Mars: Soil Analysis

Gary, an author of this website, performed his own independent research--an intensive study of the Martian soil with an eye to exploring the uses of cyclic voltametry for future Martian soil experimentation. Given access to a Martian soil analog, palagonite, and special equipment by NASA, he presented his results in the 2000 Intel International Science & Engineering Fair. This is the only webpage that displays his cutting-edge research.

Summary

The purpose of this study is to determine whether cyclic voltammetry could be used for future Martian experimentation. Such techniques have never been utilized in interplanetary missions, but the results of this project indicate that voltammetry would be ideal for Martian soil experimentation. It speciates, requires little equipment, and uses less energy than more sophisticated devices while still providing viable data. Furthermore, it takes a very short time to perform such tests.

Introduction

Since the dawn of time, humankind has had a certain fascination with the stars, planets, and other wondrous phenomena that exist outside of the Earth’s atmosphere, but perhaps one of the most intriguing is Mars. Only one planetary jump away, this reddish planet raises more questions than answers. Both the United States and Russia have launched a series of missions to the planet, hoping to survey the landscape as well as search for life. As of today, the most successful program is still the Viking program, launched by the United States in 1975. Vikings 1 and 2 did not find extraterrestrials but did map almost the entire planetary surface. The results of the Viking experiments performed on the Martian soil, however, perplex scientists even today.

The Gas Chromatograph Mass Spectrometer (GCMS) onboard the Vikings concludes that down to 10 centimeters deep the soil does not contain organic molecules. This is inconsistent with conventional wisdom because organics are inevitably produced by meteorite fall. This leads researchers to believe that the soil contains a mechanism that destroys organics. The soil itself is also known to produce oxygen in large quantities when hydrated. The rapid production of oxygen followed by a decrease in production near equilibrium levels indicates chemical as opposed to biological activity.
There are two major problems with testing the Martian soil. Firstly, samples cannot be transported back for testing because the reactions could be dependent on the Martian environment, so the landers must carry out the experiments in situ. Secondly, many techniques perfected on Earth require the use of water, but Mars is relatively dry, so the mixing of water with the soil for experimental purposes may affect the results to a large degree. The exact chemical species present in the Martian soil is unknown, but a well-supported theory suggests that a peroxide exists in the soil or atmosphere, which would explain the lack of organics and the evolution of oxygen when hydrated. This is a concern for future missions because peroxides could lead to the damage of biological and mechanical materials.

NASA researchers believe that palagonite, volcanic soil found in Hawaii, to be very similar to the Martian soil based on its spectra. As a result, palagonite has been selected as the soil of choice for a Martian analog. In this paper, cyclic voltammetry is discussed. Such techniques have never been used in interplanetary missions. Instead methods such as optics, which take up considerable amounts of energy, were used. Voltammetry should be a strong candidate for future missions because it has the ability to speciate, requires relatively little equipment, and uses less energy than more sophisticated devices. The question that arises, however, is whether such techniques would yield viable data. This paper is a pioneer work, attempting to answer that question.

Hypotheses

Peroxide can be detected in the ppm level with and without soil present.
As more peroxide is added to an electrolyte solution with or without palagonite, the anodic peak current should become more pronounced because there would be a higher concentration of redox species.
The anodic current should become less pronounced over time because peroxide decomposes over time.
The pH of the electrolyte should affect the rate of peroxide decomposition. The anodic peak should decrease as the peroxide decomposes.

Methods/Materials & Results

This material has been withheld, because his findings have not been published yet.

Conclusions

These studies indicate that cyclic voltammetry could be used to study Martian soil, but an electrolyte must be carefully chosen with regard to both (1) the chemical thought to be present in the Martian soil and (2) the pH of the Martian environment. Hypothesis 1 is correct because voltammetry can detect peroxide at the ppm level with or without soil present. Hypothesis 2 correctly states that the anodic peak current becomes more pronounced with a higher concentration of peroxide. Hypothesis 3 is validated because the anodic current becomes less pronounced as time passes. Hypothesis 4, however, is incorrect: When an electrolyte’s pH is changed with an acid or base, the resulting data does not yield useful information, but an electrolyte at its natural pH does yield useful information. This project concludes that cyclic voltammetry would be ideal for Martian soil experimentation. It has the ability to speciate, requires little equipment, and uses less energy than more sophisticated devices, including optical (e.g. Mars Oxidant Experiments) or gaseous-based machines (e.g. Viking Experiments), while still providing important data. Furthermore, the amount of time it takes to perform voltammetric tests is very short, making it very efficient.

Limitations

No one knows what exactly the Martian soil is composed of. The information we have collected come primarily from the Viking experiments done in the 1970's. This project is based upon the prominent theory that a peroxide is present in the Martian soil. The most accurate data must be procured in situ, and the palagonite tested can only be assumed to react very similarly to actual Martian soil.

Acknowledgments

This section will be updated to include the names of those who have helped in the research after obtaining their approvals to place their names on the Web.

Additional References

Grunthaner, Frank J. “Investigating the Surface Chemistry of Mars” American Chemical Society. United States: American Chemical Society, 1995.
McKaym, Christopher P. “The Mars Oxidant Experiment (MOx) for Mars '96” Planet. Space Sci. (Vol. 45, No. 00). Great Britain: Elsevier Science Ltd., 1997.
Microsoft Encarta Encyclopedia 2000 CD-ROM: (1) Anonymous. “Mars: Global Surveyor Generates Detailed Map of Planet’s Surface” (2) Anonymous. “Mars: Spacecraft Sent to Study Climate Presumed Destroyed” (3) Schaefer, Martha Williams. “Mars (planet)” (4) Tatarewicz, Joseph N. “Viking (spacecraft)”
Zent, Aaron P. “The Chemical Reactivity of the Martian Soil and Implications for Future Missions” Icarus (Vol. 108). Academic Press, Inc., 1994.