Exploring Desert Aquifers and Polar Ice Sheets and Their Responses to Climate Evolution: OASIS Mission Concept Essam Heggy, Paul A. Rosen, Richard Beatty, Tony Freeman, Young Gim and The OASIS Team Abstract The Orbiting Arid Subsurface and Ice Sheet Sounder (OASIS) mission concept is a single instrument, small-size, venture-class mission directly aimed at explor- ing the signatures of climate change in both cold and warm deserts regions on Earth: the polar ice sheets and the hyper-arid deserts (Fig. 1). OASIS has two well-defined science objectives. The first is to determine the thickness, inner structure, and basal boundary condi- tions of Earth’s ice sheets to understand their dynamics and improve models of current and future ice sheet response to climate change and, hence, to better constrain ice sheet contribution to sea level rise. The second objective is to perform detailed mapping of the spatial distribution of shallow (<100 m deep) aquifers in North Africa and the Arabian Peninisula to understand ground- water dynamic in fossil aquifers to assess their current response to climatic stresses and paleoclimatic conditions that formed them. These two mission objectives are achieved using a sounding radar operating at 45 MHz center frequency with 10 MHz bandwidth. The proposed OASIS radar would be able to map only the upper water table of fossil aquifer systems. This proceeding has been updated from the proceeding published in IEEE-IGARSS (2013). Keywords Climate change Á Groundwater Á Polar Ice Sheets Á Radar Sounding Á Sea-level rise 1 Mission Concept The OASIS mission concept can achieve the two above-mentioned objectives by orbiting the Earth for 18 months in low Earth sun-synchronous orbit, which decays gradually as the mission progresses achieving unprecedented systematic, dense coverage, with orbit track spacing ranging from 5 km at the equator to several hun- dred meters when closest to the poles. The mission concept is optimized for these measurements, and can take advan- tage of reduced solar activity at the end of 2016 and by operating in the 4 am early morning hours to open a win- dow through the Earth’s ionosphere for the low-frequency radar waves. Our preliminary analysis shows that an 18-month mission could be achieved near solar minimum even with a high-drag spacecraft with no propulsion. However, our concept includes a butane propulsion system that would provide orbit adjustment and reboost to meet mission lifetime requirements and avoid the higher drag and environmental effects at lower orbits. The OASIS payload could be hosted on a 50 kg/50 W-payload class spacecraft bus (as shown in Fig. 2) that can be launched by Pegasus XL. 2 Science Objectives OASIS is the first mission concept to directly explore the signatures of climate change in the subsurface of two of the least well understood desertic regions on earth: The polar ice sheet and the hyper-arid deserts. OASIS has seven science objectives that address key questions on ice sheets dynamics, Essam Heggy: Presenting Author E. Heggy (&) Viterbi School of Engineering, University of Southern California, 3737 Watt Way, Los Angeles, CA, USA e-mail: heggy@usc.edu E. Heggy Jet Propulsion Laboratory, Caltech, 3737 Watt Way, Pasadena, CA, USA P. A. Rosen Á R. Beatty Á T. Freeman Á Y. Gim The OASIS Team NASA ’s Jet Propulsion Laboratory, Caltech, 3737 Watt Way, Pasadena, CA, USA © Springer Nature Switzerland AG 2019 H. M. El-Askary et al. (eds.), Advances in Remote Sensing and Geo Informatics Applications, Advances in Science, Technology & Innovation, https://doi.org/10.1007/978-3-030-01440-7_2 7