Diwata-2: Earth Observation Microsatellite with a Compact Bus System, ElectronicallyTunable Multi-spectral Imager, and Amateur Radio Communications Capability

The microsatellite Diwata-2 was launched into the 600-km Sun-Synchronous Orbit (SSO) last October 29, 2018. It has a low-power, low-complexity, compact bus structure, capable of Earth observation and remote sensing mission through a 5-meter resolution Near-Infrared (NIR) High Precision Telescope (HPT) and a 125-meter resolution Space-borne Multispectral Imager (SMI) with two Liquid Crystal Tunable Filters (LCTF). The LCTF operates as an electronic-based band reconfiguration filter allowing for more than 600-channels of wavelength variation. As a secondary mission, Diwata-2 has full-duplex FM voice communications capability via a non-board module utilizing the amateur radio band at a 5W power requirement from mobile ground users. The structure has a 500-mm cubic external dimension, with JAXA’s Payload Attached Fairing (PAF) rocket interface and deployment mechanism. Deployable solar array panels (DSAP) were also introduced to increase the power generation capabilities of the microsatellite. The importance of detailed structural-mechanical models for finite-element analysis allowed for accurate structural simulation results. The observed accuracy is within 5-Hz for the first two modes compared to the actual vibration test results. Lastly, strict management of in-flight procedures allowed for consistent satellite performance, while modification of satellite maneuver based on imaging observation results improved target pointing accuracy to within 5-km

Low-Energy Parity-Violation and New Physics

The new physics sensitivity of a variety of low-energy parity-violating (PV) observables is analyzed. A comparison is made between atomic PV for a single isotope, atomic PV using isotope ratios, and PV electron-hadron and electron-electron scattering. The complementarity among these observables, as well as with high-energy processes, is emphasized. Theoretical uncertainties entering the interpretation of low-energy measurements are discussed.Comment: 37 pages, 2 figures. Omissions to Tables I and V corrected along with some minor typographical errors. To appear in Phys. Rev.