SUMMARY: AMONG THE THREE MOST RECENT MARS MISSIONS MARS GLOBAL SURVEYOR (MGS) MARS EXPRESS AND MARS ATMOSPHERE VOLATILE EVOLUTION (MAVEN) MGS IS THE ONLY MISSION THAT OBSERVED THE MAXIMUM OF SOLAR CYCLE 23 AND THE ASSOCIATED EXTREME SPACE WEATHER EVENTS INCLUDING INTERPLANETARY CORONAL MASS EJECTIONS (ICMES). DURING NOMINAL CONDITIONS THE MAGNETIC TOPOLOGY AT MARS INCLUDES THE DRAPED INTERPLANETARY MAGNETIC FIELD (IMF) LINES CONNECTED TO THE SOLAR WIND ON BOTH ENDS AND CLOSED CRUSTAL MAGNETIC FIELD WITH BOTH ENDS ANCHORED TO THE CRUST AND EXTENDING TO HIGH ALTITUDES. IN ADDITION WHERE THE MAGNETIC GEOMETRY IS FAVORABLE THE IMF CAN RECONNECT WITH CRUSTAL SOURCES CREATING OPEN FIELD LINES WITH ONE END PASSING THROUGH THE IONOSPHERE/COLLISIONAL ATMOSPHERE AND THE OTHER END CONNECTED TO THE SOLAR WIND. MODELING STUDIES HAVE SUGGESTED THAT DURING EXTREME CONDITIONS (SUCH AS ICMES) THAT THE OPEN FIELD LINE GEOMETRY DOMINATES GLOBALLY AND CONTROLS THE TAIL CONFIGURATION PLANETARY ION OUTFLOW AND ENERGY DEPOSITION ONTO THE ATMOSPHERE BY ENERGETIC IONS AND ELECTRONS. MODELING STUDIES HAVE SUGGESTED THAT ONE EFFECT OF EXTREME SPACE WEATHER EVENTS IS A SIGNIFICANT INCREASE IN THE OPEN FIELD LINE TOPOLOGY. THIS MOTIVATES US TO USE THE ELECTRON AND MAGNETIC FIELD DATA COLLECTED BY THE MAGNETOMETER/ELECTRON REFLECTOR (MAG/ER) INSTRUMENT ONBOARD MGS TO INVESTIGATE THE MAGNETIC TOPOLOGICAL RESPONSE TO EXTREME SOLAR TRANSIENT EVENTS AND THE CONSEQUENCES OF SUCH TOPOLOGICAL RESPONSE TO THE UPPER ATMOSPHERIC ENERGY BUDGET AND ATMOSPHERIC LOSS. THUS WE PROPOSED TO ANSWER THE FOLLOWING QUESTIONS: 1. WHAT IS THE TOPOLOGICAL RESPONSE TO SOLAR TRANSIENTS AT MARS AND HOW OPEN IS THE MAGNETIC TOPOLOGY AT MARS DURING EXTREME EVENTS IN COMPARISON TO QUIET CONDITIONS? 2. WHAT ARE THE CONSEQUENCES OF THE TOPOLOGICAL CHANGE? A. HOW DOES THE TOPOLOGY INFLUENCE THE ENERGETIC ELECTRON ENERGY DEPOSITION? B. HOW DOES THE TOPOLOGY INFLUENCE PLANETARY ION ESCAPE? METHODOLOGY: FOR THIS PROPOSAL WE HAVE SELECTED FIVE EXTREME ICME EVENTS OBSERVED BY MGS DURING BETWEEN 2001-2003. (A) TO ESTABLISH THE TOPOLOGICAL RESPONSE WE WILL QUANTIFY THE TOPOLOGICAL CHANGES BY COMPARING HOW OPEN CLOSED AND DRAPED FIELD LINES ARE DURING EXTREME EVENTS AND QUIET TIME PERIODS FOR THE FIVE EVENTS. THE TOPOLOGY IS DETERMINED BY EXAMINING THE SUPERTHERMAL ELECTRON PITCH ANGLE AND SPECTRAL INFORMATION. WE THEN CHARACTERIZE THE TOPOLOGICAL CHANGES WITH UPSTREAM PROXIES OBTAINED FROM MGS MAG DATA. WE WILL ALSO CONDUCT SIMILAR ANALYSIS AND USE RESULTS FROM EXISTING MAGNETOHYDRODYNAMIC (MHD) RESULTS TO COMPARE THE SIMULATED MAGNETIC FIELD TOPOLOGIES WITH THOSE OBSERVED BY MGS. (B) TO STUDY THE CONSEQUENCES WE FOCUS ON INVESTIGATE THE CHANGE OF THE ELECTRON ENERGY DEPOSITION FROM QUIET TO EVENT PERIODS. THIS PART INCLUDES THE CALCULATION OF THE NET ELECTRON ENERGY DEPOSITION DETERMINED FROM ER DATA AND ALSO THE IONIZATION PROFILES DUE TO ELECTRON IMPACT SIMULATED BY A SUPERTHERMAL ELECTRON TRANSPORT MODEL. THE ENERGY DEPOSITION CHANGES WILL BE CHARACTERIZED WITH UPSTREAM CONDITIONS AS WELL AS OTHER FACTORS. IN ADDITION WE WILL ALSO DETERMINE THE GLOBAL ION ESCAPE RATES FROM MHD RESULTS FOR THE EVENTS OBSERVED BY MGS. RELEVANCE: THE PROPOSED WORK DIRECTLY ADDRESSES THE OBJECTIVE OF MDAP BY ENHANCING THE SCIENTIFIC RETURN FROM MGS AND BROADENING SCIENTIFIC KNOWLEDGE THAT WILL AID IN FUTURE DATA ANALYSIS WITH MAVEN AND OTHER MARS MISSIONS. THIS STUDY SEEKS TO BETTER CHARACTERIZE THE MARS-SOLAR WIND INTERACTION AND SUBSEQUENT INDUCED MAGNETOSPHERE WHICH IS A HIGH-PRIORITY AREA OF RESEARCH THAT SUPPORTS PLANNING FOR FUTURE MARS MISSIONS AS THEY ARE CRITICAL FOR SPACECRAFT INTERACTIONS. ADDITIONALLY UNDERSTANDING THE SOLAR CYCLE AND SPACE WEATHER EVENTS CAN HELP US BETTER UNDERSTAND HOW THE MARTIAN PLASMA ENVIRONMENT CONDITIONS COULD HAVE DIFFERED IN THE EARLY SOLAR SYSTEM WHEN THE SUN WAS MORE ACTIVE.