An illustration depicts the possible extent of an ancient lake inside Gale Crater, where the Mars rover Curiosity landed on the Red Planet 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.
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.
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.
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, 2012. This gave 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, 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.
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 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 functional. In this image, taken on September 7, 2012, 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, 2012, 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, 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.
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.
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.
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.
The rover captured this mosiac of a rock feature called 'Snake River" on December 20, 2012.
The reclosable dust cover on Curiosity's Mars Hand Lens Imager was opened for the first time on September 8, 2012, enabling MAHLI to take this image.
The Curiosity rover used a camera located on its arm to obtain this self-portrait on September 7, 2012. 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 left eye of the Mast Camera on NASA's Mars rover Curiosity took this image of the rover's arm on Wednesday, September 5, 2012.
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.
STORY HIGHLIGHTS
- Mars Curiosity rover finds evidence of clay formations, or "mudstone"
- Clay may have held the key ingredients for life billions of years ago
- Scientist calls findings "a game changer"
(CNN) -- Curious about life on Mars? NASA's rover Curiosity has now given scientists the strongest evidence to date that the environment on the Red Planet could have supported life billions of years ago.
Since Curiosity made its
rock star landing more than a year ago at Gale Crater, the focal point of its mission, the roving laboratory has collected evidence that gives new insights into Mars' past environment.
MAVEN to study Mars from above
NASA scientists announced in March that
Mars could have once hosted life -- at least, in the distant past, based on the chemical analysis of powder collected from Curiosity's drill. An area of the crater known as Yellowknife Bay once hosted "slightly salty liquid water," Michael Meyer, lead scientist for the Mars Exploration Program at NASA headquarters in Washington, said earlier this year.
Six new studies released Monday by the journal Science add more insights about these formerly habitable conditions and provide other new knowledge that increase our understanding of the Red Planet. The results were also presented at the fall meeting of the American Geophysical Union in San Francisco.
Curiosity found evidence of clay formations, or "mudstone," in Yellowstone Bay, scientists said Monday. Martian mud is a big deal because this clay may have held the key ingredients for life billions of years ago. It means a lake must have existed in this area.
"This is a game changer since these are the kind of materials that are very 'Earth-like' and conducive for life," said Douglas Ming, lead author of one of the new studies.
This ancient environment, where the clay minerals formed, would have been favorable to microbes, Ming told CNN.
Some bacteria on Earth called chemolithoautotrophs could have lived in that kind of environment. These bacteria derive their energy from breaking down rocks and sediments, Ming said, generally by oxidizing elements in the rock.
Ming and colleagues also found hydrogen, oxygen, carbon, nitrogen, sulfur and phosphorus in the sedimentary rocks at Yellowknife Bay, elements that are all critical for life.
The new findings mean the rover's $2.5 billion mission is "turning the corner," said John Grotzinger, a California Institute of Technology planetary geologist and chief scientist for Curiosity, also known as the Mars Science Laboratory.
Grotzinger and colleagues found the habitable environment existed later in Martian history than previously thought. By studying physical characteristics of rock layers in and near Yellowknife Bay, they determined that Mars was habitable less than 4 billion years ago -- about the same time as the oldest signs we have for life on Earth.
The habitable conditions could have remained for millions to tens of millions of years, with rivers and lakes appearing and disappearing over time.
Curiosity also helped scientists figure out the age of an ancient Martian rock, as described in the new research. The rock is called Cumberland, and it now has the distinction of being the first whose age was measured on another planet through chemical analysis.
The rover used a method for dating Earth rocks that measures the decay of an isotope of potassium as it slowly changes into argon. Scientists determined the rock was between 3.86 billion and 4.56 billion years old. This age range is consistent with earlier estimates for rocks in Gale Crater.
Scientists say roughly 4 billion years ago, the environment on Mars wasn't much different from that of modern-day Earth. But things on Mars then took a drastic turn, and the planet was dramatically transformed from warm and wet to bitterly cold and dry, scientists say. In addition to the cold and dry conditions, scientists say the No. 1 reason life probably wouldn't have thrived on Mars is its extremely high levels of radiation.
"The radiation environment on Mars is unlike anything we have on Earth," said Jennifer Eigenbrode, a biogeochemist and geologist at NASA's Goddard Space Flight Center and an author of one of the studies. "We don't know if life on Mars could have ever adapted to the high levels of radiation the surface is currently experiencing."
Eigenbrode added, "This is a wide-open book, which we have barely started writing the pages of."
New radiation measurements will also be important to planning any human missions to Mars, scientists said.
"Our measurements also tie into Curiosity's investigations about habitability," study co-author Don Hassler of Southwest Research Institute in Boulder, Colorado, said in a statement. "The radiation sources that are concerns for human health also affect microbial survival as well as preservation of organic chemicals."
Organic chemicals come from a variety of sources, including meteorites and comets, but they can also be indicative of life.
What's bad for us is bad for signs of life -- but these organic chemicals could still be hiding on Mars nonetheless.