Nasa's Mars rover has been sidelined again, further delaying the restart of science experiments after its recovery from a computer problem.
The latest complication occurred over the weekend when the six-wheeled Curiosity rover entered safe mode after experiencing a software file error.
Curiosity remained in contact with ground controllers, but it cannot zap rocks, snap pictures or roam around until the problem is fixed. Rover team members had expected to resume activities on Monday, but they now have to wait perhaps until the end of the week.
"We would definitely like to get over this and get back to doing something," said project manager Richard Cook of the Nasa Jet Propulsion Laboratory.
Studies at the Gale Crater landing site have been on hold since the beginning of March after engineers discovered a problem with Curiosity's computer memory, possibly caused by space radiation.
The latest glitch is not as serious but any unexpected problem throws off the schedule, Mr Cook said.
It is the longest stretch of inactivity since Curiosity's touchdown near the Martian equator last year.
Just before halting its investigations, the nuclear-powered rover used the drill at the end of its 7ft robotic arm to bore into a rock near where it landed and analyse the powder.
Last week, scientists announced the results from the first drilling. Curiosity had discovered an ancient Martian environment that could have been favourable for primitive microbial life.
Despite the excitement over achieving one of the mission's main goals, it has yet to find complex organic molecules considered the chemical building blocks of life.