Luna (space program) - astronomy.

Luna (space program) - astronomy. I INTRODUCTION Luna (space program), series of spacecraft that the former Union of Soviet Socialist Republics (USSR) launched toward the moon in the 1950s, 1960s, and 1970s. The USSR applied the name Luna to a variety of automated lunar probes. Early Luna probes were simple, in part because they were rushed into service to win quick victories in the Cold War space race with the United States. Later Luna robots surpassed the capabilities of the unpiloted moon probes developed by the United States. Like U.S. Ranger, Surveyor, and Lunar Orbiter spacecraft, the Lunas scouted the moon in preparation for planned visits by humans. The Soviet piloted moon program suffered technical setbacks, however, and was eventually cancelled. See also Space Exploration. II EARLY SPACECRAFT AND MISSIONS The name Luna was used for several different spacecraft designs, from primitive crash-landing probes to increasingly more sophisticated soft-landing probes and probes that orbited the moon. Modified SS-6 ballistic missiles carried Luna 1 through Luna 14 to the moon. Luna 15 through Luna 24 used more powerful Proton rockets to reach the moon. Luna 1 and 2 were 'crashers,' simple 361-kg (796-lb) spheres designed to crash into the moon and not survive lunar impact. They carried meteoroid detectors to study particles in space, radiation detectors, and magnetometers to measure magnetic field intensity. Luna 1 left the earth on January 2, 1959, and missed the moon by more than 5000 km (3000 mi), going into orbit around the sun. It did manage to determine that the moon has no appreciable magnetic field, and it was the first spacecraft to reach lunar space, beating the U.S. Pioneer 4 by three months (see Pioneer (spacecraft)). Luna 2 hit the moon on September 13, 1959, to become the first artificial object on the moon. It carried a cargo of Soviet emblems that scattered across the landing site when the probe crashed. Luna 3, launched October 4, 1959, was the only Luna probe to fly past the moon by design. It was a 279-kg (615-lb) oval capsule with flexible antennas at either end. The antennas allowed the spacecraft to communicate with the earth. Equipped with cameras, Luna 3 successfully returned the first pictures of the hidden far side of the moon. Lunas 4 through 9 and Luna 13 shared the same basic spacecraft design. Each consisted of a cylindrical spacecraft that carried a small spherical lander on its top end. The combined spacecraft had a mass of about 1600 kg (about 3500 lb), and the lander alone weighed about 100 kg (about 220 lb). The carrier spacecraft had rocket engines to slow its descent to the moon. The lander was designed to eject from the carrier a few seconds before touchdown and roll away as the carrier crashed to the lunar surface. A weighted base on the lander pulled it right side up when it stopped rolling. A few seconds later, four petal-like sections that sealed the lander's top half would begin to open, exposing communications antennas and a 360-degree television camera. The first probe of this type, Luna 4, was launched in April 1963 and missed the moon. It was the first in a series of landing failures. Luna 5, 7, and 8 hit the moon, but the landers did not survive to send back any data. Luna 6 also missed the moon. This string of bad luck ended when Luna 9 achieved the first successful moon landing, touching down in the eastern Oceanus Procellarum (Ocean of Storms) region on February 3, 1966. The lander opened successfully and sent back to the earth panoramic images of its landing site. Luna 13 also landed successfully, on December 21, 1966. The lander sent back images of its landing site, also in the Oceanus Procellarum region, and measured the density and consistency of the lunar soil with instruments it carried. Lunas 10 though 12 and Luna 14 were similar to Lunas 4 though 9 and 13, but instead of ejecting landers onto the moon's surface, the carrier spacecraft ejected an orbiter into orbit around the moon. The series of spacecraft that began with Luna 10 carried instruments to study meteoroids and radiation. Luna 10 also carried a recording of the Communist anthem "Internationale," which it radioed back to the earth. The carrier