Two years ago we celebrated the incredible discovery of a neutron star merger event - GW170817 - in both gravitational and electromagnetic waves. The optical signal that accompanied GW170817 provided the first firm proof that neutron star mergers produce heavy elements. Still, it is not known exactly which elements are produced by mergers and in what proportions. Are neutron star mergers the sole astrophysical source of the heaviest elements or do other extreme events contribute? Here we will consider this question along with the astrophysical and nuclear physics uncertainties that obstruct the path to a solution. We will then explore the promise of future observations and of experimental campaigns at rare isotope beam facilities to reduce these uncertainties and provide insight into astrophysical environments of heavy element production.