The alteration of icy samples during sample acquisition

Details The alteration of icy samples during sample acquisition The alteration of icy samples during sample acquisition

Dec 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006agufm.p51d1230m&link_type=abstract

American Geophysical Union, Fall Meeting 2006, abstract #P51D-1230

Biology

5200 Planetary Sciences: Astrobiology, 6225 Mars

Scientific paper

Valid in situ scientific studies require both that samples be analyzed in as pristine condition as possible and that any modification from the pristine to the sampled state be well understood. While samples with low to high ice concentration are critical for the study of astrobiology and geology, they pose problems with respect to the sample acquisition, preparation and distribution systems (SPAD) upon which the analytical instruments depend. Most significant of the processes that occur during SPAD is sublimation or melting caused by thermal loading from drilling, coring, etc. as well as exposure to a dry low pressure ambient environment. These processes can alter the sample, as well as generating, meta-stable liquid water that can refreeze in the sample transfer mechanisms, interfering with proper operation and creating cross-contamination. We have investigated and quantified loss of volatiles such as H2O, CO, CO2, and organics contained within icy and powdered samples when acquired, processed and transferred. During development of the MSL rock crusher, for example, ice was observed to pressure-fuse and stick to the side even at -70C. We have investigated sublimation from sample acquisition at Martian temperature and pressure for a samples ranging from 10 to 100 water/dirt ratios. Using the RASP that will be on Phoenix, we have measured sublimation of ice during excavation at Martian pressure and find that the sublimation losses can range from 10 to 50 percent water. It is the thermal conductivity of the soil that determines local heat transport, and how much of the sample acquisition energy is wicked away into the soil and how much goes into the sample. Modeling of sample acquisition methods requires measurement of these parameters. There is a two phase model for thermal conductivity as a function of dirt/ice ratio but it needed to be validated. We used an ASTM method for measuring thermal conductivity and implemented it in the laboratory. The major conclusion is that for icy dirt samples that are appreciably hard, the thermal conductivity is basically that of pure ice. While the dry soil has a lower thermal conductivity due to fragmented thermal conduction paths, there are sufficient water ice paths for thermal transport that it does not affect thermal conductivity. Acknowledgement: This research was carried out at the California Institute of Technology and the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

Affiliated with

Also associated with

No associations

Rating

The alteration of icy samples during sample acquisition does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The alteration of icy samples during sample acquisition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The alteration of icy samples during sample acquisition will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-962621