Science Daily January 10, 2020 A team of researchers in the US (Industry, UC Davis, Cornell University) has discovered two alternative 4-satellite constellations with 24- and 48-hour periods, both of which attain nearly continuous global coverage. They harness energy from nonlinear orbital perturbation forces (e.g., Earth’s geopotential, gravitational effects of the sun and moon, and solar radiation pressure) to reduce their propellant and maintenance costs. The 24-hour period constellation reduces the overall required vehicle mass budget for propellant by approximately 60% compared to a geostationary Earth orbit constellation with similar coverage over typical satellite lifetimes. The discovery could drive advances […]
Tag Archives: Remote sensing
Radioactive material detected remotely using laser-induced electron avalanche breakdown
Phys.org March 22, 2019 Researchers at the University of Maryland present a proof-of-principle demonstration of a remote detection scheme using mid-infrared laser–induced avalanche breakdown of air. They observed on-off breakdown sensitivity to the presence of an external radioactive source. They correlated the shift of the temporal onset of avalanche to the degree of seed ionization from the source. They present scaling of the interaction with laser intensity, verify observed trends with numerical simulations, and discuss the use of mid-IR laser–driven electron avalanche breakdown to detect radioactive material at range. The method could be used to scan trucks and shipping containers […]