Plasma thrusters could double the lifetime of mini satellites

22 February 2012 | By Stephen Harris

Southampton University spin-out Mars Space and its partner Clyde Space claim their lightweight propulsion system — fuelled by a small block of Teflon — will enable 10cm-wide cubesats to remain in orbit for more than a month rather than a matter of weeks.

The companies have received £44,000 to demonstrate the pulsed plasma thrusters ready for deployment from the start of next year, as part of a £2.5m government programme of research and development investment for the commercial space sector.

‘Normally cubesats lose their orbit because of atmospheric drag,’ Mars Space’s director, Dr Michele Coletti, told The Engineer.

‘If they are in low-altitude orbits around 150km to 300km, cubesats will de-orbit normally within days to a month depending on how big it is and how high.

‘If you use our system with a power of 2W you can double this lifetime. So instead of staying there for two to three weeks, it’s going to be there for six weeks.’

Cubesats are typically used for research projects, often as a way for universities and smaller companies to conduct space research relatively cheaply because of the satellites’ small size.

Pulsed plasma thrusters work by ionising solid propellant fuel and accelerating the resulting ions and electrons to high speeds, firing them out in short bursts.

To create these pulses, electric capacitors are repeatedly and very quickly charged to around 1,000V and then discharged to ionise the fuel.

‘You get very small thrusts but with very high exit velocities and that means you have low propellant consumptions,’ said Coletti. ‘And the lower the propellant consumption the lighter the system.

‘If you send, with our current design, 2W of power, you have one discharge every second. The more power you add, the higher the performance. These kind of devices can work with almost any power level.’

The main challenge for Mars Space, which is developing the thruster discharge chamber, and Clyde Space, which is developing the electronics, is miniaturising the technology to create a system weighing under 160g.

Once the technology is proven, the companies hope to market it to cubesat manufacturers and projects such as the EU-funded QB50 programme.

A total of 22 British companies are to match the £2.5m of funding provided by the Technology Strategy Board, UK Space Agency and South-East England Development Agency in 28 short-term projects under the National Space Technology Programme.