Amateur space enthusiasts following the progress of the Mars Curiosity rover might have discovered debris from a Russian lander which mysteriously disappeared more than 40 years ago.
The Soviet Mars 3 lander touched down on the Martian surface on December 2, 1971.
It transmitted data for just 14.5 seconds before contact was lost.
However, the reason for the malfunction has never been determined.
Now, a group of Russian enthusiasts, who have been following the Nasa mission - which is being carried out with the help of scientists from the University of Leicester - think they have spotted four pieces of hardware from the lost lander after studying photos of Red Planet's surface.
The images show what is believed to be the Mars 3 parachute, heat shield, terminal rocket and the lander itself.
The photographs were taken by the Mars Reconnaissance Orbiter, which is tracking the progress of Curiosity – the one-ton Nasa robot searching the surface for signs of a habitable environment.
The orbiter's principal investigator Alfred McEwen, from the University of Arizona, Tucson, in the US, said: "Together, this set of features and their layout on the ground provide a remarkable match to what is expected from the Mars 3 landing, but alternative explanations for the features cannot be ruled out.
"Further analysis of the data and future images to better understand the three-dimensional shapes may help to confirm this interpretation."
The Mars 3 lander was the first spacecraft which survived a Martian landing long enough to transmit data back to Earth.
Its partner lander, Mars 2, which was launched at the same time crashed without sending anything back.
The Curiosity robot is taking a short break while Mars and the Earth are on opposite sides of the Sun.
The solar conjunction, as it is known, will last until May.
Scientists are worried that any data transmitted between Earth and Mars during this time could be lost or corrupted by solar interference.
