Originally planned as the second crewed Apollo Lunar Module and command module test, to be flown in an elliptical medium Earth orbit in early 1969, the mission profile was changed in August 1968 to a more ambitious command-module-only lunar orbital flight to be flown in December, as the lunar module was not yet ready to make its first flight.
ɚɹˈɪdʒɪnəli plˈænd æz ðə sˈɛkənd kɹˈuːd ɐpˈɑːloʊ lˈuːnɚ mˈɑːdʒuːl ænd kəmˈænd mˈɑːdʒuːl tˈɛst, təbi flˈoʊn ɪn ɐn ɪlˈɪptɪkəl mˈiːdiəm ˈɜːθ ˈɔːɹbɪt ɪn ˈɜːli nˈaɪntiːnhˈʌndɹɪd sˈɪksti nˈaɪn, ðə mˈɪʃən pɹˈoʊfaɪl wʌz tʃˈeɪndʒd ɪn ˈɔːɡəst nˈaɪntiːnhˈʌndɹɪd sˈɪksti ˈeɪt tʊ ɐ mˈoːɹ æmbˈɪʃəs kəmˈændmˈɑːdʒuːlˈoʊnli lˈuːnɚɹ ˈɔːɹbɪɾəl flˈaɪt təbi flˈoʊn ɪn dᵻsˈɛmbɚ, æz ðə lˈuːnɚ mˈɑːdʒuːl wʌz nˌɑːt jˈɛt ɹˈɛdi tə mˌeɪk ɪts fˈɜːst flˈaɪt.