NASA

An artist's conception shows how Mars' atmosphere might have been stripped away by a stream of electrically charged particles from the sun.

Scientists say new readings from NASA's Curiosity rover have confirmed how Mars lost its once-thick atmosphere.

The measurements from Curiosity's Sample Analysis at Mars instrument, or SAM, provide fresh support for the view that a high-velocity stream of electrically charged particles from the sun has been stripping off Mars' atmosphere from the top. Mars is more vulnerable to that kind of atmospheric loss than Earth because it doesn't have a global magnetic field to serve as a shield against the solar wind.

Today, Mars' atmosphere is only 1 percent as dense as of Earth's on the surface, and consists mostly of carbon dioxide. The atmosphere is so thin that warmed-up ice turns directly into water vapor without passing through a liquid state. But scientists have seen geological evidence that water flowed abundantly over parts of the Red Planet billions of years ago. That implies that the atmospheric pressure was once much more Earthlike. So where did the missing air go?

Curiosity's science team presented the verdict from SAM on Monday during the European Geosciences Union's General Assembly in Vienna. The key clue is a precise measurement of various isotopes of argon, an inert gas that exists in trace amounts in the Martian atmosphere. Different isotopes of the same element have different atomic weights, and SAM was able to distinguish between those weights with unprecedented precision.

SAM's science team determined that the Martian atmosphere contains more of a lighter argon isotope (argon-36) than a heavier isotope (argon-38) — about four times as much. However, that ratio is lower than the solar system's original ratio of 5.5-to-1, as estimated from argon-isotope measurements of the sun and Jupiter. That would favor a process that stripped away Mars' ancient atmosphere from the top down, with more of the lighter isotopes of gases blown away.

Scientists have long suspected that the solar wind was the culprit for atmospheric loss, based on what happened to other isotopes in Martian air. But the argon measurements are more conclusive, because argon doesn't react with other elements. Thus, Curiosity's team could exclude a scenario in which constituents of the Martian atmosphere were removed by reacting with surface chemicals.

"We found arguably the clearest and most robust signature of atmospheric loss on Mars," Sushil Atreya, a SAM co-investigator at the University of Michigan at Ann Arbor, said in a NASA news release.

Slideshow: Curiosity's space odyssey to Mars

Trace the Curiosity rover's journey to Mars and see the pictures that the six-wheeled robot has sent back from the Red Planet.

Launch slideshow

More about Mars:

• Parachute flaps in the Martian breeze
• Probe to study Red Planet's atmosphere
• Rover finds organics, but are they from Mars?

For more about the SAM team's findings, check out this report from the BBC's Jonathan Amos.

 Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA's Curiosity and Opportunity rovers aren't the only human-made objects that have been on the move on Mars: The Red Planet's winds have set Curiosity's discarded parachute rolling around on the surface, as seen in a series of images captured by the Mars Reconnaissance Orbiter over the course of five months.

The 65-foot-wide (20-meter-wide) parachute and the rover's protective backshell were thrown clear of the rover while it descended to its historic landing in Mars' Gale Crater last August. For a few weeks thereafter, they pretty much stayed where they were. But by the end of November, the orbiter's sharp-eyed HiRISE camera picked up changes in the parachute's shape and position. What's more, the dark marks left on the Martian surface by the backshell's impact started fading away.

The fading of the dark streaks could be explained by the deposition of airborne dust, according to the University of Arizona's Alfred McEwen, who heads the HiRISE science team. The winds that whip through Mars' thin atmosphere are also thought to be responsible for the parachute's changing position.

"This type of motion may kick off dust and keep parachutes on the surface bright, to help explain why the parachute from Viking 1 (landed in 1976) remains detectable," McEwen wrote in Wednesday's image advisory.

If you have red-blue glasses, check out this 3-D view of the parachute and the backshell.

