Using new radar technology on the 100-m Robert C. Byrd Green Bank Telescope, astronomers have imaged a relatively young lunar crater called Tycho.
Partially processed view of Tycho Crater at a resolution of nearly 5 x 5 m and containing approximately 1.4 billion pixels, taken during a radar project by Green Bank Observatory, National Radio Astronomy Observatory, and Raytheon Intelligence & Space using the Green Bank Telescope and antennas in the Very Long Baseline Array. Image credit: NRAO / GBO / Raytheon / NSF / AUI.
Tycho Crater is an impact crater located in the southern highlands of the Moon.
It has a diameter of 85 km (53 miles), a depth of 4.8 km (3 miles), and is surrounded by a distinctive ray system forming long spokes that reach as long as 1,500 km (932 miles).
Named after the Danish astronomer Tycho Brahe, it is estimated to be 108 million years old.
Like many of the craters on the Moon’s near side, it was given its name by the Jesuit astronomer Giovanni Riccioli.
The new image of Tycho Crater from the Green Bank Telescope covers an area of 200 by 175 km (124 by 109 miles).
It contains approximately 1.4 billion pixels and its resolution is close to 5 by 5 m (16 by 16 feet).
“This is the largest synthetic aperture radar image we have produced to date with the help of our partners at Raytheon,” said Dr. Tony Beasley, director of the National Radio Astronomy Observatory, and vice president for Radio Astronomy at Associated Universities, Inc.
“While more work lies ahead to improve these images, we’re excited to share this incredible image with the public, and look forward to sharing more images from this project in the near future.”
The Green Bank Telescope was outfitted in 2020 with new technology allowing it to transmit a radar signal into space.
Using this telescope and antennas from the Very Long Baseline Array, several tests have been conducted since that time, focusing on the surface of the Moon, including Tycho Crater and NASA Apollo landing sites.
“It’s done with a process called synthetic aperture radar,” said Galen Watts, an engineer at NSF’s Green Bank Observatory.
“As each pulse is transmitted by the Green Bank Telescope, it’s reflected off the target, the surface of the Moon in this case, and it’s received and stored.”
“The stored pulses are compared to each other and analyzed to produce an image.”
“The transmitter, the target, and the receivers are all constantly moving as we move through space.”
“While you might think this could make producing an image more difficult, it actually yields more important data.”
“This movement causes slight differences from radar pulse to pulse. These differences are examined and used to compute an image resolution higher than what is possible with stationary observations, as well as to increase the resolution of the distance to the target, how fast the target is moving toward or away from the receiver, and how the target is moving across the field of view.”
