Technology Quarterly | Brain scan

Britain’s spaceman

The pioneer of small satellites is laying plans for the infrastructure and services needed for travel to other planets

SOMETIMES a childhood fascination can shape a lifetime. For Sir Martin Sweeting it began with forging a communications device out of two tin cans connected with a taut piece of string. This led to a schoolboy interest in amateur radio, which turned to a passion in the late 1960s at the time of the Apollo Moon landings and intoxicating space imagery from films like “2001: A Space Odyssey”.

While studying for his PhD in the late 1970s at the University of Surrey in Guildford, a town south-west of London, Sir Martin made equipment from whatever he could lay his hands on to pick up signals from American and Soviet satellites. In 1985, with £100 ($150) borrowed from the vice-chancellor, he founded Surrey Satellite Technology (SST), a firm which has pioneered the use of small satellites built from cheap off-the-shelf equipment.

Space used to be the province of superpowers, but the arrival of lower-cost small satellites brought down the price of entering the space business to a level which companies, research groups, developing nations and even some schools could afford. Now Sir Martin is preparing SST for a future in which he plans to provide essential services to a new generation of space travellers.

Before SST, space was not a particularly promising field in flared-trousered 1970s Britain. The country had quit the space race as post-war enthusiasm for rockets had dwindled. Government spending cuts led to ambitious launch systems and manned-flight programmes being abandoned. Deciding that he did not have much chance of joining America’s space agency, NASA, Sir Martin started to try some things for himself. With the first microcomputers arriving on the scene he wondered if it was possible to use one to build a small satellite that was reasonably “intelligent” compared with the large and expensive hard-wired satellites that were being put into orbit at the time.

Sir Martin persuaded the university to let him try. “I didn’t have any money so had to go around scrounging from industry and anybody else I could think of,” he says. With a team of volunteers the satellite was built. It was about the size of a couple of microwave ovens and weighed 72kg. Some of the big satellites that government space agencies were putting into orbit were as large as a London double-decker bus. Through the amateur radio network he managed to persuade NASA to provide a free launch, and in 1981 the microsatellite piggybacked into space as part of a mission to put a large scientific satellite into orbit.

The Surrey satellite was a novel piece of engineering. Besides containing an on-board computer, allowing the satellite to be reprogrammed from the ground, it was also fitted with an early charge-coupled device, a type of sensor which would become the heart of modern digital cameras, and a digital speech-synthesiser extracted from a toy. This meant that besides being able to take pictures of Earth the satellite could “speak’’ to the world below. The idea was that radio amateurs and schools could use basic equipment to tune in to hear data, such as the temperature, being read out. “Amazingly,” says Sir Martin, “to everyone’s surprise it worked.” In 1984 the team built a second satellite containing a new computer and an updated camera. It too was given a free launch by NASA and, although now not in the best of health with its solar-powered batteries deteriorating, it is still transmitting back to Earth.

The spin-out powers up

After years of begging and borrowing, Sir Martin and a team of four others began SST to see if they could turn the production of small satellites into a business. They were encouraged by interest from a number of countries that wanted to get a foothold in space, including Pakistan, South Korea, Malaysia and Chile. “And because we were linked to a university, we were prepared to train their people and share information with them,” adds Sir Martin. Many of those tutored during the construction of the firm’s first satellites went on to form the nucleus of other countries’ space agencies—and produce overseas competitors that would come to emulate SST.

SST has, nevertheless, maintained what it says is a 40% share of the global export market for small satellites. It has built and launched more than 40 of them, ranging in weight from 3.5kg to 660kg, and has over 20 others in production along with various payloads for other space missions. The company now employs 500 people. In 2009 Airbus bought 99% of the firm’s shares from the University of Surrey, which retained 1%. As part of the deal with the European aerospace giant, SST continues to be run as an independent company and Sir Martin, who was knighted in 2002, serves as its executive chairman.

Some of whizziest components made for terrestrial use might not be up to the rigours of space

Building small satellites from industry-standard parts means reaping the benefits of huge investments by car companies, consumer-electronics firms and others in developing sophisticated components for mass-produced goods. This can limit the abilities of a satellite but it provides economies of scale which are impossible to achieve if making bespoke components. “We were being parasitic, if you like,” says Sir Martin.

