In response to a request from NASA, the National Research Council convened the Committee on the Assessment of a Plan for US Participation in Euclid.  The Committee endorsed NASA participation, and stressed that it is a first step towards meeting the science goals of the decadal survey New Worlds, New Horizons (NWNH) report.  

Specifically, in its report, the Committee recommended 

• NASA should make a hardware contribution of approximately $20 million to the Euclid mission to enable U.S. participation. This investment should be made in the context of a strong U.S. commitment to move forward with the full implementation of WFIRST in order to fully realize the decadal science priorities of the NWNH report.
• In exchange for this small, but crucial, contribution, NASA should secure through negotiation with the European Space Agency both a U.S. position on the Euclid Science Team with full data access and the inclusion of a team of U.S. scientists in the Euclid Consortium that would be selected by a peer- reviewed process with full data access as well as authorship rights consistent with Euclid policies still to be formulated.

The Committee concluded that Euclid participation is a first step, but that "Euclid on its own does not provide a viable alternative of achieving the broader NWH goals for the WFIRST mission."