The ET R&D project is organized in five Work Packages:

• WP1, "ET’s scientific potential", chaired by Sathyaprakash (Cardiff University/UK), having the following objectives:
  • Carry out a series of mock ET data and science challenges of increasing complexity
  • Explore how well astrophysical models of GW sources could be tested with ET
  • Investigate possible strong field tests of GR with ET
  • Probe ET’s potential for understanding the geometry and dynamics of the Universe
• WP2, "Long term seismic and GGN studies of selected sites", chaired by Nikhef (Netherlands), having the following objectives:
  • Studies at candidate sites
  • Sensor and network development
  • Modeling of seismic and GGN noise
• WP3, "Optical properties of silicon at cryogenic temperatures", chaired by Ronny Nawrodt (Friedrich Schiller Universität Jena, Germany), having the following objectives:
  • Stress induced birefringence of silicon-based optic
  • Homogeneity of optical properties within larger samples
  • Homogeneity of optical properties within larger samples
  • Investigation of Whispering Gallery Mode Oscillators made of silicon to probe absorption and scattering
• WP4, "ET Control systems", chaired by Andreas Freise (Birmingham University, UK)),having the following objectives:
  • Mitigation scheme for radiation pressure effects for the ET-HF interferometer.
  • Control scheme for the injection of frequency dependent squeezed light.
  • Low-frequency control scheme for the ET-LF interferometer.
  • Mitigation scheme for correlated noise in co-located interferometers.
  • Contamination of potential null stream signals by technical noises.

• WP4, "Management", chaired by Harald Lück (Leibniz Universität Hannover, Germany), addressed to the overall management of the project