▁content ▁Watch ▁the ▁ 1 9 6 2 ▁document ary ▁Kinder g arten ▁ ▁Category : E du c ational ▁years ▁Category : E du c ational ▁stages ▁Category : Sch ool ▁types ▁Category : E ar ly ▁child hood ▁education <0x0A> </s> ▁A ▁zero - prop ell ant ▁man eu ver ▁( Z PM ) ▁is ▁an ▁optimal ▁attitude ▁traject ory ▁used ▁to ▁perform ▁space craft ▁rot ational ▁control ▁without ▁the ▁need ▁to ▁use ▁thrust ers . ▁Z PM s ▁are ▁designed ▁for ▁space craft ▁that ▁use ▁momentum ▁storage ▁actu ators . ▁Space craft ▁Z PM s ▁are ▁used ▁to ▁perform ▁large ▁angle ▁rot ations ▁or ▁rate ▁d amp ing ▁( det umb ling ) ▁without ▁s atur ating ▁momentum ▁actu ators , ▁and ▁momentum ▁dump ing ▁( from ▁storage ) ▁without ▁thrust ers . ▁ ▁Background ▁Space craft ▁rot ational ▁operations , ▁such ▁as ▁turning ▁to ▁point ▁in ▁a ▁new ▁direction , ▁are ▁usually ▁performed ▁by ▁angular ▁momentum ▁storage ▁devices ▁such ▁as ▁reaction ▁whe els ▁or ▁control ▁moment ▁gy ro scop es . ▁It ▁is ▁generally ▁prefer able ▁to ▁use ▁these ▁devices ▁instead ▁of ▁traditional ▁thrust ers , ▁as ▁they ▁are ▁power ed ▁by ▁renew able ▁electric ity ▁instead ▁of ▁by ▁prop ell ant ; ▁firing ▁thrust ers ▁uses ▁up ▁the ▁fixed ▁amount ▁of ▁prop ell ant ▁on ▁the ▁space craft . ▁Prop ell ant ▁is ▁very ▁cost ly ▁because ▁it ▁must ▁be ▁carried ▁from ▁earth ; ▁once ▁it ▁is ▁used ▁up , ▁the ▁space craft ' s ▁life ▁is ▁over