The Dark Ages Radio Explorer (DARE) will probe the epoch of formation of the first stars, black holes, and galaxies, never before observed, using the redshifted hyperfine 21-cm transition from neutral hydrogen. 
The expanding universe began from a hot, nearly uniform mixture of ordinary matter (baryons) and dark matter. Once the temperature of the cosmic plasma dipped below 3000 Kelvin, protons and electrons combined to form hydrogen atoms, and the universe became transparent to the blackbody radiation bath that filled it. We currently detect that radiation as the cosmic microwave background (CMB).
Tiny fluctuations in the matter density at these early times grew gravitationally and eventually led to the collapse of the first gas clouds ~30 Myr after the Big Bang. These clumps seeded the first bursts of star formation, lighting up our universe in the cosmic dawn. Because our current picture of this cosmic dawn of structure formation has not yet been investigated observationally, its direct exploration is one of the most exciting frontiers in astrophysics.
DARE is unique in probing the universe at sufficiently early times to follow the evolution of the first stars, galaxies, and black holes from z = 35 to 11.