Science Interviews

Interview

Tue, 29th Mar 2016

How do you get a satellite into space?

Professor Martin Sweeting OBE FRS, SSTL

Listen Now    Download as mp3 from the show Adventures in Satspotting

Space is one tough cookie to crack: satellites have to work in extreme GPS satellitetemperatures, radiation and a vacuum. There are now over 3,000 satellites orbiting Earth but how did we get them up there in the first place? Graihagh Jackson finds out...

Graihagh - The first artificial satellite to launch was the Soviet Sputnik 1 mission in 1957.  A polished metal ball, it was just over half a metre in diameter with four long, radio antennae which beamed beep beep beep back down to the Russians, letting them know it had reached orbit safely. It was this Boule that sparked the Space Race between Soviet Union and the AmericansÖ

Ö 3, 2, 1, 0.  All engines running.  Lift off, we have a lift off.  32 minutes passed the hour.  Lift off on the Apollo 11.

... is arguably why we saw men on the moon a mere 12 years later...

Buzz Aldrin - Itís one small step for man, one giant leap for mankind.

Graihagh - Fast forward 60 years and guess what? Space is no less political. The launch of European satellite constellation, Galileo, was largely propelled by our over-reliance on American navigation systems. What would happen if we fell out? They could jam the signal and because weíre so dependent on these satellites, it would render us extremely vulnerable.

Think about it, we use this technology every single day like satellite navigation...

If youíre driving anywhere in your car you probably use satellite navigation to get where youíre going.

Graihagh - And then thereís the stuff you never  even think aboutÖ.

Well actually every time you go and get money out of your ATM, all of these are coordinated through satellite based timing systems.

Graihagh - And the scientific scientific and military applications that we touched on beforeÖ

There are all kinds of political reasons why you might want one.

Graihagh - And itís all seemingly invisibleÖ

But how the heck do you get from concept to object orbiting Earth? Today, the life and death of a satellite and the future of these metallic beasts.

Martin - Iím Martin Sweeting.  Iím the Executive Chairman of SSTL and Chairman of the Surrey Space Centre.

Graihagh - And when I looked you up on the internet, I have to admit you have a number of letters after your name so youíve clearly done something quite amazing in terms of industry and space and satellites.

Martin - Well...  First of all I have to say that I have to own up to saying that Iíve had a great deal of fun and the letters sort of came afterwards.  They weren't the objective, I had a lot of fun.  What we did, particularly in developing small satellites over the last 30 years, was recognised by people and the letters followed.

Graihagh - I met Martin at a conference at the Royal Academy of Engineering earlier this month. Given that SSTL - or surrey satellite technology limited - have launched more satellites than I can count on my fingers and toes put together, I asked him to talk me through how a satellite is born.

Martin - WellÖ I suppose the first thing to start with is, fairly obviously, is to decide what it is you want the satellite to do. So, are you going to take images of the earth, are you going to provide communications, or whatever, and then you go about deciding how big the satellite is, how much power itís going to need.  If itís going to carry instruments, how big are those instruments. And then that gives you an idea of the physical size and the power demands of the satellite.  Once youíve done that, obviously thereís a lot of detail that goes into the design of the spacecraft, both the electronics and mechanics.  Then, of course, having more or less got that sorted out, you actually have to build it.  Thatís, to some extent, the fun part; trying to find neat technical solutions at the right cost to meet the objectives is a big challenge.  Yes, space is inhospitable, you canít go up and fix it but actually, 20 minutes of launch is the most physically demanding because everything shakes and rattles.  After that, thereís no shaking and rattling whatsoever.  Itís a very benign environment but the environment can then suffer temperature extremes if you donít design it right and that, of course, can play havoc with the electronics, and the biggest difference between being in space and on the ground is radiation.  On the ground we are protected by the atmosphere and by the Earthís magnetic field and in orbit weíre not.

Graihagh - Itís a long list of things to think aboutÖ but thatís not all.

Martin - You then need to look for, basically, a rocket thatís the right size.  Itís a bit like going down to the shops and you have to choose a rocket thatís the right size.  One thatís too big will be delightful but much too expensive, one thatís too small wonít fit, so itís a question of optimising that.  And then, of course, thereís only a limited number of suppliers of rockets and those are all over the world in different countries so thereís a fair amount of international awareness and negotiation that goes into it.  You have to go through all the contract conditions, how do you ensure it against failure or it falling out of the sky on somebody and things like this, so thereís many legal and contractual aspects apart from the technology that goes into it.

Graihagh - And then, when youíve got your satellite in the sky, you can breath easy, right?

Martin - And one of the things we have to remember is that you canít go up and fix it, so if something goes wrong and you get the blue screen of death on your satellite, you canít just go round the back and press the reset button. You have to either find ways that you can solve it from the ground or you can switch to redundant or alternative systems which would allow you to recover the functionality and control of the satellite.

Graihagh - It sounds like a lot to worry aboutÖ

Martin - Yes, and actually, thatís not the end of the story because once the satellites launched into space, you have to be able to communicate with it and control it from the ground and if you think that a satellite in lower orbit is travelling at 7 kilometers a second, you see it for 10 minutes and then it disappears, so youíve got to be able to ensure that the satellite operates safely for most of the time when you canít talk to it.  Just building and launching the satellite is actually only half the story.  Controlling it, making sure itís safe, getting the best out of it for a long period of time so you get your money the back on your investment is just the bigger problem

Graihagh - And how long does this take from conception all the way to getting it safely up into orbit?

Martin - Well it depends.  Government missions, particularly science missions, may take 1 or 2 decades.  Commercial missions make take 4 or 5 years.  Some of the latest developments in small satellites have accelerated that so it could be twelve months or less.  So now weíre seeing small missions which are going from concept to being ready for launch in certainly less than 12 months, sometimes 9 months or thereabouts.  So the tempo is increasing for the smaller scale satellites but for very exotic, big satellites, maybe costing a billion dollars or so, typically itís a decade.

Graihagh -   And Galileo is an good example of this. The first of 30 satellites were catapulted into space in 2005. Now there are 12 up there. When the project is complete, theyíll be 30 satellites dotted above Earth providing us with a reliable and very precise location data (think cm accuracy rather than the metres accuracy weíre used to). But wonít this just make us more reliable on global navigation systems? Is that a good thing?

Martin - Most people donít realise how dependent they are on space, which is good but also frightening. As our modern society takes advantage of space, we also become dependent on it and if weíre dependent on it, there are some vulnerabilities.  Some of those vulnerabilities are fairly obvious, if a satellite fails then you lose the service but others are slightly less obvious.  One is solar activity; we havenít had very large solar storms for over a 120 years, 150 years now.  If we were to get a very large solar storm, that would affect satellite communications, and timing, and navigation, and so on and, of course, it is vulnerable to malicious cyber intrusions,  not necessarily more than anything else, but itís one of the vulnerabilities.   And so if we do lose the benefits of space we will feel it, much more now than we would have done 30 or 40 years ago.

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