Mars's poles are some of the most variable terrain on the planet, what with the growth and contraction of the poles. Pheonix represents a chance to establish a fixed point reference on just how those changes affect the local environment.

Something it doesn't have to move to document over the course of a Martian yearlong mission (or more, to start establishing some projective capability).

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I'm not completely heartless, the doctor who removed it told me he'd never be able to get it all.

Less? I thought Phoenix quickly, on the order of months quick, gets buried in dry ice.

Edit: Maybe 6 months

Planetary Society: Space Topics: Phoenix

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I guess that's why they didn't want to spend more $$$ on a rover. Mission only lasts 6+/- months due to expiring solar energy.

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