Fraunhofer Institute for High Frequency Physics and Radar Techniques FHRNew capabilities for Fraunhofer FHR’s Space Surveillance Radar TIRA (Tracking and Imaging Radar): In view of the growing amount of space debris and increasingly small and compact satellites, the demands on space surveillance are rising. The resolution of current imaging reconnaissance systems will soon be insufficient to reliably detect critical details. Therefore, TIRA will receive a comprehensive upgrade in the TIRA-HD project to be able to image space objects in low Earth orbit with high-resolution and polarimetry in the future.
In the past, only space organizations such as ESA, NASA, and JAXA sent their satellites into space; private companies like SpaceX have now entered the satellite business on a massive scale. Given the numerous objects in low Earth orbit between about 200 and 2,000 kilometers above the Earth’s surface, orderly and safe satellite operation is becoming increasingly difficult. Many satellite operators are therefore already selecting higher altitudes for their satellites. But as distance increases, objects become harder to detect and more difficult to image for ground-based radar systems, since less energy is reflected back.
In the coming years, the demand for mission support, especially for high-value satellites, will also rise noticeably. Operators need reliable information about the condition of their systems: Is there damage to the satellite? And if yes, what kind? Such questions will be increasingly difficult to answer with current systems. There is therefore an urgent need for new imaging systems.
Requirements for Space Surveillance Systems
As a space surveillance system, radar offers significant advantages over optical systems: Optical systems only yield results under cloud-free skies and the satellite has to be illuminated by the Sun, but not the sensor itself. Radar systems, on the other hand, operate regardless of weather and light conditions – equally efficiently.
However, the requirements for spatial resolution are now enormous. After all, even small satellites should appear not only as points in radar images. In the future, details such as mountings or damages should be detectable.
High-resolution Space Imaging Radar: The TIRA-HD project
The TIRA-HD project closes this gap. The goal is the development of a high-resolution imaging radar that also uses the polarization of radar waves. The antenna transmits radar waves with different polarizations, which are reflected differently by space objects and are received back by TIRA. In this way, complex structures can be recognized, distinguished, and analyzed much more clearly. While certain object structures in one polarization direction may appear weakly or not at all, they are more clearly visible in the other polarization direction.
Moreover, polarization enables separating different object parts that would otherwise lie in the same image pixels due to the inverse Synthetic Aperture Radar (ISAR) processing used. This results in significantly more precise and informative image data.
With TIRA-HD, researchers at Fraunhofer FHR equip TIRA with completely new capabilities that make the space radar fit for the future requirements of space surveillance and open up new possibilities for monitoring, analysis, and risk assessment in space.