(S (S (ADVP (RB However)) (COMMA ,) (S (NP (NP (BASENP (DT the) (NNP Union)) (PP (IN of) (BASENP (NNP Concerned) (NNPS Scientists)))) (PRN (LRB -LRB-) (BASENP (NNP UCS)) (RRB -RRB-))) (VP (VP (VBD said) (PP (IN on) (BASENP (NNP February) (NN 12)))) (SBAR (IN that) (S (BASENP (DT the) (NN debris)) (VP (MD could) (VP (VB have) (VP (VP (VBN taken) (NP (BASENP (NN 10) (NNS days)) (QP (CC or) (JJR less)))) (S (VP (TO to) (VP (VB reenter) (PP (IN over) (NP (BASENP (NNS portions)) (PP (IN of) (BASENP (DT the) (NN planet)))))))))))))))) (PERIOD .))