space.
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Cadbury, Deborah. Space Race: The Epic Battle Between America and the Soviet Union for Dominion of Space. New York: HarperCollins, 2006. A 384-page account of American and Soviet efforts to launch the first satellite and to send humans to the Moon. -
Harvey, Brian. Race into Space: The Soviet Space Programme. Chichester, England: Ellis Horwood, 1988. A complete description of Soviet unpiloted and piloted missions, ground facilities, key technical contributors, and the historical and political context in which the events occurred. Careful readers will find many small technical errors, but the breadth of this text makes it a rich source for all audiences. -
Johnson, Nicholas L. Handbook of Soviet Lunar and Planetary Exploration. San Diego, Calif.: Univelt, 1979. Provides a detailed description of the history of Soviet efforts to explore the Moon and planets. Suitable for college-level readers, it includes many technical descriptions and drawings of the spacecraft and their systems. Includes many references and an extensive bibliography. -
Kopal, Zdenek. Exploration of the Moon by Spacecraft. Edinburgh, Scotland: Oliver & Boyd, 1968. Written by an expert in lunar research, this 88-page book explains how the spacecraft worked and how their results contributed to an overall understanding of the lunar surface environment. Because it was written before the series of Apollo landings, the text necessarily relies on conclusions and speculations supported by the early unpiloted probes. -
McDougall, Walter A. The Heavens and the Earth: A Political History of the Space Age. 2d ed. Baltimore: Johns Hopkins University Press, 1997. An excellent study of the military and political history of the space age. McDougall also discusses the dangers of aerospace technocracy, both Soviet and American—a welcome change from the nonanalytical enthusiasm of most histories of spaceflight. Analyzes the connections between the space race and the Cold War. -
Moore, Patrick. The Moon. New York: Rand McNally. 1981. This well-illustrated book has only brief descriptions of the missions to the Moon but extensive and clearly presented information on the Moon’s structure, composition, and evolution. Includes many photographs and maps, with descriptions of the prominent features and an index to aid in locating features by name. -
Scott, David, and Alexei Leonov. Two Sides of the Moon: Our Story of the Cold War Space Race. New York: Simon & Schuster, 2004. A personal account of the space race between the Soviet Union and the United States by two major players in the programs of their respective countries. -
Siddiqi, Asif A. Sputnik and the Soviet Space Challenge. Gainesville: University Press of Florida, 2003. An award-winning book that offers a comprehensive and detailed history of the Soviet space program, from its earliest days. An essential resource. -
Wilson, Andrew. Solar System Log. London: Jane’s, 1987. Describes every mission to the Moon, and of planets and comets. Provides the essential facts from each flight and helps readers understand spaceflight in the context of humankind’s efforts to explore the solar system.
United States Launches Vanguard Satellite Program
Soviet Union Launches the First Artificial Satellite
Pioneer Space Program Is Launched
NASA Launches Project Gemini
Luna 2 Becomes the First Human-Made Object to Impact on the Moon
Ranger Program
Venera 3 Is the First Spacecraft to Impact Another Planet
Luna 9 Makes the First Successful Lunar Soft Landing
Surveyor Program Prepares NASA for Piloted Moon Landings
Lunar Orbiter 1 Sends Photographs of the Moon’s Surface
First Humans Land on the Moon
Soviet Rover Lunokhod 1 Lands on the Moon