The U.S. National Radio Astronomy Observatory (NRAO) website has published images of the lunar crater Tycho with a resolution of five by five meters. These are the most detailed images to date obtained using the Green Bank Observatory (GBT) radio telescope in West Virginia, equipped with new technology for converting radar signals into an image.
GBT, the world’s largest fully controlled radio telescope, was equipped with a new technology developed by one of the American military-industrial company Raytheon divisions at the end of 2020. After that, the updated GBT, together with the VLBA (Very Long Baseline Array) telescopes located throughout the United States, took pictures of several sections of the Moon’s surface, including the Tycho crater and the landing sites of NASA’s Apollo spacecraft.
After processing the results of the observations, scientists received the first most detailed image ever taken from the Earth of the surface of the satellite of our planet. It contains 1.4 billion pixels, and the resolution is approximately five by five meters.
“This is the largest synthetic aperture radar image that we have created to date,” Tony Beasley, director of the National Radio Astronomy Observatory, is quoted in the NRAO press release. — Although there is still a lot of work ahead to improve these images, we are happy to share this incredible image with the public and look forward to receiving new images as part of this project soon.”
The new technology makes it possible to convert a low-power radar signal into an image using a process called synthetic aperture radar, or SAR.
“Every pulse that GBT transmits is reflected from the target, in this case from the surface of the Moon, is received and stored,” explains Galen Watts, GBO engineer. – The stored pulses are compared with each other and analyzed to create an image. The transmitter, the target, and the receivers are all constantly moving as we move through space. Although you may think that this makes it challenging to create an image, it allows you to get more important data.”
Small differences arising from the pulse to the pulse of the radar are associated with the movement. These differences are used to achieve a higher resolution compared to that which can be obtained with stationary observations.
“Such radar data has never been recorded from such a distance before,” Watts says. “Previously, this was done at distances of several hundred kilometers, but not hundreds of thousands of kilometers, as in this project, and not with such a high resolution.”
The authors note that processing such an array of observations would have required months of calculations to get at least one image a few years ago.
The researchers hope that in the future, a powerful radar system combined with GBT sky coverage will allow obtaining images of various objects of the Solar System with unprecedented detail and sensitivity. It is expected that the following detailed images of the lunar surface will appear this fall, as digital data processing is already underway.