LOS ANGELES (AP) -- Space fans from Russia scanning NASA images have spotted what may be a Soviet spacecraft that landed on Mars in 1971 and then mysteriously stopped working.
Photos taken by NASA's Mars Reconnaissance Orbiter circling the red planet pointed to what may be the Mars 3 lander along with its parachute, heat shield and other hardware that it jettisoned during the descent through the thin Martian atmosphere.
While scientists said the find appeared promising, more follow-up was needed to rule out other possibilities.
Mars 3 operated for only 15 seconds on the Martian surface before it suddenly stopped communicating. It was part of a double mission the Soviet Union launched in 1971. Its twin, Mars 2, crashed.
The Russian space enthusiasts were part of an online group that followed the Curiosity rover, NASA's latest Mars mission. They used crowdsourcing to pore through publicly available archive images and contacted scientists about their find.
Earlier this year, at the group's request, the reconnaissance orbiter passed over the region where Mars 3 was thought to have landed and photographed the site.
While the pictures showed features that appeared consistent with a spacecraft landing, scientists said they could just be rocks or other natural geological formations.
There are future plans to take more pictures and talk to Russian engineers about the mission to get a better idea of the landing process.
There's always the chance that "we may not get a definitive answer," said Alfred McEwen of the University of Arizona, Tucson, who is in charge of the camera aboard the reconnaissance orbiter.
During Curiosity's landing last year, the reconnaissance orbiter was able to locate its parachute, rocket stage and cables that were cast away as the car-size vehicle touched down inside an ancient crater. In that case, engineers knew where Curiosity would land, allowing scientists to direct the spacecraft to be in the right place to capture the landing.