Now that the glitches caused by the Martian soil's clumpy consistency have been shaken out, the Phoenix Lander has been able to cook up a few samples to test the soil composition. The preliminary results are surprising even to the chemists at work on the project: the soil is alkaline, and much more so than anyone expected. The analysis has found trace amounts of magnesium, sodium, potassium, and other elements similar to those in the soil on Earth. On first pass, Martian dirt appears to be non-toxic and laden with the basic nutrients necessary to support life. One compound that has not been found, however, is organic carbon, which is a critical component in the formation of life.
The tests were conducted using the lander's wet chemistry technique, in which the collected soil is mixed with Earth water, then slowly heated in one of the lander's ovens. The resulting gas is fed into a mass spectrometer, which measures the mass and concentration of all the molecules in the sample and is sensitive down to the most minute quantities. Each of the lander's eight ovens is designed for one-time use.
what makes these ovens one time use?
contamination. How would the ovens be cleaned out?
Use a steam cleaner.
hahaa, would that ensure every last molecule of the previous bake was removed? No.
Even a single molecule of previous material could mess up the results from a new test. Especially if that molecule was unique. Better to have clean ovens for unambiguous results.
How do they reuse them on Earth?
Someone manually cleans the oven out it isn't that hard, just a bit tedious. I'm sure they could have built a robotic device to do this. However the weight and power requirements would be more than the lander could support. Besides the more complexity they put in the more likely something will break.
KISS -Keep It Simple Stupid (words I live by)
Keep It Simple Stupid.
I find it a bit interesting that they mix the soil with "water from Earth". Was it sterile water, I would assume so, but the devil is in the details. Not that I'm a big conspiracy guy, but what else was on board and could anything else "... from Earth" survive up there? It is yet to be seen I guess.