Project Echo

first passive communications satellite experiment

en-GB/ˈpɹɒd͡ʒɛkt ˈɛkəʊ/
en-US/ˈpɹɑd͡ʒɛktn ˈɛkoʊ/

カテゴリ：

artificial satellite of the Earthartificial satellitespacecraftballoon satellite