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The unique atmospheric compositions of \u2018ice giant\u2019 planets Uranus and Neptune were recreated to simulate a plunge deep within them, using suitably adapted European shocktubes and plasma facilities.\u00a0\u00a0<\/p>\n
Taking place as part of an effort to simulate the flight of proposed atmospheric probes, the test campaign achieved an equivalent speed up to 19 km\/s \u2013 although further work will be needed to reach the actual velocities that probes into these gas giants would attain.\u00a0<\/p>\n
Testing took place inside the hypersonic plasma T6 Stalker Tunnel at Oxford University\u00a0in the UK, along with the University of Stuttgart\u2019s High Enthalpy Flow Diagnostics Group\u2019s plasma wind tunnels\u00a0in Germany, as shown in the video clip here.\u00a0<\/p>\n
Whether by impacts, landings or atmospheric probes, human-made spacecraft have touched all the planets of the Solar System except two: the outer gas giants Uranus and Neptune.\u00a0<\/p>\n
Now both NASA\u00a0and ESA\u00a0are considering future missions to this intriguing pair, almost identical in size.\u00a0\u00a0<\/p>\n
While superficially similar to Jupiter and Saturn, with their hydrogen and helium atmospheres, Uranus and Neptune also contain sizeable heavier elements in the form of \u2018supercritical\u2019 liquid oceans deep below the surface clouds, which account for much of both planets\u2019 masses.\u00a0\u00a0<\/p>\n
Both worlds also have methane in their atmospheres \u2013 accounting for their blue appearance \u2013 although less in the case of Neptune, where it is concentrated lower in the atmosphere, so becomes less of a factor in modelling any probe flight.\u00a0<\/p>\n
As part of any future mission to one or both worlds, an atmospheric probe resembling the one flown by NASA\u2019s Galileo mission to Jupiter\u00a0is high on scientific wish lists.\u00a0<\/p>\n
\u201cThe challenge is that any probe would be subject to high pressures and temperatures, and therefore would require a high-performance thermal protection system to endure its atmospheric entry for a useful amount of time,\u201d explains Louis Walpot, ESA aerothermodynamics engineer.\u00a0\u00a0<\/p>\n
\u201cTo begin designing such a system we need first to adapt current European testing facilities in order to reproduce the atmospheric compositions and velocities involved.\u201d\u00a0<\/p>\n
The entry rate\u00a0of atmospheric probes is set by the speed\u00a0required to orbit them \u2013 about 24 km\/s velocity in the case of Uranus and Neptune.\u00a0<\/p>\n
This has been a joint UK\/German\/ESA project, supported by the Agency\u2019s General Support Technology Programme. As a next step, work is underway to extend the simulated velocities achievable in both the Oxford and Stuttgart wind tunnels.\u00a0<\/p>\n
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