NASA / JPL-Caltech

A Martian view from one of Curiosity's hazard avoidance cameras, transmitted back to Earth on Thursday, shows the shadow of the instrument turret on the rover's robotic arm.

NASA's Curiosity rover is back in business after a weeks-long communication gap caused by solar interference. The proof comes in the form of pictures transmitted back to Earth on Thursday from the 1-ton machine's vantage point at Yellowknife Bay on Mars.

"Can you hear me now? Conjunction is over. I have a clear view of Earth & am back to work!" the rover tweeted (with a little help from her entourage at NASA's Jet Propulsion Laboratory).

Dozens of raw images are on display on NASA's Mars Curiosity website, featuring rocky terrain in the foreground and the 3-mile-high (5-kilometer-high) peak known as Mount Sharp or Aeolis Mons in the background. Other Mars probes, including the Opportunity rover, Mars Odyssey and Mars Reconnaissance Orbiter, are back at work as well.

NASA's Red Planet probes were on hiatus for most of April due to an unfavorable alignment of Mars, Earth and the sun. During solar conjunction, the sun gets in the way of the communication lines between the two planets, and mission controllers generally put science operations on hold. Such conjunctions occur every 26 months. Opportunity has gone through several communication breaks during its nine years on Mars, but this is the first one to occur since Curiosity landed last August.

The spacecraft weren't completely idle during the break: Curiosity conducted in-place investigations and sent back limited transmissions via X-band radio to let controllers at NASA's Jet Propulsion Laboratory know that it was doing OK. Opportunity autonomously flipped its computer into safe mode during the break, apparently due to a glitch involving a routine camera check. A fresh set of software commands fixed the glitch, and on Wednesday controllers reported that Opportunity was back in working order.

Curiosity is due for its own software upgrade, and then the rover is scheduled to drill out a second sample of ground-up rock for analysis. The first sample, analyzed in March, suggested that the Yellowknife Bay environment was potentially habitable billions of years ago. Scientists want to use the follow-up sample to confirm what they saw in previous chemical analyses.

After Curiosity finishes up its work in Yellowknife Bay and its surroundings in the Glenelg area of Gale Crater, controllers plan to point the rover toward Mount Sharp, 6 miles (10 kilometers) away. The science team suspects that the mountain's many layers of rock will hold further evidence of ancient organic chemistry.

More about Mars:

• Cosmic Log archive on Curiosity
• Old phallic picture on Mars sparks new titters
• NASA lets poets send haiku to Red Planet

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

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.

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 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.

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.

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

A photographic mosaic shows the Curiosity rover's surroundings at a Martian location known as Yellowknife Bay. This view has been assembled from black-and-white images captured by the rover's navigation camera on Sol 132 (Dec. 19). Gaps in imagery of the Martian sky have been filled in, and the whole scene has been colorized. Click here or on the image to see the complete 360-degree panorama.

The cameras on NASA's Curiosity rover have been clicking away over the holidays — gathering enough pictures for a 360-degree panorama of its rocky surroundings at Yellowknife Bay, plus a close-up view showing a "Martian flower" seemingly sprouting from the surface.

The panorama was assembled from pictures snapped by the rover's navigation camera system on the 132nd Martian day of Curiosity's mission on the Red Planet, also known as Sol 132 or Dec. 19.

In this case, the folks doing the assembling are Ken Kremer, a New Jersey-based journalist, research chemist and photographer; and Marco Di Lorenzo, a physicist who's a high-school educator and photographer in Italy. They stitched together the black-and-white images, filled in the gaps in the Martian sky and colorized the scene to reflect what an observer on Mars might see.

We've featured the efforts of Kremer and Di Lorenzo several times before: They're part of an active online community that makes use of the raw images provided by Curiosity and other Mars probes, and then shares them via websites such as UnmannedSpaceflight.com. Even now, the folks at UnmannedSpaceflight are posting plenty of amazing pictures from Yellowknife Bay, including a must-see, zoomable GigaPan version. 

Another picture from Sol 132 has stirred up some buzz at the Above Top Secret discussion forum. The picture focuses in on a bright, crumpled object that's sitting on a Martian outcrop, as seen by the rover's Mars Hand Lens Imager, or MAHLI. The translucent shape is reminiscent of a flower's pistils, which led one of the forum's members to call it a "Martian flower."   

NASA / JPL-Caltech / MSSS

An anomalous bit of bright material can be seen left of center in this view captured by Curiosity's Mars Hand Lens Imager on Sol 132 of the mission (Dec. 19).

Update for 8:30 p.m. ET: I initially suspected that the flower was a tiny shred of plastic from the rover itself. Such a shred popped up in October. At that time, experts at NASA's Jet Propulsion Laboratory surmised that the plastic may have been a bit of wrapping that was knocked loose from the Mars Science Laboratory's descent stage during the spacecraft's August landing. The plastic was thought to have fallen on top of the rover, and then dropped to the ground weeks later.

