Coverage, Responsiveness and Accessibility for Various “Responsive Orbits”

Abstract:

We have evaluated 5 potential Responsive Orbits with the following conclusions with respect to coverage, responsiveness, payload to orbit for a small launch vehicle, and missions that they would be best suited for:

  • Cobra Orbits provide up to 4 hours of continuous access per day, 10 hours mean response time, low payload mass to orbit, very poor optical resolution, and are best used for communications.
  • Magic Orbits provide up to 1 hour of continuous access per day, 12 hours mean response time, low to moderate payload mass to orbit, poor optical resolution, and are also best for communications.
  • LEO Sun Synchronous Orbits provide 5 minutes of coverage once or twice per day, 6 hour mean response time, moderate payload mass to orbit, excellent optical resolution, and are best suited for visual or radar observations.
  • LEO Fast Access Orbits provide 5 minutes of coverage once or twice per day, 45 minute mean response time, moderate to high payload mass to orbit, excellent optical resolution, and are best suited for highly responsive visual or radar observations.
  • LEO Repeat Coverage Orbits provide 5 minutes of coverage every 90 minutes for 4 or 5 times in a row, 9 hour mean response time, high payload mass to orbit, excellent optical resolution, and are best suited for repeated visual or radar observations.

Responsive orbits have the potential to provide means for communications and high-resolution surveillance anywhere in the world within hours of an identified demand. Collectively, these orbits provide excellent opportunities for transforming space from a strategic to a tactical asset and for doing missions that cannot now be done. Coupled with the launch vehicles being developed under the AF/DARPA/NASA FALCON program and emerging smallsat technology, there is excellent potential for new, low-cost missions that can transform the way space is used.

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Wertz, J.R. 3rd AIAA Responsive Space Conference, Los Angeles, CA. April 25–28, 2005.