The European Space Agency and the Australian National University have successfully tested an ion engine that could one day take astronauts to Mars, at ESA’s European Space Research and Technology Centre in the Netherlands.
The Dual Stage 4 Grid (DS4G) engine has a specific impulse (Isp) of 19,000s, compared with existing ion systems that achieve 4,500s.To do this it uses, as its name suggests, a four-grid design developed by UK company EP Solutions.
Existing ion engines use two perforated grids, which have voltages applied to them. The gas propellant’s electron-stripped atoms, which are the ions, are pulled from their container by the first grid, which has a high voltage.
The difference in voltage between the first grid and the second, low-voltage, grid accelerates the ions. However, attempts to achieve an Isp far greater than 4,500s with this design has seen damaging ion collision with the grids.
To solve this, two grids, with a voltage difference between them, are placed close together. This proximity and voltage disparity stops collisions and the second pair of grids accelerate the ions.
The next step is further testing and selection of a demonstration mission like ESA’s Small Missions for Advanced Research in Technology (SMART)-1.
ESA used a Hall Effect thruster, which is like an ion engine, but less efficient, to send its SMART-1 probe to the Moon.
“It could be tested on a SMART-1-like craft that goes to Mars and back to prove the mission profile that would eventually take people,” says ESA’s Advanced Concepts Team’s advanced propulsion research fellow and ion engine’s technical manager Roger Walker.
Source: Flight International
