▁by ▁the ▁Vik ing ▁program . ▁Pre lim inary ▁mission ▁goals ▁expected ▁the ▁pro be ▁to ▁provide ▁planet ary ▁magnetic ▁field ▁data , ▁detection ▁of ▁certain ▁spectral ▁line ▁sign atures ▁of ▁min er als ▁on ▁the ▁surface , ▁images ▁of ▁the ▁surface ▁at ▁ 1 ▁meter / p ixel ▁and ▁global ▁elev ation ▁data . ▁ ▁Mars ▁Ob server ▁was ▁originally ▁planned ▁to ▁be ▁launched ▁in ▁ 1 9 9 0 ▁by ▁a ▁Space ▁Sh utt le ▁Or b iter . ▁ ▁The ▁possibility ▁for ▁an ▁exp end able ▁ro cket ▁to ▁be ▁used ▁was ▁also ▁suggested , ▁if ▁the ▁space craft ▁was ▁designed ▁to ▁meet ▁certain ▁constraints . ▁On ▁March ▁ 1 2 , ▁ 1 9 8 7 , ▁the ▁mission ▁was ▁res ch eduled ▁for ▁launch ▁in ▁ 1 9 9 2 , ▁in ▁lieu ▁of ▁other ▁back log ged ▁miss ions ▁( G al ile o , ▁Mag ellan , ▁U ly ss es ) ▁after ▁the ▁Space ▁Sh utt le ▁Ch allen ger ▁dis aster . ▁Al ong ▁with ▁a ▁launch ▁delay , ▁budget ▁over run s ▁necess itated ▁the ▁elim ination ▁of ▁two ▁instruments ▁to ▁meet ▁the ▁ 1 9 9 2 ▁planned ▁launch . ▁As ▁the ▁development ▁m ature d , ▁the ▁primary ▁science ▁object ives ▁were ▁final ized ▁as : ▁Det erm ine ▁the ▁global ▁element al ▁and ▁min eral og ical ▁character ▁of ▁the ▁surface ▁material . ▁Define ▁glob ally ▁the ▁top ography ▁and ▁gravit ational ▁field . ▁Est ab lish ▁the ▁nature ▁of