(S (S (BASENP (NNP NASA) (NN boss) (NNP Michael) (NNP Griffin)) (VP (VBD was) (PP (IN amongst) (NP (BASENP (JJ several) (NNS people)) (SBAR (WHNP (WP who)) (S (VP (VBD commented) (PP (IN on) (NP (BASENP (DT the) (JJ dangerous) (NN nature)) (PP (IN of) (BASENP (NN spaceflight)))))))))))) (PERIOD .))