▁chron ological ▁order , ▁and ▁in ▁greater ▁detail ▁than ▁the ▁main ▁series . ▁Third space ▁and ▁The ▁River ▁of ▁Sou ls ▁are ▁largely ▁stand - alone ▁story lines . ▁ ▁A ▁Call ▁to ▁Ar ms ▁sets ▁up ▁the ▁initial ▁prem ise ▁of ▁the ▁Cr us ade ▁series , ▁dep ict ing ▁the ▁al ien ▁D rak h ▁species ▁re le asing ▁a ▁nan ov irus ▁pl ague ▁on ▁Earth , ▁which ▁will ▁destroy ▁all ▁life ▁on ▁the ▁planet ▁within ▁five ▁years , ▁if ▁it ▁is ▁not ▁stopped . ▁To ▁that ▁end , ▁the ▁Earth ▁Alliance ▁destroy er ▁Ex cal ib ur ▁is ▁sent ▁to ▁look ▁for ▁a ▁c ure ▁beyond ▁Earth ▁itself . ▁To ▁Live ▁and ▁Die ▁in ▁Star light , ▁also ▁known ▁as ▁Bab yl on ▁ 5 : ▁The ▁Leg end ▁of ▁the ▁R angers , ▁was ▁intended ▁as ▁the ▁pilot ▁for ▁the ▁series ▁of ▁the ▁same ▁( Leg end ▁of ▁the ▁R angers ) ▁name , ▁but ▁since ▁the ▁show ▁was ▁never ▁picked ▁up , ▁it ▁is ▁now ▁considered ▁to ▁be ▁the ▁sixth ▁and ▁last ▁Bab yl on ▁ 5 ▁tele film . ▁ ▁Television ▁spin - offs ▁ ▁Cr us ade ▁▁ ▁The ▁spin - off ▁series ▁Cr us ade ▁ran ▁on ▁T NT ▁for ▁ 1 3 ▁episodes , ▁having ▁been ▁set ▁up ▁by ▁the ▁TV ▁film ▁A ▁Call ▁to ▁Ar ms . ▁The ▁production ▁team ▁received ▁help ▁from ▁NASA ' s ▁Jet ▁Prop ulsion ▁Labor atory ▁to ▁ensure ▁that ▁the ▁series ▁dep icted ▁space ▁science ▁and ▁fut