NASA / JPL-Caltech / Univ. of Arizona

A color picture from the HiRISE camera on NASA's Mars Reconnaissance Orbiter shows the Curiosity rover's parachute and backshell spread out on the Martian surface.

Although the parachute may be on the move, Curiosity itself is definitely staying put for the rest of the month: Mars and Earth are on directly opposite sides of the sun, which interferes with radio communication. As a result, NASA will suspend sending commands to the rover starting on Thursday. Opportunity, MRO and the Mars Odyssey orbiter will be out of radio contact for most of April as well. Curiosity and Opportunity will be executing pre-programmed commands to continue their scientific work, and both rovers are expected to be back on the move in May.

More about Mars:

• Curiosity resumes rock analysis after glitch
• How a Martian mountain would look on Earth
• NBC News archive on Mars

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL-Caltech / Marco Di Lorenzo / Ken Kremer

The Curiosity rover's instrument-laden robotic arm is front and center in this mosaic view captured by the Mars rover's NavCam system and assembled by Marco Di Lorenzo and Ken Kremer. The colorized black-and-white imagery was captured on March 23. Click on the image to see the full panorama.

After a week of down time due to a computer glitch, NASA's Mars Curiosity rover is once again sending back pictures of its rocky Red Planet locale at Yellowknife Bay. In this fresh panorama, the rover looks as if it's sticking its drill-equipped robotic arm right in your face.

"That drill is hungry, looking for something tasty to eat, and 'you' (loaded with water and organics) are it," jokes scientist-writer Ken Kremer, who collaborated with Italian colleague Marco Di Lorenzo to assemble the panorama.

Curiosity's percussive drill played a key role in the science team's most recently reported breakthrough: the finding that powder drilled out of a Martian rock contained the chemical traces of a life-friendly environment that existed on Mars billions of years ago. The team's chemical analysis of the powder indicated that the minerals were probably formed in the presence of drinkable water.

That kind of water no longer exists in liquid form on the Martian surface. The place where Curiosity is currently working may have once been in the vicinity of a riverbed, but it's now a cold and dry wasteland of sand and rock. In the weeks to come, Curiosity's scientists plan to drill into the rock again, looking for confirmatory clues about the potentially habitable environment in the Red Planet's past.

The plan has been held up due to a series of minor setbacks — including a memory failure that may have been due to a cosmic-ray strike, a precautionary stand-down to weather a solar storm, and most recently a computer file glitch that put the rover into safe mode. The Curiosity team has been carefully bringing the rover back to full operation, and this picture is presumably part of the checkout process.

It won't be long before the rover will once more have to reduce its contact with its handlers back on Earth, due to an Earth-Mars-sun conjunction that will interfere with radio signaling. Curiosity's communication gap is expected to last from April 4 to May 1, as detailed in a mission update from NASA's Jet Propulsion Laboratory. During the break, Curiosity is expected to carry on with its experiments, but the transmission of science data and images will have to wait until May. So let's enjoy these fresh images while we can.

For more of Curiosity's raw imagery, check out the galleries on JPL's Mars Science Laboratory website. You'll also find great pictures on UnmannedSpaceflight.com, where Kremer, Di Lorenzo and other image-processing gurus post their work. If you have 3-D glasses, whip 'em out and take a look at Ed Truthan's red-blue view of Curiosity's first drilling site.

Slideshow: Curiosity's space odyssey to Mars

Trace the Curiosity rover's journey to Mars and see the pictures that the six-wheeled robot has sent back from the Red Planet.

Launch slideshow

More about Mars:

• How a Martian mountain would look on Earth
• What's next for the Curiosity rover
• NBC News archive on Mars

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log and the rest of NBCNews.com's science and space coverage, sign up for the Tech & Science newsletter, delivered to your email in-box. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Slideshow: Curiosity's space odyssey to Mars

Trace the Curiosity rover's journey to Mars and see the pictures that the six-wheeled robot has sent back from the Red Planet.

