ing ▁s izable ▁obst acles . ▁ ▁The ▁Jet ▁Prop ulsion ▁Labor atory ▁states ▁that ▁this ▁ro cker ▁bog ie ▁system ▁reduces ▁the ▁motion ▁of ▁the ▁main ▁M ER ▁vehicle ▁body ▁by ▁half ▁compared ▁to ▁other ▁susp ension ▁systems . ▁Each ▁of ▁the ▁Cur ios ity ▁ro ver ' s ▁six ▁whe els ▁has ▁an ▁independent ▁motor . ▁The ▁two ▁front ▁and ▁two ▁rear ▁whe els ▁have ▁individual ▁ste ering ▁mot ors ▁which ▁allow ▁the ▁vehicle ▁to ▁turn ▁in ▁place . ▁Each ▁wheel ▁also ▁has ▁cle ats , ▁providing ▁g rip ▁for ▁clim bing ▁in ▁soft ▁sand ▁and ▁scr amb ling ▁over ▁rocks . ▁The ▁maximum ▁speed ▁of ▁the ▁rob ots ▁operated ▁in ▁this ▁way ▁is ▁limited ▁to ▁eliminate ▁as ▁many ▁dynamic ▁effects ▁as ▁possible ▁so ▁that ▁the ▁mot ors ▁can ▁be ▁ge ared ▁down , ▁thus ▁en abling ▁each ▁wheel ▁to ▁individually ▁lift ▁a ▁large ▁portion ▁of ▁the ▁entire ▁vehicle ' s ▁mass . ▁ ▁In ▁order ▁to ▁go ▁over ▁a ▁vertical ▁obst acle ▁face , ▁the ▁front ▁whe els ▁are ▁forced ▁against ▁the ▁obst acle ▁by ▁the ▁center ▁and ▁rear ▁whe els . ▁The ▁rotation ▁of ▁the ▁front ▁wheel ▁then ▁lif ts ▁the ▁front ▁of ▁the ▁vehicle ▁up ▁and ▁over ▁the ▁obst acle . ▁The ▁middle ▁wheel ▁is ▁then ▁pressed ▁against ▁the ▁obst acle ▁by ▁the ▁rear ▁whe els ▁and ▁pulled ▁against ▁the ▁obst acle ▁by ▁the ▁front ▁until ▁it ▁is ▁lifted ▁up ▁and ▁over . ▁Finally , ▁the ▁rear ▁wheel ▁is ▁pulled ▁over ▁the ▁obst acle ▁by ▁the ▁front ▁two