Satellites in space

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  1. Satellites in space

1.1 A space engineer

Jeremy Curtis is an engineer and business development manager for space science at the Rutherford Appleton laboratory (RAL) in Oxfordshire. His job includes on the joint European telescope for X-ray astronomy (JET-X), due to have been launched in 1999 on the Russian Spectrum-X spacecraft. He says “I trained as a mechanical engineer, but I find space engineering exciting because I have to work with all kinds of experts such as astronomers, physicists, designers, programmers and technicians working around the world”. He was sponsored by RAL during his university degree and then spent several years on designs for a large proton synchrotron (a machine for accelerating protons to very high energies) before moving over to space instrument design. In the following passage he describes some of the aspects of space engineering.

Why satellites?

Getting spacecraft into orbit is a very expensive activity with typical launch costs generally measures in tens of thousands per kilogram. So what makes it worth the bother? There are three key reasons.

First, a satellite is a good vantage point for studying the earth’s surface and atmosphere – just think how many aircrafts would be needed to photograph the whole of the earth, or how many ships to monitor the temperature of the oceans.

Second, if we want to study most of the radiation coming for distant parts of the universe we have to get above the atmosphere. The earth’s atmosphere absorbs almost everything that tries to go through it – from X-rays to ultraviolet and from infrared to millimetre waves. Only visible light and radio waves can get through it. In fact, even visible light suffers – convection in the earth’s atmosphere makes stars seem to jump about or twinkle, blurring telescope images, so a telescope in space produces sharper images than possible from earth.

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Finally, and not least, a communications satellite can beam TV pictures across the globe and link telephone users from different continents.

The problem with space

Once you’ve got through the huge trouble of expense of launching your satellite, a new set of problems confront you in space.

First, a typical spacecraft may need several kilowatts of power – but where do you plug in? The only convenient renewable source of power is the sun, so most spacecrafts are equipped with panels of solar cells. You can see these on the Infrared space observatory (ISO). Unlike earth there is ...

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