That's what led me to go with the plastic-scrap hypothesis. However, some of the folks commenting on the pictures noted that the object seemed to be embedded in the rock — which would argue against my hypothesis. So I put in an inquiry with Guy Webster, who serves as JPL's main spokesman for NASA's Mars missions.

A couple of hours later, Webster emailed me the verdict: "That appears to be part of the rock, not debris from the spacecraft."

Mystery solved? It's certainly an intriguing bit of mineral that stands out prominently in the MAHLI picture. If I find out anything more, I'll be sure to pass it along. And if it turns out that flowers are really sprouting up on Mars, you'll know it's time to cue up the "X-Files" theme. Either way, the truth is out there.  

More pictures from Kremer and Di Lorenzo:

• Scenes from Mars' 'Promised Land'
• Rover checks out its belly on Mars
• Curiosity adds color to Martian peak
• Mars rover points to its destination
• Still more from KenKremer.com

More about Martian anomalies:

• Opportunity's rover rotini
• Spirit's 'Mermaid on Mars'
• Opportunity's bunny ears
• Phoenix's Martian spring

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. You can also check out "The Case for Pluto," my book about the 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

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

This mosaic of imagery from Curiosity's navigation camera system shows a scoop on the end of the rover's robotic arm taking a sample of Martian soil on Sol 66 (Oct. 12).

NASA's Curiosity rover is rooting around what scientists call the Martian "Promised Land" — a place where three geological formations come together to provide a deliciously complex picture of Mars' ancient past.

Although the ultimate destination for Curiosity's $2.5 billion, two-year mission is a 3-mile-high mountain called Aeolis Mons or Mount Sharp, the rover is going to be spending the next few weeks nosing around its current site, which is called Glenelg. That name comes from a geological formation in Canada's Northwest Territories, but it's also a fitting name because it's spelled the same forward and backward. Similarly, Curiosity will be going backward and forward, retracing its steps for a while when it's time to head for the mountain.

Considering that Curiosity will be in the Promised Land for several weeks, we might as well get to know the place. These pictures from Ken Kremer and Marco Di Lorenzo show you the rover's surroundings. Kremer is a New Jersey-based journalist, research chemist and photographer; Di Lorenzo is a physicist who's a high school educator and photographer in Italy.

Both men are part of an active "amateur" community that makes use of the imagery provided by Curiosity and other Mars probes, such as NASA's Mars Reconnaissance Orbiter and Opportunity rover. "Amateur" is in quotes, because the work done by amateur image-processing gurus is such a great complement to the professional work from the Mars mission teams.

Many of these gurus hang out online at UnmannedSpaceflight.com. Some also maintain their own Mars-related websites, such as Martian Vistas, the Gale Gazette and the Road to Endeavour. If you haven't checked out these sites yet ... well, what are you waiting for? And if you have other recommendations for interplanetary imagery, such as the Mars Science Laboratory mission's home page or the Planetary Society's blog network, feel free to pass them along as a comment below.

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

A series of images captured by Curiosity's Mastcam system shows the foreground terrain on Sol 50 (Sept. 26), with eroded hills in the background. Click on the picture to see a larger image.

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

This panorama shows Curiosity's view of Glenelg on Sol 64 (Oct. 10), with hills in the far distance. The mosaic was assembled from 75 images acquired by the Mastcam 100 camera. Click on the picture to see a larger image.

Where in the Cosmos
I used a section of one of the Kremer/Di Lorenzo panoramas as today's "Where in the Cosmos" puzzle picture on the Cosmic Log Facebook page, and it took only a matter of seconds for Bart Salatka (and many others) to name Glenelg as the place where the picture was taken. To reward his quick wits and fast fingers, I'm sending Salatka a pair of 3-D glasses that are being provided courtesy of Microsoft Research's WorldWide Telescope project. Two of the close runners-up, Josh Sandler and Manny Acevedo, are eligible to receive 3-D glasses as well. Those cardboard specs will come in handy for seeing 3-D pictures from Curiosity's mission, such as this fresh view of the Rocknest site at Glenelg.

Congratulations to the other recent winners of "Where in the Cosmos" honors: Kevin Seaford, Lee Robbins and Tom Phillips for recognizing a satellite image of the aurora borealis; and Jeff Henager and Jenn Mason for identifying dust streaks on Mars. To get in on the action, click the "like" button for the Cosmic Log Facebook page. But hang tight: Due to travel plans, the next "Where in the Cosmos" contest won't take place until December. More about that later...

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

Three bite marks left in the Martian ground by the scoop on the Curiosity rover's robotic arm are visible in this image taken by the rover's right navigation camera during the mission's 69th Martian day, or sol (Oct. 15).

NASA's Curiosity rover is analyzing its first Martian soil sample, a load of dirt that may well include some of the "bright shiny objects" noticed by Curiosity's cameras.

