Exploration Under the Space Exploration Initiative

The Space Exploration Initiative (SEI) of NASA has three phases related to the Moon: (1) the Lunar Orbiter Missions; (2) the Common Lunar Lander program (CCL), and the First Lunar Outpost program (FLO). The program of the SEI is outlined in the NASA publication entitled ``3rd Technical Interchange Proceedings'' (610 pp.), which covers the meeting of May 5 and 6, 1992. Except as noted below, all references below are to that volume. The ``Proceedings'' are actually the sets of viewgraphs presented by the various speakers on the program. As such they give illustrated outlines of the talks, not the full texts. Nor do they give any modifications of the program that may have resulted from discussions at or subsequent to the meeting.

The Lunar Orbiter Missions should yield further information on the distribution of high-TiO regolith on the whole Moon, through gamma-ray spectroscopy. The value of the gamma-ray spectroscopy will depend on how much this technique has been improved in both resolution and accuracy over the original partial survey of the Moon [see Metzger and Parker (1980)]. Orbiter equipment will include soft x-ray, neutron, and imaging spectrometers. The purpose is stated to be to provide a detailed geochemical and mineralogical map of the Moon. Global stereoimaging to aid in site selection is also given as a function of the mission.

The CCL program will consist of a series of Apollo-type missions, mostly robotic. The mission of particular interest here is entitled ``Outpost Site Survey and Resource Assessment'' (pp. 53-58). This will involve the use of rovers. It will include preparation of large-scale topographic maps (high-resolution stereoimaging), rover traverses to map surface soil properties, block distribution and lateral variability, and study of hydrogen abundance.

The site selected is in Mare Tranquillitatis ``near 15^o N. 22^o E.'' This point is on the boundary between mare material and the ejecta blanket of the huge (45 km diameter) crater Plinius, on the east margin of a 25-40 km-wide band of material separating the ejecta blanket from highlands to the west. This is not a good site for study of volatile elements in the mare. Reflectance ratio mapping by Johnson and others (1991) shows regolith of only 3-5% TiO, hence helium content should be low. As suggested above, a much better site would be an area at 9^o N. 20^o E. This area is indicated by Johnson and others (1991) to have regolith with 7-10+% TiO.

Vertical distribution of hydrogen is to be inferred by measuring its concentration in the ejecta of fresh, small craters (20-50 m in diameter). I do not understand this. It would seem to rest on the dubious assumption that H content of regolith is not affected by impacts. The full capabilities of the mission for sample recovery and analysis are not indicated in the publication. No mention is made of volatiles other than hydrogen, but it should be possible to include analyses for the other gases within the scope of the program.

The chief opportunities for systematic exploration of regolith as a source of volatiles would appear to be in the FLO missions, scheduled to begin in 1999. These missions would be fully equipped for photography and for soil sampling and analysis. The DEMO package (pp. 100,101) includes experimental units for oxygen extraction, for testing gas-solid transport, and for testing pneumatic size-sorting methods. Activities include regolith sampling and analysis. Radar scanning equipment is not mentioned, but presumably it could be added.

For establishment of the First Lunar Outpost (FLO) two possible sites are mentioned: (1) Mare Smythii, which has an equatorial position straddling the eastern terminator of the nearside of the Moon, and (2) the Aristarchus Plateau at 23^o N. 48^o W. The rationale for a FLO on Mare Smythii is given by Spudis and Hood (1992). Based on remote sensing by the Apollo 15 and 16 spacecraft, the mare regolith is taken to have 4 to 6% TiO. If this is correct, the He content could be in the 20-30 wppm He. This would not be as desirable a source of He as the regolith of Mare Tranquillitatis, but it could serve for purposes of testing methods of beneficiating and processing regolith for He and other gases. The regolith of the site on the Aristarchus Plateau is shown on the map by Johnson and others (1991) as having only 3-4% TiO, hence this site is ostensibly less desirable than the Mare Smythii site.

To sum up, the CCL and FLO programs do not have exploration of regoliths for volatile elements as a primary concern. However, the development of a systematic exploration program for volatiles appears well within the capabilities of the missions.

Next: Acknowledgment Up: Table of Contents Previous: Exploration Beyond Tranquillitatis

WCSAR-TR-AR3-9301-1
Eugene N. Cameron

Back to Lecture 19 (fall'96)
Back to Lecture 13 (fall'96)
Back to Lecture 13 (fall'97)

University of Wisconsin Fusion Technology Institute · 439 Engineering Research Building · 1500 Engineering Drive · Madison WI 53706-1609 · Telephone: (608) 263-2352 · Fax: (608) 263-4499 · Email: fti@engr.wisc.edu

University of Wisconsin-Madison

Fusion Technology Institute

Exploration Under the Space Exploration Initiative