Mars rover to seek safe winter haven The New Scientist

While Spirit busily studies a finely layered outcrop dubbed Home Plate, mission planners say the rover’s daily power supply is steadily dropping. And with the Martian winter looming and dust accumulating on Spirit’s solar arrays, the team is preparing to drive Spirit to a safe haven.
The Martian winter does not officially begin until August, but Byron Jones, rover mission manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, US, says the team would like to get Spirit situated on a slope called McCool Hill, with its solar arrays tilted northward, in plenty of time.
That tilt maximises the sunlight falling on the arrays and worked well for the rovers during their first Martian winter, which peaked in September 2004.