Life may have existed on Mars for a long period of time, new images from Nasa suggest.
Scientists who have been studying pictures captured by the space agency's Mars Reconnaissance Orbiter think clay-bearing sediments can be seen in them.
The images show a specific area of Mars known as Margaritifer Terra, which is ancient and littered with many craters. Nasa has previously shared an image of what it believes was once an ancient pond on the planet.
