ach ; ▁and ▁one ▁fruit , ▁st raw ber ries . ▁The ▁whe at ▁provided ▁the ▁main ▁source ▁of ▁cal ories ▁and ▁the ▁primary ▁source ▁of ▁o xygen . ▁Me at ▁was ▁the ▁primary ▁food stock ; ▁however , ▁meat ▁was ▁grown , ▁in ▁the ▁form ▁of ▁yellow ▁me al w orm s , ▁the ▁crew ' s ▁primary ▁protein ▁source . ▁ ▁The ▁di et ▁studied ▁was ▁to ▁determine ▁if ▁a ▁space ▁crew ▁could ▁subs ist ▁on ▁a ▁high ▁protein ▁di et ▁with ▁veget ables ▁and ▁me al w orm s . ▁The ▁me al w orm s , ▁composed ▁of ▁ 3 / 4 ▁protein , ▁were ▁chosen ▁due ▁to ▁a ▁United ▁Nations ▁study ▁recomm ending ▁them ▁as ▁a ▁food ▁source ▁for ▁the ▁poor ▁and ▁und ern our ished ; ▁however , ▁it ▁was ▁met ▁with ▁resistance ▁from ▁Western ▁astr onaut s . ▁They ▁have ▁a ▁t endency ▁to ▁escape ▁conf in ement . ▁Me al w orm s ▁reached ▁the ▁size ▁of ▁fingers ▁in ▁weeks . ▁The ▁me al w orm s ▁were ▁fed ▁the ▁le f to ver ▁and ▁in ed ible ▁parts ▁of ▁the ▁produce . ▁ ▁The ▁mission ' s ▁e colog ical ▁system ▁was ▁to ▁be ▁a ▁test bed ▁for ▁the ▁controlled ▁e colog ical ▁life ▁support ▁system ▁( CE L SS ) ▁for ▁the ▁permanent ▁Chinese ▁space ▁station ▁of ▁the ▁China ▁Mann ed ▁Space ▁Engineering ▁Office ▁( CS ME ). ▁The ▁B L SS ▁system ▁used ▁on ▁the ▁mission ▁was ▁at ▁the ▁time ▁the ▁most