( ( ( A ( good example ) ) ( of ( ( a ( military ( space system ) ) ) ( available ( for ( commercial use ) ) ) ) ) ) ( ( is ( ( ( ( the ( Navstar ( Global ( Positioning System ) ) ) ) ( -LRB- ( GPS -RRB- ) ) ) , ) ( ( ( a constellation ) ( of ( 24 satellites ) ) ) ( providing ( 24-hour ( navigation services ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (JJ good) (NN example)) (PP (IN of) (NP (NP (DT a) (JJ military) (NN space) (NN system)) (ADJP (JJ available) (PP (IN for) (NP (JJ commercial) (NN use))))))) (VP (VBZ is) (NP (NP (NP (DT the) (NNP Navstar) (NNP Global) (NNP Positioning) (NNP System)) (PRN (-LRB- -LRB-) (NP (NNP GPS)) (-RRB- -RRB-))) (, ,) (SBAR (WHNP (WHNP (DT a) (NN constellation)) (PP (IN of) (NP (CD 24) (NNS satellites)))) (S (VP (VBG providing) (NP (JJ 24-hour) (NN navigation) (NNS services))))))) (. .)))
A good example of a military space system available for commercial use is the Navstar Global Positioning System (GPS),  a constellation of 24 satellites providing 24-hour navigation services.
(ROOT (S (S (NP (PRP We)) (VP (VBP call) (NP (NP (DT the) (JJ worldwide) (JJ radio-navigation) (NN system)) (VP (VBN formed) (PP (IN from) (NP (NP (DT a) (NN constellation)) (PP (IN of) (NP (CD 24) (NNS satellites))))))))) (CC and) (S (NP (PRP$ their) (NN ground) (NNS stations)) (VP (VBP gps))) (. .)))