AFTER THE COSMIC MICROWAVE BACKGROUND PHOTONS DECOUPLED FROM BARYONS THE DARK AGES EPOCH BEGAN: DENSITY FLUCTUATIONS IMPRINTED FROM EARLIER TIMES GREW UNDER THE INFLUENCE OF GRAVITY EVENTUALLY COLLAPSING INTO THE FIRST STARS AND GALAXIES DURING THE SUBSEQUENT COSMIC DAWN. EXPLORING THESE EARLY UNOBSERVED EPOCHS A KEY SCIENCE GOAL OF NASA WAS DEMONSTRATED TO BE ACHIEVABLE BY RECENT OBSERVATIONS BY THE EXPERIMENT TO DETECT THE GLOBAL EPOCH OF REIONIZATION (EOR) SIGNATURE (EDGES). IN THE EARLY UNIVERSE MOST OF THE BARYONIC MATTER WAS IN THE FORM OF NEUTRAL HYDROGEN (HI) DETECTABLE VIA ITS GROUND STATE S SPIN-FLIP TRANSITION. THIS LINE S REST FRAME FREQUENCY (WAVELENGTH) OF 1420 MHZ (21-CM) ARRIVES TODAY HIGHLY REDSHIFTED TO LOW RADIO FREQUENCIES (<200 MHZ) DUE TO COSMIC EXPANSION. A MEASUREMENT OF THE 21-CM SPECTRUM MAPS THE HISTORY OF THE HI GAS THROUGH THE DARK AGES AND COSMIC DAWN AND UP TO EOR WHEN IONIZATION OF HI EXTINGUISHED THE SIGNAL. EDGES RECENTLY REPORTED A 78 MHZ (REDSHIFT Z~17) ABSORPTION TROUGH ROUGHLY CONSISTENT WITH THAT EXPECTED FROM COSMIC DAWN BUT ~3 TIMES DEEPER THAN WAS THOUGHT POSSIBLE FROM STANDARD COSMOLOGY AND ADIABATIC COOLING OF HI. INTERACTIONS BETWEEN BARYONS AND MILDLY-CHARGED DARK MATTER PARTICLES WITH A PROTON-LIKE MASS PROVIDE A POTENTIAL EXPLANATION OF THIS DIFFERENCE BUT OTHER COOLING MECHANISMS ARE ALSO BEING INVESTIGATED. THE COSMIC DAWN TROUGH IS AFFECTED BY COSMOLOGY AND THE COMPLEX ASTROPHYSICAL HISTORY OF THE FIRST LUMINOUS OBJECTS. A TROUGH REPRESENTING THE DARK AGES PREDICTED TO OCCUR AT LOWER FREQUENCIES (HIGHER Z) HOWEVER IS DETERMINED ENTIRELY BY COSMOLOGICAL PHENOMENA (INCLUDING DARK MATTER) THAT TOOK PLACE BEFORE STAR FORMATION BEGAN. THE DARK AGES POLARIMETER PATHFINDER (DAPPER) WILL OBSERVE THIS PRISTINE EPOCH (15-30 MHZ; Z~93-46) WHICH IS INACCESSIBLE FROM EARTH DUE TO IONOSPHERIC OPACITY. DAPPER WILL SEARCH FOR DEVIATIONS FROM THE TROUGH PREDICTED BY THE STANDARD COSMOLOGICAL MODEL (MINIMUM AT ~18 MHZ AMPLITUDE=40 MK). IN ADDITION TO DARK MATTER PROPERTIES SUCH AS ANNIHILATION DECAY TEMPERATURE AND INTERACTIONS THE LOW-FREQUENCY BACKGROUND RADIATION LEVEL CAN SIGNIFICANTLY MODIFY THIS TROUGH. HENCE THIS OBSERVATION CONSTITUTES A POWERFUL CLEAN PROBE OF EXOTIC PHYSICS IN THE DARK AGES. THE MAIN CHALLENGE OF THIS MEASUREMENT IS THE REMOVAL OF BRIGHT FOREGROUNDS. DAPPER IS DESIGNED TO OVERCOME THIS BY UTILIZING TWO PIONEERING TECHNIQUES: (1) A POLARIMETER TO MEASURE BOTH INTRINSICALLY POLARIZED EMISSION AND POLARIZATION INDUCED BY THE ANISOTROPIC FOREGROUNDS AND LARGE ANTENNA BEAM TO AID IN THE SEPARATION OF THE FOREGROUNDS FROM THE ISOTROPIC UNPOLARIZED GLOBAL SIGNAL AND (2) A PATTERN RECOGNITION ANALYSIS PIPELINE BASED ON WELL-CHARACTERIZED TRAINING SETS OF FOREGROUNDS FROM SKY OBSERVATIONS INSTRUMENT SYSTEMATICS FROM SIMULATIONS AND LABORATORY MEASUREMENTS AND SIGNALS FROM THEORETICAL PREDICTIONS. DAPPER TEAM MEMBERS RECENTLY DEMONSTRATED THE EFFECTIVENESS OF DYNAMIC POLARIMETRY TO MEASURE FOREGROUNDS USING THE PROTOTYPE COSMIC TWILIGHT POLARIMETER. SIMULATIONS USING THE DAPPER PATTERN RECOGNITION PIPELINE ILLUSTRATE SEPARATION AND DETECTION OF THE STANDARD SIGNAL WHICH HAS A MINIMAL AMPLITUDE. NON-STANDARD COOLING WOULD INCREASE THIS AMPLITUDE IMPROVING THIS MEASUREMENT AND POINTING TO NEW PHYSICS. DAPPER S SCIENCE INSTRUMENT CONSISTS OF DUAL ORTHOGONAL 7-M TIP-TO-TIP DIPOLE ANTENNAS AND A TONE-INJECTION RECEIVER BASED ON HIGH TRL COMPONENTS FROM THE PARKER SOLAR PROBE/FIELDS CURIE AND WIND/WAVES. DAPPER WILL BE PLACED IN A RADIO-QUIET ENVIRONMENT IN LUNAR ORBIT IN THE VICINITY OF NASA S LUNAR GATEWAY WHICH OFFERS A NUMBER OF ADVANTAGES SUCH AS REGULAR RIDESHARE TRANSPORT A FAST COMMUNICATION SYSTEM A POTENTIAL LAUNCH FACILITY AND ON-BOARD DATA STORAGE AND COMPUTATIONAL EQUIPMENT. DAPPER IS A COLLABORATION BETWEEN THE UNIVERSITIES OF COLORADO-BOULDER AND CALIFORNIA-BERKELEY NRAO AND NASA ARC S MISSION DESIGN CENTER.