LOS ANGELES – In a Mars first, the Curiosity rover drilled into a rock and prepared to dump an aspirin-sized pinch of powder into its onboard laboratories for closer inspection.

The feat marked yet another milestone for the car-size rover, which landed last summer to much fanfare on an ambitious hunt to determine whether environmental conditions were favorable for microbes.

Using the drill at the end of its 7-foot-long robotic arm, Curiosity on Friday chipped away at a flat, veined rock bearing numerous signs of past water flow. The result was a drill hole 2 1/2 inches deep.

The exercise was so complex that engineers spent several days commanding Curiosity to tap the rock outcrop, drill test holes and perform a “mini-drill” in anticipation of the real show. Images beamed back to Earth overnight showed a fresh borehole next to a shallower test hole Curiosity had made earlier.

“It was a perfect execution,” drill engineer Avi Okon at the NASA Jet Propulsion Laboratory said Saturday.

Previous Mars landings carried tools that scraped away the exterior layers of rocks and dirt. Opportunity and Spirit toted around a rock grinder. Phoenix, which touched down near the Martian north pole in 2008, was equipped with an ice rasp to chisel frozen soil.

None, however, were designed to bore deep into rocks and collect pulverized samples from the interior.

It will take several days before Curiosity transfers the powder to its instruments to analyze the chemical and mineral makeup.