VikingScienceMars Sample Return Site Selection & Sample Acquisition Study (1980)By David S F PortreeScienceRobot Rendezvous in Mars Orbit (1999)By David S F PortreeScienceBeyond Apollo Posts on Robotic Exploration PlanningBy David S F PortreeScienceMars Polar Ice Sample Return (1976-1978)By David S F PortreeScienceViking on the Moons of Mars (1972)By David S F PortreeScienceSagan & Swan's Voyager Mars Landing Sites (1965)By David S F PortreeScienceThe Earliest Candidate Viking Landing Sites (1970)By David S F PortreeScienceMaking Rocket Fuel on Mars (1978)By David S F PortreeScienceThe Moon and Beyond: A 1963 Plan to Expand NASA's Robotic Exploration ProgramsBy David S F PortreeScienceA Flying Rover: JPL's Mars Airplane (1978)By David S F PortreeScienceMars 1984 Rover-Orbiter-Penetrator Mission (1977)By David S F PortreeScienceMars Multi-Rover Mission (1977)By David S F PortreeScienceAntaeus Orbiting Quarantine Facility (1978)By David S F PortreeScienceBlueprint for 1970s Planetary Exploration (1968)By David S F Portree
