Photogrpah above shows the CEDEX instrument - image copyright Professor Underwood, University of Surrey
By 2020 the Galileo programme will have 30 satellites providing a global navigation system run by civil authorities. Central to the project is the world-leading expertise at the University of Surrey and Surrey Satellite Technology.
The world increasingly depends on satellite positioning, from mundane activities such as personal apps, to essential information for shipping, aircraft crews and rescue services during natural disasters. GPS, the USA's satellite positioning network, has become almost synonymous with satellite positioning, and is the most used system around the world. GPS however could be subjected to restriction for military use in extreme circumstances, as could GLONASS, the Russian system. The European Union’s Galileo project was set up to provide an alternative system for civilian use only, on which European citizens can rely in case GPS or GLONASS were shut down.
The University of Surrey and its spin-off company Surrey Satellite Technology (now owned by Airbus) is a world leader in small satellites, and have been important players in the Galileo project. Back in the 1970s only countries with large aerospace could afford such technology. But Martin Sweeting, a young PhD student at the time believed that by repurposing the new generation of computer processors, the economics of space could be transformed. Sir Martin Sweeting is now Executive Chairman of SSTL and director of the Surrey Space Centre at the University. The early satellites were used for educational purposes which was how Professor Underwood, Head of the Planetary Environments Group at Surrey, got involved. He explains, ‘I was a school teacher in those days and I used it with my students and I was able to pick up information from the satellites on VHF (Very High Frequency). It transmitted a mixture of digital data and it had a voice synthesiser, using a thing called ‘Speak and Spell’. It had about 500 words of vocabulary with a Dalek-like voice!’ Underwood joined the small University team in 1986.
On the Galileo project, Underwood helped on the protection design for the test spacecraft launched in 2005. ‘One of the challenging things for us is that we had always been launching spacecraft into lower orbit, typically 800 km, 1320 km was the highest we’d gone with an SSTL craft – somewhat lower down than 23,000km!’ The key issue at that height was the radiation effects on the electronic systems. They had to protect against two possibilities: the accumulated dosage of radiation which damages the electronics and a single event. Professor Underwood explains that they ‘used a combination of material shielding and fairly careful component selection from a commercial off-the-shelf set of components to get a system that would work.’ They also had to produce new instrumentation to monitor the radiation. Underwood produced an instrument called CEDEX (French for post-box) while UK collaborators QinetiQ created MERLIN. Despite now being in space now for 9 years, the spacecraft, and the MERLIN payload are still operational, and the SSC is still analysing the data on behalf of the European Space Agency.
Just as the Galileo project is an international collaboration so the Surrey Space Centre is richly diverse. ‘We are very international in our outlook,’ says Underwood, ‘and we have students from all over the world here. The Space Centre looks after about 60 or so PhD students with about 12 academic staff and 25 research fellows. There are about 100 people in the space centre and about 600 in SSTL.’ Each institution mutually benefits the other. ‘The role in the Space Centre is to carry out the long term research, that the company then exploits later,’ says Underwood. ‘It works brilliantly well as an extremely close relationship between academia and industry, it enables us to take the research and to push it out into commercialisation rapidly.’
The older GPS is being upgraded and the Russian system is being improved too. Underwood adds, ‘China wants its own and has started producing one called Compass. We are seeing a multiplicity of navigation satellites. That’s a good thing because receivers that are capable of receiving the different signals from spacecraft can actually make use of this. Particularly in the urban areas where you get what’s called Urban Canyon effect, ‘ he says, where buildings can block out much of the sky. ‘You do need to see four satellites to get a fix. The more satellites the merrier.’