(S (S (PP (IN During) (BASENP (DT this) (NN spacewalk))) (COMMA ,) (S (BASENP (DT the) (NN station)) (VP (ADVP (RB again)) (VP (VBD encountered) (NP (BASENP (DT the) (JJ mysterious) (NNS forces)) (SBAR (WHNP (WDT that)) (S (VP (VBP have) (VP (VBN been) (VP (VP (VBG saturating) (BASENP (DT the) (NNP Control) (NNP Moment) (NNS Gyros))) (PP (IN during) (BASENP (JJ previous) (NNS spacewalks))))))))))))) (PERIOD .))