On the geological side the objective of E-TEST is to provide a comprehensive survey of geological conditions of the EMR site for ET and to identify exact coordinates for the where to optimally place ET in the Euregio Meuse-Rhine.

The unique selling points of the E-TEST geology program can be summaries as follows:

  • Drilling five deep boreholes in the Euregio Meuse-Rhine
  • Extensive seismic surface campaigns to image the underground
  • It provides the essential prerequisites for a bid of hosting ET in the Euregio Meuse-Rhine

The objective of the E-TEST instrumentation program is to develop a facility for validating ET-LF technology, i.e. a ‘large’ silicon mirror, an excellent suspension system for isolating the mirror from seismic motion, and a cooling strategy that is compatible with the isolation system. An active isolation system will be used and combined with a quasi-radiative cooling system at 10 K. A new patterned heat exchanger working radiatively have to be designed and implemented.  To take advantages of the existing expertise and infrastructure available in the EMR region, it is proposed to mount E-TEST in the existing facilities at the Space Centre of Liège (CSL) and to keep advantages of their knowledge cryogenic qualification of Space Instruments.

The unique selling points of E-TEST instrumentation program can be summarized as follows:

  • Development of a quietly-suspended, large, cryogenic silicon mirror
  • Development and characterization of subsystems and innovative components

E-TEST Prototype

Development of a facility to improve, validate and test vibration control for gravitational wave telescope at ultra-low temperature and under vacuum.


WPT1: Ultra-cold vibration control

Head of WP: Nikhef
Partners involved: ULiege, RWTH Aachen, KUL, UCLouvain

Activity 1.1 Vacuum and cryogenics
Activity 1.2 Active vibration isolation for the heat link
Activity 1.3 Seismic isolation system

WPT2: Optical engineering

Head of WP: Fraunhofer ILT
Partners involved: ULiege, Fraunhofer ILT, KUL, Universiteit Hasselt, Nikhef, Maastricht University

Activity 2.1. Large Silicon Mirror Manufacture and test
Activity 2.2 Laser and optics at 2 microns wavelength
Activity 2.3 Assembly and validation of the whole setup

E-TEST Geology

Advanced studies of the underground in the EMR region leading to an open geo-model and an in-situ observatory.


WPT3: EMR cross-border underground observatory

Head of WP: ULiege
Partners involved: ULiege, RWTH Aachen, UniBonn, KNMI, Nikhef

Activity 3.1 Hydro-geophysical observatory and monitoring public database
Activity 3.2 Open cross-border groundwater model for ecosystem services
Activity 3.3 Seismic noise model
Activity 3.4 Improved cross-border seismic hazard map

WPT4: Geological modelling and Engineering Geology of the ET

Head of WP: RWTH Aachen
Partners involvedULiegeRWTH AachenUniBonn, KNMINikhef

Activity 4.1 Cross-border open geological model
Activity 4.2 Einstein telescope feasibility and optimal positioning in the EMR