Daniel M. Janes

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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(More)
Introduction: We report preliminary data on the concentrations of Si, Fe, H, K, and Th on the Martian surface. K and Th are also discussed in the context of crustal evolution and the bulk composition of Mars in a companion abstract [1]. The data reveal that the varies considerably in composition. We present these variations and use the data to assess the(More)
The gamma ray spectrometer on the Mars Odyssey spacecraft measured an enhancement of atmospheric argon over southern high latitudes during autumn followed by dissipation during winter and spring. Argon does not freeze at temperatures normal for southern winter (approximately 145 kelvin) and is left in the atmosphere, enriched relative to carbon dioxide(More)
Introduction: The 2001 Mars Odyssey Gamma-Ray Spectrometer (GRS) [1] has been a very useful instrument for estimating the amount of sub-surface ice in the polar regions. In our first preliminary look at ice content in these regions [2], we modeled the surface with two layers: a dry layer containing no ice over an ice-rich layer with a variable ice content.(More)
Introduction: Mid-infrared spectra from the Mars Global Surveyor Thermal Emission Spectrometer (TES) instrument indicated two distinct mineralogical units concentrated respectively in northern and southern low albedo regions of Mars [1]. Material comprising " surface type 1 " (ST1), found primarily in the southern hemisphere, has been interpreted to be(More)
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