Prior to LIGO’s discovery, other organizations had also planned experiments for detection of gravitational waves. In the early 2000s, NASA and ESA collaborated in finding ways to detect gravitational waves. After several theories, they came up with LISA (Laser Interferometer Space Antenna). LISA is an interferometer that will detect gravitational waves while existing out in space. It will have three spacecraft in the formation of an equilateral triangle with arms lengths of 5 million kilometers and will be able to measure amplitude, direction, and polarization of gravitational waves all at once. However, due to cost and practicality, NASA and ESA called off their collaboration in 2011. Still, ESA continued to pursue LISA. When LIGO made the first discovery of gravitational waves in 2015, it re-sparked a sudden attraction to the research and a new space race began. Due to LIGO’s discovery and the successful testing of LISA Pathfinder (a small spacecraft designed to test the technologies necessary for a successful LISA mission), NASA has strongly considered rejoining ESA in the LISA mission.
LISA is much more powerful than any ground-based interferometer in that it can detect frequencies as small as 0.1 millihertz, which will allow observations from many more sources, especially those that are most predictable and most powerful that we cannot detect now because their frequencies are too low. The lowest frequency that LIGO can detect is about 1 hertz, due to excessive amount of noise on Earth. The noise signals on Earth are caused from everyday disruptions such as traffic or ocean waves. In space, the only noise that would be detected would be from solar winds and solar radiation pressure which can both be compensated for and hardly show up as noise at all. For the most powerful sources of gravitational waves, their signal would be approximately 10 million times stronger than any expected noise detected.
LIGO has been a tremendous success in opening opportunities in the gravitational wave research. Now, scientists need to expand on that foundation and use gravitational wave research to find out more about our universe. Learn more information about LISA and the NASA-ESA collaboration from two articles, "NASA and ESA May Team Up to Measure Gravitational Waves" and "Space Science: LISA Overview."