<P> The mission had two goals . One was to study the geologic history of water, the key to unlocking the story of past climate change . The second was to evaluate past or potential planetary habitability in the ice - soil boundary . Phoenix's instruments were suitable for uncovering information on the geological and possibly biological history of the Martian Arctic . Phoenix was the first mission to return data from either of the poles, and contributed to NASA's main strategy for Mars exploration, "Follow the water ." </P> <P> The primary mission was anticipated to last 90 sols (Martian days)--just over 92 Earth days . However, the craft exceeded its expected operational lifetime by a little over two months before succumbing to the increasing cold and dark of an advancing Martian winter . Researchers had hoped that the lander would survive into the Martian winter so that it could witness polar ice developing around it--perhaps up to 1 metre of solid carbon dioxide ice could have appeared . Even had it survived some of the winter, the intense cold would have prevented it from lasting all the way through . The mission was chosen to be a fixed lander rather than a rover because: </P> <Ul> <Li> costs were reduced through reuse of earlier equipment (the total mission cost was estimated to be about US $386 million, which includes the launch); </Li> <Li> the area of Mars where Phoenix landed is thought to be relatively uniform and thus traveling is of less value; and </Li> <Li> the equipment weight that would be required to allow Phoenix to travel can instead be dedicated to more and better scientific instruments . </Li> </Ul> <Li> costs were reduced through reuse of earlier equipment (the total mission cost was estimated to be about US $386 million, which includes the launch); </Li>

What was a major finding of the pheonix mission to mars