In 2016, the NASA Juno spacecraft will initiate its one-year mission around
Jupiter and become the first probe to explore the polar regions of Jupiter. The
HST UV instruments (STIS and ACS) can greatly contribute to the success of the
Juno mission by providing key complementary views of Jupiter's UV aurora from
Earth orbit. Juno carries an ultraviolet Spectrograph (UVS) and an infrared
spectral mapper (JIRAM) that will obtain high-resolution spectral images
providing the auroral counterpart to Juno's in situ particles and fields
measurements with the plasma JADE and JEDI particle detectors. The Juno mission
will be the first opportunity to measure simultaneously the energetic particles
at high latitude and the auroral emissions they produce. Following programmatic
and technical limitations, the amount of UVS data transmitted to Earth will be
severely restricted. Therefore, it is of extreme importance that HST captures
as much additional information as possible on Jupiter's UV aurora during the
one-year life of the Juno mission. This white paper is a plea for a "Juno
initiative" that will ensure that a sufficient number of orbits is allocated to
this unique solar system mission.Comment: Paper submitted to the Space Telescope Science Institute in response
to the call for HST White Papers for Hubble's 2020 Visio