providing the Apollo spacecraft with a free-return trajectory, one that would allow it to coast around the Moon and safely return to Earth without requiring any engine firings should a problem arise on the way to the Moon;
pɹəvˈaɪdɪŋ ðɪ ɐpˈɑːloʊ spˈeɪskɹæft wɪð ɐ fɹˈiːɹᵻtˈɜːn tɹədʒˈɛktɚɹi, wˈʌn ðæt wʊd ɐlˈaʊ ɪt tə kˈoʊst ɚɹˈaʊnd ðə mˈuːn ænd sˈeɪfli ɹᵻtˈɜːn tʊ ˈɜːθ wɪðˌaʊt ɹᵻkwˈaɪɚɹɪŋ ˌɛni ˈɛndʒɪn fˈaɪɚɹɪŋz ʃˌʊd ɐ pɹˈɑːbləm ɚɹˈaɪz ɔnðə wˈeɪ tə ðə mˈuːn;