Washington, December 4 (ANI): Reports indicate that NASA's Mars rover Spirit has hit "wet" pay dirt, which is evidence of relatively recent groundwater activity on the red planet.

For almost six months the rover has been precariously perched on the edge of a shallow crater in an equatorial region of Mars.

The area is filled with cooled lava flows pitted by meteorite impacts.

While on a routine drive, Spirit broke through a thin crust of hard soil that capped a filled-in impact crater, and its wheels became half buried in the soft sand.

Since early November, the rover team has been remotely spinning Spirit's wheels to try and maneuver the rover out of its trap.

During one of these rescue attempts, Spirit churned up the soil and uncovered an intriguing layer of bright, fluffy soil.

According to a report in National Geographic News, mission managers had the rover take a closer look, and they discovered that the layer is in sulfates, minerals known to form on Earth only in the presence of liquid water.

Spirit's data revealed that the newfound sulfates are likely evidence of past "wet eruptions" on Mars, when lava and sulfur-rich steam spewed from volcanic vents dotting the landscape billions of years ago.

But, the crater contains a clue that liquid water continues to be active on Mars, at least in the long term.

The soil is full of iron sulfate covered with a thin crust of calcium sulfate. "This is the first time we've established this kind of layering," Arvidson said.

The layers support the theory that Mars's equator experiences a long-lasting snowfall every several hundred million years or so, when Mars's axis naturally tilts and one of its poles faces the sun.

When this happens, water ice at the sunny pole sublimates-turns directly from a solid to a gas-and it snows at the equator, where the temperature has dropped.

Mars is too cold and its atmosphere too thin for liquid water to exist on its surface today.

But, during the periodic polar tilt, dark, heat-trapping soils at the equator allow the bottom layers of accumulated snow to melt into a liquid.

The water then mixes with the sulfate-rich soil, where it dissolves the iron sulfate and carries it deeper underground, leaving calcium sulfate on top. (ANI)