▁to ▁a ▁higher ▁alt itude . ▁Because ▁on ▁board ▁prop ell ant ▁capacity ▁is ▁limited , ▁the ▁space craft ▁can ▁only ▁perform ▁a ▁limited ▁number ▁of ▁momentum ▁des atur ations ▁or ▁re boost s . ▁Therefore , ▁if ▁momentum ▁des atur ations ▁can ▁be ▁reduced ▁or ▁elimin ated , ▁a ▁larger ▁fraction ▁of ▁prop ell ant ▁can ▁be ▁used ▁to ▁maintain ▁the ▁space craft ▁in ▁its ▁desired ▁orbit , ▁and ▁it ▁will ▁have ▁a ▁longer ▁oper ational ▁lifetime . ▁ ▁Typ ically ▁space craft ▁rot ations ▁are ▁performed ▁as ▁qu atern ion ▁rot ations ▁or ▁about ▁a ▁fixed ▁axis ▁( E uler ' s ▁rotation ▁theorem ) ▁usually ▁referred ▁to ▁as ▁an ▁eigen axis . ▁Rot ations ▁about ▁an ▁eigen axis ▁result ▁in ▁the ▁smallest ▁angle ▁between ▁two ▁orient ations . ▁Moreover , ▁eigen axis ▁rot ations ▁are ▁performed ▁with ▁a ▁fixed ▁rotation ▁rate ▁or ▁man eu ver ▁rate . ▁However , ▁to ▁maintain ▁the ▁space craft ▁rotation ▁about ▁the ▁eigen axis , ▁and ▁at ▁a ▁fixed ▁man eu ver ▁rate , ▁requires ▁the ▁momentum ▁storage ▁actu ators ▁to ▁overcome ▁disturb ance ▁tor ques ▁acting ▁on ▁the ▁space craft . ▁Depending ▁on ▁the ▁intensity ▁of ▁the ▁dist urban ces , ▁the ▁size ▁of ▁rotation ▁and ▁momentum ▁storage ▁device ▁capacity , ▁momentum ▁storage ▁devices ▁can ▁become ▁s atur ated ▁even ▁if ▁the ▁space craft ▁is ▁rot ated ▁at ▁a ▁small ▁man eu ver ▁rate . ▁ ▁Fort un ately , ▁however , ▁the ▁choice ▁of ▁rotation ▁path ▁impact s ▁the ▁space craft ▁performance .