Space race ‘hero’ pushes UK to front

Technology that gives the UK a firm lead in the space race to develop small affordable satellites for commercial and military use has won Professor Martin Sweeting OBE a gold medal for outstanding engineering achievement. Sweeting, who heads the Surrey University Space Centre, received the Engineering Council Chairman’s Medal on 30 April at the council’s […]

Technology that gives the UK a firm lead in the space race to develop small affordable satellites for commercial and military use has won Professor Martin Sweeting OBE a gold medal for outstanding engineering achievement.

Sweeting, who heads the Surrey University Space Centre, received the Engineering Council Chairman’s Medal on 30 April at the council’s annual conference ‘Engineering the Competitive Edge’.

Describing the professor as an unsung hero, HRH The Duke of Kent highlighted the many earthbound applications that rely upon satellites from the operation of the National Lottery to the Global Positioning System for land, sea and air transport.

Since beginning its UoSAT satellite programme in 1978, the University of Sheffield has pioneered the development of low-cost, high-powered microsatellite technologies for low Earth orbit (LEO) applications.

Spinoff company Surrey Satellite Technologies Limited manufactures and commercialises the satellites which take around 12 months to develop from concept to orbit, at a cost of £2-3m each. SSTL’s turnover is currently £7m.

It is generally accepted that a microsatellite weighs less than 100kg and costs less than £4m. A small satellite, in comparison, weighs less than 1000kg and costs less than £100m.

Attracting worldwide media interest in 1996, Cerise, a military satellite developed by SSTL for the French ministry of defence, became the first space craft to be struck by space debris, which severed its stabilisation boom. Cerise was restabilised by uploading new attitude control algorithms to allow it to continue its successful 700km low Earth orbit.

SSTL has launched 12 microsatellites so far. They carry a variety of communications, space science, remote sensing and in-orbit technology demonstration payloads.

Surrey’s first experimental microsatellites, UoSAT-1 and 2, were launched in 1981 and 1984 as piggyback payloads on Delta missile launchers assigned to NASA.

They carried the first experimental 2D-CCD Earth imaging cameras, which led to the development of the greyscale CCD Earth Imaging System now on board UoSTAT-5.

That mission aims to demonstrate the potential for low-cost Earth observation and remote sensing. Earlier missions have cost typically more than £150m each.

UoSAT-5 also carries a Solar Cell Technology Experiment to evaluate the performance of 27 types of solar cell, from various makers, when exposed to prolonged radiation.

Low-power and solar-powered microelectronic systems make low-cost microsatellite technology possible.

Two other microsatellites, HealthSat-1 and 2, built by SSTL, form a mini constellation for the HealthNet email communications network. HealthNet is the only small LEO satellite service to be fully operational.

On 23 June, two 50kg microsatellites from SSTL, KITSAT and PoSAT, commissioned by Chile and Thailand, will be launched from the de-militarised Baikonor Cosmodrome in Moscow.

They will carry advanced imaging systems that use multi-spectral imaging to simulate colour. True colour images based on the RGB spectrum are not possible in space because the Earth’s atmosphere acts as a filter that colours everything blue. Narrow-field ground resolutions of 100m are 10 times better than on UoSTAT-5.

Other microsatellites due for launch in 1999 will provide imaging resolutions down to 50m. At this range an individual house can not be pinpointed, but it is possible to identify crops.

Larger minisatellites capable of heavier payloads than microsatellites are also being pioneered by SSTL in preparation for the first low-cost interplanetary mission to the Moon in 2001.

The first, due to be launched next year, is the experimental minisatellite UoSTAT-12 weighing 350kg. The final version will be launched from Ariane V in geostationary transfer orbit and from there to the Moon, powered by its own engine.

It will take long-term measurements from the hidden south pole of the Moon, spending six months looking for weather and seasonal changes. The cost is put at around £10m.