2019-05-22 Wed

Switzerland released a .835 fine silver 20-franc collector coin to celebrate the 50th anniversary of the Apollo 11 Moon landing. The coin features an image of a solar wind sail that was developed by the University of Bern and carried by Apollo 11. astronauts Designed by engraver Remo Mascherini from Swissmint, the 20 grams coin has a diameter of 33 millimetres. Uncirculated and Proof versions of the coin are available. The packaging, mintage limits and pricing is different for each version.

The solar wind sail was the only non-American experiment that was attempted during the Apollo 11 mission. Astronaut Edwin Aldrin hung a Swiss solar sail before hoisting the American flag on the moon. Professor Johannes Geiss from the Institute of Physics led a team of Bern physicists to develop and monitor the “Solar Wind Composition Experiment”. The experiment was aimed at verifying and measuring Solar Wind on Moon. The sail was made of coated aluminium foil and was oriented towards the sun to capture Solar Wind. The foil was analyzed after Apollo 11 returned back to earth. The experiment was repeated on all lunar missions except on Apollo 17, and Apollo 13 mission.

The chemical composition of the embedded solar wind was determined accurately. However, unlike remotely controlled experiments, observation periods were limited. The isotopes of the light noble gases like helium-3, helium-4, neon-20, neon-21, neon-22, and argon-36 were measured. Variation in the composition was observed during different missions due to the variations in the intensity of the solar wind.

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Image Courtesy: Swiss Mint