▁but ▁they ▁are ▁widely ▁believed ▁to ▁be ▁success ors ▁to ▁the ▁Vor tex / Ch alet ▁sat ell ites . ▁ ▁The ▁last ▁launch ▁attempt , ▁on ▁ 1 2 ▁August ▁ 1 9 9 8 ▁failed , ▁with ▁the ▁US D ▁$ 7 0 0 – 8 0 0 ▁million ▁satellite ▁and ▁the ▁$ 3 4 4 ▁million ▁T itan ▁IV ( 4 0 1 ) A ▁launch ▁vehicle ▁expl oding ▁over ▁the ▁Atlantic ▁Ocean . ▁The ▁failure ▁was ▁caused ▁by ▁a ▁short ▁circuit ▁in ▁the ▁guidance ▁system , ▁which ▁lost ▁power ▁and ▁reset , ▁causing ▁the ▁vehicle ▁to ▁pitch ▁over . ▁This ▁in ▁turn ▁led ▁to ▁prem ature ▁separation ▁of ▁one ▁of ▁the ▁SR B s , ▁which ▁automatically ▁self - dest ruct ed . ▁The ▁resulting ▁explos ion ▁also ▁destroyed ▁the ▁core ▁vehicle , ▁and ▁the ▁second ▁SR B ▁then ▁initi ated ▁its ▁own ▁self - dest ruction . ▁R ough ly ▁ 4 ▁seconds ▁later ▁the ▁Range ▁Saf ety ▁Officer ▁also ▁issued ▁a ▁self - dest ruct ▁signal ▁to ▁the ▁ro cket . ▁Ob ser vers ▁estimate ▁each ▁space craft ▁has ▁a ▁mass ▁of ▁ 4 , 0 0 0 – 5 , 0 0 0   kg . ▁ ▁La unch es ▁ ▁References ▁ ▁External ▁links ▁Mercur y ▁EL INT ▁at ▁Encyclopedia ▁A str onaut ica ▁Mercur y / Ad vanced ▁V OR TE X ▁from ▁Federation ▁of ▁American ▁Scient ists ▁Video ▁of ▁the ▁launch ▁and ▁destruction ▁ ▁Category : Re con na issance ▁sat ell ites