Quoting the webpage of the project: "Gravity is the dominant force in the universe. We propose the first ever mission to survey the entire universe directly with gravitational waves, to tell us about theformation of structure and galaxies, stellar evolution, the early universe, and the structure and nature of spacetime itself. Most importantly, there will be enormous potential for discovering the parts of the universe that are invisible by other means, such as black holes, the Big Bang, and other, as yet unknown objects.
The European Space Agency has recently launched the process for choosing candidates for the next large mission launch slots. The first step in this process is the submission of white papers advocating science themes. The eLISA team will submit a compelling science case, which will be addressed by our eLISA mission concept in 2028."
79 authors and 80 contributors have worked intensively to produce this impressive white paper. The proposed mission itself is epic:
"Today we can see the beauty of the universe with modern telescopes in many wavelengths. Observing the universe with gravitational waves—which are analogous to acoustic waves—will allow us to hear the universe for the first time.
eLISA will be the first observatory to directly detect low frequency gravitational waves. It will measure the relative displacement of free-falling test masses, one million kilometers apart, by means of laser interferometry. This will enable us to determine parameters like mass, spin, orbital elements, and luminosity distance of the sources with unprecedented precision. Large parts of the technologies necessary for such a mission have already been developed, and will be tested in space by LISA Pathfinder in 2015."Almost 1000 scientists worldwide are supporting the mission, including Stephen Hawking, Edward Witten, Nobel Laureate Gerard 't Hooft and many of the most renewed faculties of Physics and Astrophysics worldwide.
If you want to learn what all of this is for, check out the project webpage!