Mars rover Curiosity

The rover drilled this dime-sized hole to collect a sample from a rock called "Buckskin" on July 30.

Mars rover Curiosity

This April 10 view from the navigation camera on Curiosity shows the terrain ahead of the rover as it makes its way west through a valley called "Artist's Drive."

Mars rover Curiosity

The Mars rover Curiosity does a test drill on a rock dubbed "Bonanza King" to determine whether it would be a good place to dig deeper and take a sample. But after the rock shifted, the test was stopped.

Mars rover Curiosity

Curiosity used the equivalent of a dust broom to sweep away reddish oxidized dust from the Bonanza King rock. The rover's team decided to ditch the site and drive Curiosity toward other destinations.

Mars rover Curiosity

Wheel tracks from Curiosity are seen on the sandy floor of a lowland area dubbed "Hidden Valley" in this image taken August 4.

Mars rover Curiosity

The rover recently encountered this iron meteorite, which NASA named Lebanon. This find is similar in shape and luster to iron meteorites found on Mars by the previous generation of rovers.

Mars rover Curiosity

Curiosity took this nighttime photo of a hole it drilled May 5 to collect soil samples. NASA said this image combines eight exposures taken after dark on May 13.

Mars rover Curiosity

An arm of Curiosity drills two holes into sandstone on May 5. The rock powder collected will be analyzed by the rover's onboard instruments.

Mars rover Curiosity

This view of the twilight sky and Martian horizon, taken by Curiosity, includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth. A human observer with normal vision, if standing on Mars, could easily see Earth and the moon as two distinct, bright "evening stars."

Mars rover Curiosity

This mosaic of images from the Navigation Camera on Curiosity shows the terrain to the west from the rover's position on the 528th Martian day, or sol, of the mission on January 30. The images were taken right after Curiosity had arrived at the eastern edge of a location called "Dingo Gap."

Mars rover Curiosity

An illustration depicts the possible extent of an ancient lake inside Gale Crater, where the rover landed in August 2012. The $2.5 billion NASA mission set out to explore Gale Crater, which was thought to have once hosted flowing water. Curiosity found evidence of clay formations, or "mudstone," in the crater's Yellowknife Bay, scientists said in 2013. This clay may have held the key ingredients for life billions of years ago. It means a lake must have existed in the area.

Mars rover Curiosity

The Curiosity rover took this image of a rock formation informally dubbed "Darwin." Scientists had the rover stop in this region, called Waypoint 1, because it appeared to be a prime area to study the inner makeup and history of the floor of the Gale Crater. Analysis of Darwin may provide evidence of whether water played a role in the layering of rocks in this region.

Mars rover Curiosity

Curiosity began a trek toward Mount Sharp after spending more than six months in the "Glenelg" area. This image was taken on July 16, 2013, after the rover passed the 1-kilometer mark for the total distance covered since the start of the mission.

Mars rover Curiosity

The lower slopes of Mount Sharp are visible at the top of this image, taken on July 9, 2013. The turret of tools at the end of the rover's arm, including the rock-sampling drill in the lower left corner, can also be seen.

Mars rover Curiosity

This image, taken by the rover on July 8, 2013, shows the tracks left behind after the rover's first drive away from the "Glenelg" area.

Mars rover Curiosity

Curiosity drilled into a rock target called "Cumberland" on May 19, 2013, and it collected a powdered sample of material from the rock's interior. The sample will be compared to an earlier drilling at the "John Klein" site, which has a similar appearance and is about 9 feet away.

Mars rover Curiosity

Mars once had conditions favorable for microbial life, NASA scientists announced on 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.

Mars rover Curiosity

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 was situated. These rocks are suggestive of water with a neutral pH, which is hospitable to life formation.

Mars rover Curiosity

Curiosity shows the first sample of powdered rock extracted by the rover's drill. The image was taken by Curiosity's mast camera on February 20, 2013.

Mars rover Curiosity

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 February 8, 2013.

Mars rover Curiosity

Curiosity's first set of nighttime photos include 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, 2013.

Mars rover Curiosity

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 would soon begin.

Mars rover Curiosity

Other night photos included 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.

Mars rover Curiosity

A view of what NASA describes as "veined, flat-lying rock." It was selected as the first drilling site for the Mars rover.

Mars rover Curiosity

Curiosity used a dust-removal tool for the first time to clean this patch of rock on the Martian surface on January 6, 2013.

Mars rover Curiosity

The rover captured this mosaic of images of winding rocks known as the Snake River on December 20, 2012.

Mars rover Curiosity

A view of the shallow depression known as "Yellowknife Bay," taken by the rover on December 12, 2012.

Mars rover Curiosity

The Mars rover Curiosity recorded this view from its left navigation camera after an 83-foot eastward drive on November 18, 2012. The view is toward "Yellowknife Bay" in the "Glenelg" area of Gale Crater.

Mars rover Curiosity

Three "bite marks" made by the rover's scoop can be seen in the soil on Mars surface on October 15, 2012.

Mars rover Curiosity

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, 2012.

Mars rover Curiosity

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, 2012. 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.

Mars rover Curiosity

This image shows what the rover team has determined to be a piece of debris from the spacecraft, possibly shed during the landing.

Mars rover Curiosity

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.

Mars rover Curiosity

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, 2012.

Mars rover Curiosity

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.

Mars rover Curiosity

Curiosity cut a wheel scuff mark into a wind-formed ripple at the "Rocknest" site on October 3, 2012. This gave researchers a better opportunity to examine the particle-size distribution of the material forming the ripple.

Mars rover Curiosity

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.

Mars rover Curiosity

This photo is 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.

Mars rover Curiosity

Curiosity completed its longest drive to date on September 26, 2012. The rover moved about 160 feet east toward the area known as "Glenelg." As of that day the rover had moved about a quarter-mile from its landing site.

Mars rover Curiosity

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.

Mars rover Curiosity

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.

Mars rover Curiosity

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.

Mars rover Curiosity

Researchers used the Curiosity rover's mast camera to take a photo of the Alpha Particle X-Ray Spectrometer. The image was used to see whether it had been caked in dust during the landing.

Mars rover Curiosity

Researchers also used the mast camera to examine the Mars Hand Lens Imager on the rover to inspect its dust cover and check that its LED lights were functional. In this image, taken on September 7, 2012, the imager is in the center of the screen with its LED on. The main purpose of Curiosity's imager camera is to acquire close-up, high-resolution views of rocks and soil from the Martian surface.

Mars rover Curiosity

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, 2012, by the imager and is used to check that the instrument is operating correctly.

Mars rover Curiosity

This is the calibration target for the imager. This image, taken on September 9, 2012, 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.

Mars rover Curiosity

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 September 9, 2012, the 34th day of Curiosity's work on Mars. In the distance is the lower slope of Mount Sharp.

Mars rover Curiosity

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. Also visible are the hazard avoidance cameras on the front of the rover.

Mars rover Curiosity

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.

Mars rover Curiosity

The rover captured this mosiac of a rock feature called 'Snake River" on December 20, 2012.

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