'Blueberries' on Mars! Stunning images of the red planet taken by Spirit and Opportunity rovers are revealed in a new exhibition

• Photographs part of exhibition by Smithsonian's National Air and Space Museum opening in Washington tomorrow
• Incredible close up shows spheres, dubbed blueberries, that may suggest ancient microbial life on the planet
• Along with ‘blueberry’ clusters, the exhibition includes photographs of craters, dunes, dust clouds and meteorites
• One image of the Martian sunset shows a bluish colour in the sky, which is usually pink in the daytime due to the reddish dust in the atmosphere. It turns blue at sunset - the opposite of Earth

These hematite-rich spherules were embedded in this Martian rock like blueberries in a muffin and released over time by erosion. The Mars Rover Opportunity found this cluster at its Eagle Crater landing site and analysed their composition with its spectrometers. Hypotheses about their formation have contributed to the story of water on Mars

The discovery of Martian clusters, known as ‘blueberries’, a decade ago provided some of the first evidence of liquid water on the red planet.

This incredible close up, taken by the Mars Rover Opportunity, reveals these spheres embedded in Martian rock like blueberries in a muffin.
The image is part of an exhibition by the Smithsonian's National Air and Space Museum presenting more than 50 of the best photographs from two rovers known as Spirit and Opportunity.
Ten years after Nasa landed the two rovers on Mars for a 90-day mission, one is still exploring, and the project has generated hundreds of thousands of images from the planet's surface. 

The Mars Rover Opportunity found this 'blueberry' cluster at its Eagle Crater landing site and analysed the composition with its spectrometers.

Previous theories suggested they were created by simple chemical reactions without the help of life. However, research last year revealed clear evidence that microbes were essential in their formation.
This raised the possibility that Martian ‘blueberries’ may not only reveal that water was present on Mars - but also ancient microbial life.

A view by the Mars Rover Spirit of a sunset over the rim of Gusev Crater, about 80 km (50 miles) away. Taken from Husband Hill, it looks much like a sunset on Earth, a reminder that other worlds can seem eerily familiar. Sunset and twilight images help scientists to determine how high into the atmosphere the Martian dust extends and to look for dust or ice clouds

‘Spirit and Opportunity: 10 Years Roving Across Mars’, curated by the scientists who have led the mission, opens tomorrow in Washington.
Along with unusual ‘blueberry’ clusters, it includes large-scale photographs of craters, hills, dunes, dust clouds, meteorites, rock formations and the Martian sunset.
John Grant, a planetary geologist at the museum who is part of the rover mission team, organised the exhibition, in part as a travel log with images on one side from Sprit and images from Opportunity on the other.

Rover tracks are shown disappearing toward the horizon in a sea of sand between the craters Endurance and Victoria on the Meridiani Plains. Mars rover Opportunity took the image while stuck in the sand ripple, dubbed Purgatory, for over a month

The rovers landed in January 2004 on opposite sides of Mars and began exploring volcanic deposits and plains, as well as meteorites and impact craters.