Canceling the Orion Crew Exploration Vehicle (CEV) makes no sense if the government is serious about a "Flexible Path" approach for lunar fly-bys and visits to asteroids and Mars.rnIf Americans want to venture beyond low Earth orbit (LEO), a heavy-lift launch vehicle is necessary. But a vehicle just like Orion will also be needed to safely return the crew to Earth, using an Apollo-type re-entry after surviving a mission lasting up to several years. Atmospheric entry from lunar missions occurs at nearly escape velocity, and exceeds escape velocity for missions to the asteroids or Mars, resulting in significantly higher peak temperature, heat flux and heat load imparted to the spacecraft dian entry from LEO. Missions beyond LEO are of long duration, with up to six months planned for lunar missions and up to three years projected for Mars missions (not including time for vehicle assembly in LEO).
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