Launch slideshow

By Mike Wall
Space.com

NASA's Curiosity rover is back in action on Mars after being sidelined by a computer glitch for the second time in three weeks.

Curiosity went into a precautionary "safe mode" on Sunday, apparently because a file slated for deletion was connected to one still in use by the rover. But the mission team has now sorted things out and returned the robot to active status, NASA officials announced Tuesday.

The car-size Curiosity rover has not resumed science operations yet, however. It's still recovering from a separate memory glitch that knocked out its main, or A-side, computer in late February. Engineers swapped Curiosity over to its backup (B-side) computer at the time, spurring the rover to go into safe mode on Feb. 28.

Curiosity bounced back on March 2, only to stand down briefly once again a few days later to wait out a Mars-bound solar eruption. [Curiosity Rover's Latest Amazing Mars Photos]

Mission engineers continue to configure and check out the B-side computer, which remains the Curiosity rover's active computer. The A-side is now available as a backup if needed, officials said.

All of this drama has delayed Curiosity's activities at a Martian site called Yellowknife Bay, which mission scientists announced last week could have supported microbial life. This discovery was based on Curiosity's study of material pulled out of a hole it drilled last month into a Yellowknife Bay rock. Further such analytical work should be possible soon, rover team members said.

"We expect to get back to sample-analysis science by the end of the week," Curiosity mission manager Jennifer Trosper, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

The rover team also wants to drill another hole in the Yellowknife Bay area to confirm and extend their previous observations. But this won't happen until May, partly because of an upcoming unfavorable planetary alignment.

Engineers won't send commands to the six-wheeled robot for most of April, because Mars and Earth will be on opposite sides of the sun during this time. "The moratorium is a precaution against interference by the sun corrupting a command sent to the rover," NASA officials wrote in a mission update.

Curiosity is the centerpiece of NASA's $2.5 billion Mars Science Laboratory mission. The huge robot touched down inside Mars' Gale Crater last August, kicking off a planned two-year surface mission to determine if the area ever could have supported microbial life.

While Curiosity has already achieved its main mission goal, the rover's handlers have no desire to rest on their laurels. They still plan to send Curiosity on to its main science destination — the base of 3-mile-high (5 kilometers) Mount Sharp — when it's done at Yellowknife.

Mount Sharp's foothills, which lie about 6 miles (10 kilometers) from the rover at present, show signs of long-ago exposure to liquid water. The mountain's many layers also contain a record of how Mars' environmental conditions have changed over time, and researchers want Curiosity to read these layers like a book as it climbs up Mount Sharp's slopes.

Follow Mike Wall on Twitter @michaeldwall. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

• Ancient Mars Could Have Supported Life (Photos)
• Mars Could Have Supported Life, NASA Finds | Video
• A 'Curiosity' Quiz: How Well Do You Know NASA's Newest Mars Rover?

Copyright 2013 Space.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

NASA / JPL-Caltech / MSSS

This mosaic of images from the Mast Camera (Mastcam) on NASA's Mars rover Curiosity shows Mount Sharp, also known as Aeolis Mons, in a white-balanced color adjustment that makes the sky look overly blue but shows the terrain as if under Earthlike lighting. This is just a small segment of a wider panorama assembled from image data collected on Sept. 20, 2012. The sky has been filled out by extrapolating color and brightness information from the portions of the sky that were captured in images of the terrain. A raw-color version of the mosaic shows the scene's colors as they would look in a typical smartphone camera photo taken on Mars. Click on the image to see a larger version from NASA.

If you could pull up a 3-mile-high mountain from Mars and plop it down in California's Mojave Desert, it'd probably look much like this latest color panorama from the Curiosity rover's science team. This little piece from the panorama doesn't do justice to the whole picture: You really should see the whole thing at high resolution to get a sense of just how much Mount Sharp, a.k.a. Aeolis Mons, looms over the scene where NASA's six-wheeled robotic lab has been working.

