Highest-ever resolution radar Moon images pave the way for next-gen planetary defense

The highest-resolution radar Moon images ever taken were captured using a transmitter less powerful than a microwave oven.
Chris Young
A synthetic aperture radar image of the Moon’s Tycho Crater.
A synthetic aperture radar image of the Moon’s Tycho Crater.

Raytheon Technologies 

A team of scientists used the National Science Foundation's Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA) to capture the highest-resolution radar images ever taken of the Moon from Earth.

Impressively, they used a transmitter less powerful than a microwave oven to capture their images, as per a press release.

Their work paves the way for a next-generation system that could capture high-detail radar images of distant worlds and could also image near-Earth asteroids with unprecedented detail, helping to boost global planetary defense efforts.

The highest-resolution radar moon images ever

The new radar images were captured as part of a collaboration between the National Radio Astronomy Observatory (NRAO), Green Bank Observatory (GBO), and Raytheon Intelligence & Space (RIS). They are in the process of designing a next-generation planetary radar system for the GBT, which is the world's largest fully steerable radio telescope.

Using a prototype for their next-gen system, the organizations were able to capture incredibly high-detail images. They did this using a low-power radar transmitter, with up to 700 watts of output power at 13.9 GHz, designed by RIS. They pointed their system at the Moon and received radar echoes using NRAO's ten 25-meter VLBA antennas.

Highest-ever resolution radar Moon images pave the way for next-gen planetary defense
One of the radar images of the moon's Tycho Crater, showing 5-meter resolution detail.

The result is an impressive image of the Moon's Tycho crater, captured with 5-meter resolution. "It's pretty amazing what we've been able to capture so far, using less power than a common household appliance," said Patrick Taylor, radar division head for GBO and NRAO. 

The next-gen radar system will be a valuable tool for planetary defense

The image not only shows unprecedented detail of the lunar surface from Earth, but it also serves as a test for a flagship state-of-the-art system that is currently in development. That system will be a 500 kilowatt, Ku-band (13.7 GHz) planetary radar for the GBT that will use the VLBA as well as the in-development future Next Generation Very Large Array (ngVLA) as receivers.

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That system will have roughly 1,000 times the output power and much more waveform bandwidth, allowing for much higher-resolution imaging. The scientists behind the new system say it will be a valuable tool for future planetary defense efforts, as it will be able to help detect, track, and collect data on potentially hazardous asteroids.

In fact, GBT data was actually used to help NASA determine the outcome of its planetary defense test mission, DART. The in-development system will allow for the observation of much more distant objects.

"In our tests, we were able to zero in on an asteroid 2.1 million kilometers away from us — more than five times the distance from the Earth to the Moon. The asteroid is about a kilometer in size, which is large enough to cause global devastation should there be an impact," Taylor said.

"With the high-power system, we could study more objects much further away," he continued. "When it comes to developing strategies for possible impacts, having more warning time is everything."

Aside from keeping us safe, the system will also allow scientists to probe our Solar System and gain new insight into the many moons and planets orbiting our sun.