 The teams tested their solutions in August 1968 at the Marshall Space Flight Center . A Saturn stage IC was equipped with shock absorbing devices to demonstrate the team 's solution to the problem of pogo oscillation , while a Saturn Stage II was retrofitted with modified fuel lines to demonstrate their resistance to leaks and ruptures in vacuum conditions . Once NASA administrators were convinced that the problems were solved , they gave their approval for a manned mission using SA @-@ 503 . 