Besides lower costs, commodity components have become increasing reliable—essential in building a satellite which, once in orbit, may not be repairable. In the early days, this could mean testing individual widgets, such as transistors or capacitors. Hundreds of them might have to be shaken, cooked and abused in various ways to see which ones were best. Nowadays, with modern manufacturing methods, components have been miniaturised and integrated into units, like microchips. So testing can be done on more complete systems. And because tolerances have become much tighter, fewer parts now contain defects. However, even some of the whizziest components made for terrestrial use might not be up to the rigours of space. One of the biggest problems is radiation. Some bits of a smartphone, a common source of miniaturised electronic components and sensors, are not as resilient to radiation as other parts. So knowing which bits to use and which to avoid has become part of the satellite-making art.

In 1998 the company’s engineers wanted to see how small they could make a functioning satellite. The result was about the size of a beachball (the 3.5kg one in SST’s inventory). It was one of the first of what came to be called a nanosat. Over the next five years or so some 1,000 nanosats are expected to be launched by companies, startups and researchers.

By 2000 SST had reached a turning point. “Before then these small satellites were useful, interesting, but could carry out only a few niche tasks,” says Sir Martin. After 2000 technology improved rapidly, providing greater capabilities. “Now our satellites can rival the majority of conventional satellites,” he adds. Taking pictures of Earth, for instance, can now be done in high resolution with a small satellite fitted with the latest high-power image sensors and, maintains Sir Martin, at about one-fifth of the cost of most traditional large satellites.

Some of SST’s latest satellites have a one-metre resolution (ie, one pixel on the spacecraft’s sensor represents one square metre on the ground). This means it might be possible to identify a shape smaller than one metre, but not in detail. So the satellite could, for instance, easily spot a car. Some big high-end satellites can take pictures down to a resolution of 50cm (the legal limit in America for commercial satellites), although military ones are thought to be able to zoom closer.

The snag is, at some point the laws of physics dictate a more powerful telescope means a bigger and more expensive satellite to transport it. And as the resolution increases the field of view diminishes, so the image produced is a bit like looking at the world through a drinking straw.

As a result there are plenty of uses for satellites with resolutions of 20 metres or so, including the ability to take a picture of an area several hundred kilometres wide. This can, for instance, help in geographic surveys, monitoring deforestation or observing crops. In partnership with groups in other countries SST also operates a constellation of satellites which can rapidly be deployed in the event of a disaster. The lower-resolution ones can, say, reveal the extent of a flooded area, and the higher-resolution cameras take a look at specific problems, such as a bridge that has been washed away. These satellites were used following the Asian tsunami in 2004, Hurricane Katrina in 2005 and after the recent earthquake in Nepal.

To a new wavelength

The company is now developing observation systems that go beyond the visible spectrum. These satellites use synthetic-aperture radar, which can penetrate clouds and work at night. It relies on using algorithms to process radar pulses bounced back from the ground to build a high-resolution image.

SST is also looking at ways to address worries about space debris. There are some 500,000 bits of space junk in orbit, but Sir Martin does not think that putting up more satellites—even 1,000 nanosats—will make much difference. “The real risk is when a satellite fragments,” he says. One satellite exploding because of a fault or when it reaches the end of its working life can produce thousands of pieces of debris. Hence there are plans to develop systems that can tip old satellites out of orbit for them to burn up safely on re-entry. TechDemoSat-1, a one-cubic-metre satellite which SST launched in 2014 to carry out a number of studies, is fitted with a “de-orbit sail” developed by Cranfield University in Britain. The ultra-thin sail will be deployed at the end of the mission to turn it towards Earth.

Other satellites give another hint of where SST is going. The company is building its first small geostationary platform, which instead of orbiting Earth will remain in a fixed position relative to the surface, as telecommunications satellites tend to be. This is for Eutelsat, a Paris-based company, which provides satellite services to telecoms firms and broadcasters. In addition SST is building equipment for Galileo, a new constellation of satellites that will operate a European GPS navigation system.

“The reason we are doing that is we want to learn about navigation payloads,” says Sir Martin. The discovery of water deposits, he believes, means that in the coming decades there will be sustained habitation on the Moon and Mars. “We need to play a part in supporting this,” he adds. In likening space travel to the Californian gold rush that began in 1848, Sir Martin points out that it was not necessarily those who went to find gold that made money, but rather those who provided the infrastructure: railways, hotels, picks, shovels and the like. So, SST aims to be a service provider supplying, say, a GPS system around the Moon, or communications satellites to relay data from other planets. “We need to be building the expertise up now if we are going to be ready to do such things,” he says. It is a far cry from the days of tin-can telephones.

This article appeared in the Technology Quarterly section of the print edition under the headline "Britain’s spaceman"

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