LOS ANGELES — NASA’s Mars rover Curiosity has collected its first sample from the interior of a rock on Mars, marking a major milestone for the Mars Science Laboratory project and the achievement of what the agency describes as an historic moment for robotic space exploration.

“We received confirmation from Curiosity that the drill sample has made it into the scoop, which allows us to verify for the first time that the drill acquired the sample,” says Scott McCloskey, rover planner and drill systems engineer for Curiosity at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

The sample, taken from a 2.5-in. bore hole, was “about a tablespoon of powder, which is a great result,” he adds. The event marks the first time a sample has been collected from the interior of a rock on another planet.

“Going beyond the surface of the rock gets us behind the environmental exposure that top surfaces have seen. So we get powder up that hasn’t been affected by these weathering processes,” says Louise Jandura, sample system chief engineer for Curiosity.

“These are potentially ancient rocks that preserve some sort of record of the environment in which they were formed,” adds Curiosity sampling system scientist Joel Hurowitz.

The first sample is already causing excitement among scientists because it is a different gray color than the usual rust-tinted, oxidized terrain seen up until now on Mars. The drill sample was taken from a spot in the bedrock that appears to be “fine-grained rocks like a siltstone or mudstone. So to have a fine-grained rock that could have been deposited in water couldn’t be better,” Hurowitz says.

The scoop now holding the sample is part of Curiosity’s Collection and Handling for In-Situ Martian Rock Analysis (Chimra) device. The powder will next be enclosed inside Chimra and shaken over a sieve that screens out particles larger than 0.006 in. (150 microns) across. Portions of the sieved sample will later be delivered through inlet ports on top of the rover deck into the Chemistry and Mineralogy (CheMin) instrument and Sample Analysis at Mars (SAM) instrument.

With preparations under way for upcoming analysis, project engineers are meanwhile focusing on ways to mitigate the development of a minor tear that has formed along one of the edges holding the 150-micrometer sieve screen on an identical Earth-based test unit. The device is used to remove larger particles from samples before delivery to science instruments and lies within the Chimra structure, which is on the end of the rover’s turret.

“The edge welds are slowly popping and unzipping from structure,” says Daniel Limonadi, lead systems engineer for Curiosity’s surface sampling and science system. “We have several theories about why welds might be popping but we have not converged on a root cause yet.” Tests of two identical sieves on two units on Earth have shown differing results, with one not showing any signs of the fault and another exhibiting the problem. “So given this reason to be cautious, which may or may not apply to flight, we are taking a conservative tack and reducing wear and tear on it. We are shortening the sieving time and we’re reducing the number of times we ‘thwack’ the hardware to extend its life,” Limonadi says.