WASHINGTON // A spacecraft circling the Moon has snapped the sharpest photos ever of the tracks and rubbish left behind by Apollo astronauts in their visits from 1969 to 1972.
Images taken by Nasa's Lunar Reconnaissance Orbiter from between 21 and 24 kilometres up show the astronauts' paths when they walked on the Moon, as well as ruts left by a moon buggy. Experts could even identify the backpacks astronauts pitched out of their lunar landers before they returned to Earth.
"What we're seeing is a trail," said Mark Robinson, an Arizona State University geology professor and the orbiter's chief scientist. "It's totally awesome."
However, the photos were not close enough to see individual bootprints, Professor Robinson said.
The pictures were taken two weeks ago and show the landing sites for Apollo 12, 14 and 17. The closest images are of the 1972 Apollo 17 site, the last Moon mission.
The Apollo 17 commander, Eugene Cernan, said the photo gives him a chance to revisit those days, "this time with a little nostalgia and disappointment. Nostalgia because those special days are fondly etched in my memory and disappointment because it looks like now we will not be going back within the days I have left on this planet."
Two years ago, images from the same spacecraft from between 48km and 96km out showed fuzzier images. But this year the orbiter dipped down to take about 300,000 more close-ups. The trails left by the astronauts are clear, but the places where backpacks were discarded, Apollo 17's moon buggy, and the bottom parts of the three lunar landers are blurry.
Professor Robinson said: "You have to really look at it for a long time to figure out what you're looking at." For example, when it comes to the moon buggy he said, "if you squint really hard you can resolve the wheels and that the wheels are slightly turned to the left".
At first, scientists thought they had a bit of a mystery: they saw more stuff than they expected. It turned out to be packing material and an insulation blanket, Professor Robinson said.
After 40 years there does not seem to be much moon dust covering the man-made trails. It probably will take about 10 million to 100 million years for dust to cover them, Professor Robinson said.
The photos were released a few days after the debut of the fictional movie Apollo 18 and before tomorrow's planned launch of Nasa's twin robotic spaceships to explore the Moon's gravity.