This morning's priority was to set up dust traps for the USGS (US Geological Survey). We set up Petra's UV radiation dosimeter, then Mark, Joan and I found a suitable location for the dust traps. After doing a quick soil profile to see what dust the local soil might produce, we took a couple samples from different horizons and then set up the traps.

The local soil/weathered rock (part of the Morrison Formation) was covered with a thin (2cm) pavement layer made up of wind-polished pebbles and soft clay. Under this was a 20cm horizon of weathered, red, oxidized clay and silt. Below the red layer was a white/beige layer of silt stone that was less weathered. We could only dig about 15cm into this horizon until it became too hard. It appeared that there were desiccation cracks in the white rock that were filled by the later oxidized silt, suggesting that these sediments were deposited in a shallow marine or deltaic environment. Samples were taken from all three horizons and have yet to be analyzed.

We put up 3 dust traps - cake pans perched on rebar five and a half feet above ground, with a marble-covered screen over the top of the pan. The marbles are supposed to stop the wind from blowing out dust that has already settled in the pans. The pans have a non-stick coating on the inside to inhibit contamination from the pan and allow the pan to be cleaned out easily when needed. The dust traps should be checked every six months to a year, depending on the rate of dust deposition. Average dust deposition rates in California are generally between one to ten grams per year per square meter, so we have to wait until there is a measurable amount in the traps. Information will be available for next season's crews when they need to collect the dust. Currently, the USGS has about 40 sites in California and Nevada, and this would be their first permanent (hopefully) site in Utah.

There was no soil development in the area and almost no plant life nearby, which was expected, considering the high erosion and low precipitation in the area. On our way back to the Hab, we also sampled some recent dust deposits. These were mostly sand and silt sized particles, due to the 30-40 mph winds during the day. A cursory look at these particles revealed that they were composed mostly of quartz and some clay minerals. More work will be done on these between EVA's later in the mission.