61.  While liquid water cannot exist on the Martian surface because of its low air pressure, water could flow just below the surface.

62.  And any environment on Earth that has liquid water, nutrients and a volcanic heat source inevitably has life.

63.  Scientists are keenly interested in whether there is water on Mars, because liquid water is considered an essential chemical for the development of life.

64.  The meteorite may be a piece of a larger asteroid that had liquid water flowing over its surface.

65.  The latest findings are particularly important because they suggest liquid water is still present beneath the surface.

66.  The rest of the dozen or so planets that have been discovered circling distant stars follow orbits too misshapen to sustain liquid water.

67.  There is much evidence now that Mars had an ocean of liquid water, said Vladimir A. Krasnopolsky of Catholic University of America.

68.  There needs to be liquid water and oxygen.