Leonard David's INSIDE OUTER SPACE

Image credit: Fraunhofer FHR/Jens Fiege

In an experiment carried out by a large radar facility, Earth’s Moon was “beam bathed” to appraise the equipment’s stability and performance abilities.

The result: high-resolution radar imaging of the lunar surface, made possible by the Tracking and Imaging Radar (TIRA), a central and important part of research at Fraunhofer FHR, and one of the leading and largest European research institutes in the area of high frequency and radar techniques.

The Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR is headquartered in Wachtberg, Germany.

Radar image of the southern hemisphere of the Moon.
Image credit: Fraunhofer FHR

Northern hemisphere of the Moon captured in radar image.
Image credit: Fraunhofer FHR

First light

The experiment is referred to as “First Light” with the Moon illuminated by the powerful 34-meter TIRA antenna. Echoes reflected from the lunar surface were received after roughly 2.6 seconds. Processing of the signals included use of real-time graphics processors using special software methods.

Radar image of crater Tycho with a diameter of about 53 miles (85 kilometers) on the southern hemisphere of the Moon. The image resolution is about 65 feet (20 meters).
Image credit: Fraunhofer FHR

“By utilizing the motion of Earth and the Moon, a significantly larger, virtual aperture was created using the 34-meter antenna of the TIRA facility, thereby achieving high resolution imaging,” explains the institute in an August 22 statement.

This method of generating a synthetic antenna aperture enables coherent imaging of the entire visible Moon’s surface.

Satellite reentry

The Fraunhofer FHR regularly conducts assignments for the German Space Situational Awareness Center (GSSAC). The unique attributes of the institute’s radar work has proven useful for space debris appraisals, collision predictions, fragmentation event appraisals, as well as reentry forecasts.

Radar for Space Situational Awareness.
Image credit: Fraunhofer FHR/Andreas Schoeps

For example, the group’s radar skills were utilized to image the European Space Agency’s European Remote Sensing satellite, ERS-2, prior to it auguring into the Earth’s atmosphere on February 21 of this year. For the first time, changes in the structure during re-entry were also captured in radar images.

Radar image of the ERS-2 spacecraft from February 20, 2024 showing bent solar module.
Image credit: Fraunhofer FHR

ISS battery pallet

Similarly, Fraunhofer FHR kept an eye on the reentry of that discarded 2.6 ton battery pallet unleashed in 2021 from the International Space Station (ISS).  

The space observation radar TIRA observed the object during its final days on behalf of the joint GSSAC, providing meaningful radar data during its flyovers above Germany. TIRA likely snagged the final radar image of the battery. On March 8, a leftover from the reentry of that ISS pallet hit a house in Florida, later confirmed by NASA.

The likely last radar image of the ISS battery before its reentry, captured by the space observation radar TIRA on March 8, 2024.
Image credit: Fraunhofer FHR