The early Universe’s Dark Ages, probed by the highly redshifted 21-cm neutral hydrogen signal, is the ideal epoch for a new rigorous test of the standard LCDM cosmological model. The Dark Ages Polarimeter PathfindER (DAPPER), operating in a low lunar orbit above the radio-quiet farside, shall search for divergences from the standard model that will indicate new physics such as heating or cooling produced by dark matter.

DAPPER is a part of the Network for Exploration and Space Science (NESS), a multifaceted, multidisciplinary, and innovative investigation in the space sciences, including the areas of astrophysics and heliophysics that are enabled through human and robotic exploration of the target bodies.