Taiwan Space Agency showcases patents for optical remote sensing satellites

Misha Lu, DIGITIMES Asia, Taipei 0


Taiwan Space Agency (TASA) showcased its latest satellite technology patents on January 11th, marking its first event in 2024. Originally founded in 1991 as the National Space Program Preparatory Office, and later known as the National Space Program Office under the National Applied Research Laboratories, the Taiwan Space Agency officially came into being following the passages of Taiwan's first space law - the Space Development Law - and the Act for the Establishment of the Taiwan Space Agency in 2021 and 2022, respectively.

At the event on January 11th, TASA primarily demonstrated its patents born out of the agency's optical remote sensing satellite project, specifically its catadioptric optical system, auto-focus method for remote sensing, and mobile object detection system. Other patents included a pulsed plasma thruster and satellite attitude data fusion system. Through the demonstration, the agency seeks licensing and technology transfer opportunities.

The payload of an optical remote sensing satellite includes three subsystems: remote sensing instrument, focal plane array (FPA), and electronic unit. While a traditional telescope adopts the Cassegrain reflecting telescope design, the remote sensing instrument adopts a variation of the Cassegrain design known as Ritchey-Chrétien (RC) telescope. In this context, TASA designed a method to correct incident light into FPA imaging with a small chief ray angle (CRA) and extended the back focal length (BFL) for longer-distance spatial focusing. The technology, according to TASA, applies to smallsats, microsats, and nanosats.

When it comes to mobile object detection, TASA unveiled a method, deployable to both drones and optical remote sensing satellites, to detect moving objects in near real-time without the need for ground image post-processing analysis. According to the agency, the ground post-processing stage is a common challenge facing airborne or spaceborne platforms when they send time-sensitive images back to Earth. Another problem comes from the unstable nature of the moving platforms themselves, affecting image quality. In this context, TASA came up with an FPGA-based system that allows multiple-image processing and analysis on the edge to address the issue.

For optical remote sensing satellites, TASA also showcased a technology that can instantly detect the degree of blurring in captured images, consequently enabling the direct determination of optimal focal length on the satellites without sending the information back to the ground. The automatic verification mechanism, according to TASA, eliminates the need for specific pattern imaging or dedicated onboard illumination, in addition to reducing the complexity of the autofocus module.

The TASA launched its remote-sensing satellite program, known as FORMOSAT-8, back in 2017 when the meetings for the satellite system design review and the satellite mission definition review were completed, and the development of indigenous key components and satellite system design began. In 2019, the FORMOSAT-8 Program Office was officially established. The program is a priority as Taiwan's "National Space Technology Long-Term Development Program" enters its third phase. Notably, the bus platform developed for FORMOSAT-8 will also serve as a common platform for all of the satellite missions in the third-phase program. Six high-resolution optical sensing satellites with a resolution of 1 meter will be deployed to the sun-synchronous orbit to form a constellation, and through ground image post-processing, resolutions can achieve a sub-meter level. TASA indicates that the satellites will have multiple daily revisit capabilities, and will have 70-80% of components sourced from Taiwan.

Due to the COVID-19 pandemic, the first and second satellites of FORMOSAT-8 are planned to be launched in 2024 and 2025; the third and fourth satellites will be launched in 2026 and 2027; the fifth and sixth satellites will be launched in 2028 and 2029.