摘要 :
Uranus and Neptune, known collectively as the Ice Giants, are the only two planets in the solar system that are yet to be explored with a dedicated mission. Planetary entry probe missions to the Ice Giants were proposed in 2010 by...
展开
Uranus and Neptune, known collectively as the Ice Giants, are the only two planets in the solar system that are yet to be explored with a dedicated mission. Planetary entry probe missions to the Ice Giants were proposed in 2010 by NASA and ESA which prompted a resurgence of interest in experimental simulation of the aeroheating environment that would be encountered by such a spacecraft. More recently, the 2023 - 2032 Decadal Survey recommended that NASA's highest priority new flagship mission should be a Uranus orbiter and probe with a launch date in the early 2030s. The Oxford T6 Stalker tunnel is the only facility in Europe capable of replicating the high speeds required for Ice Giant entry and is therefore a key stepping stone on the path to realising the goal of an Ice Giant mission. In the present work, a 1:10 scaled model of the Galileo probe has been tested at Ice Giant entry conditions. Conditions for nominal composition (85%H_2-15%He), Stalker substituted, and nominal composition with methane (0.5% and 5% CH_4) gas mixtures have been developed and validated for use with a new expansion nozzle via a Pitot rake survey. Test flows with flight equivalent velocities greater than 18 km/s have been produced with test times on the order of 30 μs. Heat flux into the model for the developed conditions has been inferred from temperature measurements with a series of coaxial thermocouples. High speed video, with and without schlieren, has been captured to aid in characterisation of the test conditions.
收起
摘要 :
The Ice Giants, Uranus and Neptune, represent a largely unexplored, interstitial class of planetary objects that fit between the Gas Giants and the smaller terrestrial worlds, such as Earth, in terms of their size and elemental co...
展开
The Ice Giants, Uranus and Neptune, represent a largely unexplored, interstitial class of planetary objects that fit between the Gas Giants and the smaller terrestrial worlds, such as Earth, in terms of their size and elemental composition and are therefore a missing link in our understanding of extrasolar planetary evolution. The scientific potential of a mission to the Ice Giants is well recognised and has been identified by NASA and ESA as a high priority on several occasions, most recently in the 2023 - 2032 Decadal Survey. The payload capacity of such a spacecraft is limited by the requirement for a bulky heat shield, made necessary by the paucity of ground test data for convective and radiative heat flux at proposed entry trajectories. This paper describes an experimental study of shock layer radiation via emission spectroscopy at Ice Giant entry conditions in the T6 free-piston driven wind tunnel. Significant engineering upgrades have been made to T6 that extend the performance envelope and allow operation with flammable test gases. Shock waves of up to 18.9 km/s were driven through H/He mixtures containing up to 5% CH_4 by mole. The magnitude of spectral radiance at the peak and in the immediate post-shock region appears to be strongly affected by the concentration of CH_4 in the test gas. Spectral fitting with the NEQAIR program shows that radiation in the 410 - 560 inn range is dominated by C2 and CH and has allowed the spatial evolution of mode temperatures and species concentrations to be extracted.
收起
摘要 :
An approach for the experimental simulation of entry conditions into the atmosphere of gas giant Neptune is presented. The PWK1 facility at the Institute of Space Systems of the University of Stuttgart has been modified in order t...
展开
An approach for the experimental simulation of entry conditions into the atmosphere of gas giant Neptune is presented. The PWK1 facility at the Institute of Space Systems of the University of Stuttgart has been modified in order to be used with hydrogen-helium mixtures. Additionally, methane was injected aiming at investigating the influence of methane on the radiation behavior. Methane could significantly change the radiative heating behavior during the entry flight. Based on first emission spectroscopic measurements, it is shown that methane influences the spectra behavior considerably. CH and C_2 moleular radiation appear and the overall radiation level is higher. The prominent hydrogen Balmer series are saturating the spectrometer, which needs further attention in future measurements.
收起
