Castalia Space Mission
The Castalia Space Mission will be launched in the late-2020s, to go and explore Comet 133P/Elst-Pizarro, a Main Belt Comet.

6 August 2018
The aim of the Castalia mission is to explore a Main Belt Comet (MBC). Studying this recently discovered class of minor bodies in the solar system would allow us to learn more about the distribution of volatiles in the early stages of planet formation, and the link between water and organics in the asteroid belt, and life on Earth.
The Castalia mission was not selected for the ESA M4 call but will be proposed again.