Low-Frequency Electrical Properties for Subsurface Exploration of the Earth and Planets, 15-R9709Printer Friendly Version
Inclusive Dates: 03/01/07 07/01/08
Background - The focus of this project was to make low-frequency electrical-properties measurements of saline ice, salt hydrates, and ice/hydrate/soil mixtures to determine the geophysical detection limits and properties of ices on the Moon, Mars and outer-planet satellites. The project further sought to assess bioelectrical signatures from soil-microbe mixtures for both terrestrial and extraterrestrial assays.
Approach - SwRI's Planetary Electrical Properties and Geochemistry Laboratory is equipped to measure complex dielectric constant over a wide range of frequency and temperature. From these broadband dielectric spectra, individual mechanisms of storage and dissipation of electrical energy can be modeled and identified. The project team performed dozens of individual experiments, varying ice-impurity composition and content, ice content, and soil type.
Accomplishments - During the course of the investigation, the team discovered that much more detailed study of saline ice and salt hydrates was necessary to provide the proper foundation for later analysis of mixtures. This work resulted in new fundamental contributions in structural chemistry that were not originally anticipated, namely:
For ice-soil mixtures:
The team did not complete the microbe study. Initial tests were not successful and were not followed up because of additional effort spent early in the project on saline ice and salt hydrates. The team did conclude, however, that unfrozen water at subfreezing temperatures cannot support microbial life in contrast to speculation in the astrobiology literature because the electrical conductivity is not high enough to indicate useful transport of nutrients and wastes.
This project resulted in six conference presentations (one invited), and two journal articles. SwRI won three NASA grants based on work in progress. The work has led to several additional pending and planned proposals, including flight instruments. The work performed for this project is the foundation for many years of electrical-properties studies relevant to ices throughout the Solar System.