The KAGRA underground gravitational-wave observatory held a special public open house on June 20 [2].
This event provides a rare glimpse into one of the world's most advanced scientific installations, highlighting Japan's role in detecting ripples in spacetime. Because the facility is located deep underground to minimize interference, public access is strictly limited.
Located in the Kamioka mine in Hida City, Gifu Prefecture, the facility sits approximately 200 meters below the ground [2]. About 200 members of the public attended the event [1]. The guests were given the opportunity to view the low-temperature gravitational-wave detector, which features interferometer arms totaling three kilometers in length [1].
Nobel laureate in physics Takaaki Kajita attended the opening. He said that the event was a significant occasion given the long gap since the last public tour.
"The special opening is the first in nine years," Kajita said [1]. "It will be a very precious opportunity."
KAGRA is designed to detect gravitational waves—distortions in space and time caused by massive cosmic events—using cryogenic mirrors to reduce thermal noise. The facility's location within the mountains of Gifu helps shield the sensitive equipment from seismic activity and human-made vibrations. This open house marks the first time in nine years [1] that the general public has been permitted to enter the underground complex to see the technology firsthand.
“The special opening is the first in nine years.”
The reopening of KAGRA to the public reflects a transition from the facility's construction and calibration phases toward a period of sustained scientific operation and public outreach. By allowing civilians to see the 3-kilometer interferometer, the research community aims to build transparency and support for the massive investment required for gravitational-wave astronomy.
