{"id":3277,"date":"2011-06-30T20:42:03","date_gmt":"2011-06-30T20:42:03","guid":{"rendered":"https:\/\/mtlsites.mit.edu\/annual_reports\/2011\/?p=3277"},"modified":"2011-07-19T20:21:40","modified_gmt":"2011-07-19T20:21:40","slug":"mems-space-thrusters-the-ion-electrospray-propulsion-system-ieps-2","status":"publish","type":"post","link":"https:\/\/mtlsites.mit.edu\/annual_reports\/2011\/mems-space-thrusters-the-ion-electrospray-propulsion-system-ieps-2\/","title":{"rendered":"MEMS Space Thrusters: The ion Electrospray Propulsion System (iEPS)"},"content":{"rendered":"

Electric Propulsion (EP) brings benefits for space missions requiring relatively large changes in satellite velocity, for example by reducing the propellant mass compared to traditional, less fuel-efficient chemical engines. Introducing EP in small satellites would enable them to perform interesting missions, such as long term attitude control\/drag cancellation, orbital modification and, perhaps, deep space travel [1<\/a>] <\/sup>. However, most EP technologies are challenging to miniaturize to the required levels, especially for nano\/pico-satellites. Our group has developed an ion Electrospray Propulsion System (iEPS) as a candidate of an EP technology amenable for efficient miniaturization. The thruster core is based on a porous metal structure, which is bonded to an oxidized silicon package frame, followed by masking of the metal with a pattern of circles. The metal is then electrochemically etched in a regime that prevents material removal inside the pores, thus forming an array of porous tips [2<\/a>] <\/sup>, as shown in Figure 1. To finalize the device, an extractor silicon grid with a matching array of holes and coated with a gold film is aligned and bonded to the frame holding the porous metal. Electrical isolation is provided by the bonding material and grown silicon oxide layers. A zero vapor pressure ionic liquid (the propellant) is then injected to the device from the back through a port in the silicon frame. The liquid wicks through the porous structure reaching the tips. Ion emission is the produced when applying a voltage of about 1kV between the metal and extractor grid. Figure 2 shows a typical I-V curve and a picture finished devices on a CubeSat [3<\/a>] <\/sup>. A thruster pair should be able to produce 60-70 micro-N, enough to raise the orbit of a 1 kg CubeSat by 400 km in about 25 days of operation consuming 6-7 grams of propellant with 1W of power.\n\t\t