TandEM had been proposed as an L-class candidate mission for the Cosmic Vision 2015-2025 programme in response to the Call for Proposals issued by ESA in March 2007, and has been one of the mission concepts selected by the SSAC in October 2007 for an Assessment study. The SSAC had decided that an Outer Planet mission should be one of the L-class mission candidates for the first slice of the Cosmic Vision plan, and recommended that both TandEM and Laplace (a mission to the Jupiter system) concepts should be studied initially, with a decision on which one to pursue to take place following a better definition of the mission's characteristics.
The ESA internal assessment phase, or phase 0, for all candidate missions began in November 2007. The CDF study, part of the phase 0 process, for TandEM ran from June 2008 to July 2008.
In early February 2009 ESA and NASA jointly announced that the Europa-Jupiter System Mission, or Laplace, would be the candidate for the first L mission, with a possible launch date in 2020.
Following the joint ESA-NASA decision to further pursue the Jupiter mission, the studies concerning the TandEM mission concept within ESA have been terminated.