Sira takes a Martian view of fibre-optic components

Sira takes a Martian view of fibre-optic components

Sira Electro-optics Division is currently looking at how conditions found on missions to the Moon and the planet Mars could affect the use of fibre-optic systems in spacecraft.

Under the terms of a contract awarded by the European Space Agency (ESA), Sira is reviewing the worldwide availability and suitability of fibre-optic components which ESA could potentially use in its space programmes. Part of the work includes testing selected components under the conditions they will experience during launch, in orbit, and when they are located in a planetary base on the Moon or on Mars

Fibre-optic components are likely to be used in space for high-speed data transfer, communication networks and fibre-based measurement systems. During the launch of a spacecraft, however,they will need to withstand mechanical shocks typically of up to 2,000 x g at frequencies above 1.5kHz ­ low-frequency and random vibrations, rapid declines in pressure of about 10mbar/second, and peak ambient temperatures in the payload area of up to 100°C for several minutes.

 Sira fibre optic system

And when the fibre-optic components are in space, they will have to withstand ionising radiation,including high-energy cosmic ray particles.

The major problems for optical-fibre-based systems will be posed by geomagnetically-trapped electrons and protons. These usually originate from solar flares and the solar wind and have energies ranging from a few thousand electron-volts (keV) to several million (typically 5MeV).

According to Sira project manager Dr Mike Cutter, a spacecraft going into geostationary orbit at about 36,000km above the Earth's surface experiences very significant irradiation.

"Exact levels are difficult to predict", he says, "as they depend on the amount of solar activity. In finding out the ability of key fibre-optic components to survive and operate under the actual conditions peculiar to space, we have made allowances for wide variations in radiation levels by applying large safety margins".

At the end of the two-phase contract, Sira will be providing ESA with written guidelines and recommendations on how to select fibre-optic components for specific duties in space and on other planets.

For further information contact Richard Brook, Sira Ltd, Electro-optics Division, South Hill,Chislehurst, Kent BR7 5EH, UK. Tel: 0181 467 2636.