Scientists demonstrate the existence of these waves with highly-sensitive detectors at multiple observation sites. As of 2012, the LIGO and VIRGO observatories were the most sensitive detectors, operating at resolutions of about one part in 5 × 10. The Japanese detector KAGRA was completed in 2019; its first joint detection with LIGO and VIRGO was reported in 2021. Another European ground-based detector, the Einstein Telescope, is under development. A space-based observatory, the Laser Interferometer Space Antenna, is also being developed by the European Space Agency.