A presenatation which summarizes the "Sun in Time" project can be found on Ribas (2005) which was presented at the International Space Science Institute (ISSI) in Bern at a meeting of the ISSI Team "Evolution of Habitable Planets" in 2005.
An actual article related to the evolution of the solar radiation environment related to the ?Sun in Time? project by Dr. Manuel Güdel can be found on:
http://solarphysics.livingreviews.org/Articles/lrsp-2007-3/
References related to the Sun in Time Project:
Other relevant references: