The 2,000-pound Mars rover Curiosity made its landing on Mars on August 6, 2012, and has been sending back fascinating images and data ever since. Mars once had conditions favorable for microbial life, NASA scientists announced Tuesday, March 12, 2013. One piece of evidence for that conclusion comes from this area of the Martian surface, nicknamed "Sheepbed." It shows veins of sediments that scientist believe were deposited under water and was an environment once hospitable to life. See more images sent by the rover:
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(CNN) -- NASA's rover Curiosity successfully carried out a highly challenging landing on Mars early Monday, transmitting images back to Earth after traveling hundreds of millions of miles through space to explore the red planet.
Scientists praised the landing Monday.
"This is a stunning achievement. The engineering went flawlessly," said Scott Hubbard, who was the first Mars program director at NASA headquarters and is now a consulting professor at Stanford University.
The 10 science instruments aboard Curiosity are in "perfect health," and testing and calibration are under way, NASA said Monday.
Some rover team specialists are analyzing the data from the landing, while others are preparing Curiosity for exploring Gale Crater, where it landed, NASA said. On its first full day on Mars, the rover is tasked with raising its high-gain antenna, enabling it to communicate directly with Earth at higher data rates. The primary method of transmitting data is through the orbiters, because that is more energy-efficient.
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Water-ice clouds, polar ice and other geographic features can be seen in this full-disk image of Mars from 2011. NASA's Mars Curiosity Rover touched down on the planet on August 6. Take a look at stunning photographs of Mars over the years. Check out images from the Mars rover Curiosity.
Photos: Exploring Mars
When asked whether anything had gone wrong during the landing, Jennifer Trosper, a mission manager with NASA's Jet Propulsion Laboratory in California, said simply, "No."
"There's a lot ahead of us, but so far we are just ecstatic about the performance of the vehicle," she told reporters at an afternoon news conference.
She said the rover will start sending weather data Tuesday but some of the "exciting science" won't begin for about nine Mars days.
"It does take time to check out the vehicle," she said.
Social media sites were bubbling with posts from enthusiastic Earthlings on Monday. The rover even has its own Twitter account, @MarsCuriosity. It informs readers: "FYI, I aim to send bigger, color pictures from Mars later this week once I've got my head up & Mastcam active #MSL"
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The $2.6 billion Curiosity made its dramatic arrival on Martian terrain in a spectacle popularly known as the "seven minutes of terror."
This jaw-dropping landing process, involving a sky crane and the world's largest supersonic parachute, allowed the spacecraft carrying Curiosity to target the landing area that scientists had meticulously chosen.
The mission control in the Jet Propulsion Laboratory burst into cheers as the rover touched down Monday morning. Team members hugged and high-fived one another as Curiosity beamed back the first pictures from the planet, while some shed tears.
At the news conference, NASA showed off some of the initial images, including one of Mount Sharp, which rises 3.4 miles above the floor of the Gale Crater, according to NASA.
"We can see more clearly these pebbles all over the ground," said Joy Crisp, a deputy project scientist with the mission. "We can see that it is very flat. ... There are no obstacles for driving [the few miles from the landing site]" to Mount Sharp.
Scientists cannot tell yet how easy it will be to scoop up the surface material, she said.
"I think the science team has a lot of work to do to figure out how were these materials put there," she said. "Was water involved? We don't know yet."
President Barack Obama weighed in on the historic moment.
"The successful landing of Curiosity -- the most sophisticated roving laboratory ever to land on another planet -- marks an unprecedented feat of technology that will stand as a point of national pride far into the future," Obama said in a statement congratulating the NASA employees who had worked on the project.
The scientific community reacted with a mixture of elation and relief.
"Rationally I know it was supposed to work all along, but emotionally it always seemed completely crazy," said James Wray, assistant professor at Georgia Tech, who is affiliated with the science team of Curiosity. "So to see all those steps being ticked off and actually working, it's a huge relief."
The initial images the SUV-size rover sent back to Earth were black and white and grainy, but one showed its wheel resting on the stony ground, and the vehicle's shadow appeared in another.
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A camera on NASA's Mars Reconnaissance Orbiter captured an image of the 2,000-pound rover with its parachute still attached as it made its way down toward Gale Crater. At that point, the rover was about two miles from the planet's surface.
The spacecraft had been traveling away from Earth since November 26 on a journey of about 352 million miles (567 million kilometers), according to NASA.
Curiosity, which will be controlled from the Jet Propulsion Laboratory, has a full suite of sophisticated tools for exploring Mars. They include 17 cameras, a laser that can survey the composition of rocks from a distance and instruments that can analyze samples from soil or rocks.
The aim of its work is "to assess whether Mars ever had an environment able to support small life forms," NASA said.
Curiosity's first stop was Gale Crater, which may have once contained a lake. After at least a year, the rover will arrive at Mount Sharp, in the center of the crater. The rover will drive up the mountain examining layers of sediment. This process is like looking at a historical record because each layer represents an era of the planet's history, scientists said.
The phenomenon of sedimentary layers is remarkably similar to what is seen on Earth, in California's Death Valley or in Glacier National Park in Montana, said John Grotzinger, chief scientist of the Mars Science Laboratory mission.
Rocks and minerals found on Earth are different than on Mars, but the idea of a mountain made of layers is familiar to scientists. Unlike on Earth, however, Mars has no plate tectonics, so the Martian layers are flat and not disrupted as they would be on Earth. That also means that Mount Sharp was formed in a different way than how mountains are created on Earth -- no one knows how.
In these layers, scientists are looking for organic molecules, which are necessary to create life. But even if Curiosity finds them, that's not proof that life existed -- after all, these molecules are found in bus exhaust and meteorites, too, said Steve Squyres, part of the Mars Science Laboratory science team.
If there aren't any organics, that may suggest there's something on the planet destroying these molecules, said Georgia Tech's Wray. But if Curiosity detects them, Wray said, that might help scientists move from asking, "Was Mars ever habitable?" to "Did Mars actually host life?"
Curiosity's mission is also significant in an era when NASA's budgets are shrinking and China is becoming more ambitious in its space exploration program.
"I feel like it's a signal that we have the capability to do big and exciting things in the future." said Carol Paty, assistant professor at Georgia Tech's School of Earth and Atmospheric Sciences. "You can't not be excited."
Liquid water is not something scientists expect to be apparent on Mars because the planet is so cold and dry, Squyres said. If the planet does harbor liquid water today, it would have to be deep below the surface, perhaps peeking out in a few special places, but not likely to be seen by Curiosity, Squyres said.
Rover to search for clues to life on Mars
It's hard to know how long ago liquid water would have been there because there's no mechanism to date the rocks that rovers find on Mars, Squyres said.
Evidence from the spacecraft NASA has sent to Mars so far suggests that the "warm and wet" period on the planet lasted for the first billion years of the planet's history.
"In order to create life, you need both the right environmental conditions -- which include liquid water -- and you need the building blocks from which life is built, which includes organics," Squyres said. The Mars Science Laboratory is a precursor mission to sharper technology that could do life detection, Grotzinger said.
There aren't specific molecules that scientists are looking for with Curiosity. The attitude is: "Let's go to an interesting place with good tools and find out what's there," Squyres said.
What do you think about the Mars mission? Go to iReport
Curiosity is supposed to last for two years on Mars, but it may operate longer -- after all, Spirit and Opportunity, which arrived on Mars in 2004, were each only supposed to last 90 Martian days. Spirit stopped communicating with NASA in 2010 after getting stuck in sand, and Opportunity is still going.
"You take what Mars gives you," said Squyres, also the lead scientist on the Mars Exploration Rover Mission, which includes Spirit and Opportunity. "If we knew what we were going to find, it wouldn't be this much fun."
CNN's Jethro Mullen contributed to this report.
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The rock on the left, called Wopmay, was discovered by the rover Opportunity, which arrived in 2004 on a different part of Mars. Iron-bearing sulfates indicate that this rock was once in acidic waters. On the right are rocks from Yellowknife Bay, where rover Curiosity is situated. These newly discovered rocks are suggestive of water with a neutral pH, which is hospitable to life formation.
NASA's Curiosity rover shows the first sample of powdered rock extracted by the rover's drill. In subsequent steps, the sample will be sieved to be analyzed. The image was taken by Curiosity's mast camera on Wednesday, February 20.
The rover drilled this hole, in a rock that's part of a flat outcrop researchers named "John Klein," during its first sample drilling on Mars on February 8.
The latest self-portrait of the rover combines dozens of images taken by the rover's Mars Hand Lens Imager (MAHLI) on February 3.
