Simulation of the interaction of spacecraft with the rarefied ionospheric plasma

Principles of simulation of the physical-chemical and electromagnetic interaction of a spacecraft with the near-satellite environment and principles of probe diagnostics of rarefied plasma flows onboard a spacecraft are stated. Equivalence criteria are formulated for the interaction of a spacecraft with the near-satellite environment and hypersonic rarefied plasma flows on dedicated setups, in particular on the plasmaelectrodynamic setup of the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, which has the status of the National Patrimony of Ukraine. The features of spacecraft interaction with the near-satellite environment were studied along the following three lines: - degradation of the materials and performance characteristics of spacecraft components in a long-term orbital service: - magnetohydrodynamic interaction of a spacecraft with hypersonic rarefied plasma flows; - probe diagnostic of rarefied plasma flows onboard a spacecraft. Along the first line, a calculation-and-experiment procedure was developed to evaluate the power decrease of spacecraft silicon solar batteries under long-term (~ 10 years) exposure to the space factors and the near-satellite environment in circular orbits. Principles of accelerated life tests for the resistance of spacecraft polymer materials to long-term exposure to atomic oxygen flows and vacuum ultraviolet radiation were developed. Simultaneous exposure of polymers to atomic oxygen and vacuum ultraviolet radiation results in the synergic effect of mass loss by materials that contain a monomer of the (CH)n group. Along the second line, models were formulated for magnetohydrodynamic interaction in the magnetized spacecraft – ionospheric plasma system. It was shown that the interaction of a ?0,8 – 1.5 T magnetic field of a space debris object (in particular, a spent spacecraft) with the ionospheric plasma produces an electromagnetic drag force sufficient for removing it to a low orbit followed by its burn-up in the dense atmosphere. Along the third line, procedures were developed for ionospheric plasma probe diagnostics using onboard instrumentation that includes mutually orthogonal cylindrical electrical probes and a two-channel neutral-particle detector. It was shown that this instrumentation with the use of proprietary output signal interpretation algorithms and procedures allows one to locate sources of space-time disturbances in inospheric plasma parameters caused by natural and technogeneous catastrophic phenomena on the subsatellite track.

Juno observations of spot structures and a split tail in Io-induced aurorae on Jupiter

Jupiter’s aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet’s magnetic field lines. A northern and a southern main auroral oval are visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots, the extended tail is split in two. Both of Ganymede’s footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede’s magnetosphere. These features suggest that the magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated.