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. After nearly seven minutes of pounding, 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 today.

Previous Mars landings carried tools that scraped away the exterior layers of rocks and dirt. Opportunity and Spirit — before it died — 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.

With the maiden drilling out of the way, it’ll take several days before Curiosity transfers the powder to its instruments to analyze the chemical and mineral makeup.

The cautious approach is by design. Curiosity is the most high-tech spacecraft to land on Earth’s nearest planetary neighbor and engineers are still learning how to efficiently operate the $2.5 billion mission.

The team won’t know until next week how much rock powder Curiosity collected. But judging by the small amount left in the drill hole, Okon said he was confident the rover has enough for its upcoming lab analysis.

Another unknown is whether any Teflon rubbed off from the drill and got mixed with the rock sample. Before Curiosity launched, engineers discovered that microscopic flakes of Teflon can break off from the instrument and have been studying workarounds. Okon said any Teflon contamination would be small because Curiosity did not drill for long.

As images from the drilling operation streamed to Earth, some team members shared their excitement on social media.

The “full drill hole was a success! I’m sure it was LOUD and they heard the drilling action for MILES!” tweeted rover driver Paolo Bellutta.

Mission managers previously predicted that drilling would be the hardest engineering task since the landing, which relied on never-before-tried tricks including a rocket-powered platform and cables that lowered Curiosity in an ancient crater last August.

The dramatic landing gave way to a labor-intensive checkup of Curiosity’s various instruments. The drill was the last tool to be tested.

While Curiosity executed the first rock drilling on Mars, the method has been used on other celestial bodies.

The Apollo astronauts wielded a handheld, battery-powered drill into rocks and delivered pieces to Earth. The Soviets deployed spacecraft that drilled into the lunar surface to collect rocks for Earth return and also used robotic drills on missions to Venus.

Once Curiosity finishes its rock analysis, the team’s focus will turn to starting the drive to a mountain, expected to take nine months with stops. It is there that scientists hope Curiosity would uncover signs of organic molecules, the chemical building blocks of life.