A faulty wheel on the Mars rover Spirit is complicating efforts to free it from a sand trap where it has been stuck for the past eight months.
NASA said Thursday it will continue to run tests to see if there's any movement in the right rear wheel. Spirit, which landed on the red planet with six working wheels, lost the ability to move its right front wheel three years ago.
Engineers are studying whether it's possible to free Spirit with only four operable wheels.
Spirit became bogged down in soft soil in April during a routine drive. NASA last month outlined a rescue plan with little progress made.
Spirit and its twin Opportunity landed on Mars in 2004 and have outlasted expectations.