SpinSat Mission Overview
Abstract : The SpinSat flight is a small satellite mission proposed by the Naval Research Laboratory and Digital Solid State Propulsion (DSSP) LLC to demonstrate and characterize the on-orbit performance of electrically controlled solid propellant technology in space. This is an enabling technology for the small satellite community that will allow small satellites to perform maneuvers. The mission consists of a spherical spacecraft fitted with Electrically Controlled Solid Propellant thrusters and retro-reflectors for satellite laser ranging (SLR). The spacecraft will be deployed from the International Space Station. This paper presents a mission overview and emphasis will be placed on the design, thruster design, optical layout, and unique SSA observation opportunities of the mission.
Multi-sensor Observations of the SpinSat Satellite
Abstract : The Naval Research Laboratory developed and launched the spherical SpinSat satellite to accomplish two primary goals: 1) study the performance of a new class of micro-thrusters, and 2) provide a calibrated drag experiment to characterize Earths upper atmosphere during the current period of relatively high solar activity. The 55.9 cm diameter aluminum sphere is equipped with a set of Electrically-Controlled Solid Propellant (ESP) thrusters, oriented to allow both translational and spin-up/spin-down maneuvers. To facilitate remote observations of the satellites spin rate, the spheres exterior features a reflectance pattern much like that of a beach-ball, a distributed sequence of retro-reflectors, as well as an ensemble of eight light-emitting diodes (LEDs) arranged along a meridian (i.e., a line of longitude) which can be turned on for brief periods. The Air Force Research Laboratory has conducted optical observations of SpinSat from several Advanced Maui Optical and Space Surveillance (AMOS) observatory sensors. The observational goals include: 1) obtaining time-resolved, multi-band measurements of the satellite actively firing its micro-thrusters, 2) characterizing the detectability and spatial/temporal morphology of the ESP thruster plumes, 3) measuring the spin rate of the satellite with the LEDs turned on, ideally before and after a spin rate adjustment maneuver, and 4) measuring the spin rate of the satellite in its completely inactive mode, using only passive observations of reflected light and/or thermal emissions.
Single step formation of biocompatible bimetallic alloy nanoparticles of gold and silver using isonicotinylhydrazide.
Manufacturing nanoparticles with controlled physicochemical properties using environment-friendly routes have potential to open new prospects for a variety of applications. Accordingly, several approaches have been established for manufacturing metal nanoparticles. Many of these approaches entail the use of hazardous chemicals and could be toxic to the environment, and cannot be used readily for biomedical applications. In the present work, we report a single step bio-friendly approach to formulate gold (Au), silver (Ag), and Au-Ag alloy nanoparticles with desired surface corona and composition using isonicotinylhydrazide (INH) as a reducing agent. INH also functioned as a stabilizing agent by enabling a surface corona around the nanoparticles. Remarkably, within a single step INH could also provide a handle in regulating the composition of Au and Ag in bimetallic systems without any additional chemical modification. The physicochemical and surface properties of the different nanoparticles thus obtained have been examined by analytical, spectroscopic and microscopic techniques. Cell cytotoxicity (release of lactate dehydrogenase), cell viability and intracellular reactive oxygen species (ROS) assays confirmed that the Au, Ag, and Au-Ag bimetallic nanoparticles prepared with INH are biocompatible. Finally, the presence of organic surface corona of INH on the nanoparticles was found to impart nanozyme activity and antimycobacterial sensitivity to the nanoparticles.