RESUMO
The Juno spacecraft has been collecting data to shed light on the planet's origin and characterize its interior structure. The onboard gravity science experiment based on X-band and Ka-band dual-frequency Doppler tracking precisely measured Jupiter's zonal gravitational field. Here, we analyze 22 Juno's gravity passes to investigate the gravity field. Our analysis provides evidence of new gravity field features, which perturb its otherwise axially symmetric structure with a time-variable component. We show that normal modes of the planet could explain the anomalous signatures present in the Doppler data better than other alternative explanations, such as localized density anomalies and non-axisymmetric components of the static gravity field. We explain Juno data by p-modes having an amplitude spectrum with a peak radial velocity of 10-50 cm/s at 900-1200 µHz (compatible with ground-based observations) and provide upper bounds on lower frequency f-modes (radial velocity smaller than 1 cm/s). The new Juno results could open the possibility of exploring the interior structure of the gas giants through measurements of the time-variable gravity or with onboard instrumentation devoted to the observation of normal modes, which could drive spacecraft operations of future missions.
RESUMO
Organic diodes manufactured on a plastic substrate capable of rectifying a high-frequency radio-frequency identification signal (13.56 MHz), with sufficient power to operate an interactive smart tag, are reported. A high-performance conjugated semiconductor (an indacenodithiophene-benzothiadiazole copolymer) is combined with a carefully optimized architecture to satisfy the electrical requirements for an organic-semiconductor-based logic chip.