Belfast boost with electric space thrust
Further evidence of the UK space industry’s good health was demonstrated as Thales Alenia UK (a joint venture between Thales and Leonardo) unveiled new satellite propulsion technology based on solar power and xenon.
This first UK all-electric module, called SpaceBus Neo, is intended to become the standard propulsion module for the new generation of all-electric geostationary satellites to be built in the UK. It will be deployed for its first mission late in 2019 with European satellite operator Eutelsat. Its mission is called Konnect, a new-generation high-throughput satellite for African broadband.
Large satellites currently use a bi-propellant system, which uses monomethylhydrazine and nitrogen tetroxide. When these are mixed they heat up and expand to provide a very high thrust for a short time. Ben Oliver, CEO of Thales Alenia Space, explained: “That chemical system might give you 400 newtons of thrust, while an electric system might give you just 1N or 2N of thrust. So they operate differently.”
The electric system uses the power from the solar arrays to ionise the xenon and fire it out through the thruster at high velocity with huge efficiency. “An electric system is five to ten times more efficient than a chemical system,” said Oliver. “You need much less volume of propellant. Xenon is chosen because it is a fairly heavy gas [therefore able to provide more thrust] and you can compress it and ionise it relatively easily. It is very effective in this particular application because there is no air resistance and therefore you can get away with very low levels of thrust – it takes a long time to climb into its orbit. So it is launched into a low orbit and can take several months to spiral up into its position.”
This two- or three-month time span to gain final geostationary position compares with a matter of hours or a day or two with chemical propulsion systems. This time difference, claimed Oliver, is more than countered by other advantages: “It is more efficient to use a smaller and lower-cost launcher to launch the satellite and then do more of the transfer with the electric propulsion because it is five to ten times more efficient, so you can afford to do more of the work yourself on board the satellite, given that you are going to have to have a system on board anyway. The equation is to take 20 per cent out of the cost of the mission and that is the big win and why operators are attracted to it.”
The module is 2.6m x 1.8m, weighs nearly a couple of tonnes and is planned to have a 15-18-year lifespan.
“It is probably one of the most significant bits of space hardware designed and built in the UK,” said Oliver. “It meets the main market in space, which is geostationary communications. Although Airbus in Germany and Boeing in the US already build electric thrust modules, we think we will have cost and performance advantages over those systems. What we think will make us competitive is the very high level of manufacturing skills we have in the facility in Belfast. It’s often an under-reported story about the UK industrial base.”