Radar technology can be used to obtain a variety of astronomical observations, ranging from the rotation of Venus to stunning photographs of things in space. One of these images was revealed earlier this year, and as technology advances, new perspectives emerge.
Researchers created the highest-resolution photographs of the moon ever acquired from Earth using a radar beam less powerful than a microwave oven. The stunning image was created with the help of the Green Bank Telescope (GBT) using a technology known as synthetic aperture radar (SAR). The radio telescope, the world’s largest fully steerable, sends signals that bounce off the moon’s surface and return to Earth, where they are received, stored, and analyzed into a complete image.
“Radar data like this has never been recorded before at this distance or resolution,” added Galen Watts, an engineer at the Green Bank Observatory. “This has been done before at distances of a few hundred kilometers, but not on the scale of hundreds of thousands of kilometers as in this project, and not with the high resolution of a meter or so at these distances.” It all takes a lot of computing time. Ten or so years ago, it would have taken months of computing to get one of the images from one receiver, and maybe a year or more from more than one.
The image also acts as a test for a cutting-edge flagship system now in development. That system will be a 500-kilowatt Ku-band (13.7 GHz) planetary radar for the GBT, 1,000 times more powerful, with receivers based on the VLBA and the planned Next Generation Very Large Array (ngVLA), which is now under construction. This approach could one day be used to create radio maps of much more distant worlds, like the moons of gas giants. Also, the image from Tycho is only the first of many others that will be released in the next few months.
