Now, scientists will be able to tackle the main question they hope to answer: Did the ice ever melt and turn Mars into a habitable place?
While Mars is too cold for liquid water, in the past, if its axis occasionally tipped over, the polar regions might have warmed above freezing during the summer.


-NY Times

I dont get this part. The water would have to be in another form other than solid at sometime during the history of this planet. It had to be very hot for some amounnt of time after its formation just like the earth but not quite as hot cause its a bit smaller. It still had to be hot enough the water was gas and then liquid. I thought the question would be how long did it remain in the liquid form before turning solid.