▁Sol . ▁While ▁some ▁instruments ▁could ▁provide ▁a ▁real - time ▁data ▁link ▁when ▁Earth ▁was ▁in ▁view ▁of ▁the ▁space craft , ▁data ▁would ▁also ▁be ▁recorded ▁to ▁the ▁digital ▁t ape ▁record ers ▁and ▁played ▁back ▁to ▁Earth ▁each ▁day . ▁Over ▁ 7 5   g ig aby tes ▁of ▁scientific ▁data ▁was ▁expected ▁to ▁be ▁yield ed ▁during ▁the ▁primary ▁mission , ▁much ▁more ▁than ▁any ▁previous ▁mission ▁to ▁Mars . ▁The ▁end ▁of ▁the ▁oper able ▁life ▁for ▁the ▁space craft ▁was ▁expected ▁to ▁be ▁limited ▁by ▁the ▁supply ▁of ▁prop ell ant ▁and ▁the ▁condition ▁of ▁the ▁batter ies . ▁ ▁Communic ations ▁loss ▁ ▁On ▁August ▁ 2 1 , ▁ 1 9 9 3 , ▁at ▁ 0 1 : 0 0 ▁UTC , ▁three ▁days ▁prior ▁to ▁the ▁scheduled ▁Mars ▁orb ital ▁insert ion , ▁there ▁was ▁an ▁" ine xp lic able " ▁loss ▁of ▁contact ▁with ▁Mars ▁Ob server . ▁New ▁commands ▁were ▁sent ▁every ▁ 2 0 ▁minutes ▁in ▁the ▁hopes ▁that ▁the ▁space craft ▁had ▁dr ift ed ▁off ▁course ▁and ▁could ▁reg ain ▁contact . ▁However , ▁the ▁attempt ▁was ▁un success ful . ▁It ▁is ▁unknown ▁whether ▁the ▁space craft ▁was ▁able ▁to ▁follow ▁its ▁automatic ▁programming ▁and ▁go ▁into ▁Mars ▁orbit ▁or ▁if ▁it ▁fle w ▁by ▁Mars ▁and ▁is ▁now ▁in ▁a ▁hel i oc ent ric ▁orbit . ▁ ▁On ▁January ▁ 4 , ▁ 1 9 9 4 , ▁an ▁independent ▁investigation ▁board ▁from