31.  Liquid water is not known to exist anywhere on present-day Mars.

32.  Never before have scientists had liquid water from outer space to study in a lab.

33.  One of the necessary conditions for life is liquid water.

34.  Over time, Mars lost its atmosphere and liquid water vanished.

35.  Put back in the freezer, the liquid water turns back to ice.

36.  Second, a search for evidence of liquid water.

37.  Some scientists recently saw in surface markings evidence of possible subsurface liquid water there.

38.  Such conjecture has stirred wide interest among scientists because liquid water is one of the essential ingredients of life.

39.  Such salts, McCord says, form only in the presence of liquid water.

40.  That means that liquid water, the basis of all life as we know it, could exist there.