The Nexus for Exoplanet System Science (NExSS) was the first RCN established in collaboration with the Astrophysics, Heliophysics and Earth Sciences divisions at NASA. NExSS was reviewed after 3 years and based on the success of this test case, four additional RCNs were established: NfoLD, Prebiotic Chemistry and Early Earth Environments (PCE3), Network for Ocean Worlds, and LIFE: From Early Cells to Multicellularity.