Keywords: seaspace, gps

Sea and Space / Navigation

# NAVIGATION

This part of the of Sea & Space is concerned with a very old and fundamental problem.

Imagine for a moment that you are in the middle of a big desert! All around you there is nothing but stony ground and sand - almost no vegetation and certainly no obvious landmarks that may help you to learn where you are! You can see some low mountains in the distance, but you have no idea of your true location.

How can you find out? And how can you learn which is the direction towards North so that you may start walking in the right direction and to get out of this difficult situation?

Or imagine that you are a lonely sailor, perhaps on a viking ship or a caravel in the middle of the Atlantic Ocean, on your way towards new territories beyond the vast sea. No land in view - there is nothing but water around you. How do you know where you are and how far you still have to sail? In which direction?

You probably have some ideas already. The Sun rises in the East, is seen towards South at midday and sets in the West. So watching the Sun will already give you a first feeling for the cardinal directions. If you are not too far north, a magnetic needle will indicate approximately where North is. If you are in the northern hemisphere, the Polar Star is also seen in this direction during the night - if there are no clouds.

People of all times have always wanted to know their location with some certainty. Sea & Space shows you how this fundamental problem may be solved in different ways.

The primary intention is to give a small, and hopefully inspiring introduction to some of the historical, mathematical and educational possibilities within the general field of navigation.

There are three general sections:

- Astronomical navigation.
- GPS navigation
- Navigation using satellite images

When you have read about these and tried your skills on some of the exercises, then imagine that you are suddenly on planet Mars! Within some years, perhaps two decades, the first astronauts may indeed land on our sister planet - think if you were one of them!

Images were obtained last year on the surface of Mars by the NASA Mars Pathfinder; they are available on the web, for instance at http://mars.eso.org/default.html. More recently, images have also been released from the Mars Global Surveyor - they may be accessed via the same site.

On the basis on some of these images, discuss with your friends and your teacher, how you may try to establish your location on the surface of Mars. For this, you may be guided by photos that show distant formations.

Here is an image of the Pathfinder landing site.