The most jarring thing about the picture is the blue sky. No, the Martian sky doesn't really look like that. The Red Planet's atmosphere is filled with iron-rich dust that turns everything into shades of butterscotch, burnt orange and brick. To see Mount Sharp as you or your smartphone camera might see it if you were actually there, check out this true-color version of the panorama.

The blue-sky version has been processed to reflect a white-balanced view, as if the picture were taken in an earthly rather than a Martian setting. Why would scientists bother with a phony view of Mars? "White-balancing helps scientists recognize rock materials based on their experience looking at rocks on Earth," NASA's Jet Propulsion Laboratory explains in Friday's photo advisory. It's as if Curiosity was able to get rid of all that red dust in the air and take a clear picture of the mountainside from miles away.

The pictures for this panorama was taken in September, while the rover was en route to its first destination. For the past couple of months, Curiosity has been studying the rocks at a site known as Yellowknife Bay, and it's already turned up some amazing discoveries about Mars' past — including evidence that the area was capable of supporting microbial life billions of years ago.

Within the next couple of months, Curiosity is due to turn around and begin its 6-mile (10-kilometer) trek to the foothills of that big mountain. Pictures like this panorama will help scientists figure out exactly where their nuclear-powered robotic geologist should be going.

Slideshow: Curiosity's space odyssey to Mars

Trace the Curiosity rover's journey to Mars and see the pictures that the six-wheeled robot has sent back from the Red Planet.

Launch slideshow

More about Mars:

• Martian rock reveals life-friendly conditions
• What's next for Mars Curiosity rover
• NBC News archive on Mars

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other science coverage, sign up for the Tech & Science newsletter, delivered to your email in-box. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL-Caltech / Ken Kremer / Marco Di Lorenzo

This colorized view is part of a panorama produced by Ken Kremer and Marco Di Lorenzo from NASA imagery. The picture shows NASA's Curiosity rover putting its drill to work at Yellowknife Bay on Mars. Click on the picture to see a larger version, and visit KenKremer.com for more from Ken Kremer.

Even as the scientists behind NASA's Curiosity rover mission announced that they found evidence of life-friendly chemistry inside a Martian rock, the $2.5 billion mission's engineers continued their efforts to get the rover back into full operation after a serious computer glitch.

The rover's scientific work in a spot known as Yellowknife Bay has been put on hold while the mission operations team rebuilds the memory for one of Curiosity's two redundant computers, known as the A-side. The A-side computer experienced a memory failure on Feb. 28, forcing controllers to switch over to the B-side backup brain. Since then, the team has been putting the A-side through a series of tests to make sure it's OK.

"We have been able to store new data in many of the memory locations previously affected and believe more runs will demonstrate more memory is available," Jim Erickson, the mission's deputy project manager at NASA's Jet Propulsion Laboratory, said Monday in a status report. A couple of software patches are due to be uploaded and tested this week, and then the team will reassess when to resume full mission operations, including the analysis of additional rock samples.

Engineers still don't know why the A-side failed, although they suspect it may have been due to a cosmic-ray hit. Such hits are thought to have affected Mars Reconnaissance Orbiter in the past. After the computer system returns to full redundant mode, the B-side will continue to operate as Curiosity's main computer while the A-side serves as backup, NASA spokesman Guy Webster told NBC News on Wednesday.

Mars is heading into a solar conjunction in April that will interfere with communications between Curiosity and Mission Control, and science operations will have to be suspended again during that hiatus. That means the rover won't drill out another sample of rock powder from Yellowknife Bay until May.

Scientists say Yellowknife Bay could have been a riverbed or lake bed in ancient times — just the right kind of place for figuring out what Mars was like billions of years ago.

"I have an image now of possibly a lake, a freshwater lake on a Mars with probably a thicker atmosphere, maybe a snow-capped Mount Sharp. Who knows?" said John Grunsfeld, NASA's associate administrator for the science mission directorate.

