7 of 8Image
Rocks on Mars
Five years after this image was taken by Spirit in 2005, Nasa scientists concluded that this area showed a past that was wet and non-acidic and could potentially sustain life as we know it.
The rocks were identified as magnesium iron carbonate with a concentration of carbonate 10 times that ever seen on Mars. According to the space agency, carbonates originate in wet, near-neutral conditions, but dissolve in acid.
Photo credit: Nasa
See more space photos on ZDNet UK.