LISA and LISA PathFinder, the endeavour to detect low frequency GWs
  This is a review about LISA and its technology demonstrator, LISA PathFinder. We first describe the conceptual problems which need to be overcome in order to set up a working interferometric detector of low frequency Gravitational Waves (GW), then summarise the solutions to them as currently conceived by the LISA mission team. This will show that some of these solutions require new technological abilities which are still under development, and which need proper test before being fully implemented. LISA PathFinder (LPF) is the the testbed for such technologies. The final part of the paper will address the ideas and concepts behind the PathFinder as well as their impact on LISA. 
Henrique Araujo, Cesar Boatella, Mokhtar Chmeissani, Aleix Conchillo,   Enrique Garcia-Berro, Catia Grimani, Wojtek Hajdas, ...