Earlier this year it was officially announced that researchers had detected gravity waves with the Laser Interferometer Gravitational-Wave Observatory (LIGO), a pair of observatories located in the United States. Today, just a few months later, researchers announced a key step in building the next generation of gravitational wave observatories, in space.

In a paper published today in Physical Review Letters, researchers announced that the free fall experiment on the LISA Pathfinder spacecraft was a success.

The Pathfinder mission is a spacecraft that carries two identical 'test masses', small blocks made of a gold-platinum alloy that are situated exactly 38 cm apart. The recent experiment showed that it was possible for these two blocks to be in a constant state of free fall inside the spacecraft. Launched by the European Space Agency in December of last year, it is currently located 1.5 million miles away from Earth, and has only been operating since March. It is a test mission, designed to show that a larger project, the currently mothballed Laser Interferometer Space Antenna (LISA) is possible.