 But production of the LM fell behind schedule , and when Apollo 8 's LM arrived at the Kennedy Space Center in June 1968 , significant defects were discovered , leading Grumman , the lead contractor for the LM , to predict that the first mission @-@ ready LM would not be ready until at least February 1969 . This would mean delaying the " D " and subsequent missions , endangering the program 's goal of a lunar landing before the end of 1969 . 
