Phoenix and Elusive Success

Potential Problems

You recall that JPL and U. of Arizona were delayed a couple of days in their attemts to analyze the first soil sample with the Phoenix TEGA (Thermal and Evolved Gas Analyzer). The soil would not dump into the ovens without being given a good shake. The project team thinks that the shaking may cause another, more severe problem, severe enough to threaten the success of the mission – a short circuit.

The short circuit was believed to have been caused when TEGA’s oven number four was vibrated repeatedly over the course of several days to break up clumpy soil so that it could get inside the oven. Delivery to any TEGA oven involves a vibration action, and turning on the vibrator in any oven will cause oven number 4 to vibrate as well, which could cause a short.

It hasn’t happened yet, but mission specialists have chosen to take the most conservative course. Every sample that they take for the rest of the mission will be treated like it’s the last.

A team of engineers and scientists assembled to assess TEGA after a short circuit was discovered in the instrument, and came to a fairly disheartening conclusion. “Since there is no way to assess the probability of another short circuit occurring, we are taking the most conservative approach and treating the next sample to TEGA as possibly our last,” said Peter Smith, Phoenix’s principal investigator. Therefore, the Phoenix team is doing everything they can to assure the next sample delivered to TEGA will be ice-rich.

Ice rich, indeed. The project statement (linked above) puts that in “positive, definite”) terms.

Emily Lakdawalla at The Planetary Society notes that the mission has not met the stated mission success criteria “until it gets that second, ice-rich sample in to TEGA”.

There’s a write-up at MSNBC too.

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