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shadowed region of the Moon's southern polar region,11 such an interpretation requires confirmation with independent data obtained using a less ambiguous approach.

Even if one is optimistic about how much information on lunar composition might be gleaned from Clementine, a systematic global mineralogical and geochemical mapping of the lunar surface will still be necessary. Geochemical mapping is needed to identify concentrations of major elements to the degree that would indicate Mg/Fe ratios and abundance's of radioactive elements (U, Th, and K). Another high priority is confirmation of the existence of possible polar ice deposits. Unambiguous mineral identification will require an optimized high-spectral-resolution spectrometer.

Clementine's Contribution to Lunar Science Objectives

Clementine measurements made significant contributions to recognized lunar science goals in geophysics and geodesy, demonstrated the potential for limited lithological mapping, and provided a valuable supplement to earlier imaging of the lunar surface. The spacecraft did not furnish information on surface geochemistry, the magnetic field, global heat flow, or deep internal structure.

In summary, most of the work in data reduction and analysis for Clementine is still in progress, but there is reason to hope for a yield of important new understanding of the Moon. If this proves true, this constrained mission will have accomplished significant lunar science. The fact that the majority of the fundamental scientific questions posed by COMPLEX and other groups such as NASA's Lunar Exploration Science Working Group12 may not be answered with data provided by the Clementine instrument complement is not relevant to an overall assessment of the Clementine mission. It was not designed to achieve these or any other scientific objectives, and so cannot be judged by these standards. To critically assess questions that deal with the origin and evolution of the Moon, further orbiters and landers seem necessary. COMPLEX notes, but does not discuss within the context of this report on Clementine, that NASA has selected Lunar Prospector as the third (but first competitively chosen) Discovery mission.

References

1. S. Nozette et al., ''The Clementine Mission to the Moon: Scientific Overview," Science 266:1835-1839, 1994.

2. Space Studies Board, National Research Council, 1990 Update to Strategy for Exploration of the Inner Planets, National Academy Press, Washington, D.C., 1990, page 18.

3. S. Nozette et al., "The Clementine Mission to the Moon: Scientific Overview," Science 266:1835-1839, 1994.

4. P.G. Lucey, G.J. Taylor, and E. Malaret, "Abundance and Distribution of Iron on the Moon," Science 268:1150, 1995.

5. B.J. Buratti, J.K. Hillier, and M. Wang, "The Lunar Opposition Surge: Observations by Clementine," Icarus 124:490-499, 1996.

6. A.S. McEwen and M.S. Robinson, "Mapping of the Moon by Clementine," Advances in Space Research, 1997, in press.

7. A.C. Cook et al., "Clementine Imagery: Selenographic Coverage for Cartographic and Scientific Use," Planetary and Space Science 44:1135-1148, 1996.

8. T.L. Becker et al., Bulletin of the American Astronomical Society 28:17.01, 1996.

9. Space Studies Board, National Research Council, 1990 Update to Strategy for Exploration of the Inner Planets, National Academy Press, Washington, D.C., 1990, page 18.

10. P.G. Lucey, G.J. Taylor, and E. Malaret, "Abundance and Distribution of Iron on the Moon," Science 268:1150, 1995.

11. S. Nozette et al., "The Clementine Bistatic Radar Experiment," Science 274:1495, 1996.

12. Lunar Exploration Science Working Group, A Planetary Science Strategy for the Moon, JSC-25920, NASA Solar System Exploration Division, Houston, Texas, 1992.



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