"Observation Possible Even with Night Sky Thousands of Times Darker"... Development of Domestic Ultra-High-Performance Astronomical Telescope

Korea Astronomy and Space Science Institute Completes 30cm-Class Freeform Mirror Telescope K-DRIFT Using Purely Domestic Technology

[Asia Economy Reporter Kim Bong-su] A celestial telescope capable of observing celestial bodies thousands of times darker than the night sky has been developed using domestic technology.

The Korea Astronomy and Space Science Institute (KASI) announced on the 31st that it has successfully developed a 30cm-class off-axis freeform telescope, K-DRIFT (KASI-Deep Rolling Imaging Fast optics Telescope), using purely domestic technology, which can efficiently observe ultra low surface brightness (Ultra LSB) celestial bodies that are thousands of times darker than the night sky.

Generally, the larger the aperture of an optical telescope, the greater its light-gathering power and resolution, which is the ability to distinguish objects. Therefore, leading observatories worldwide aim to increase the aperture size of telescopes to observe distant, faint celestial bodies that retain the early appearance of the universe. However, in the relatively nearby universe, various traces of celestial bodies that have grown over a long time exist faintly in the ultra low surface brightness range over a wide area. For observing ultra LSB celestial bodies in the nearby universe, a low-magnification telescope with a wide field of view can be more advantageous even if the aperture is not large.

The ultra LSB celestial observation research team led by Dr. Ko Jong-wan at KASI recently installed a test model of K-DRIFT at Bohyunsan Optical Astronomy Observatory and succeeded in observing the ultra LSB region around the NGC 5907 galaxy, which is about 1000 times darker than the brightness of the night sky. Although the developed telescope is a small optical telescope with a 30cm aperture, it obtained ultra LSB observation images around giant galaxies with quality comparable to the world's largest single aperture 8.2m Subaru telescope. K-DRIFT has about 1/750th the aperture area of the Subaru telescope, but considering light-gathering power, exposure time, and observation conditions according to aperture size, it showed more than 100 times better observation performance than the Subaru telescope for ultra LSB celestial observations in the nearby universe.

Typical reflecting telescopes are made as axisymmetric telescopes centered on the primary axis, but this axisymmetric structure causes a major disadvantage called secondary mirror obstruction. The newly developed K-DRIFT uses an off-axis freeform three-mirror system (Linear Astigmatism Free-Three Mirror System) to eliminate the secondary mirror obstruction, which is a drawback of conventional axisymmetric reflecting telescopes, while removing scattered light and aberrations inside the telescope and securing a wide field of view, optimizing it for ultra LSB celestial observations in the nearby universe. The off-axis freeform three-mirror system applied to this telescope requires advanced ultra-precision processing technology, and all processes from design, processing, assembly, and alignment were developed purely by domestic researchers, marking the first successful actual observation case.

Off-axis freeform reflecting telescopes like K-DRIFT can acquire high-quality images over a wider field of view even with small-aperture telescopes, making them suitable for studying the structure of the universe and our galaxy. Therefore, off-axis freeform reflecting telescopes are an efficient alternative for space telescopes, which have strict weight constraints on construction and launch costs. In particular, NASA is preparing to utilize off-axis freeform reflecting telescope technology in two of the four major missions planned for the next-generation space telescopes.

The research team has completed the installation of the K-DRIFT test model observation system at Bohyunsan Optical Astronomy Observatory and plans to begin ultra LSB region survey observations around giant galaxies in the nearby universe from the end of the year. Additionally, by further improving the performance of the off-axis freeform three-mirror system, they plan to install K-DRIFT in locations suitable for astronomical observations such as Chile after 2024 and start an all-sky ultra LSB survey.

KASI has been conducting related research since 2019 in cooperation with domestic small and medium optical component manufacturers to develop the off-axis freeform telescope domestically. KASI was responsible for ultra LSB region survey mission analysis, design, and related testing; Green Optics Co., Ltd. handled mirror processing and measurement technology development; and S&Lab Co., Ltd. was in charge of telescope mount fabrication.

Senior Researcher Ko said, “Off-axis freeform reflecting telescopes, which are competitively being developed mainly by advanced space exploration countries, are cutting-edge technologies that can be used not only for future space telescope development but also for various fields such as Earth observation.” He added, “K-DRIFT, developed through collaboration between government research institutes and industry, will pioneer a new path for ultra LSB survey observations, which have been an unknown territory until now.”

This content was produced with the assistance of AI translation services.