Until about 25 years ago mariners needed a sextant, a chronometer and a set of mathematical tables to find their way at sea, which probably explains why those days sported less cretinous captains on ships’ bridges. Today you don’t need any maths any more to navigate, push on a few buttons and a little machine will give you latitude an longitude and if you don’t know what that means you’d better buy my books. This Global Positioning System, based on a number of american satellites has been working quite well but the setback is that the system belongs to the american army and that belligerent lot can switch it off when they feel like it.

The Europeans were of course not too happy with this american monopoly but until their satellite launching capacity improved they couldn’t do much about it but, at last,  two days ago they succeeded in launching the first satellites for their future ‘Galileo System’ of celestial computer navigation. It is a civil enterprise that pays the costs and so the military can’t get their filthy hands on it. And what I really like about the whole undertaking is that that whole bunch of Europeans involved went about the launch of these satellites in a sensible, economic way. Looking at the financial cock-ups the politicians of that part of the world are capable of, Galileo is still more surprising.

I’ll explain a bit because most bloody newspapers won’t tell you. You see, the 2 satellites to be launched weighed together about a ton and a half. The european rocket, ‘Ariane’ can launch much more and costs a hell of a lot more. The Russians have a rocket, ‘Soyuz’, very successful for the last 50 years but, from where the thing is launched, it can’t throw much more in space than 1.6 ton. To launch 1.5 tons with a rocket that can’t handle more than 1.6 tons is a dicey business, despite the fact that the launching price was a lot lighter.

“But,” said one of the space fellows, “we have a launching pad in French Guyane, which is near the equator. The Russians launch their Soyuz from latitude N 46 °. If we launch from Kourou in French Guyane that rocket should be able to launch our satellites with ease because the circumferential speed of the Earth near the equator is a lot more than in Siberia!”

That’s all I was told, it made sense and I worked it out.

Most of us know that the Earth’s circumference at the equator is 40.000 km. (I’m rounding of figures). As the Earth does a spin every 24 hours, the surface Earth speed is 40 000/24 is 1666km/hour. When you shoot of your rocket in the right direction you profit by that speed. At the russian launch pad in Siberia at Lat. 46°N the circumference of the Earth is a lot smaller, 27.839 km  and the resultant hourly speed is 1159km/hour. That difference in circumferential earth speed of 507km/hour made it possible for the ‘Soyuz’ rocket to launch 3 tons at Guyane, near the equator instead of 1.6 tons in Siberia. Simple reckoning, it worked fine..

You would think that the equator being such a good place as a launching site for rockets, why isn’t  it used more. A look at the world globe soon shows that on that imaginary equator line not many bits of solid earth are available, because the Pacific- Indian and Atlantic Oceans use up most of that line. The line goes through a fair bit of african real estate but that continent has a copper cable hungry population which might interfere with launchings. In South America only that bit of french Guyane is suitable, elsewhere cocaine fumes will probably interfere. In time to come great sea-borne barges, positioned bang on the equator will be used, I imagine. 

If anyone is interested to work out the Earth’s circumference at any latitude, take the cosine of the latitude angle, multiply it by the Earth’s radius, which is 6378km and multiply again by twice pi.