Luna 2 (E-1A series) was the second of the Soviet Union's Luna programme spacecraft launched to the Moon. It was the first spacecraft to reach the surface of the Moon. It successfully impacted with the lunar surface east of Mare Serenitatis near the craters Aristides, Archimedes, and Autolycus.
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, Cherenkov detectors, and micrometeorite detectors. There were no propulsion systems on Luna 2 itself.
Van Allen Radiation Belt
Luna 2 showed time variations in the electron flux and energy spectrum within the outer belt.
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 nanoteslas (gammas) so that the quantization uncertainty was -12 to +12 nT. 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 nT. 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 nT on the lunar magnetic field at the surface.
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 for the purpose of slowing the huge impact velocity. This was designed as a very simple way to provide the last necessary delta-v for those elements on the retro side of the sphere to not get vaporized. Each pentagonal element was made of stainless steel and had the USSR Coat of Arms and the Cyrillic letters СССР (Russian; it translates into English as USSR) relief engraved on one side, and the words СССР СЕНТЯБРЬ 1959 (English: USSR SEPTEMBER 1959) relief engraved on the other side. 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 СЕНТЯБРЬ (English: 1959 SEPTEMBER) and the words СОЮЗ СОВЕТСКИХ СОЦИАЛИСТИЧЕСКИХ РЕСПУБЛИК (English: UNION OF SOVIET SOCIALIST REPUBLICS) were engraved.
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