This design meant the spacecraft could be launched by a single Saturn V rocket that was then under development.
ðɪs dɪzˈaɪn mˈɛnt ðə spˈeɪskɹæft kʊd biː lˈɑːntʃt baɪ ɐ sˈɪŋɡəl sˈæɾɜːn vˈiː ɹˈɑːkɪt ðæt wʌz ðˈɛn ˌʌndɚ dɪvˈɛləpmənt.