LISA Pathfinder will pave the way for the eLISA mission by testing in space the very concept of gravitational wave detection.
The quietest place in the solar system
LISA Pathfinder (LPF) will place two test masses in a nearly perfect gravitational free-fall, and will control and measure their relative motion with unprecedented accuracy. This is achieved through innovative technologies comprising inertial sensors, an optical metrology system, a drag-free control system and micro-Newton thruster system. The test-masses and their environment will be the quietest place in the solar system.
All these technologies are not only essential for eLISA, they also lie at the heart of any future space-based test of Einstein's General Relativity.
LPF is scheduled to launch in 2015.