Although the moon is conveniently close for observations, astronauts haven't stepped on the lunar surface since 1972.
원문출처 : https://www.cnn.com/2020/02/07/world/moon-dust-grain-apollo-17-scn/index.html
원문출처 : https://www.cnn.com/2020/02/07/world/moon-dust-grain-apollo-17-scn/index.html