AS101 Lecture Notes - Lecture 1: Permafrost, Solar Wind
Document Summary
Marshasaverythinatmospherewithapressureofabout1/150ththatofearth(0. 007bar) consisting of mostly carbon dioxide (95. 3%) and smaller amounts of other gases . 2. 7% nitrogen, 1. 6% argon, 0. 13% oxygen, and 0. 07% carbon monoxide. Theamountofco intheatmospherevarieswiththeseasonsasthepolardryicecapsgrow 2 andrecedewithtemperatureandco sublimatesintotheatmosphereandthenfreezesout 2 during winter. Mars once had a greater (higher pressure) atmosphere and a stronger greenhouse effect, maybe even as much as twice as great as earth"s current pressure (quite a change from what it now is). 2 required for the greenhouse effect that warmed the planet at that time (3 billion years ago). 2 weakened, liquid water receded into the permafrost, and the atmospheric pressure plummeted (the smaller surface gravity, weak magnetic field and the solar wind helped clear out the atmosphere). Also,withnouvlayerthewatervapourmoleculesarebrokenintolighth (whichwaslost 2 throughthermalescape)ando (whichwaslostthroughsolarwindbombardmentand 2 through chemical reactions with surface rocks). There appears to be no measurable magnetic field (less than at least 1/800th that of. Earth"s) although recent measurements by the mars global surveyor (1999) show some weak surface magnetic field signatures.