Curiosity's science team members are so intrigued by what they've been finding that they're willing to go slow with the rover's long-planned trip to Mount Sharp, a 3-mile-high (5-kilometer-high) peak in the middle of Mars' Gale Crater. The layers of rock that make up that mountain, also known as Aeolis Mons, are thought to preserve Mars' geological record over billions of years.

"When we start driving to Mount Sharp, and you see us dragging our feet as we go along there and stop to look at a few things, that's because we'll be trying to figure out how the rocks we're at now, at Yellowknife Bay, relate to Mount Sharp," said Caltech's John Grotzinger, the mission's project scientist.

Slideshow: Curiosity's space odyssey to Mars

Trace the Curiosity rover's journey to Mars and see the pictures that the six-wheeled robot has sent back from the Red Planet.

Launch slideshow

Extra credit: The Mars Curiosity crew is coming in for more accolades. The Mars Science Laboratory Project, which is in charge of building and operating the rover, has been selected to receive the National Air and Space Museum's Trophy for Current Achievement at a ceremony next month. Meanwhile, the folks who manage Mars Curiosity's online persona have won the 2013 South by Southwest Interactive Award for best social media campaign. Congratulations to the "hive mind" behind @MarsCuriosity on Twitter.

More about Mars:

• Organics found, but are they from Mars?
• Radar reveals traces of huge Martian flood
• Cosmic Log archive on Mars

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL-Caltech / MSSS

This self-portrait of NASA's Curiosity rover was assembled from dozens of images captured by the rover's Mars Hand Lens Imager on Feb. 3. Because of the way the pictures were taken, the rover's robotic arm is not visible in this mosaic.

LOS ANGELES — Curiosity hunkered down Wednesday after the sun unleashed a blast that raced toward Mars.

While the hardy rover was designed to withstand punishing space weather, its handlers decided to power it down as a precaution since it suffered a recent computer problem. "We're being more careful," said project manager Richard Cook of the NASA Jet Propulsion Laboratory, which runs the $2.5 billion mission.

While Curiosity slept, the Opportunity rover and two NASA spacecraft circling overhead carried on with normal activities.

On Tuesday, scientists noticed a huge flare erupting from the sun that hurled a stream of radiation in Mars' direction. The solar burst also spawned a cloud of superheated gas that barreled toward the Red Planet at 2 million mph (3.2 million kilometers per hour). The eruption did not appear severe or extreme, but "middle of the road, all things considered" said space weather chief Bob Rutledge at the National Oceanic and Atmospheric Administration.

The solar tempest was not expected to have an impact on Earth. In the past, such outbursts have triggered solar storms with the ability to disrupt utility grids, airline flights, satellite networks and GPS services. They're also known to produce shimmering auroras in places farther from the poles.

Since Mars lacks a planetwide magnetic field, it does not experience geomagnetic storms. Rather, the planet sees a spike in radiation, Rutledge said.

Powerful solar blasts can cause trouble to Mars spacecraft. In 2003, an intense solar flare knocked out the radiation detector on the Odyssey orbiter.

NASA does not expect similar drama from the latest solar activity. In the worst-case scenario, one or more of the working Mars spacecraft may enter "safe mode" in which science activities are halted, but they remain in contact with Earth.

"We'll be watching and seeing what happens," said Roger Gibbs, JPL deputy manager for the Mars exploration program.

The unsettled space weather comes as Curiosity is recovering from a memory hiccup that put its science experiments on hold. It was the first major problem to hit the car-sized rover since it landed last year in an ancient crater near the Martian equator to hunt for the chemical building blocks of life.

Engineers were in the middle of troubleshooting when they decided to wait for the weather to pass. The delay means it'll take longer for Curiosity to return to analyzing the pinch of rock powder it collected from a recent drilling.

