Airflight and spaceflight gave mankind different perspectives and opened new paths for communication. A gap remains, between 50 km and 250 km of altitude, where the rarefied atmosphere makes it hardly viable to operate with either spacecraft or planes. Air-breathing Electric Rockets (AERs) will allow to close this gap, lowering the altitude of spacecraft operations below 250 km, in the so-called Very Low Earth Orbits (VLEOs). Operations in VLEOs will give radical advantages in terms of orbit accessibility, payload performance, protection from radiations, and end-of-life disposal. AERs combine an intake to collect the residual atmosphere in front of the spacecraft and an electric thruster to ionize and accelerate the atmospheric particles. Such residual gas can be exploited as renewable resource not only to keep the spacecraft on a VLEO, but also to remove the main limiting factor of spacecraft lifetime, i.e., the amount of stored propellant. Several realizations of the AER concept have been proposed, but limited evidence of the concept feasibility is available. The few end-to-end experimental campaigns highlighted the need to improve the AER functional design and the representativeness of simulated atmospheric flows. The difficulty in recreating the VLEO environment in a laboratory limits the data available to validate scaling laws and modelling efforts. The objective of BREATHE is to increase the understanding of air-breathing electric propulsion and to pave the way toward the in-orbit demonstration of the AER concept. With this aim, project activities will focus on: 1) Developing theoretical models and simulation tools, to characterize atmospheric flows and low-temperature plasmas; 2) Merging on-ground testing and virtual simulations, to provide a controlled environment for the characterization of prototypes and the extrapolation to flight conditions; 3) Identifying the main scaling laws governing AERs and, thus, the optimal operating principle and design.