Journey to the edge of time: The GREAT mission
  We are surrounded by radiation that originated from the big bang. It has traveled to us from the farthest reaches of the Universe, carrying with it an unaltered record of the beginning of time and space. The radiation is in the form of gravitational waves - propagating ripples in the curvature of spacetime. We describe a mission to detect these Gravitational Echos Across Time (GREAT) that would open up a new window on the very early universe. By studying the gravitational echoes of the big bang we will gain insight into the fundamental structure of matter, gravity, and how the Universe formed. 
Neil J. Cornish, David N. Spergel & Charles L. Bennett