NASA/JPL-Caltech/MSSS

The Curiosity rover's powerful impact drill has successfully collected its first subsurface sample, about a tablespoon of powdered rock that will be fed into the spacecraft's on-board laboratory instruments for detailed chemical analysis, project officials said Wednesday.

The drill is the last major system on the rover to be tested since landing in Gale Crater last August and the successful collection of subsurface material marks a major milestone in Curiosity's quest to find signs of past or present habitability.

"Curiosity's first drill hole at the John Klein site is a historic moment for the MSL (Mars Science Laboratory) mission," said Louise Jandura, chief engineer of Curiosity's sample system. "This is the first time any robot, fixed or mobile, has drilled into a rock to collect a sample on Mars.

"In fact, this is the first time any rover has drilled into a rock to collect a sample anywhere but on Earth. In the five-decade history of the Space Age, this is indeed a rare event."

The drill, mounted on the end of Curiosity's robot arm, was used to bore 2.5 inches into a rock for the first time on February 8. Photographs beamed back to Earth on Wednesday showed a sample of pulverized light gray rock collected from the interior of the target bedrock resting in a scoop on the rover.

The scoop is part of Curiosity's Collection and Handling for In-Situ Martian Rock Analysis, or CHIMRA. Over the next few days, the sample will be vibrated over a sieve to screen out any particles larger than 150 microns across, or six-thousandths of an inch.

A portion of the fine-grained result will be delivered to the Chemistry and Mineralogy, or CheMin, suite of instruments for a detailed chemical analysis. Another set of instruments, known as the Sample Analysis at Mars, or SAM, package is designed to look for signs of organic compounds like those necessary for life as it is known on Earth.

"Seeing the powder from the drill in the scoop allows us to verify for the first time that the drill successfully acquired sample as it was boring down into the rock," said Scott McCloskey, rover planner and drill systems engineer. "We estimate that we collected about a tablespoon of powder, which meets our expectations and is a great result. We're all very happy to get this confirmation and relieved that the drilling was a complete success."

So far, Curiosity is chalking up a near flawless record with no technical problems of any significance.

NASA/JPL-Caltech/MSSS

But engineers have decided to change the way they operate the rover's sample acquisition system in the wake of problems with welds on a test unit sieve at the Jet Propulsion Laboratory.

The problem showed up only after extensive operation, and troubleshooters concluded the unit could successfully operate for a full year longer than Curiosity's planned two-year mission. A second test unit showed no signs of trouble and the sieve aboard Curiosity is working normally.

But engineers opted to take a conservative approach, deciding to operate Curiosity's sieve hardware only when absolutely necessary.

"Given this kind of reason to be cautious, based on what our test program is telling us that hey, there might be an issue here, it may or may not apply to flight, we're taking the conservative tack," said Daniel Limonadi, lead systems engineer for Curiosity's surface sampling and science system.

"We're reducing the amount of wear and tear we're putting on the hardware. We've shortened our sieving time...to help minimize whatever might be going on and extend its life."

Joel Hurowitz, sampling system scientist for Curiosity, said the science team is eager to finally get the opportunity to examine rock samples that have not been subjected to surface weathering.

"This drilling operation we just completed allows us to get beneath the surface and analyze for the first time rock samples that have not been exposed to the effects of the Martian surface environment and truly understand the chemistry and mineralogy of a Martian rock," he said.

"The science team is just superexcited to find out what CheMin and SAM will have to say about the mineralogy and chemistry of this material and what it means for the geologic history and habitability of Gale Crater."

Jandura said the ability to drill is a major step forward in the Mars exploration program.

"It allows us to go beyond the surface layer of the rock, unlocking a kind of time capsule of evidence about the state of Mars going back 3 or 4 billion years," she said. "Because the drill's on a rover, the rock choices are plentiful."