• more optimization necessary
• exploration needed
  
  Several parameters need to be optimized in order to pursue the best approach to near Earth object (NEO)
  resource utilization. These parameters include:
• Which NEO's to exploit?
• Which materials to utilize?
• What scale should the transportation "bus" be sized to?
• What is the optimal speed (energy) of the round trips between low Earth orbit (LEO) and the NEOs
  
  Currently planned analysis will help answer the above questions. A "trade space" approach will be taken that will
  effectively and systematically quantify pertinent decision criteria corresponding to the variables in these questions.
• very large payback ratios
  
  The analysis shows that even simple systems would return much more mass than is launched to get it. A 23 Mg
  launch of a 10 Mgextractor using an NEP Ion engine would return 500 Mg every 4 years. If a gravity assist were
  used it could deliver in excess of 2000 Mg.
  
  Once in space the system might never need to be fueled from Earth. A cryo fueled vehicle returning 500 Mg would
  use 20 Mg of that payload to return for the next load. Nothing further would be launched from Earth.
  
  Other potential benefits of utilizing near-Earth object resources include the incentive to commercialize space
  operations with the potential profit motive of marketing a variety of commodities from space. The availability of
  these commodities in Earth orbit at affordable prices, compared to Earth launch costs, may finally open the space
  frontier to humans as never before imagined.

Acknowledgments

This work was performed at the Idaho National Engineering Laboratory (INEL), Idaho Falls, Idaho, under the
sponsorship of the U.S. Department of Energy,Assistant Secretary for Nuclear Energy,Office of Space and
Defense Power Systems under DOE contract No. DE-AC07-76ID01570. Dr. Dave Buden, INEL, caused us to
compose this paper and provided key Mars mission data. Dr. Ted Fay and Stan Schneider, at McDonnell Douglas
Space Systems Company, Huntington Beach, California, and Dr. Ben Clark, Martin Marietta, Denver, provided key
architecture information. Dr. Mark Sykes and Dr. John Lewis, both at University of Arizona, provided key space
resource data.

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