Advanced MEMS Components in Closed-loop Micro Propulsion Applications

This paper presents recent advances in the development of two MEMS (Micro Electro Mechanical Systems) components suitable for small satellite propulsion applications. First a cold gas MEMS thruster with proportional and closed-loop thrust control and secondly a Xenon flow control module for precision control of extremely low flow rates to Ion engines. The development of these products is ongoing but recent achievements have demonstrated that besides miniaturization also unique performance and functionality can be achieved. The components are described in terms of design, manufacturing, and test results. The flow control module can regulate flows in the range of 5-50 μg/s with a resolution better than 0.2 μg/s. By using the same closed-loop control in a MEMS-based thruster configuration, the combination of milli-Newton thrust range, sub micro-Newton resolutions, and fast response time can be achieved. In our view, using MEMS technology and integrating the flow control valve, mass flow sensor and chamber/nozzle on a single chip is the best –if not the only- way to realize a closed-loop control thruster that can meet new tough small satellite propulsion requirements

MEMS Micropropulsion Components for Small Spacecraft

This paper presents a number of MEMS-based micropropulsion components for small spacecraft. First a description of four components, all integral parts of the cold gas micropropulsion system custom designed for the Prisma satellites (launched June 2010). One of the most complex miniaturised micropropulsion components on board Prisma is the MEMS thruster chip, comprising four microthrusters integrated in a six-silicon-wafer package weighing only 4 grams. Proportional MEMS thruster valves and internal gas heaters are key integral parts of the thruster chip, providing μN-to-mN thrust in four orthogonal directions. Other MEMS components on Prisma are: a MEMS isolation valve, a MEMS pressure relief valve, and a MEMS pressure sensor. Hereafter, further developments of the MEMS components are presented, e.g. implementation of closed-loop thrust control on the MEMS thruster chip and proportional valves for ion engines to regulate xenon in the 5-50 μg/s regime with a 0.2 μg/s resolution. Finally, a concept of a completely miniaturised propulsion system intended for CubeSat applications is shown. All components are good examples of how extreme mass savings can be achieved by using MEMS technology, and by integrating several components and functionalities into one common chip or housing, which is of special interest for small spacecraft missions

Closed-loop Thrust Control in a MEMS-based Micro Propulsion Module for CubeSats

This paper presents a MEMS-based micro propulsion system with closed-loop thrust control. It is a cold gas system with butane as propellant packaged in module with the size one third of a 1U CubeSat. The module is described in terms of design, manufacturing, and test results. The development of this product is on-going but recent achievements have demonstrated that besides miniaturization also unique performance and functionality can be achieved. By using MEMS components in a closed-loop control configuration, the combination of milli-Newton thrust range, sub micro-Newton resolutions, and fast response time can be achieved. In our view, using MEMS technology and integrating the flow control valve, mass flow sensor and chamber/nozzle on a single chip is the best –if not the only- way to realize a closed-loop control thruster that can meet new tough small satellite propulsion requirements. Today, most thrusters and fluid control components are operated in ON/OFF mode and in a control system where the feed-back signal comes from sensors (such as accelerometers, sun sensors or star trackers) on-board the spacecraft. The novel MEMS devices presented here do enable both continuous/proportional and closed-loop flow control. In the application of a thruster (cold gas or chemical) this enables continuous throttling capability with a real time measurement of the delivered thrust. Such functionality does enable advanced missions such as precise formation flying or drag free flights. Furthermore, the miniaturization that comes along with the MEMS technology does also in general open up for propulsion on-board CubeSats. The MEMS-based micro propulsion module comprises four complete MEMS thruster and one centralized tank. In addition to the MEMS components e.g. valves, nozzles, and mass flow sensors it also holds front-end electronics inside the mechanical housing using the Pumpkin CubeSat interface standard. Electrical interface is 21 pins analog (0-12V) and digital (SPI)

Electric Solar Wind Sail in tailwind

The Electric Solar Wind Sail (E-sail) is a novelpropulsion concept that enables faster space travel tomany solar system targets. E-sail uses charged solarwind particles as the source of its propulsion. This isachieved by deploying long, conducting and chargedtethers, which get pushed by the solar wind byCoulomb drag [1].E-sail technology is being developed to technicalreadiness level (TRL) 4-5 by the European Union’sSeventh Framework Programme for Research andTechnological Development, EU FP7, in a projectnamed ESAIL (http://www.electric-sailing.fi/fp7).Prototypes of the key parts are to be produced. Thedesign will be scalable so that a real solar winddemonstration mission could be scaled up from them.We review here the latest results of the constantlyevolving E-sail project

Electric Solar Wind Sail in tailwind

The Electric Solar Wind Sail (E-sail) is a novelpropulsion concept that enables faster space travel tomany solar system targets. E-sail uses charged solarwind particles as the source of its propulsion. This isachieved by deploying long, conducting and chargedtethers, which get pushed by the solar wind byCoulomb drag [1].E-sail technology is being developed to technicalreadiness level (TRL) 4-5 by the European Union’sSeventh Framework Programme for Research andTechnological Development, EU FP7, in a projectnamed ESAIL (http://www.electric-sailing.fi/fp7).Prototypes of the key parts are to be produced. Thedesign will be scalable so that a real solar winddemonstration mission could be scaled up from them.We review here the latest results of the constantlyevolving E-sail project