Because water is life.

What about those bacteria things they were looking for on mars because they were producing CO2? There is no water on mars.

I'm assuming they found evidence that indicates the posibilty of bacteria existence/existed on mars. However, could you please post me a link. I would love to read this.

There was a thread on it called Life on Mars on this website. Although i would avoid reading the part where everyone attacked me because of my beliefs but thats your call.

Biology as we know it requires water to exist. That is why it is so important and popular to find evidence of on various planets and locations.

Also, it is critical to our biology. If we could not find water on the moon, it would be difficult to sustain our life there. Water is very important to our future exploration methods.

That isn't to say that life can exist outside of known biology - our understanding of solar system formation has been stood on its head for the past decade due to the crazy ways that planets have formed and orbited around various solar systems - models thought impossible. So life could exist outside of our constraints. However, it still stands as the best chance for life to develop to our understanding.

For the Martian example, there are 3 theories concerning the life there:

1. Life existed on Mars at some point, and standing water did exist on the planet
2. Life still exists on Mars, and there is water somewhere underground that is causing life to exist still on the planet
3. Life existed (or exists) anerobically to a degree we simply do not understand

We know that Mars had water at some point, so #1 and #2 are assumed to be more plausible than #3. Not saying its impossible, just likely. We won't have true answers until we put a scientist on the planet (or a dozen scientists), but for now, we can go off what we know

The accleration you experience caused by an object equals GM/r^2 where G is a constant, M is the objects mass, and r is the distance between you and it.  When you put in Earth's mass and radius, you get 9.81 m/s^2 (or 1g).  When you put in 6.55 times the mass of the earth and 2.678 times the radius of the earth, you get 8.96 m/s^2 (or .913 g).  You can try it yourself.

More plainly, distance (radius) plays a larger role in the gravity than mass because it's squared, as opposed to just being to the first power like mass.

Edit: So, even though mass is 6.55 times bigger and the radius is only 2.678 times as big, the increased radius has a larger effect because it's squared in the equation (2.678 squared is 7.17).

Great explanation. Thanks for the formula and everything. That square explains the really counter-intuitive part. I'm just so used to thinking of planets as either dense rocks or enormous gas giants.