vehicles for Luna 10 and Luna 11 crashed to the moon's surface as previous carrier vehicles did. The Luna 12 lunar orbiter carried a camera for taking detailed lunar surface photographs. The carrier vehicles of Luna 12 and 14 remained attached to the orbiters to provide stability--Luna 12 needed the stability for its camera and Luna 14 shared Luna 12's design. Luna 10 became the world's first lunar orbiter when it entered orbit around the moon on April 4, 1966. The Luna 11 orbiter was launched on August 24, 1966, and made radio-astronomy studies of the sun and moon; it also studied the moon's gravitational field. Luna 12 was launched on October 22, 1966, and returned the first moon photos from a Soviet lunar orbiter (the U.S. spacecraft Lunar Orbiter 1 had returned the first photographs from lunar orbit in August 1966). Luna 14 was launched April 7, 1968, and studied how the mass of the earth and moon affect each other. All of the orbiters relied on batteries to power their instruments and ended transmission when their batteries went dead. The life-spans of the orbiters ranged from 33 days for Luna 11 to 108 days for Luna 12. III LATER SPACECRAFT AND MISSIONS Luna 1 through Luna 14 paved the way for more advanced missions. The U.S. Surveyor program was near its end and the United States was almost ready to launch the piloted Apollo Program missions to the moon while the USSR prepared Luna 15 in 1968. The USSR claimed that the later Luna probes accomplished more than the Apollo program without risking human lives. The Luna 15 through 24 spacecraft were complex vehicles, each weighing about 1900 kg (about 4190 lb). The missions included orbiters, radio-controlled roving vehicles, and probes designed to send lunar soil back to the earth. Lunas 15, 16, 18, 20, 23, and 24 carried four-legged landers. These landers acted as the launchpad for a capsule that carried a lunar dirt sample back to the earth. The landers carried a 39-kg (86-lb) spherical capsule and a drill on a long arm. The drill was hollow and was designed to fill up with lunar soil as it twisted into the ground. The drill arm then lifted the full drill up to the reentry capsule, which used its own rockets to launch itself back toward the earth. The capsule entered the earth's atmosphere and landed in the USSR using a parachute. Lunas 17 and 21 each delivered a tub-shaped, eight-wheeled, 756-kg (1667-lb) rover called a Lunokhod. Each Lunokhod carried several cameras, soil-testing equipment, and panels of solar cells to produce electricity from sunlight (see Solar Energy) to provide power for the rover and its instruments. Luna 19 and Luna 22 were orbiters. They used the tub-shaped Lunokhod instrument compartment, but carried cameras for photographing the moon instead of rovers. Luna 15, the first sample collection attempt, crashed on July 20, 1969, while Apollo 11, the first U.S. piloted lunar landing, was on the moon. The USSR may have hoped to show its technical superiority over the piloted U.S. Apollo program by returning a sample from the moon ahead of Apollo 11. Luna 16 landed on the moon on September 24, 1970. It drilled into the surface of the Mare Fecunditatis (Sea of Fertility) region, collecting 100 g (4 oz) of lunar soil for return to the earth. Luna 17 delivered the Lunokhod 1 rover to the moon on November 10, 1970. The first wheeled vehicle on the moon, Lunokhod 1 explored for 11 months, much longer than expected. Its twin, Lunokhod 2, lasted four months after it separated from Luna 21 in January 1973. Luna 18, launched in 1971, and Luna 23, launched in 1974, both failed to return samples. Luna 20 successfully returned a sample of 50 g (2 oz) in February 1972. Luna 19 and Luna 22 were launched in 1971 and 1973, respectively. Both of these spacecraft orbited the moon successfully, returning images, information about the moon's density, and information about radiation in space around the moon. Luna 24, launched in August 1976, carried an improved drill for collecting soil. The probe returned 170 g (6 oz) of soil to the earth. Luna 24 was the last of the Luna series and is still the most recent spacecraft to have soft-landed on the moon. Contributed By: David S. F. Portree Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.