Cosmic Explorer is a concept for a much larger LIGO-like
gravitational-wave observatory, with arms possibly 40 km in length.
The length contributes to the sensitivity, the goal being
to detect more sources, sensing events that are more distant,
that are weaker at the source, and/or that are
at frequencies for which LIGO is marginal.
Aim is an initial set-up, Cosmic Explorer 1 (CE1) in the 2030s
and an upgrade, Cosmic Explorer 2 (CE2) in the 2040s.