Since its instruments are turned off, it can't use its radiation sensor to track the solar particles. "It's just bad timing," Cook said. 

Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

NASA / JPL-Caltech / MSSS

The left-hand Mast Camera on NASA's Curiosity rover took this image of the rover's sample-processing and delivery tool just after the tool delivered a portion of powdered rock into the rover's Sample Analysis at Mars instrument, also known as SAM.

The Associated Press 

PASADENA, Calif. — The Mars rover Curiosity has successfully transferred a pinch of rock dust to its onboard laboratories for inspection, two weeks after drilling into its first rock.

NASA said Monday it received confirmation of the deliveries over the weekend. Scientists will spend the next several weeks studying the rock's chemical and mineral makeup.

Curiosity landed in Gale Crater near the equator last summer on a mission to determine whether the environment was favorable for microbes. It drilled into a flat rock earlier this month and collected a tablespoon-size sample from the interior — the first time this was achieved on Mars.

The car-sized rover still has to drive to Mount Sharp rising from the center of the crater floor. The trip is expected to take at least nine months with stops.

More about Mars:

• Rover works on first sample drilled from rock
• Curiosity finds organics, but are they from Mars?
• Mars rover driving through dried-up stream bed

© 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

NASA / JPL-Caltech / MSSS

This image from NASA's Curiosity rover shows the first tablespoon of powdered rock extracted by the rover's drill. The image was taken after the sample was transferred from the drill to the rover's scoop.

The scientists and engineers behind NASA's Curiosity rover say they're thrilled to see the first tablespoon of rock dust drilled from the interior of a rock on Mars — and they're intrigued by the fact that it's gray, not red.

"We're seeing a new coloration for Mars here, and it's exciting for us," Joel Hurowitz, sampling system scientist for the Curiosity mission at NASA's Jet Propulsion Laboratory, told reporters during a teleconference on Wednesday.

Things could get more exciting in the next few days, when Curiosity's sampling system drops dollops of the dust into the rover's onboard chemistry labs, known as CheMin (which stands for Chemistry and Mineralogy) and SAM (Sample Analysis at Mars). The main goal of the $2.5 billion mission is to find organic compounds on Mars, and scientists suspect that the gray interior of rocks could preserve those organics better than the red, highly oxidized surface.

"All things being equal, it's better to have a gray color than a red color," said Caltech's John Grotzinger, the mission's project scientist, "just simply because oxidation ... is something that we know destroys organic compounds."

The rover has spent several weeks at a rock formation known as John Klein in preparation for this first drilling operation, six months into what's expected to be a two-year primary mission. Some scientists and engineers have been working for years in anticipation of Wednesday's first sight of ground-up rock in Curiosity's sampling cup.

"For the sampling team, this is the equivalent of the landing team going crazy after the successful touchdown," said JPL's Scott McCloskey, drill systems engineer for the Curiosity mission.

The sample came from a 2.5-inch-deep hole that Curiosity drilled into the Martian bedrock on Feb. 8. One of McCloskey's colleagues at JPL, sample system chief engineer Louise Jandura, noted that this was the first time a rover has drilled samples out of a rock on another planet. Earlier missions have used grinders to scrape off the top layer of a Martian rock, but none has gone down as deeply as Curiosity did.

"In the five-decade history of the Space Age, this is indeed a rare event," she said.

Grotzinger said getting the samples represented the final milestone in the commissioning process for the rover. Last week marked the "passing of the keys to the rover" from the engineering team to the science team, he noted. "It's a real big turning point for us," Grotzinger said. 

NASA / JPL-Caltech / MSSS

At the center of this image from NASA's Curiosity rover is the hole in a rock called "John Klein" where the rover conducted its first sample drilling on Mars. The drilling took place on Feb. 8. Several preparatory activities with the drill preceded this operation, including a test that produced the shallower hole on the right two days earlier.

