The proper operation of the S-IVB third stage of the rocket was crucial, and in the last uncrewed test, it had failed to reignite for this burn.
ðə pɹˈɑːpɚɹ ˌɑːpɚɹˈeɪʃən ʌvðɪ ˈɛsˌaɪvˌiːbˈiː θˈɜːd stˈeɪdʒ ʌvðə ɹˈɑːkɪt wʌz kɹˈuːʃəl, ænd ɪnðə lˈæst ʌŋkɹˈuːd tˈɛst, ɪt hæd fˈeɪld tə ɹˌiːɪɡnˈaɪt fɔːɹ ðɪs bˈɜːn.