XCOR Exploration Alternatives - Jeff Greason

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Exploration AlternativesIs human exploration possible without U.S. government funding it?

Earth Departure StageMaximum performance for minimum price achieved by launching payload first, then a LOX/LH2 departure stageDepots or a refrigerant module to avoid boiloff changes this orderCan buddy tank stages together but $/kg gets worseCan have a lower kick stage (solid or liquid) but $/kg gets worseEarth escape of existing stagesLauncher StageProp (kg)MECO (kg)Thrust (lbf)Isp (s)Propellant @ zero payload (250km)3.22km/sdV payloadNo refuel$/kg to Escape (very rough)Ariane 5 ECA ESC149005290145004461490013820$26000Atlas 551 Centaur208302550223004512040016170$11000Delta IV-H 5m stage2720034902720046227200

22720$15500Falcon 9900004900180000342131503230$27000

Light capsuleScaling human missions down to current launchers requires minimum crew (2), and a minimal capsuleHelps a lot if there are several docking adapters to allow flexibility in stackingMars Curiosity heat shield 4.6m diameter with 2600kg entry mass to Earth or MarsCan be used in several beyond earth missions; has volume for 2 crew on lunar missions without additional habLEO to L1/Lunar SurfaceLong term LOX/LH2 storage needed10-20kWe, plus radiators of similar capacitySunshade to keep tanks shaded reduces thisDocking ports for Centaurs plus reusable landers based on Centaur tanks plus to habHab module based on BEAM or CygnusCan put both hab and refrigerator at L1 with Atlas 551. Second 551 to place a lander.Including boiloff allowance full Centaur puts 10800kg to L1, so can push an F9 payloadLight capsule/heatshield allows crew to be brought up with enough propellant for a lunar round trip on single Atlas 551Total launch cost: $720M for first mission, $270M for each following manned round trip, or $450M to soft land 5t cargo with one way lander: can just keep going for more missions

LEO to Mars FlybyInspiration Mars studies suggest 12000-13000 kg for hab, consumables, and SMWith light capsule, perhaps 15000-16000kgDelta IV Heavy upper stage pushes ~18500kg from LEO to 3.6 km/s delta VRemaining 1.3 km/s provided by electric propulsion,


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