NASA / JPL-Caltech / MSSS

This image from October 2012 shows the location of a sieve screen on the Curiosity rover that is used to remove large particles from samples before delivery to science instruments. Scientists say problems that came to light on a test unit on Earth have led them to change their procedures for sifting Martian samples.

Going through glitches
It will take a few more days to start analyzing the ground-up rock: Some of the material in the cup is being used to clear out the plumbing in the rover's sample delivery system. Once scientists back on Earth see imagery confirming that everything is working as expected, they'll give the go-ahead for more of the material to be shaken through a sieve and then deposited into CheMin and SAM for analysis.

A software glitch delayed the sampling operation, McCloskey said, but the team found a work-around that allowed the task to continue with no loss of functionality. "It didn't end up being a significant roadblock to getting this done," he said.

Another concern arose when engineers found that the sieve on one of the test items back on Earth started coming loose after about 60 shaking operations, also known as "thwacks." That was a signal to the rover team that there was "reason to be cautious," said JPL's Daniel Limonadi, lead systems engineer for Curiosity's surface sampling and science system.

The team decided to reduce the shaking time from 60 minutes to 20 minutes at a time, which should be long enough for most samples. If it isn't, the rover will just keep shaking the stuff until the job is done, Limonadi said.

What the rocks may reveal
Hurowitz said the evidence so far suggests that Curiosity is looking at a sedimentary rock formation that was "more likely deposited in water." Veins of whitish material appear to consist of calcium sulfate, which could provide additional clues to the formation's aqueous origins. He said about 25 separate analyses have been conducted with Curiosity's Alpha Particle X-ray Spectrometer, more than 100 images have been recorded by the Mars Hand Lens Imager, and the ChemCam instrument has taken 12,000 laser shots at the rock.

The gray color of the rock dust suggests that the interior of Martian rocks may reflect ancient geological processes that are significantly different from the current weathering process on the Red Planet, Hurowitz told NBC News.

"This is something that the science team is really excited about — the fact that the tailings from our drill operation aren't the typical rusty orange red that we associate with just about everything on Mars," he said. "You can probably bet that when things turn orange, it's because there's a rusting process of some kind going on that oxidizes the iron in the rock. So the fact that these rocks aren't that color may be telling us that these rocks didn't go through that process that usually turns things to rust on Mars. It may preserve some indication of what iron was doing in these samples without the effect of some later oxidative process."

Eventually, Curiosity will be commanded to retrace its route and head for a 3-mile-high (5-kilometer-high) mountain known as Aeolis Mons or Mount Sharp. But Grotzinger emphasized that the mission was "discovery-driven" — and that the rover team was in no hurry to have the rover make its mountain trek.

"We're going to take it one step at a time," Grotzinger said.

More about Mars:

• Curiosity finds organics, but are they from Mars?
• Mars rover driving through dried-up stream bed
• Cosmic Log archive on the Curiosity mission

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

By Mike Wall, Space.com

NASA's Curiosity rover has drilled into a Martian rock and collected samples, marking the first time any robot has ever performed this complicated maneuver on the surface of another planet.

The 1-ton Curiosity rover used its arm-mounted drill to bore a hole 0.63 inches (1.6 centimeters) wide and 2.5 inches (6.4 cm) deep in a section of sedimentary bedrock on Friday. The activity paves the way for the first-ever analysis of fresh Martian subsurface material and provides the last major checkout of the robot's gear and instruments, researchers said.

"The most advanced planetary robot ever designed now is a fully operating analytical laboratory on Mars," John Grunsfeld, associate administrator for NASA's Science Mission Directorate, said in a statement Saturday. "This is the biggest milestone accomplishment for the Curiosity team since the sky-crane landing last August, another proud day for America."

