In the first half of 2019 the NL-RIA consortium initiative and its satellite concepts have been presented by TU-Delft at several key international events for the remote sensing community.
March2019. The swarmSAR concept is for the first time introduced at the workshop “Bi and Multistatic SAR Systems and Applications” organized by TU-Delft and ESA in the TU-Delft campus.
The main concept design envisions the achievement of high-resolution, low-noise and multi-application imagery by a swarm of lightweight (within 100 Kg) instruments flying in a close formation (within a few kilometres distance) and capable to operate in MISO or MIMO mode at S-Band frequencies. The use of N receiving antennas would open the way to ATI/GMTI and high-resolution imaging modes through DPC (Displaced Phase Center) techniques. This opens up a possibility to reduce the length of the SAR antenna considerably, thereby miniaturizing the radar satellites, without sacrificing swath or image quality due to ambiguities. Enhanced imaging mode performance requires small baselines (much smaller than the critical apertures) and optimal along track positioning of the antenna phase centres with respect to the pulses. The achievement of such ideal conditions is however hindered by the variations of the relative satellite positions along the orbits and by the uncertainty in their knowledge. In practice, the achievable performance is hence lower and the added value of a new satellite in the constellation will diminish with N. The presentation shed light on the performance of different PRF approaches and highlight an optimal trade-off between number of satellites (and hence mission costs) and the image quality.
May 2019. The same concept has been presented to a broader public during the ESA Living Planet Symposium held in Milan, a key event for stakeholders in remote sensing applications and technologies. The presentation, titled “SwarmSAR: a Dutch Mini-Satellite S-Band SAR Formation Concept”, revealed the ambitions of the Dutch consortium and brought further reflection on formation design aspects and challenges.
Jul 2019. Further technical aspects of SAR imaging by means of a swarm satellite formation have been exposed at the IEEE IGARSS event in Yokohama through a SPRINT oral presentation and a poster. The event allowed further debate and networking with space agencies and private upstream players in the active microwave satellite community.