Development of MEMS-Based Components and Subsystems for Spacecraft Propulsion

Abstract

Development of a MEMS-based (Micro Electro Mechanical System) components and subsystems has been pursued at Uppsala University, Sweden since 1997. Since 2005, the continued development towards the first flight the subject MEMS products onboard a satellite in 2008 is done within the frame of NanoSpace — a company dedicated to MEMS-based products for space. Currently, two major efforts to develop MEMS-based propulsion products are ongoing. First, NanoSpace is developing a miniaturized cold gas propulsion system. The major challenge in this effort is to develop the thruster module containing four individual thrusters with the capability to deliver proportional, low noise thrust in the micro- to milli-Newton range. The thruster pod even includes valves, filters, pressure- and temperature sensors and heaters. In a future step, even control electronics and a CAN interface will be included in the thrusters pod which has the size of a golf ball and a weight of about 100 grams. A prototype of this miniaturized cold gas propulsion will be flight tested onboard the PRISMA satellite. PRISMA is an international technology demonstration program with focus on rendezvous and formation flying. It is a two satellite LEO mission with a launch scheduled to September 2008. The other major development effort underway is a MEMS-based Xenon flow control system intended for electrical propulsion systems. Using MEMS technology, a Xenon feed system including an micro isolation valve, pressure regulator, and a number of parallel flow control modules can be built with significantly reduced size and mass compared to existing systems based on conventional technology. NanoSpace is a Swedish company with the goal to be a component and subsystem supplier of MEMS-based products to space industry, based on own research and development and intellectual property rights.

Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension

“…The plenum pressure during operation in vacuum was calculated from (7), using the measured mass flow (figure 11). Inserting the pressure in (6), the Knudsen number was calculated (figure 12).…”

“…Other, more sensitive, integratable flow sensors with different fabrication processes have also been developed with the goal of being integratable with silicon-based systems [26]. Other components that can be integrated are for instance valves and filters [6][7][8]. A possible concern with the design of the FMMR here is the structural stability during launch vibrations.…”

“…Using microfabrication, different parts of a propulsion system, such as thrusters, filters, valves and sensors for measuring flow and pressure, can be integrated on a single MEMS chip [6][7][8]. This may reduce the system mass and size considerably since the components do not need individual housing and tubing in between them.…”

Investigation of exhausts from fabricated silicon micronozzles with rectangular and close to rotationally symmetric cross-sections

“…The probably most studied, and space-qualified, type of microfabricated (heated) cold gas thrusters are nozzles fabricated in silicon using DRIE [3,9,10,13,14]. With DRIE, the walls obtained are smooth and well-defined, but the nozzles are not symmetrical about their centre-axis.…”

“…To obtain low thrust and small components, microfabrication is a frequently used technique [3][4][5][6][7][8][9][10][11][12][13][14] where the small and precise feature sizes can be utilized for miniaturized nozzles, small spacing between electrodes, propellant capillaries, etc. Furthermore, microfabrication enables high levels of integration where a thruster can be on-chip integrated with components such as valves, filters, sensors and electronics.…”