Curiosity will process the sample over the next few days, researchers said. The rover will use some of the material to scour its sample-handling hardware clean of any residues that may remain from Earth before transferring any powder to the analytical instruments on the rover's body. [Curiosity Rover's Amazing Mars Photos]

"We'll take the powder we acquired and swish it around to scrub the internal surfaces of the drill bit assembly," said Curiosity drill systems engineer Scott McCloskey, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "Then we'll use the arm to transfer the powder out of the drill into the scoop, which will be our first chance to see the acquired sample."

NASA / JPL-Caltech / MSSS

At the center of this image from NASA's Curiosity rover is the hole in a rock called "John Klein" where the rover conducted its first sample drilling on Mars. The drilling took place on Feb. 8.

Drilling so deep into a Red Planet rock is a complex and unprecedented maneuver, so the mission team worked its way up to the first effort in a steady, stepwise fashion.

About two weeks ago, Curiosity began assessing the target rock, which is part of an outcrop called "John Klein" that was exposed to liquid water long ago. The rover first pressed down on the rock with its arm-mounted drill in a series of "pre-load" tests. It then used the drill's percussive action to hammer the outcrop without spinning the drill bit, which cleared the way for a recent "mini-drill" that bored into rock but didn't collect samples.

Getting Curiosity ready for all these steps — and for yesterday's successful full-up drilling run — also took a lot of prep work here on Earth, researchers said.

"Building a tool to interact forcefully with unpredictable rocks on Mars required an ambitious development and testing program," said JPL's Louise Jandura, chief engineer for Curiosity's sample system said Saturday. "To get to the point of making this hole in a rock on Mars, we made eight drills and bored more than 1,200 holes in 20 types of rock on Earth."

Curiosity landed inside Mars' huge Gale Crater on the night of Aug. 5 to determine if the area has ever been capable of supporting microbial life. Along with its 10 science instruments and 17 cameras, the rover's drill is considered key to this quest, for it allows scientists to peer deep into Martian rocks for evidence of past habitability. 

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NASA / JPL-Caltech / MSSS

This image from the Mars Hand Lens Imager on NASA's Curiosity rover shows the patch of rock cleaned by the first use of the rover's wire-bristle brush on Jan. 6.

NASA's Curiosity rover used the wire-bristle brush on the end of its 7-foot-long robotic arm for the first time over the weekend, to sweep the dust off a patch of rock wide enough to put a soda can on.

Sunday's use of the motorized Dust Removal Tool, or DRT, marks yet another first for the $2.5 billion Mars Science Laboratory mission, which began operations on the Red Planet with Curiosity's landing last August. The mission team selected an easy target for the tryout: a flat patch of rock known as "Ekwir_1" in the Yellowknife Bay area of Mars' Gale Crater, where Curiosity has been spending the past few weeks.

"We wanted to be sure we had an optimal target for the first use," Diana Trujillo of NASA's Jet Propulsion Laboratory, the mission's activity lead for the DRT, explained in today's status report. "We need to place the instrument within less than half an inch of the target without putting the hardware at risk. We needed a flat target, one that wasn't rough, one that was covered with dust. The results certainly look good."

The area cleaned by the DRT measured about 1.85 inches by 2.44 inches (47 by 62 millimeters). In addition to the brush, the end of Curiosity's robotic arm is equipped with a percussive drill, a close-up camera known as the Mars Hand Lens Imager, the Alpha Particle X-ray Spectrometer and a dirt scooper.

The rover team is evaluating several rocks in the area as potential targets for the first use of the drill sometime in the next few weeks. Brushing off potential targets will be part of the preparation for that drilling operation.

The primary aim of Curiosity's two-year mission is to sample rocks, soil and the atmosphere at Mars' Gale Crater to determine whether the chemical requirements for life could have been present there billions of years ago.

More about Curiosity's mission:

• Tiny 'Martian flower' stirs up some buzz
• Curiosity spends the holidays at 'Grandma's House'
• Rover finds organic compounds, but are they from Mars?
• Cosmic Log archive on Curiosity's Mars mission

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.