Pioneer missions

American

The early American lunar attempts, named Pioneer, began in the summer of 1958. Pioneer 1A, 1B, 2, and 3 all either exploded or fell back to Earth. In 1959 Pioneer 4 finally made a successful lunar flyby.

Ranger 7, 8, 9 1964-1965

American

The Ranger were deliberately crash-landed on the Moon in the years 1964 and 1965, obtaining the first close-up pictures of the Moon showing boulders and meter-size craters.

Luna missions 1958-1974

Soviet

The Soviet Luna missions began in September 1958 and continued through 1974.Two early Soviet missions named Luna failed in the fall of1958 before Luna 1 launched successfully in 1959. Luna 1 missed the Moon by 3,750 miles (6,000 km), and thus became the first artificial satellite of the Sun. In the same year Luna 2 became the first human artifact to reach the Moon. It landed at 1 degree west longitude and 30 degrees north latitude, and determined that the Moon has no magnetic field. Luna 3 then took the first pictures of the far side of the Moon, and showed that there are no maria (floods of dark mare basalts) on the far side. Soviet aerospace had a watershed year in 1959, with several unique achievements and impressive data returns.

From 1963 through 1965, Luna 4 through 8 all failed: Luna 4 missed the Moon by 5,250 miles (8,400 km); the retrorocket on Luna 5 failed, and it crashed into the Moon; Luna 6 was given an incorrect midcourse correction, and it missed the Moon by 100,000 miles (160,000 km); and both Luna 7 and Luna 8 crashed in the Oceanus Procellarum.

In 1966 the Luna missions achieved another major milestone: the first soft landing on the Moon. Luna 9 landed softly in the Oceanus Procellarum, at 64.37 degrees west longitude and 7.13 degrees north latitude. This mission also provided the first television programming from a space mission, and showed that the soil had enough strength to support a lander: Arthur C. Clarke had written about seas of dust on the Moon, and some scientists also thought that a lander might simply sink.This lander was a sphere that landed on airbags that then deflated. Four petal-shape panels of metal unfolded to form braces on each side, revealing the camera at the top of the sphere. This is a simple, effective design, similar to that later used in Mars Pathfinder. Later the same year Luna 10 became the first lunar satellite (meaning it orbited the Moon). It carried a gamma-ray composition sensor (see the sidebar "Remote Sensing" on page 156). Luna 11 followed, another lunar orbiter, carrying X-ray, plasma, and micrometeorite sensors. Luna 12 was the third lunar orbiter in the series, carrying an onboard television and making crater measurements. Luna 13, launched at the end of 1966, made another soft landing in Oceanus Procellarum at 18.87 degrees north latitude and 62.05 degrees west longitude. It transmitted television panoramas, and made measurements of soil mechanics.

Luna 14, launched in 1968, also orbited the Moon, making gravity measurements and measuring plasma and particles in space. Following Luna 14, serious attempts at sample returns from the Moon began. Luna 15 attempted a sample return from Mare Crisium.The intended soft landing failed, and the geologists were blamed because the spacecraft hit a mountain. Later it was determined that the Doppler radar device failed. Quickly, though, success followed: Luna 16 was the Soviet Union's first successful unmanned sample return, from Mare Fecunditatis in 1970. The great achievement of a robotic sample return was somewhat overshadowed by the United States' Apollo 11 the previous year, which had successfully landed the first men on the Moon and returned the first samples. The Soviets followed Luna 16 in 1970 with Luna 17, which carried the Lunokhod 1 rover. This was the first robotic rover in the history of space travel, and it was a tremendous success: It functioned for more than a year, traveling about six miles (10 km) around Mare Imbrium.

In 1972 Luna 20 completed an unmanned sample return from the highlands.The capsule fell back to Earth in a snowy swamp in Siberia, and the scientists were relieved to be able to detect its beacon. The following year Luna 21 carried the Lunokhod 2 rover to the Moon. The rover traveled around the crater Le Monier, near Serenitatis basin. It worked for about four months, traveling about 19 miles (30 km). Luna 24, the final Luna mission, was the third robotic sample return (from Mare Crisium to a landing in western Siberia), and a fittingly successful ending to this marathon series of space missions.

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