1. The problem statement, all variables and given/known data A Xenon (mass = 131 AMU) ion propulsion system has specific impulse 4920.0 sec. Calculate how much Xenon (in kg) required to maintain GEO orbit for 12 years for 8000 kg spacecraft. Assume thrust = .046 N. Calculated this to be 360 kg. Asked to find other values such as: exit velocity of ions (48.265 km/s) ion acceleration voltage (1581 V) mass flow (9.5307 E-7 kg/s) # ions exiting per sec (4.381 E18 ions/sec) ion current (.70198 A) ion beam power (1110 W) I did not want to write out all the equations for this problem, so I attached the sheet that had the formulas on it. Anyway, assuming my answers are correct I am stuck on the last question: Calculate the number of hours the thruster should work, on average, each day to maintain the spacecraft in GEO orbit. Any ideas?