The UK and US have announced a $35m upgrade to the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO). The improvement will see the twin observatories — located near Hanford, Washington and Livingston, Louisiana in the US – double their sensitivity to gravitational waves. Work on the upgrade will start in 2023 and be complete two years later.
Each LIGO facility works by sending twin laser beams down two 4 km-long tubes – arranged as an L-shape – that are kept under a near-perfect vacuum. The beams are reflected back down the tubes by mirrors precisely positioned at the ends of each arm. As a gravitational wave passes through the observatory, it causes extremely tiny distortions in the distance travelled by each laser beam.
LIGO first turned on 2002 and was upgraded between 2010 and 2015 to improve the facilities’ ability to spot gravitational waves by a factor of 10. Thanks to this $221m upgrade – known as Advanced LIGO, or aLIGO – researchers can detect gravitational waves that originate anywhere within a sphere of about 420 million light-years in radius, centred on the Earth.
That breakthrough was announced in February 2016 when researchers working on aLIGO directly detected gravitational waves for ...