Luna 2 was the second of the Luna program of spacecraft launched in the direction of the Moon. The first spacecraft to land on the Moon, it impacted the lunar surface east of Mare Serenitatis near the Aristides, Archimedes, and Autolycus craters. Luna 2 was similar in design to Luna 1, a spherical spacecraft with protruding antennae and instrument parts. The instrumentation was also similar, including scintillation counters, geiger counters, a magnetometer, and micrometeorite detectors . There were no propulsion systems on Luna 2 itself.

After launch and attainment of escape velocity on September 13 1959, Luna 2 separated from its third stage, which travelled along with it towards the Moon. On September 13 the spacecraft released a bright orange cloud of sodium gas which aided in spacecraft tracking and acted as an experiment on the behavior of gas in space. On September 14, after 39.5 hours of flight, radio signals from Luna 2 abruptly ceased, indicating it had impacted on the Moon. The impact point, in the Palus Putredinus region, is roughly estimated to have occurred at 0 degrees longitude, 29.1 degrees N latitude. Some 30 minutes after Luna 2, the third stage of its rocket also impacted the Moon. The mission confirmed that the Moon had no appreciable magnetic field, and found no evidence of radiation belts at the Moon.

Luna 2 and the Van Allen Radiation Belt

Luna 2 showed time variations in the electron flux and energy spectrum within the outer belt.

This space probe Luna 2 was instrumented with 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 (nanoteslas) so that the quantization uncertainty was -12 to +12 gammas. The spacecraft spin period was 840 seconds about the major axis, and there was a precession with a period of 86 seconds. The sampling rate of the instrument was approximately once per minute. According to the Principal Investigator, the errors associated with the experiment zero levels and spacecraft fields were such that the accuracy was approximately 50 to 100 gammas. The spacecraft gave results similar to those of Luna 1 in the earth's radiation belts and, upon impact, placed an upper limit of 100 gammas on the lunar magnetic field at the surface.

USSR pennants

The spacecraft also carried Soviet pennants. Two of them, located in the spacecraft, were sphere-shaped, with the surface covered by identical pentagonal elements. In the center of this sphere was an explosive to scatter these elements around on impact. Each of pentagonal elements was made of the stainless steel and had the USSR Coat of Arms and the word СССР (in Russian, it translates into English as USSR) relief engraved on one side of it and words СССР СЕНТЯБРЬ 1959 (English:USSR SEPTEMBER 1959) relief engraved on the other side. The third pennant was located in the last stage of Luna 2 rocket, which impacted the moon 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 СЕНТЯБРЬ (English:1959 SEPTEMBER) and the words СОЮЗ СОВЕТСКИХ СОЦИАЛИСТИЧЕСКИХ РЕСПУБЛИК (English:UNION OF SOVIET SOCIALIST REPUBLICS) were engraved.

September 15 1959 the USSR leader Nikita Khrushchev made a present to the USA president Dwight D. Eisenhower of a copy of the spherical pennant.

See also

• Sinus Lunicus
• List of artificial objects on the Moon