Distribution of Hydrogen in the near Surface of Mars: Evidence for Subsurface Ice Deposits

• Published in: Science (American Association for the Advancement of Science) Vol. 297; no. 5578; pp. 81 - 85
• Main Authors: Boynton, W. V., Feldman, W. C., Squyres, S. W., Prettyman, T. H., Brückner, J., Evans, L. G., Reedy, R. C., Starr, R., Arnold, J. R., Drake, D. M., Englert, P. A. J., Metzger, A. E., Mitrofanov, Igor, Trombka, J. I., d'Uston, C., Wänke, H., Gasnault, O., Hamara, D. K., Janes, D. M., Marcialis, R. L., Maurice, S., Mikheeva, I., Taylor, G. J., Tokar, R., Shinohara, C.
• Format: Journal Article
• Language: English
• Published: United States American Society for the Advancement of Science 05.07.2002; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Atmosphere; Discovery and exploration; Dry Ice; Extraterrestrial Environment; Gamma Rays; Groundwater; Hydrogen; Ice; Italian ices; Mars; Mars (Planet); Mars surface; Models, Theoretical; Neutrons; Planets; Porosity; Regolith; Scientific Concepts; Scientific imaging; Space exploration; Spacecraft; Spectrometry, Gamma; Spectrum Analysis; Thermal neutrons; Topography; Water; Water, Underground
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1073722

Using the Gamma-Ray Spectrometer on the Mars Odyssey, we have identified two regions near the poles that are enriched in hydrogen. The data indicate the presence of a subsurface layer enriched in hydrogen overlain by a hydrogen-poor layer. The thickness of the upper layer decreases with decreasing distance to the pole, ranging from a column density of about 150 grams per square centimeter at -42° latitude to about 40 grams per square centimeter at -77°. The hydrogen-rich regions correlate with regions of predicted ice stability. We suggest that the host of the hydrogen in the subsurface layer is ice, which constitutes 35 ± 15% of the layer by weight.