(Image: NASA/JPL-Caltech/MSSS )

Ever get a pebble stuck in your shoe? Curiosity knows the feeling. The rover used the camera at the end of its robotic arm to snap this picture yesterday of a Martian rock wedged between the grousers of its tire.

No need to fear, says Chris Roumeliotis, rover driver team lead for Curiosity at NASA’s Jet Propulsion Laboratory in Pasadena, California. They don’t expect the rock to affect Curiosity’s performance in any way, or cause any harm to the wheels, as the ground will usually give.

The team could try trenching the wheel to shake the rock off, but they’d rather wait. “It is better to let this fall off naturally,” Roumeliotis says.

Update 5 May: A previous version of this story used a previous version of Chris Roumeliotis’ job title.