Ground-based gravitational wave observatory

One of LISA's ground-based counterparts: the LIGO (Light Interferometry Gravitational-wave Observatory) observatory in Hanford, Washington, USA, with twin lasers fired along an L-shaped vacuum tunnel, each arm 4km long. It operates in conjunction with a second LIGO observatory 3000 km away in Livingston, Louisiana.
Earth’s seismic noise disturbs these detectors over seconds-long timescales, a fact that limits them to looking for higher-frequency gravitational waves from smaller astronomical objects, such as neutron stars and small black holes.

However, deep space opens a new window to the low frequency gravitational wave spectrum with which LISA will observe, among other phenomena, the most powerful events in the universe – the collision and merger of super-massive black holes.