Exploring Habitable Zones: Searching for Life Beyond Earth

[cstoos]

With the confirmation of water on at least two other major bodies in our solar system so far (Mars, Moon), has this expanded the range of the "habitable zone" when searching for locations of possible life in the solar system?

 

[mgb_phys]

The habitable zone is the range of distances from a sun where water is liquid.
water ice is present pretty much everywhere in the outer solar system - comets for instance are mostly ice

 

[cstoos]

Right, but we know that liquid water once flowed on Mars, correct?

There are also basic lifeform that survive in environments without water in it's liquid form so it seems to me that life could exist on the limits of the liquid water range...or even slightly past.

http://serc.carleton.edu/microbelife/extreme/withoutwater/

 

[mgb_phys]

Right, but we know that liquid water once flowed on Mars, correct?

Not sure if that's totally accepted, water could have flowed as ice or as a hydrate, if there was liquid water it would only have existed while Mars had a much thicker atmosphere.

A bigger argument for a wider habitable zone is probably the moons of Jupiter, they can have liquid water ,below an ice covered surface, with the heat provided by tidal forces from jupiter.

 

[Chalnoth]

Right, but we know that liquid water once flowed on Mars, correct?

From what I can gather, there's still a fair amount of uncertainty where this is concerned. See this blog post, for instance:
http://blogs.discovermagazine.com/b...5/are-martian-gullies-formed-by-water-or-not/

As near as I can tell, the evidence for liquid water on Mars largely consists of evidence from formations that we see on Mars that look very similar to formations on Earth which are, on Earth, formed only with water. However, as this paper shows, it is conceivable that other processes are producing these formations on Mars instead.

Regardless, the possibility of liquid water on Mars is one significant reason why probes we send there frequently look for life. We expect that if there is life on Mars, it would consist of a few hardy microbes.