NASA's Mars rover Curiosity has taken its first set of nighttime photos, including this image of Martian rock illuminated by ultraviolet lights. Curiosity used the camera on its robotic arm, the Mars Hand Lens Imager, to capture the images on January 22. The rover began beaming back pictures of Mars' surface after arriving on the planet in August 2012.
Another nighttime image includes this rock called Sayunei in the Yellowknife Bay area of Mars' Gale Crater. Curiosity's front-left wheel had scraped the rock to inspect for fresh, dust-free materials in an area where drilling for rock soon will begin.
Other night photos includes this image of the calibration target for the Mars Hand Lens Imager camera at the end of the rover's robotic arm. For scale, a penny on the calibration target is three-fourths of an inch in diameter.
A view of what NASA describes as "veined, flat-lying rock" selected as the first drilling site for the Mars rover taken on January 10.
Curiosity used a dust-removal tool for the first time to clean this patch of rock on the Martian surface on January 6.
The rover captured this mosaic of images of winding rocks known as the Snake River on December 20.
A view of the shallow depression known as "Yellowknife Bay," taken by the rover on December 12.
The Mars rover Curiosity recorded this view from its left navigation camera after an 83-foot eastward drive on Sunday, November 18. The view is toward "Yellowknife Bay" in the "Glenelg" area of Gale Crater.
Three "bite marks" made by the rover's scoop can be seen in the soil on Mars surface on October 15.
The robotic arm on NASA's Mars rover Curiosity delivered a sample of Martian soil to the rover's observation tray for the first time on October 16.
This image shows part of the small pit or bite created when NASA's Mars rover Curiosity collected its second scoop of Martian soil on October 15. The rover team determined that the bright particle near the center of the image was native to Mars, and not debris from the rover's landing.
This image shows what the rover team has determined to be a piece of debris from the spacecraft, possibly shed during the landing. The image was taken on October 11.
The rover's scoop contains larger soil particles that were too big to filter through a sample-processing sieve. After a full-scoop sample had been vibrated over the sieve, this portion was returned to the scoop for inspection by the rover's mast camera on October 10.
This 360-degree panorama shows the area where the rover will spend about three weeks collecting scoopfuls of soil for examination. The photo comprises images taken from the rover's navigation camera on October 5.
An area of windblown sand and dust downhill from a cluster of dark rocks has been selected as the likely location for the first use of the scoop on the arm of NASA's Mars rover Curiosity.
Curiosity cut a wheel scuff mark into a wind-formed ripple at the "Rocknest" site on October 3, to give researchers a better opportunity to examine the particle-size distribution of the material forming the ripple.
NASA's Curiosity rover found evidence for what scientists believe was an ancient, flowing stream on Mars at a few sites, including the rock outcrop pictured here. The key evidence for the ancient stream comes from the size and rounded shape of the gravel in and around the bedrock, according to the Jet Propulsion Laboratory/Caltech science team. The rounded shape leads the science team to conclude they were transported by a vigorous flow of water. The grains are too large to have been moved by wind.
This photos shows an up-close look at an outcrop that also shows evidence of flowing water, according to the JPL/Caltech science team. The outcrop's characteristics are consistent with rock that was formed by the deposition of water and is composed of many smaller rounded rocks cemented together. Water transport is the only process capable of producing the rounded shape of conglomerate rock of this size.
Curiosity completed its longest drive to date on September 26. The rover moved about 160 feet east toward the area known as "Glenelg." The rover has now moved about a quarter-mile from its landing site.
This image shows the robotic arm of NASA's Mars rover Curiosity with the first rock touched by an instrument on the arm. The photo was taken by the rover's right navigation camera.
This image combines photographs taken by the rover's Mars Hand Lens Imager at three distances from the first Martian rock that NASA's Curiosity rover touched with its arm. The images reveal that the target rock has a relatively smooth, gray surface with some glinty facets reflecting sunlight and reddish dust collecting in recesses in the rock.
This rock will be the first target for Curiosity's contact instruments. Located on a turret at the end of the rover's arm, the contact instruments include the Alpha Particle X-Ray Spectrometer for reading a target's elemental composition and the Mars Hand Lens Imager for close-up imaging.
Researchers used the Curiosity rover's mast camera, on September 7, to take a photo of the Alpha Particle X-Ray Spectrometer. The image was used to see if it had been caked in dust during the landing.
Researchers also used the mast camera to examine the Mars Hand Lens Imager (MAHLI) on the rover to inspect its dust cover and check that its LED lights were fucntional. In this image, taken on September 7, the MAHLI is in the center of the screen with its LED on. The main purpose of Curiosity's MAHLI camera is to acquire close-up, high-resolution views of rocks and soil from the Martian surface.
