Trailblazing Gravitational Wave Satellite Meets Its End

Scientists are shutting down the LISA Pathfinder spacecraft after a successful mission.

We're standing at the beginning of a new era for astronomy. Last January, the LIGO observatory made an astounding discovery when it detected gravitational waves—ripples in the fabric of spacetime—for the first time ever. This means that now astronomers can use gravitational waves, in addition to light, to probe the mysteries of the cosmos.

There's only one problem: LIGO is too small.

LIGO uses two tunnels that are about 2.5 miles long, where it fires laser beams to detect gravitational waves. LIGO's tunnels are so long because the further the lasers travel, the easier it is to pick up the waves. But even at that length, LIGO is sensitive enough to spot gravitational waves from only some of the largest black hole collisions in the universe. Anything smaller and LIGO can't pick it up.

That's why the European Space Agency is going to build another gravitational wave detector in space. The proposed LISA observatory would use three satellites more than a million miles apart, shooting lasers between them to spot gravitational waves.

But it's not easy to place three satellites a million miles apart and still have them be sensitive enough to spot tiny vibrations in spacetime. So to test whether this would be possible, in 2015 the ESA launched LISA Pathfinder, a small spacecraft designed to see just how still something can get in space.

LISA Pathfinder surpassed all expectations, and in June ESA announced that the fullscale LISA satellites would be ready sometime in the 2030's. But this is the end of the road for LISA Pathfinder, as principal investigator Stefano Vitale has triggered the final kill switch on the spacecraft.

LISA Pathfinder is now little more than debris floating in the vastness of space. But it has accomplished a great deal, enabling us to start a new chapter in astronomy and explore the universe all over again in a brand new way.