The "Atmospheric Reentry Physics" conference will provide a single focal point to allow for the better integration and advancement of a multidisciplinary research community of scientists and engineers, representing government agencies, the private sector, and University systems across the world. The primary objectives of the conference are to foster improved communication across national and discipline boundaries, and to expose the atmospheric reentry community to new ideas and techniques from adjacent disciplines in the hopes of bringing new experimental techniques to bear on the problem as well as brainstorm about challenges faced by expanding the range of application of existing techniques. The topic area encompasses the physics and chemistry relevant to a spacecraft entry into the Earth or a planetary atmosphere. At hypersonic speeds, strong shock waves form in front of the reentry spacecraft, and the boundary layer is typically highly turbulent, leading to complex compressible fluid dynamics. Such entries are further characterized by dissociation, ionization, and excitation of the gaseous species behind the hypersonic shock wave. At sufficiently high velocity, the hot atmospheric gas begins to radiate due to atomic and molecular excitation. This radiation can become strong enough that it is a significant source of heat transfer to the spacecraft. At the higher entry velocities, the heat generated at the vehicle surface is large enough that no material can withstand it without degrading. Therefore, a spacecraft design typically relies on ablating thermal protection materials, which are intended to pyrolize and char in response to the incident heat. These materials thus efficiently cool the spacecraft via energy absorption of the endothermic breakdown of the polymeric constituents, transpiration cooling as the pyrolysis gases percolate from the interior of the material toward the surface, and re-radiation from the hot char layer that forms on the surface. At the high altitude conditions typical of atmospheric entry, many or all of these processes can be in non-equilibrium, which greatly complicates the required physical models that must be employed in their simulation. Finally, all of these phenomena, including the fluid dynamics, molecular chemistry, radiation emission and transport, and ablative material response, can be coupled, requiring the development and validation of complex multi-physics models. Such models exist today at varying levels of fidelity and validation. A significant impediment to properly validating the models has been the inability to conduct truly flight-like experiments in ground-based laboratories. However, we believe that, under the auspices of the GRC, the current state of the art can be considerably advanced by bringing new ideas and methodologies to bear on the problem. The GRC series will focus on each of these elements (or the coupling between them) in turn, ensuring a dynamic, ever changing research discussion for many years to come. The first meeting of the GRC will focus on the development, validation and uncertainty quantification of the high-fidelity models used to simulate the behavior of ablative materials. Sessions will be held on the various aspects of modeling the surface and in-depth performance of ablative materials, experimental techniques and methodologies to validate the resulting models, and uncertainty quantification methodologies. The area of ablation modeling is an ideal topic for the first year conference, since the discipline involves multi-disciplinary simulation of complex finite-rate chemical processes that is notoriously difficult to validate in flight-relevant conditions. In fact, the state of the art of ablation modeling has changed little in the past 40 years, largely because of a lack of validation data with which to justify improvements to the baseline models. However, in recent years significant progress has been made on the numerical side, and it is now time to develop a set of validation experiments to test key aspects of the new and proposed models, quantify remaining uncertainties, and prioritize limited research budgets on those aspects that will have the largest impact on the eventual customer of such models: flight programs seeking to minimize mass and maximize reliability of spacecraft thermal protection systems.