|Mission type||Lunar impactor|
|Harvard designation||1959 Xi 1|
|Mission duration||1 day, 14 hours, 22 minutes and 42 seconds (launch date to impact date)|
|Launch mass||390.2 kilograms (860 lb)|
|Start of mission|
|Launch date||September 12, 1959, 06:39:42UTC|
|Launch site||Baikonur 1/5|
|Impact date||September 13, 1959, 21:02:24UTC|
Luna 2 (E-1A series) or Lunik 2 (Russian: Луна 2) was the sixth of the Soviet Union's Luna programme spacecraft launched to the Moon. It was the first spacecraft to reach the surface of the Moon, and the first human-made object to make contact with another celestial body. On September 13, 1959, it hit the Moon's surface east of Mare Imbrium near the craters Aristides, Archimedes, and Autolycus.
The first mission of the Luna programme was an unnamed probe that exploded on launch on September 23, 1958. Luna missions that did not achieve orbit were not given official names and the launch attempt would not be publicly acknowledged. The first partial success of the program was the fourth launch attempt. Luna 1, which launched January 2, 1959, was a lunar impacter that missed the Moon. One mission separated Luna 1 and Luna 2, a launch failure that occurred on an unnamed probe on June 18, 1959. Luna 2 would be the Soviet Union's sixth attempt to impact the Moon.
Luna 1 and the three spacecraft before it were a part of the E1 series of spacecraft. Luna 2 was the second of the E1A series, which had a couple of changes incorporated into its design.
Luna 2 was similar in design to Luna 1, a spherical spacecraft with protruding antennas and instrumentation. The instrumentation was also similar to Luna 1, including scintillation counters, Geiger counters, a magnetometer, Cherenkov detectors, and micrometeorite detectors. There were no propulsion systems on Luna 2 itself.
Luna 2 carried five different instruments to conduct various tests while it was on its way to the Moon. The scintillation counters would be used to measure any ionizing radiation; the Cherenkov radiation detectors would be measuring for electromagnetic radiation caused by charged particles. "The Geiger Counter carried on Luna 2 had the primary scientific objective of determining the electron spectrum of the outer radiation belt. The instrument consisted of three STS-5 gas-discharge counters mounted on the outside of the hermetically sealed container", and would be powered by silver-zinc and mercury-oxide batteries. The last instrument on Luna 2 was, "a three component fluxgate magnetometer similar to that used on Luna 1 but with the dynamic range reduced by a factor of 4 to −750 to +750 gammas so that the quantization uncertainty was −12 to +12 gammas."
The spacecraft also carried Soviet pennants. Two of them, located in the spacecraft, were sphere-shaped, with the surface covered by pentagonal elements. In the center was an explosive charge designed to shatter the sphere, sending the pentagonal shields in all directions. This was a low-tech method that would blow back a few elements in the direction opposite of its velocity vector to greatly reduce the energy upon reaching the surface (in the way that landers are designed to reduce velocity) which would improve the chance that some part of the sphere might survive the impact. Each pentagonal element was made of stainless steel and had the USSR Coat of Arms and the Cyrillic letters СССР ("USSR") engraved on one side, and the words СССР январь 1959 ("USSR January 1959") on the other side. They most likely vaporized on impact, however. The third pennant was located in the last stage of the Luna 2 rocket, which collided with the Moon's surface 30 minutes after the spacecraft did. It was a capsule filled with liquid, with aluminium strips placed into it. On each of these strips the USSR Coat of Arms, the words 1959 январь ("1959 January"), and the words СОЮЗ СОВЕТСКИХ СОЦИАЛИСТИЧЕСКИХ РЕСПУБЛИК (English: "Union of Soviet Socialist Republics") were engraved.
The scientists took extra, unspecified precautions in preventing biological contamination from the Earth to the Moon.
