CubeSat Electrothermal Plasma Micro-Thruster: System Development and Integration

Amid growing demand to expand CubeSat mission capability, several propulsion devices have been proposed for use in nanosatellites. One device, a scalable electrothermal plasma thruster named Pocket Rocket, has been researched and designed as an inexpensive and high-performance propulsion solution. A full integration of two Pocket Rocket thrusters into a 1U CubeSat form factor for spin maneuver testing has been completed, including Argon propellant storage, pressure regulation, an RF power and thruster controller, and a complete modular support structure. This prototype module was completed and tested in an environmental vacuum chamber to ensure space-capable operation, with future plans to complete a space mission to demonstrate the full potential of Pocket Rocket. Results show that the full assembly fits together inside the 1U CubeSat form factor and that the thrusters can be controlled individually. The burn time using the current proof of concept model is approximately 3 hours with an ion number density in the plume of approximately 2 x 1015 showing that the thruster is scalable from previous Pocket Rocket thruster tests and that the performance was not affected by the CubeSat integration of the thruster

Comparative Analysis of Parallel vs Series Hybrid Electric Powertrains

In the United States, more than a quarter of greenhouse gas (GHGs) emissions (27%) are attributed to the transportation sector which comprises mainly of vehicles powered by internal combustion engines (ICE). To reduce the dependence on fossil fuels and the resulting GHG emissions associated with conventional ICE vehicles, plug-in hybrid vehicles are being promoted as a viable near-term vehicle technology. This paper is a comparative experimental study of two types of hybrid systems: parallel (also known as plug-in hybrid) and series (also known as extended-range electric) hybrid systems. The two hybrid systems are modelled on an electric bicycle platform and field tested to analyze their performance. The fuel economy was measured and compared in L/100km and the electric powertrain efficiency of the system was measured and compared in watt-hours per kilometer (Wh/km). A sensitivity analysis is carried out in terms of different transmission gear ratios and the variable setpoints in the hybrid control logic to access the impact these factors have on the performance of the hybrid system. This paper focuses only on the technological aspect of the hybrid system and any social and policy aspects associated are not considered. The constructive modeling of the hybrid system, the limitations faced during the process and the results of the field tests are presented

Battery-aware design exploration of scheduling policies for multi-sensor devices

Lifetime maximization is a key challenge in battery-powered multi-sensor devices. Battery-aware power management strategies combine task scheduling with dynamic voltage scaling (DVS), accounting for the fact that the power drawn by the device is different from that provided by the battery due to its many non-idealities. However, state-of-the-art techniques in this field do not take into account several important aspects, such as the impact of sensing tasks on the overall power demand, the (operating point dependent) losses due to multiple DC-DC conversions, and the dynamic modifications in battery efficiency caused by different distributions of the currents in the temporal and in the frequency domains. In this work, we propose a novel approach to identify optimal power management solutions, that addresses all these limitations. Specifically, using advanced battery and DC-DC converter models, we propose methods to explore the scheduling space both statically (at design time) and dynamically (at run-time), accounting not only for computation tasks, but also for communication and sensing. With this method, we show that the battery lifetime can be increased by as much as 23.36% if an optimal power management strategy is adopted

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

A Wireless, Battery-Powered Probe Based on a Dual-Tier CMOS SPAD Array for Charged Particle Sensing

A compact probe for charged particle imaging, with potential applications in source activity mapping and radio-guided surgery was designed and tested. The development of this technology holds significant implications for medical imaging, offering healthcare professionals accurate and efficient tools for diagnoses and treatments. To fulfill the portability requirements of these applications, the probe was designed for battery operation and wireless communication with a PC. The core sensor is a dual-layer CMOS SPAD detector, fabricated using 150 nm technology, which uses overlapping cells to produce a coincidence signal and reduce the dark count rate (DCR). The sensor is managed and interfaced with a microcontroller, and custom firmware was developed to facilitate communication with the sensor. The performance of the probe was evaluated by characterizing the on-board SPAD detector in terms of the DCR, and the results were consistent with the characterization measurements taken on the same chip samples using a purposely developed benchtop setup

Apollo experience report: Development of the extravehicular mobility unit

The development and performance history of the Apollo extravehicular mobility unit and its major subsystems is described. The three major subsystems, the pressure garment assembly, the portable life-support system, and the oxygen purge system, are defined and described in detail as is the evolutionary process that culminated in each major subsystem component. Descriptions of ground-support equipment and the qualification testing process for component hardware are also presented

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Analysis and optimal design of micro-energy harvesting systems for wireless sensor nodes

Presently, wireless sensor nodes are widely used and the lifetime of the system is becoming the biggest problem with using this technology. As more and more low power products have been used in WSN, energy harvesting technologies, based on their own characteristics, attract more and more attention in this area. But in order to design high energy efficiency, low cost and nearly perpetual lifetime micro energy harvesting system is still challenging. This thesis proposes a new way, by applying three factors of the system, which are the energy generation, the energy consumption and the power management strategy, into a theoretical model, to optimally design a highly efficient micro energy harvesting system in a real environment. In order to achieve this goal, three aspects of contributions, which are theoretically analysis an energy harvesting system, practically enhancing the system efficiency, and real system implementation, have been made. For the theoretically analysis, the generic architecture and the system design procedure have been proposed to guide system design. Based on the proposed system architecture, the theoretical analytical models of solar and thermal energy harvesting systems have been developed to evaluate the performance of the system before it being designed and implemented. Based on the model’s findings, two approaches (MPPT based power conversion circuit and the power management subsystem) have been considered to practically increase the system efficiency. As this research has been funded by the two public projects, two energy harvesting systems (solar and thermal) powered wireless sensor nodes have been developed and implemented in the real environments based on the proposed work, although other energy sources are given passing treatment. The experimental results show that the two systems have been efficiently designed with the optimization of the system parameters by using the simulation model. The further experimental results, tested in the real environments, show that both systems can have nearly perpetual lifetime with high energy efficiency