(SINV (SINV (QT (DQL ``) (QTC (S (S (BASENP (NN Space) (NN exploration)) (VP (VBZ is) (NP (BASENP (DT a) (NN dream)) (VP (ADVP (RB deeply)) (VP (VBN rooted) (PP (IN in) (BASENP (NN humanity)))))))) (CONJP (COMMA ,) (CC and)) (S (S (NP (BASENP (DT the) (NN seven) (JJ brave) (NNS astronauts)) (PP (IN of) (BASENP (NNP Columbia)))) (VP (VBD sacrificed) (BASENP (PRPD their) (NNS lives)))) (SBAR (IN so) (S (NP (BASENP (DT the) (NN rest)) (PP (IN of) (BASENP (NNP mankind)))) (VP (MD could) (VP (VB realize) (BASENP (DT that) (NN dream)))))))) (COMMA ,)) (DQR '')) (SINV (VP (VBD said)) (NP (BASENP (NNP Bush) (POS 's)) (NN letter)))) (PERIOD .))