This is the open inlet where powdered rock and soil samples will be funneled down for analysis. The image is made up of eight photos taken on September 11, by MAHLI and is used to check that the instrument is operating correctly.
This is the calibration target for the MAHLI. This image, taken on September 9, shows that the surface of the calibration target is covered with a layor of dust as a result of the landing. The calibration target includes color references, a metric bar graphic, a penny for scale comparison, and a stair-step pattern for depth calibration.
This view of the three left wheels of NASA's Mars rover Curiosity combines two images that were taken by the rover's Mars Hand Lens Imager on Sunday, September 9, the 34th Martian day of Curiosity's work on Mars. In the distance is the lower slope of Mount Sharp.
This view of the lower front and underbelly areas of NASA's Mars rover Curiosity was taken by the rover's Mars Hand Lens Imager on Sunday. Also visible are the hazard avoidance cameras on the front of the rover.
The penny in this image is part of a camera calibration target on NASA's Mars rover Curiosity. The image was taken by the Mars Hand Lens Imager camera on Sunday.
The reclosable dust cover on Curiosity's Mars Hand Lens Imager was opened for the first time on Saturday, September 8, enabling MAHLI to take this image.
Curiosity rover used a camera located on its arm to obtain this self-portrait on Friday, September 7. The image of the top of Curiosity's Remote Sensing Mast, showing the Mastcam and Chemcam cameras, was taken by the Mars Hand Lens Imager. The angle of the frame reflects the position of the MAHLI camera on the arm when the image was taken. The image was acquired while MAHLI's clear dust cover was closed.
The left eye of the Mast Camera on NASA's Mars rover Curiosity took this image of the rover's arm on Wednesday, September 5.
Sub-image one of three shows the rover and its tracks after a few short drives. Tracking the tracks will provide information on how the surface changes as dust is deposited and eroded.
Sub-image two shows the parachute and backshell, now in color. The outer band of the parachute has a reddish color.
Sub-image three shows the descent stage crash site, now in color, and several distant spots (blue in enhanced color) downrange that are probably the result of distant secondary impacts that disturbed the surface dust.
An image released Monday, August 27, was taken with Curiosity rover's 100-millimeter mast camera, NASA says. The image shows Mount Sharp on the Martian surface. NASA says the rover will go to this area.
The Mars rover Curiosity moved about 15 feet forward and then reversed about 8 feet during its first test drive on Wednesday, August 22. The rover's tracks can be seen in the right portion of this panorama taken by the rover's navigation camera.
NASA tested the steering on its Mars rover Curiosity on Tuesday, August 21. Drivers wiggled the wheels in place at the landing site on Mars.
Curiosity moved its robot arm on Monday, August 20, for the first time since it landed on Mars. "It worked just as we planned," said JPL engineer Louise Jandura in a NASA press release. This picture shows the 7-foot-long (2.1-meter-long) arm holding a camera, a drill, a spectrometer, a scoop and other tools. The arm will undergo weeks of tests before it starts digging.
With the addition of four high-resolution Navigation Camera, or Navcam, images, taken on August 18, Curiosity's 360-degree landing-site panorama now includes the highest point on Mount Sharp visible from the rover. Mount Sharp's peak is obscured from the rover's landing site by this highest visible point.
This composite image, with magnified insets, depicts the first laser test by the Chemistry and Camera, or ChemCam, instrument aboard NASA's Curiosity Mars rover. The composite incorporates a Navigation Camera image taken prior to the test, with insets taken by the camera in ChemCam. The circular insert highlights the rock before the laser test. The square inset is further magnified and processed to show the difference between images taken before and after the laser interrogation of the rock.
An updated self-portrait of the Mars rover Curiosity, showing more of the rover's deck. This image is a mosiac compiled from images taken from the navigation camera. The wall of Gale Crater, the rover's landing site, can be seen at the top of the image.
This image shows what will be the rover's first target with it's chemistry and camera (ChemCam) instrument. The ChemCam will fire a laser at the rock, indicated by the black circle. The laser will cause the rock to emit plasma, a glowing, ionized gas. The rover will then analyze the plasma to determine the chemical composition of the rock.
This is a close-up of the rock that will be the ChemCam's first target.
