Probing upper thermospheric neutral densities at Mars using electron reflectometry

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95666/1/grl20594.pd

Four Martian years of nightside upper thermospheric mass densities derived from electron reflectometry: Method extension and comparison with GCM simulations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95498/1/jgre2766.pd

Mapping Surface Materials on Mars From Mars Pathfinder Spectral Images With HYPEREYE

A comprehensive mapping of spectral variations is presented for one octant of the Imager for Mars Pathfinder SuperPan data set. Both left eye and right eye images are analyzed, and for each, all respective spectral bands are utilized simultaneously. We use a Self-Organizing Map to achieve fine discrimination of over 20 surface units including previously published classes. Agreement with earlier analyses are very good where data are available for comparison. In spite of the separate analysis of the left and right eye data, which cover different spectral windows with little overlap, many classes show very similar spatial distribution in the left and right eye images. The SOM clustering produced refinements within the unit formerly labeled as “black rock”, discovered previously undiscussed units that may be various coatings on rocks, and presented some disagreements with existing units. The clustering tools are part of HYPEREYE, a dedicated research software developed with NASA/OSSA AISRP support

Time‐history influence of global dust storms on the upper atmosphere at Mars

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95570/1/grl29277.pd

The 2003 November 14 occultation by Titan of TYC 1343-1865-1. II. Analysis of light curves

We observed a stellar occultation by Titan on 2003 November 14 from La Palma Observatory using ULTRACAM with three Sloan filters: u', g', and i' (358, 487, and 758 nm, respectively). The occultation probed latitudes 2 degrees S and 1 degrees N during immersion and emersion, respectively. A prominent central flash was present in only the i' filter, indicating wavelength-dependent atmospheric extinction. We inverted the light curves to obtain six lower-limit temperature profiles between 335 and 485 km (0.04 and 0.003 mb) altitude. The i' profiles agreed with the temperature measured by the Huygens Atmospheric Structure Instrument [Fulchignoni, M., and 43 colleagues, 2005. Nature 438, 785-791] above 415 km (0.01 mb). The profiles obtained from different wavelength filters systematically diverge as altitude decreases, which implies significant extinction in the light curves. Applying an extinction model [Elliot, J.L., Young, L.A., 1992. Astron. J. 103, 991-1015] gave the attitudes of line of sight optical depth equal to unity: 396 +/- 7 and 401 +/- 20 km (u' immersion and emersion); 354 7 and 387 +/- 7 km (g' immersion and emersion); and 336 +/- 5 and 318 +/- 4 km (i' immersion and emersion). Further analysis showed that the optical depth follows a power law in wavelength with index 1.3 +/- 0.2. We present a new method for determining temperature from scintillation spikes in the occulting body's atmosphere. Temperatures derived with this method are equal to or warmer than those measured by the Huygens Atmospheric Structure Instrument. Using the highly structured, three-peaked central flash, we confirmed the shape of Titan's middle atmosphere using a model originally derived for a previous Titan occultation

In situ measurements of the physical characteristics of Titan's environment

On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained because of uncertainties in the detailed composition. The extent of atmospheric electricity ('lightning') was also hitherto unknown. Here we report the temperature and density profiles, as determined by the Huygens Atmospheric Structure Instrument (HASI), from an altitude of 1,400 km down to the surface. In the upper part of the atmosphere, the temperature and density were both higher than expected. There is a lower ionospheric layer between 140 km and 40 km, with electrical conductivity peaking near 60 km. We may also have seen the signature of lightning. At the surface, the temperature was 93.65 0.25 K, and the pressure was 1,467 1 hPa