(S (S (BASENP (DT The) (NN observation)) (VP (VBD was) (VP (VBN made) (PP (IN by) (NP (BASENP (DT the) (NNP Gravity) (NNP Probe) (NNP B) (NN satellite)) (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ carries) (BASENP (JJ finely-machined) (NNS gyroscopes)))))))))) (PERIOD .))