  We map the parameter space for MSSM neutralino dark matter which freezes out
to the observed relic abundance, in the limit that all superpartners except the
neutralinos and charginos are decoupled. In this space of relic neutralinos, we
show the dominant dark matter annihilation modes, the mass splittings among the
electroweakinos, direct detection rates, and collider cross-sections. The mass
difference between the dark matter and the next-to-lightest neutral and charged
states is typically much less than electroweak gauge boson masses. With these
small mass differences, the relic neutralino surface is accessible to a future
100 TeV hadron collider, which can discover inter-neutralino mass splittings
down to 1 GeV and thermal relic dark matter neutralino masses up to 1.5 TeV
with a few inverse attobarns of luminosity. This coverage is a direct
consequence of the increased collider energy: the Standard Model events with
missing transverse momentum in the TeV range have mostly hard electroweak
radiation, distinct from the soft radiation shed in compressed electroweakino
decays. We exploit this kinematic feature in final states including photons and
leptons, tailored to the 100 TeV collider environment.
