( Those ( ( are ( ( the last ) ( of ( ( the ( major countermeasures ) ) ( developed ( to ( ( keep ( ( the ( first forces ) ) ( of gravity ) ) ) ( from ( ( ( causing them ) ( to ( black ( ( out ( as ( the shuttle ) ) ) rolls ) ) ) ) ( to ( ( a stop ) ( on ( the runway ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT Those)) (VP (VBP are) (NP (NP (DT the) (JJ last)) (PP (IN of) (NP (NP (DT the) (JJ major) (NNS countermeasures)) (VP (VBN developed) (S (VP (TO to) (VP (VB keep) (NP (NP (DT the) (JJ first) (NNS forces)) (PP (IN of) (NP (NN gravity)))) (PP (IN from) (S (VP (VBG causing) (NP (PRP them)) (PP (TO to) (NP (JJ black) (ADJP (IN out) (PP (IN as) (NP (DT the) (NN shuttle)))) (NNS rolls))) (PP (TO to) (NP (NP (DT a) (NN stop)) (PP (IN on) (NP (DT the) (NN runway)))))))))))))))) (. .)))
Those are the last of the major countermeasures developed to keep the first forces of gravity from causing them to black out as the shuttle rolls to a stop on the runway.
(ROOT (S (NP (NNP Gravity)) (VP (VBZ causes) (S (NP (NNS rocks)) (VP (TO to) (VP (VB roll) (ADVP (RB downhill)))))) (. .)))