This image, cropped from a larger panorama, shows an area, near the rover's rear left wheel, where the surface material was blown away by the descent-stage rockets.
This image, with a portion of the rover in the corner, shows the wall of Gale Crater running across the horizon at the top of the image.
This image, taken from the rover's mast camera, looks south of the landing site toward Mount Sharp.
This partial mosaic from the Curiosity rover shows Mars' environment around the rover's landing site on Gale Crater. NASA says the pictured landscape resembles portions of the U.S. Southwest. The high-resolution mosaic includes 130 images, but not all the images have been returned by the rover to Earth. The blackened areas of the mosaic are the parts that haven't been transmitted yet. 
In this portion of the larger mosaic from the previous frame, the crater wall can be seen north of the landing site, or behind the rover. NASA says water erosion is believed to have created a network of valleys, which enter Gale Crater from the outside here.
In this portion of the larger mosaic from the previous frame, the crater wall can be seen north of the landing site, or behind the rover. NASA says water erosion is believed to have created a network of valleys, which enter Gale Crater from the outside here.
Two blast marks from the descent stage's rockets can be seen in the center of this image. Also seen is Curiosity's left side. This picture is a mosaic of images taken by the rover's navigation cameras.
A color image from NASA's Curiosity rover shows the pebble-covered surface of Mars. This panorama mosaic was made of 130 images of 144 by 144 pixels each. Selected full frames from this panorama, which are 1,200 by 1,200 pixels each, are expected to be transmitted to Earth later.
A panoramic photograph shows the Curiosity rover's surroundings at its landing site inside Gale Crater. The rim of Gale Crater can be seen to the left, and the base of Mount Sharp is to the center-right.
A partial view of a 360-degree color panorama of the Curiosity rover's landing site on Gale Crater. The panorama comes from low-resolution versions of images taken Thursday, August 9, with a 34-millimeter mast camera. Cameras mounted on Curiosity's remote sensing mast have beamed back fresh images of the site.
NASA's Curiosity rover took this self-portrait using a camera on its newly deployed mast.
A close-up view of an area at the NASA Curiosity landing site where the soil was blown away by the thrusters during the rover's descent on August 6. The excavation of the soil reveals probable bedrock outcrop, which shows the shallow depth of the soil in this area.
This color full-resolution image showing the heat shield of NASA's Curiosity rover was obtained during descent to the surface of Mars on Monday, August 13. The image was obtained by the Mars Descent Imager instrument known as MARDI and shows the 15-foot diameter heat shield when it was about 50 feet from the spacecraft.
This first image taken by the Navigation cameras on Curiosity shows the rover's shadow on the surface of Mars.
The color image captured by NASA's Mars rover Curiosity on Tuesday, August 7, has been rendered about 10% transparent so that scientists can see how it matches the simulated terrain in the background.
This image comparison shows a view through a Hazard-Avoidance camera on NASA's Curiosity rover before and after the clear dust cover was removed. Both images were taken by a camera at the front of the rover. Mount Sharp, the mission's ultimate destination, looms ahead.
The four main pieces of hardware that arrived on Mars with NASA's Curiosity rover were spotted by NASA's Mars Reconnaissance Orbiter. The High-Resolution Imaging Science Experiment camera captured this image about 24 hours after landing.
This image is a 3-D view in front of NASA's Curiosity rover. The anaglyph was made from a stereo pair of Hazard-Avoidance Cameras on the front of the rover. Mount Sharp, a peak that is about 3.4 miles high, is visible rising above the terrain, though in one "eye" a box on the rover holding the drill bits obscures the view.
This view of the landscape to the north of NASA's Mars rover Curiosity was acquired by the Mars Hand Lens Imager on Monday afternoon on the first day after landing.
This view of the landscape to the north of NASA's Mars rover Curiosity was acquired by the Mars Hand Lens Imager on Monday afternoon, the first day after landing.
This is one of the first pictures taken by Curiosity after it landed. It shows the rover's shadow on the Martian soil.
Another of the first images taken by the rover. The clear dust cover that protected the camera during landing has popped open. Part of the spring that released the dust cover can be seen at the bottom right, near the rover's wheel.
This image shows Curiosity's main science target, Mount Sharp. The rover's shadow can be seen in the foreground. The dark bands in the distances are dunes.
Another of the first images beamed back from NASA's Curiosity rover on August 6 is the shadow cast by the rover on the surface of Mars.
NASA's Mars Curiosity Rover, shown in this artist's rendering, touched down on the planet on August 6.
