(S (S (BASENP (DT The) (NNP U.S.) (NN space) (NN agency) (NNP NASA)) (VP (VP (VP (VP (VBD called) (PRT (RP off))) (NP (BASENP (DT the) (NN launch)) (PP (IN of) (BASENP (NNP Space) (NN shuttle) (NNP Discovery))))) (BASENP (NN today))) (PP (IN after) (NP (BASENP (DT a) (NN problem)) (PP (IN with) (NP (NP (BASENP (DT a) (NN fuel) (NN sensor)) (PP (IN in) (BASENP (DT the) (JJ external) (NN tank)))) (VP (VBN used) (S (VP (TO to) (VP (VB detect) (BASENP (NN fuel) (NN exhaustion)))))))))))) (PERIOD .))