Towards a more complete understanding of Haumea's family tree

The dwarf planet Haumea is the only object in the trans-Neptunian population known to be the parent body of a collisional family. The accepted family of objects share extremely low delta-V values relative to Haumea, and very strong water ice absorption bands (like Haumea itself). Several collisional-formation mechanisms for the family have been proposed, but none of these models seem to satisfy all of the physical and dynamical properties of Haumea and its family. This could reflect problems with the models, but could also be a result of an incomplete census of the family resulting in biases such as the very low delta-V, incorrect inferred size distribution, a paucity of fainter (low albedo and/or smaller) objects, or combinations of those biases. In recent years, deep surveys in the trans-Neptunian region have detected new objects that could be part of the family. A recent dynamical study by Proudfoot and Ragozzine (2019) has identified new objects with comparably low delta-V values to the accepted family members, many of which are too faint to be effectively characterized from the ground. Here we propose SNAP observations of 20 of these fainter targets using HST/WFC3 in the F139M and F153M filters in order to cahracterize the strength of their 1.5 micron water-ice absorption, and test whether any of them possess stronger absorptions than were found in previous large WFC3 studies of TNOs.