User:Racineswick/Swiss cheese features

Swiss Cheese Halo Features

Bright transient halo features around the carbon dioxide pits were found during the southern hemisphere's summer, during Mars year 28 (Earth year 2007). However, this was the only time these features have ever been seen. The data to understand these halos were taken from the MRO (Mars Reconnaissance Orbiter) Context Camera, the HiRISE (High Resolution Imaging Science Experiment) camera, and the MOC (Mars Orbiter Camera). The halo features were only visible during the solar longitudes (position of Mars around the Sun) of 279 degrees and 331 degrees. The halo's appearance correlates to the global dust storm that began earlier in the same Martian year. The lifetime of the halos were broken into trimesters; the first being 285-295 degrees Ls (Solar Longitude, time in the Martian Year), the second being 295-305 degrees Ls, and the final was counted at 305 - 340 degrees Ls. The average width of the high albedo area around the swiss cheese features changes through out it's lifetime. In the first trimester the width was calculated to be 12.14 +/- 1.44 meters wide, the second trimester was 32.96 +/- 4.02 meters wide, and the final trimester the average width was 55.48 +/- 6.98 meters. The Hapke's reflectance theory was used to calculate the brightness of the features. During the first trimester, the halos were 4 +/- .3% brighter than the non-halo areas. Then in the second trimester the halos became more prominent at 7 +/- .7% brighter. Toward the end of their life they were the brightest recorded at 8 +/- .6% brighter than the surrounding topography. The halos are brighter than the surrounding region due to the impurities in the ice. The global dust storm filled the CO2 ice with sand and increased the grain size of the ice crystals.