By Irene and Klotz

CAPE CANAVERAL, Florida (Reuters) - The Mars rover Curiosity drilled into the Martian surface for the first time as part of an effort to learn if the planet most like Earth in the solar system ever had conditions to support microbial life, NASA said on Saturday.

Pictures beamed back to Earth on Saturday showed a hole about 0.63 inches wide and 2.5 inches deep in a patch of fine-grained sedimentary bedrock that appears to have been in contact with water.

The drilling, which took place on Friday, produced a small pile of powder that will be fed into two onboard laboratory instruments to determine the rock's chemical makeup.

"First drilling on Mars to collect a sample for science is a success," NASA posted on Twitter.

Engineers spent days preparing to use Curiosity's drill, including boring practice holes earlier in the week. Previous Mars probes have had tools to scrape and grind into rock, but never a drill to collect interior samples.

Curiosity's first drill target was a rock laced with veins of what appear to be water-deposited minerals. The rover, which landed on Mars on August 6 for a two-year mission, is looking for geologic and chemical conditions needed to support and preserve microbial life.

Engineers do not yet know exactly how much powder was produced, but are confident there is enough for a planned instrument cleaning and lab analysis, Avi Okon, a drill engineer with NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement.

NASA's lead scientist, John Grunsfeld, said using the drill was "the biggest milestone accomplishment for the Curiosity team since the sky-crane landing last August."

Curiosity's ultimate target is a 3-mile- (5-km) high mound of layered sediment rising from the floor of the Gale Crater landing site.

The drill is the last of the rover's 10 science instruments to be tested.

(Editing by Peter Cooney)