Blueberries and signs of water on the Red Planet

The twin Mars rovers have found a wonderland of weird rocks and enticing dunes along with more evidence the Red Planet once had water, Nasa scientists said. The robotic vehicles landed in January and first found signs in March that Mars had water eons ago.

The Spirit rover has now rolled nearly two miles across the plains of its Gusev Crater landing site and into an area dubbed the Columbia Hills, writes Scotsman.

The right front wheel has become balky, requiring more electrical current to turn, said Mark Adler, mission manager at NASA's Jet Propulsion Laboratory in Pasadena.

Engineers are considering whether to simply continue using the wheel until it fails or drive on five wheels and use the problem wheel only when necessary. The Spirit rover also had a problem last week receiving commands from Earth.

The communication problem was the result of cold temperatures, which caused the rover's receiver to drift out of the frequency range in which the commands were sent. The range was broadened, and the rover received commands after the loss of only one day of work, Adler said, informs CBS News.

"We still need to understand the nature of that interaction, and better yet we need to understand if it was hot water, cold water, was it water in vapor phase, or was it really in the liquid phase." Spirit finally set its drill bit into bedrock on Columbia Hills, a mineral-rich rise of land inside Gusev Crater where the rover landed more than seven months ago. Scientists believe the crater, which is bigger than Connecticut, once held a lake that might have been suitable for life to arise. Initial studies around the landing site, however, proved fruitless.

Spirit's sister rover, Opportunity, landed three weeks later on the opposite side of the planet in an area known as Meridiani Planum and almost immediately found signs of an ancient salty sea. The rover is now inside a crater looking for information to help researchers determine how big the ocean was and how long it lasted.

Opportunity also is giving the science team pause for thought. After carefully navigating down into a stadium-sized depression known as Endurance Crater, the rover has found a variation of the small, hard spheres that the science team nicknamed blueberries. These particles have been found everywhere Opportunity has looked.

During a press conference on Wednesday, scientists announced they had discovered a new form of the blueberries throughout a reddish slab of rock called Bylot. The particles are rougher in texture, more varied in size and are the same color as the rock rather than gray. "We really have no idea what this is," said Cornell University's Zoe Learner, says Discovery Channel.