The Mars rover Curiosity has penetrated a rock on the red planet and collected a sample for the first time, Nasa has announced.
Using a drill at the end of its robotic arm, Curiosity bore a hole 1.6cm wide and 6.4cm deep into the rock, generating powder which will be analysed.
"The most advanced planetary robot ever designed now is a fully operating analytical laboratory on Mars," said agency official John Grunsfeld.
"This is the biggest milestone accomplishment for the Curiosity team since the sky-crane landing last August, another proud day for America."
The rock Curiosity targeted was described as flat and veiny and is believed to hold evidence about "long-gone wet environments," Nasa said.
The rock has been named "John Klein" in memory of a Mars science laboratory deputy project manager who died in 2011.
Over the coming days ground controllers will command the rover's arm to carry out steps to process the sample.
Beforehand, some of the powder will be checked for contamination that may have made it onto the hardware while Curiosity was still on Earth.
Creating a tool that could handle "unpredictable" Martian rocks was difficult, Nasa said.
"To get to the point of making this hole in a rock on Mars, we made eight drills and bored more than 1,200 holes in 20 types of rock on Earth," said engineer Louise Jandura.
The \$2.5bn (£1.6bn) mission, set to last at least two years, aims to study the Martian environment to prepare for a possible future manned mission.
US President Barack Obama has set a goal of sending humans to the planet by 2030.