Scientists have determined that the mysterious bright flecks of material are native to Mars, and may represent a different kind of mineral. That's one big reason why Curiosity's science team members are so anxious to get back the first detailed mineralogical analysis of Martian soil.

"The most important thing about our mobile laboratory is that it eats dirt," Caltech's John Grotzinger, project scientist for the $2.5 billion Curiosity mission, told reporters today. "That's what we live on."

The bright bits in the sandy soil measure about a millimeter wide, as big as a medium-sized grain of sand. In close-up pictures taken by Curiosity's MAHLI imager, those bits were so unlike the typical reddish grains that scientists held up on scooping dirt into the rover's CheMin (Chemistry and Mineralogy) analyzer until they could figure out what the schmutz was. (Grotzinger said that the science team adopted the Yiddish word for dirt when referring to anomalous bits of bright material on the Martian surface.) 

Last week, Curiosity's cameras spotted a different kind of schmutz that the scientists concluded was plastic debris from the rover itself. This time around, scientists were "super-paranoid" about the potential for putting a contaminated sample into the highly sensitive CheMin lab, Grotzinger said. That's why they took their time deciding whether the latest bright flecks were artificial or natural.

By Monday, the scientists decided they were natural — which raised a new question: What's behind the brightness?

NASA / JPL-Caltech / MSSS

This image shows part of the small pit or bite created when NASA's Curiosity rover collected its second scoop of Martian soil at a sandy patch called "Rocknest." The bright particle near the center of this image, and similar ones elsewhere in the pit, prompted concern because a small, light-toned shred of debris from the spacecraft had been observed previously nearby. However, the mission's science team assessed the bright particles in this scooped pit to be native Martian material rather than spacecraft debris. This image was taken by Curiosity's Mars Hand Lens Imager, or MAHLI camera, during the 69th Martian day, or sol, of the mission (Oct. 15).

NASA / JPL-Caltech / MSSS

The robotic arm on NASA's Curiosity rover Curiosity delivered a sample of Martian soil to the rover's observation tray for the first time during the mission's 70th Martian day, or sol (Oct. 16). This image taken later that same sol by the rover's left Mast Camera shows the sample on the tray. The tray is 3 inches (7.8 centimeters) in diameter. The sample came from the third scoopful of material collected at Rocknest.

Grotzinger said there were two hypotheses on the table. The first was that the mineral grains were cleaved during their formation to create flat, shiny surfaces that reflect sunlight better than typical Martian sand. The second was that the bright grains really are a different kind of mineral, mixed in with the garden-variety dirt.

The X-ray analysis from the CheMin lab, coupled with additional readings from Curiosity's laser-blasting ChemCam analyzer, should tell the tale, Grotzinger said. "We're kind of hoping that ChemCam can be useful to analyze these particles on a grain-by-grain basis," he said.

One scoopful of dirt, collected by an attachment on the rover's robotic arm, had been used earlier to clean out the internal surfaces of Curiosity's soil-sampling system. A second scoopful was dumped out without being used because of the contamination concerns. The third scoopful was shaken through the system this week, and some of that dirt was fed into CheMin's inlet funnel on Wednesday.

The mineralogical analysis is a big part of Curiosity's two-year mission to determine whether ancient Mars had the chemical wherewithal to be potentially habitable. Grotzinger said that Martian soil could well have served as a home for subsurface life billions of years ago, when the planet was warmer and wetter.

"Now, once and for all, we hope to address what's in the soil of Mars, mineralogically," he said.

Curiosity's other onboard lab — known as Surface Analysis on Mars, or SAM for short — was expected to get its first sample next week. Later on, the rover will use its drill for the first time on Martian rock. Grotzinger suggested that Curiosity would spend the next few weeks investigating the site where it is now: a place known as Glenelg, where three geologically distinct formations come together.

"We consider ourselves to be in the promised land," he said.

By the end of the year, Curiosity is expected to turn back from Glenelg and make its way toward a 3-mile-high (5-kilometer-high) mountain sitting in the middle of Gale Crater, about 6 miles (10 kilometers) away. The six-wheeled, nuclear-powered rover landed on Mars on Aug. 5. Today is the mission's 72nd Martian day, or sol — and although Curiosity has picked up a few dings on its wheels, project manager Richard Cook said the rover "continues to be in great health."

The only recent glitch involved NASA's Mars Reconnaissance Orbiter, which temporarily went into safe mode. That meant the Curiosity team had to turn instead to NASA's Mars Odyssey probe as a backup communication relay for data from the surface. Fortunately, MRO's controllers resolved the safe-mode issue, and "yesterday they went back to full operations," Cook said.

Slideshow: Curiosity's space odyssey to Mars

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

Launch slideshow

More about the Curiosity mission:

• Rover digs up shiny particles on Mars
• Rock turns out to be a true curiosity
• Weird Martian object traced to rover
• Cosmic Log archive for 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.