The Laser Interferometer Gravitational Wave Observatory (LIGO) has been responsible for some tremendously exciting science this decade.

• On September 14, 2015, LIGO detected (through gravitational waves) the merger of two black holes billions of light years away.
• This triumph opened a new era of gravitational wave astronomy, giving us a radical new tool to probe the cosmos.
• LIGO and friends (like VIRGO in Europe) have since seen other black hole mash-ups and even, amazingly, the smashing of 2 neutron stars.
• The engineering required to make this observatory hop is just ridiculous.

However, per astrophysicist Ethan Siegel, LIGO misses ~100,000 black hole mergers every year. Whoa!

We need backup, apparently!

Well, help may soon be on the way, in the form of another LIGO detector under construction in India. LIGO-India "is a planned advanced gravitational-wave observatory to be located in India as part of the worldwide network." Possible benefits include:

Adding a new detector to the existing network will increase the expected event rates, and will boost the detection confidence of new sources (by increasing the sensitivity, sky coverage and duty cycle of the network). But the dramatic improvement from LIGO-India would come in the ability of localizing GW sources in the sky. Sky-location of the GW sources is computed by combining data from geographically separated detectors ('aperture synthesis'). Adding a new detector in India, geographically well separated from the existing LIGO-Virgo detector array, will dramatically improve the source-localization accuracies (5 to 10 times), thus enabling us to use GW observations as an excellent astronomical tool.

LIGO-India is set to be built by 2025. That's 2 years before our question's deadline. But delays on massive science projects happen with some frequency. (Ahem, Elon Musk. Ahem, James Webb Telescope.)