Considerations relating to these technical and programmatic issues include the following:

  • Fraction of launch mass for science—On typical planetary missions flown over the last 30 years, the ratio of science payload mass to total mass has varied between 0.09 and 0.17. The science payload mass ratios for Cassini and JIMO are ≥0.1 and ≤0.06, respectively. The much larger masses necessitated by large NEP systems should offer the opportunity for much larger science payloads.

  • The Deep Space Network and the Planetary Data System—The ability to accommodate the extremely large volume of data returned by NEP missions will require some combination of advanced onboard data processing, high-bandwidth communications, and improvements in the Deep Space Network. The Planetary Data System and other data repositories will have to be expanded, and data-analysis programs will have to be established and/or augmented to meet the needs of future missions and ensure that the data returned are fully analyzed.

  • Radiation-hardened components and radiation-tolerant detectors—The development of new, more capable, radiation-hardened electronic components, together with new detector materials and detection concepts, will enhance measurement capabilities.

  • Contamination mitigation for instruments—To enhance or enable scientific measurements from spacecraft equipped with nuclear reactors, power and propulsion systems must be “clean” and “stable” in terms of transient magnetic and electric fields, chemical contamination, radiation and charged-particle levels, and vibration. In addition, nuclear reactors should not be operated within Earth’s magnetosphere unless it can be demonstrated that interference to other spacecraft caused by primary and secondary gamma rays, electron bremsstrahlung, and positron-annihilation radiation will not occur.

Recommendation: Determination of the cost of NEP-class missions should take into account the cost of necessary associated technologies and programs. Particular emphasis should be placed on studies of the means to maintain or, if possible, increase the fraction of launch mass allotted to science payloads above that typical for current space science missions.

REFERENCES

1. National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, Space Studies Board, The National Academies Press, Washington, D.C., 2003, pp. 202–205.

2. National Research Council, The Sun to the Earth—and Beyond: A Decadal Research Strategy in Solar and Space Physics, Space Studies Board, The National Academies Press, Washington, D.C., 2003.

3. National Research Council, Astronomy and Astrophysics in the New Millennium, Board on Physics and Astronomy–Space Studies Board, National Academy Press, Washington, D.C., 2001.

4. National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, Space Studies Board, The National Academies Press, Washington, D.C., 2003, pp. 202–205.

5. National Research Council, The Sun to the Earth—and Beyond: A Decadal Research Strategy in Solar and Space Physics, Space Studies Board, The National Academies Press, Washington, D.C., 2003, pp. 10–11 and 85.

6. National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, Space Studies Board, The National Academies Press, Washington, D.C., 2003, p. 205.

7. See, for example, National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, Space Studies Board, The National Academies Press, Washington, D.C., 2003, pp. 176–177 and 189.

8. See, for example, National Research Council, Connecting Quarks with the Cosmos—Eleven Science Questions for the New Century, Board on Physics and Astronomy, The National Academies Press, Washington, D.C., 2003.



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