More signs that there was once water on Mars have been uncovered by a Nasa rover.
A rock crushed under the Curiosity Mars rover's wheels split open to reveal a dazzling white interior - a sign that it contains hydrated minerals, formed when water flowed through it, scientists say.
Powder drilled from a Martian rock last week revealed evidence of drinkable water and conditions favourable to life.
Now instruments on the rover have found more water-bearing minerals in the area around the rock.
NASA images of a rock known as 'Tintina' broken under one of the Mars rover Curiosity's wheels reveals its striking white interior. Powder drilled from Martian rocks has revealed evidence of drinkable water and conditions favourable to life
Curiosity is exploring a region within Gale Crater, near the Martian equator, called Yellowknife Bay.
Scientists believe that billions of years ago water poured down the rim of the crater and formed streams that might have been up to three feet deep.
The new discoveries were made using the infrared imaging capability of Curiosity's mast camera, and an instrument that shoots neutron particles into the ground to probe for hydrogen.
Differences in brightness between near-infrared wavelengths of light can indicate the presence of some hydrated minerals that have been altered by water.
An image captured by the Mast Camera (Mastcam) on NASA's Mars rover Curiosity revealing interesting internal color in this rock which was broken by Curiosity when it drove over it
Water-bearing minerals in Tintina and elsewhere have added to a list of water evidence at the area
'These bright veins contain hydrated minerals that are different from the clay minerals in the surrounding rock matrix.'
The Russian-made Dynamic Albedo of Neutrons (DAN) instrument detected hydrogen in water molecules bound into minerals in the soil beneath the rover.
GROUNDBREAKING DISCOVERY
The rock is made up of a fine-grained mudstone containing clay minerals, sulfate minerals and other chemicals.
The patch of bedrock where Curiosity drilled for its first sample lies in an ancient network of stream channels descending from the rim of Gale Crater.
This ancient wet environment, unlike some others on Mars, was not harshly oxidizing, acidic or extremely salty.
The bedrock also is fine-grained mudstone and shows evidence of multiple periods of wet conditions, including nodules and veins.
The patch of bedrock where Curiosity drilled for its first sample lies in an ancient network of stream channels descending from the rim of Gale Crater.
This ancient wet environment, unlike some others on Mars, was not harshly oxidizing, acidic or extremely salty.
The bedrock also is fine-grained mudstone and shows evidence of multiple periods of wet conditions, including nodules and veins.
'More water is detected at Yellowknife Bay than earlier on the route,' said DAN deputy principal investigator Dr Maxim Litvak, from the Space Research Institute in Moscow.
'Even within Yellowknife Bay, we see significant variation.'
The findings were presented at the Lunar and Planetary Science Conference in The Woodlands, Texas.
Just last week Nasa announced that analysis of a rock sample collected by the rover found key chemical ingredients that show Mars could once have supported primitive life.
Scientists identified sulphur, nitrogen, hydrogen, oxygen, phosphorus and carbon - some of the key chemical ingredients for life - in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed.
The data indicated the Yellowknife Bay area the rover is exploring was the end of an ancient river system or an intermittently wet lake bed that could have provided chemical energy and other favourable conditions for microbes.
'We have found a habitable environment that is so benign and supportive of life, that probably if this water was around and you had been there, you would have been able to drink it,' said project scientist John Grotzinger at the time.
Michael Meyer, lead scientist for NASA's Mars Exploration Program at the agency's headquarters in Washington, added: 'A fundamental question for this mission is whether Mars could have supported a habitable environment.
'From what we know now, the answer is yes.'
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