The word itself had been known earlier; for example, in Percy Greg's 1880 book Across the Zodiac, "astronaut" referred to a spacecraft.
ðə wˈɜːd ɪtsˈɛlf hɐdbɪn nˈoʊn ˈɜːlɪɚ; fɔːɹ ɛɡzˈæmpəl, ɪn pˈɜːsi ɡɹˈɛɡz wˈʌn θˈaʊzənd ˈeɪthˈʌndɹɪd ˈeɪɾi bˈʊk əkɹˌɑːs ðə zˈoʊdiˌæk, "ˈæstɹənˌɔːt" ɹᵻfˈɜːd tʊ ɐ spˈeɪskɹæft.