This image was captured in 1976 by Viking 2, one of two probes sent to investigate the surface of Mars for the first time. NASA's Viking landers blazed the trail for future missions to Mars.
The Valles Marineris rift system on Mars is 10 times longer, five times deeper and 20 times wider than the Grand Canyon. This composite image was made from NASA's Mars Odyssey spacecraft, which launched in 2001.
The Nili Fossae region of Mars is one of the largest exposures of clay minerals discovered by the OMEGA spectrometer on Mars Express Orbiter. This image was taken in 2007 as part of a campaign to examine more than two dozen potential landing sites for NASA's new Mars rover, Curiosity, also known as the NASA Mars Science Laboratory.
NASA's Mars Phoenix Lander descends to the surface of Mars in May 2008. Fewer than half of the Mars missions have made successful landings.
Phoenix's robotic arm scoops up a sample on June 10, 2008, the 16th Martian day after landing. The lander's solar panel is seen in the lower left.
In 2006, NASA's Mars Exploration Rover Spirit captured a 360-degree view known as the McMurdo panorama. The images were taken at the time of year when Mars is farthest from the sun and dust storms are less frequent.
The European Space Agency's Mars Express captured this view of Valles Marineris in 2004. The area shows mesas and cliffs as well as features that indicate erosion from flowing water.
This view is a vertical projection that combines more than 500 exposures taken by Phoenix in 2008. The black circle on the spacecraft is where the camera itself is mounted.
A portion of the west rim of the Endeavour Crater sweeps southward in this view from NASA's Mars Exploration Rover Opportunity in 2011. The crater is 22 kilometers (13.7 miles) across.
A photo captured by NASA's Mars Global Surveyor in 2000 offers evidence that the planet may have been a land of lakes in its earliest period, with layers of Earth-like sedimentary rock that could harbor the fossils of any ancient Martian life.
A U.S. flag and a DVD containing a message for future explorers of Mars, science fiction stories and art about the planet, and the names of 250,000 people sit on the deck of Phoenix in 2008.
A rock outcrop dubbed Longhorn and the sweeping plains of the Gusev Crater are seen in a 2004 image taken by the Mars Exploration Rover Spirit.
Although it is 45 kilometers (28 miles) wide, countless layers of ice and dust have all but buried the Udzha Crater on Mars. The crater lies near the edge of the northern polar cap. This image was taken by NASA's Mars Odyssey Orbiter in 2010.
NASA's Opportunity examines rocks inside an alcove called Duck Bay in the western portion of the Victoria Crater in 2007.
Pictured is a series of troughs and layered mesas in the Gorgonum Chaos region of Mars in 2008. This photo was taken by Mars Orbiter Camera on the Mars Global Surveyor.
An image captured in 2008 by NASA's Mars Reconnaissance Orbiter shows at least four Martian avalanches, or debris falls, taking place. Material, likely including fine-grained ice and dust and possibly large blocks, detached from a towering cliff and cascaded to the gentler slopes below.
This 2008 image spans the floor of Ius Chasma's southern trench in the western region of Valles Marineris, the solar system's largest canyon. Ius Chasma is believed to have been shaped by a process called sapping, in which water seeped from the layers of the cliffs and evaporated before it reached the canyon floor.
Pictured is the Martian landscape at Meridiani Planum, where the Mars Exploration Rover Opportunity successfully landed in 2004. This is one of the first images beamed back to Earth from the rover shortly after it touched down.
An image from the Mars Global Surveyor in 2000 shows potential evidence of massive sedimentary deposits in the western Arabia Terra impact crater on the surface of Mars.
The Mars Reconnaissance Orbiter captures a dust devil blowing across the Martian surface east of the Hellas impact basin in 2007. Dust devils form when the temperature of the atmosphere near the ground is much warmer than that above. The diameter of this dust devil is about 200 meters (650 feet).
Soft soil is exposed when the wheels of NASA's Mars Exploration Rover Spirit dig into a patch of ground dubbed Troy in 2009.
An image from NASA's Mars Reconnaissance Orbiter shows the floor of the Antoniadi Crater in 2009.
The larger of Mars' two moons, Phobos, is seen in 2008 from the Mars Reconnaissance Orbiter.
Earth and the moon are seen in 2007 from the Mars Reconnaissance Orbiter. At the time the image was taken, Earth was 142 million kilometers (88 million miles) from Mars.
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