Originally Posted by DeviousAddict
The fact that people insist that lifeforms require water to exist on other planets baffles me. life on this planet evolved to use water/oxygen to survive because it was an abundant source of nourishment/food. Theoretically any single planet could have once if not still sustain life because they would have evolved to cope with the conditions. Just because we cant survive there doesn't mean nothing can.
for example look at the current lifeform found on earth that is arsnic based rather than carbon based (link)
it would never survive in any other environment
I don't think anyone insists that life requires water. The reason people look for water is because we only have one confirmed example of life existing, and that is on this planet. So far, we have found one planet with heat, water, electricity, hydrogen sulfide, CO2, nitrogen, etc, and that planet is earth. This planet is absolutely LOADED with life in every crevice, even when we think life couldn't possibly exist (like that arsenic life you linked).
So if you only get a chance to send a probe every 30 years to one planet/moon based on NASA's budget, are you going to make a philosophical argument about the probability of silicon based waterless life, or are you going to aim that probe at a moon relatively close to earth with comparable conditions? Sounds like an easy choice to me. We need to take one step at a time and base decision off of the best evidence we have.
Maybe someday we will be able to prove otherwise, but for now we just don't have enough information, technology, or money to chase anything but life that resembles life on earth.