Could a Styrofoam like ice cap protect liquid water? I know very little about Mars, but found this interesting.
"If the ice is porous, there should be more insulated lakes hidden beneath the ice cap, Orosei says. The Mars Express team may have seen some hints of such lakes already, although it’s too early to be sure.
"Finding additional lakes would be great news for the possibility of life there. If life took root in the past, it could still hang on in these long-lived subglacial lakes, like life does in similar lakes in Antarctica (SN: 9/20/14, p. 10).
‘“This means you would have a sort of Noah’s ark for life to exist today, if it ever developed on early Mars,” Orosei says. “The chances of finding extant life today would be much greater.”’
The article alludes to Antarctica, with its frozen lakes hiding pockets of life, as well.