One of the reasons that NASA is so interested in Mars is to determine if the planet once had water on its surface. If there was water, there is a chance that the planet once had life of some sort as well. NASA has been studying the planet with rovers and orbiters for a long time and scientist have now made a new determination.
NASA scientists have determined that the Red Planet once held more water on its surface than is found in the Earth's Arctic Ocean. Researchers say that the planet has lost 87% of that water to space.