Atmospheric Entry Studies for Uranus

The present paper describes parametric studies conducted to define the Uranus entry trade space. Two different arrival opportunities in 2029 and 2043, corresponding to launches in 2021 and 2034, respectively, are considered in the present study. These two launch windows factor in the 84-year orbital period, significant axial tilt, and the wide ring system of Uranus. As part of this study, an improved engineering model is developed for the Uranus atmosphere. This improved model is based on reconciliation of data available in the published literature and covers an altitude range of 0 km (1 bar pressure) to 5000 km. Two different entry scenarios are considered: 1) direct ballistic entry, and 2) aerocapture followed by entry from orbit. For ballistic entry a range of entry flight path angles are considered for probe entry masses ranging from 130 kg to 300 kg and diameters ranging from 0.8 m (Pioneer-Venus small probe scale) to 1.3 m (Galileo scale). The larger probes, which offer a larger packing volume, are considered in an attempt to accommodate more scientific instruments. For aerocapture a single case is studied to explore the feasibility and benefits of this option.