Launch and trajectory
Launch was scheduled for September 9, but the Blok I core stage was shut down after it failed to reach full thrust at ignition. The booster was removed from the pad and replaced by a different vehicle, delaying the flight by three days. Luna 2, like Luna 1, took a direct path to the Moon, with a velocity high enough to result in a travel time of around 36 hours.
Luna 2 hit the Moon about 800 kilometers (500 mi) from the centre of the visible disk on 1959 September 13 at 21:02:24 UTC. It hit with an estimated velocity of 12,000 kilometers/hour. The satellite's impact made it the first man-made object to crash-land on another celestial body. Once Luna 2 was split from its upper stage it started transmitting information back to Earth using three different transmitters. These transmitters provided precise information on its course, allowing scientists to calculate that Luna 2 would hit its mark on the Moon around 00:05 on September 14 (Moscow Time). In order to be able to provide a visual from Earth on September 13, the spacecraft released a vapor cloud that would expand to 650-kilometer (400 mi) diameter that would be seen by observatories in Alma Ata, Byurakan, Abastumani, Tbilisi, and Stalinabad. This vapor cloud also acted as an experiment to see how the sodium gas would act in a vacuum and zero gravity. The last stage of the rocket that carried Luna 2 did not carry any type of tracking device so there was uncertainty as to where it landed, but it did hit the Moon surface about 30 minutes after Luna 2 hit.
The radiation detectors and magnetometer were searching for lunar magnetic and radiation fields similar to the Van Allen radiation belt around Earth, sending information about once every minute until its last transmission which came about 55 km away from the lunar surface. Although it did prove previous measurements of the Van Allen radiation belts that were taken from Luna 1 around the Earth, it was not able to detect any type of radiation belts around the Moon. Because of claims that information received from Luna 1 was fake, as soon as the scientists of Luna 2 started receiving transmissions they sent out the intended time of impact, and the transmission and trajectory details. Even though Soviet scientists gave all this information, the Americans were still skeptical until Bernard Lovell was able to prove that the radio signal was coming from Luna 2 by showing the Doppler shift from its transmissions. After this no one seemed to question the veracity of the Soviets.
Van Allen radiation belt
Luna 2 showed time variations in the electron flux and energy spectrum in the Van Allen radiation belt. Using ion traps on board, the satellite made the first direct measurement of solar wind flux outside the Earth's magnetosphere.
For a time, Americans were starting to believe that they were making progress in the Space Race and that although the Soviets might have had larger rockets, the United States had better guidance systems. This myth was busted after the Soviets were able to crash Luna 2 onto the Moon. At that time the closest Americans had come to the Moon was about 37,000 miles (60,000 km) with Pioneer 4. Soviet Premier Khrushchev, on his only visit to the U.S., gave President Eisenhower a replica of the Soviet pennants that Luna 2 had just placed onto the lunar surface. Luna 2 and its predecessors all came to be used throughout the USSR and around the world as pro-communist propaganda. Donald W. Cox explains, in his book The Space Race, "Although the Sputniks and Luniks did not themselves provide better cars, refrigerators, color TV sets, and homes for the peasants and laborers of the Soviet Union and her satellite states, they did evoke added inspiration for the earthbound followers of the communist way of life helping to take their minds off shortages of consumer goods. The people were spurred on to work just a little harder for the glorious motherland and to outstrip the west in the less dramatic and more basic things of life, like coal and steel production." Although Luna 2 was a success for the Soviets, it also helped the U.S. by starting a trend of crash landing. It would eventually lead to the U.S.-made Rangers which would go on to also crash land on the Moon in exactly the same way. Crash landing proved useful even after soft landing was mastered. NASA used crash landings to test whether Moon craters contained ice by crashing space probes into craters and testing the debris that got thrown out.
The sphere presented to President Eisenhower is kept at the Eisenhower Presidential Library and Museum in Abilene, Kansas. The only other known copy of the spherical pennant is located at the Kansas Cosmosphere in Hutchinson, Kansas.
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