Breakthroughs in space research have always come from big science facilities. Gravitational-wave detectors using laser interferometers, neutrino observatories that use water tanks on the scale of hundreds of thousands of tons, and radio telescopes with diameters of hundreds of meters are representative. It was thanks to such facilities that humanity could directly capture gravitational waves, unravel the mysteries of neutrinos, and sketch the shadow of a black hole.
Scientists believe that even if research on gravitational waves or neutrinos has no immediate practical value, it becomes an intellectual asset for future generations. Kajita Takaaki, a University of Tokyo professor who won the 2015 Nobel Prize in physics for neutrino research, said earlier in an interview with ChosunBiz, "Advances in semiconductors were made possible by understanding quantum mechanics, and aircraft were possible because we understood physical phenomena," adding, "If we do basic science, ideas will emerge that future generations can use."
Recently, the United States, Japan, and China have raced to complete or expand next-generation big science facilities, establishing themselves as hubs of international space research. Korea has also demonstrated competitiveness as researchers produced world-class results under limited conditions, but it shows stagnation as it falls behind in investment in large research infrastructure.
◇ United States, Japan, China, forward bases for new discoveries
In 2015, the United States, through the Laser Interferometer Gravitational-Wave Observatory (LIGO), detected gravitational waves, the "vibrations of the universe," for the first time in the world. Gravitational waves are what happens when gravitational energy ripples outward like waves during colossal events such as black hole mergers or stellar explosions. LIGO's observations confirmed gravitational waves predicted by Einstein in the general theory of relativity after 100 years and opened a new field called "gravitational-wave astronomy" to study the universe from a new perspective.
LIGO, together with Europe's Virgo interferometer and Japan's KAGRA (Kamioka Gravitational Wave Detector), is building an international network, ushering in an era of real-time capture of extreme cosmic phenomena such as black hole mergers. As sensitivity has been boosted more than twofold, the observable range of the universe has doubled, and galaxies can be captured eight times more. As of 2015, the three detectors LIGO-Virgo-KAGRA have recorded more than 300 gravitational-wave events.
Japan has also led neutrino research with big science facilities. Neutrinos are one of the fundamental particles that make up the universe, and neutrinos have been such a core research subject in modern physics and astronomy that they have yielded the Nobel Prize in physics four times so far. Thanks to the Super-Kamiokande neutrino detection experiment laboratory, Japan has accounted for half of those. Japan is building Hyper-Kamiokande with completion targeted for 2027. It is more than eight times larger than Super-Kamiokande and is being pursued in cooperation with research institutes in more than 20 countries on six continents.
The country that stands out most recently in the field of big science facilities is China. It leads the world in gravitational waves, neutrinos, and radio telescopes alike. Based on a space gravitational-wave observation plan proposed in 2014, China is pushing the "Tianqin Project." It is a project to launch three satellites around 2035 to form a space gravitational-wave observatory.
On Aug. 26, the Jiangmen Underground Neutrino Observatory (JUNO) in China, the world's most powerful neutrino detector, began official operation. It is a project that has invested about 420 billion won since 2014 and plans to analyze neutrino data over the next six years.
In 2016, China put into operation Tianyan (Sky Eye), the world's largest radio telescope with a diameter of 500 meters, seizing the forefront of global radio astronomy. Before Tianyan, the Arecibo radio telescope in the United States with a diameter of 305 meters was the world's largest, but its operation was halted due to a collapse in 2020. Tianyan's official name is FAST (Five-hundred-meter Aperture Spherical radio Telescope).
China is also building the QTT (Qitai Radio Telescope), the world's largest fully steerable radio telescope, in the Xinjiang Uygur Autonomous Region. Tianyan is a fixed radio telescope. QTT broke ground in September 2022, is scheduled for completion in 2028, and will have a diameter of 110 meters.
◇ Korea studies neutrinos at nuclear plants and dark matter in mine tunnels
Korea has also secured competitiveness in space research with big science facilities. Earlier, results from the RENO neutrino research facility built at the Hanbit Nuclear Power Plant in Yeonggwang, South Jeolla, won the Bruno Pontecorvo Prize in 2016 and the European Physical Society Prize in 2023. Neutrinos are emitted by the sun and supernovae, but they can also be detected from nuclear fission in nuclear power plants.
Yemilab in Jeongseon, Gangwon Province, is continuing the search for new dark matter. Scientists say that matter emitting light that we can observe accounts for only 5% of the universe, 68% is dark energy that drives the universe's expansion, and 27% is dark matter that does not emit light but pulls objects. Yemilab is a research facility built by utilizing the mine tunnels of Handeok Iron Mine on Mount Yemi in Jeongseon. It was completed in 2022 and has been operating since 2023.
But follow-up large projects have repeatedly fallen through. Yoo In-tae, a physics professor at Sungkyunkwan University, said, "We planned to build the world's largest neutrino observatory, 800,000 cubic meters in size at a depth of 100 meters underground, but it was halted because it did not receive government investment, and there has been little progress to this day," adding, "With a new administration in place, we are seeking to continue pushing the neutrino observatory project."
Yoo said, "Scientific research is becoming increasingly advanced, and accordingly large research facilities are needed," adding, "It is time to build large facilities to have international competitiveness not only in basic science but across science as a whole."
The situation is the same in the field of gravitational waves. Since 2013, the Korea Gravitational-Wave Research Collaboration has conceived and proposed a next-generation gravitational-wave detector model, but it stalled at the discussion stage after failing to secure research funds. Lee Kyung-ha, a Sungkyunkwan University professor who currently heads the LIGO Korea Experimental Group, said that now, beyond international cooperation, research for large facilities should be revitalized domestically.
Lee said, "The LIGO project is fully funded by the U.S. National Science Foundation (NSF), but as political conditions in the United States have recently heightened uncertainty over research funding, attempts are continuing to seek external funding from places like Europe," adding, "With a new administration and increased research and development (R&D) support in Korea, this is a timely moment to cooperate with LIGO."
The key component of a gravitational-wave observatory is the mirror. LIGO installs mirrors at both ends of a vacuum tunnel several kilometers apart and shoots a laser. If a gravitational wave passes as this laser travels, the mirrors move minutely. To have the laser reflect without noise, coating technology is crucial. Lee said, "Right now, only a French company called LMA can do (mirror coating), but as a semiconductor powerhouse, Korea can fully develop this area," adding, "It is regrettable that attempts are not even being made because the market is small."