text: Curiosity Rover has discovered strange, multi-coloured veins on Mars that could give astronomers new insights into the red planet's watery past. The mineral veins were found at a site called 'Garden City' on the slopes of Mount Sharp and stick up from the rock by up to 6cm (2.5 inches). Scientists believe the bizarre network of ridges formed in Mars' wet past billions of years ago above the now eroded, much softer bedrock. This March 18,  view from the Mast Camera on the Curiosity rover shows a network of two-tone mineral veins. Scientists believe the bizarre formed in Mars' wet past billions of years ago above the now eroded bedrock . The ridges contain both bright and dark material. While Curiosity has found brightly coloured veins before, the darker ones remain have stumped scientists. 'Some of them look like ice-cream sandwiches: dark on both edges and white in the middle,' said Linda Kah, a Curiosity science-team member at the University of Tennessee, Knoxville. 'These materials tell us about secondary fluids that were transported through the region after the host rock formed.' Veins such as these form where fluids move through cracked rock and leave minerals in the fractures, often affecting the chemistry of the rock surrounding the fractures. This view from the Mars Hand Lens Imager on the arm of Curiosity rover is a close-up of a two-tone mineral vein at a site called 'Garden City' on lower Mount Sharp. It was taken during night, illuminated by LEDs . Kah said, 'At least two secondary fluids have left evidence here. 'We want to understand the chemistry of the different fluids that were here and the sequence of events. How have later fluids affected the host rock?' Some of the sequence is known: Mud that formed lake-bed mudstones must have dried and hardened before the fractures formed. The dark material that lines the fracture walls reflects an earlier episode of fluid flow than the white, calcium-sulphate-rich veins do - although both flows occurred after the cracks formed. In total, what is now the planet's arid northern plains would have contained at least 12.4 million cubic miles (20 million cubic km) of water . Thanks to missions like Nasa's Curiosity rover, we know Mars once had water - but until now we didn't know how much. Scientists have provided the best estimates yet, claiming it once had more water than the Arctic Ocean - and the planet kept these oceans for more than 1.5 billion years. The findings suggest there was ample time and water for life on Mars to thrive, but over the last 3.7 billion years the red planet has lost 87 per cent of its water - leaving it barren and dry. The study by scientists at Nasa's Goddard Space Flight Center in Greenbelt, Maryland, is the first to determine just how much water Mars had in its past. During its wet Noachian period - 4.1 to 3.7 billion years ago - it is estimated that it had enough water to cover the entire surface in a liquid layer 450 feet (137 metres) deep. However, it's likely that most of the water formed an ocean that occupied the northern hemisphere of Mars, which would have been as deep as one mile (1.6km) in places - comparable to the Mediterranean Sea on Earth. The research estimates that, in total, what is now the planet's arid northern plains would have contained at least 12.4 million cubic miles (20 million cubic kilometres) of water. Curiosity has been studying rocky areas since landing on the Martian surface in 2012. Garden City is about 39 feet (12 meters) higher than the bottom edge of the 'Pahrump Hills' outcrop of the bedrock forming the basal layer of Mount Sharp, at the center of Mars' Gale Crater. 'We investigated Pahrump Hills the way a field geologist would, looking over the whole outcrop first to choose the best samples to collect, and it paid off,' said David Blake of Nasa's Ames Research Center. Analysis is still in its early stages, but the three drilled samples from Pahrump Hills have clear differences in mineral ingredients. It seems that the two-toned minerals were created from two distinctive wet periods on the planet. Curiosity is now exploring different layers of Mount Sharp in the hope of finding more clues to the red planet's history.
target: Mineral veins were found at a site called 'Garden City' on  Mount Sharp .
  They formed in Mars' watery past above the now eroded, softer bedrock .
  Two-toned minerals were created from two wet periods on the red planet .