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A new telescope system has successfully captured the highest resolution image of the Moon ever taken from Earth using radar technology.
The feat took years of work and the result is spectacularly detailed. The focal point is Tycho Crater, one of the most important impressions on the Moon. And even though it was taken hundreds of thousands of miles away, the image appears to be flying just above the surface of Earth’s only natural satellite.
The resulting image resolution is five meters by five meters and contains approximately 1.4 billion pixels. Together, it encompasses the entire width of Tycho Crater, all 86 kilometers in diameter (53 miles), and much more.
From this bird’s-eye view, every ripple on the Moon’s battered surface seems to stand out in great detail.
Radar image of Tycho crater. (NRAO / GBO / Raytheon / NSF / AUI)
The National Science Foundation’s Green Bank Telescope (GBT) is located in West Virginia and is the largest fully steerable radio telescope in the world. This allows astronomers to point its globular eye in any direction they want.
Earlier this year, the satellite was fitted with a new radar transmitter, developed by Raytheon Intelligence & Space, capable of sending pulses into near space.
As each of these signals bounce off the surface of the Moon, they are picked up by the Very Long Baseline Array at the National Radio Astronomy Observatory (NRAO), which is also headquartered in West Virginia.
“The stored pulses are compared to each other and analyzed to produce an image,” explains GBO engineer Galen Watts.
In January, researchers tested the system by taking a radar image of the Apollo 15 landing site, proving that they could, in fact, take high-definition images from Earth.
The radar image of the Apollo 15 landing site. (Sophia Dagnello / NRAO / GBO / Raytheon / AUI / NSF / USGS)
Months later, they managed to capture an even higher resolution image of Tycho Crater.
“The transmitter, target, and receivers are all in constant motion as we move through space,” says Watts.
“While you might think it might make producing an image more difficult, it actually produces more important data.”
Because each returning radar pulse contains information from a slightly different orientation, astronomers can obtain more angles than a stationary observation.
This means that scientists can calculate the distance to a target and the speed of that target with greater precision.
“Radar data like this has never been recorded before at this distance or resolution,” says Watts.
“This has already been done at distances of a few hundred kilometers, but not at the scale of hundreds of thousands of kilometers of this project, and not with the high resolutions of about a meter at these distances.”
Just 10 years ago, Watts says it would have taken months of computation to get an image from a single radar signal received. More than that would have taken over a year.
Astronomers hope the new technology will allow us to explore parts of the solar system that we have never seen before, all from the comfort of our own planet.
