Context: Biology lab work from EVA #10 (Biology EVA #4) to Phobos Peak on March 6, 2004.

Summary of Lab Work: On March 6, 15 samples from Phobos Peak were prepared to test for microbial richness. Open vials of approximately 4 g of soda lime were placed in the sampling containers, which were then sealed for approximately 6 days. Instead of being placed in an incubator, the samples were set on the lab counter in the Hab. Today, the samples were opened, and the masses of the sample and soda lime were re-measured. The used soda lime was placed in an empty soda lime container, which was re-labeled "Used Soda Lime" and the samples were thrown outside. The soda lime vials were left out to dry and may be cleaned later, while the sampling containers were discarded.

CO₂ Experimentation Status: These samples were the last of four sets. The mass data were added to the Excel spreadsheet from previous lab work, which was submitted to RST.

Summary of Data and Observations: For all the samples in this set, the re-measured soil sample masses are greater than the original masses. This change was expected because after the initial mass measurement 2 mL of water was added. This water could not evaporate through the sealed lid, so it remained in the system. Some was absorbed by the soda lime, but some would have remained in the sample. The mass changes range from 1.62 to 2.15 g. They are not the same because the amount of water absorbed by the soda lime depends on the amount of CO2 produced by microbes, which depends on the sample. In this data set, most of the final masses of soda lime for this sample set are greater than the initial masses. This trend was expected because the soda lime should absorb water and CO2, thus increasing in mass. The positive changes range from 0.04 to 0.24 g. For two samples (9 and 12), the change in soda lime mass was negative. These values do not seem to make sense, and they are probably due to measurement errors, since the zero value of the balance tended to creep. Other possible explanations for the deviations are not forthcoming. The time at which the samples were first processed should be noted. Memory cannot be relied on to remember times for many sample sets, unless they are prepared at the same time each day. For the previous three sets, memory served well enough, but the time this set was prepared is uncertain. Therefore, the six day period may have accidentally been lengthened or shortened by up to two hours.

Conclusions: This data set is not completely consistent, but it seems to provide some good data. With the exception of samples 9 and 12, all of the changes in soda lime mass fit expectations. All of the samples exceeded the minimum recommended size, so the results of the experiment should be noticeable and valid, except where measurement errors were made. Like the previous set, a few of the samples had noticeable pieces of plant roots in them, which may or may not affect the results. These data will be compared with previous data, with physical sampling site factors taken into account. This analysis should determine which factors affect the microbial richness of the soil and to what extent they do so.