Future of Life in the Solar SystemFuture of Life in Solar SystemTerra form other planets (Mars most likely)Space ColoniesSolar Power from spaceDyson spheresRobotsVon Neumann DevicesFuture of Life in the Solar System Seed other planets with “bio-engineered organisms”Use these to make more habitable for humansTerraform (need H2O, O2, O3)e.g. Melt polar caps on Mars (1014 tons of ice)2500 to 10000 years to build up atm. pressure, get liquid waterTerraformed MarsOcean in northern lowlands covers25% of planetSpace coloniesSolar Power satellitesDyson sphere (Type II Civilization)Role of RobotsVon Neumann deviceLiving in Space to Robots…RocketsPrinciple: Newton’s Third Law1. Exhaust velocity Ve (km s-1)Ve ∝ √FexhaustFrocketFrocket = FexhaustTM2. Thrust (Force) F = M Ve(Newtons, Pounds)( M = rate of mass ejected)3. Mass ratioRM = Total Mass at Takeoff Mass After Fuel Used Up4. Specific impulse (s.i.)Thrust (Newtons/kg/sec,Rate of Fuel Use Pounds/Pounds/sec = “sec”)A measure of efficiency.Highest possible s.i. with chemical fuels is < 500RocketsTo take off: Thrust > WeightTo escape gravity v > vesc = 11.2 km s-1 (7 miles/sec)FgravFthrustRocketsMulti-stage RocketsSpace Shuttle: Mass = 2 × 106 kgFthrust = 29 × 106 Newtons RM = 68s.i. = 455 sec. ~ best possible with chemical fuelFor more adventurous exploitation of Solar SystemProbably want Nuclear PropulsionFission could give s.i. = 1.5 × 106 sec(in principle, more likely to get 20,000 sec)Current Initiative• Human mission to Mars• Several attempts to get started in past• Exploration Vision in 2004– First return to Moon– Then Mars– Long-term program needed–
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