Assessment of the feasibility of space-based stellar occultation observations of Uranus and Neptune

UV occultation measurements made by Voyager 2 of the upper atmospheres of Uranus and Neptune in the late 1980s found both planets contain warm stratospheres and extremely hot thermospheres. Sunlight reaching the ice giants is far too weak to account for these reported temperatures. This is sometimes called the Giant Planet Energy Crisis. Theorized mechanisms to account for the heating observed at Uranus and Neptune suffer from a dearth of reliable observations. A similar energy crisis was reported from Voyager observations of Jupiter and Saturn, but observations made by the Galileo, Juno, and Cassini-Huygens missions as well as from ground-based facilities have vastly improved efforts to understand upper atmospheric heating. For Uranus and Neptune, Earth-based stellar occultation observations can fill in this significant gap in observations and produce reliable atmospheric measurements. These measurements can also assist in motivating and planning for a flagship mission to either ice giant.