SUBJECTS: Maths, Technologies
YEARS: 9–10
In space there are thousands of human-made objects (satellites and space junk) orbiting Earth.
To avoid collision with space debris, satellites are manoeuvred out of its path.
Discover how space debris is tracked using lasers, and about accuracy's effects on the lifetime of the satellite.
Find out, using trigonometry, the effect even 1 degree has on accuracy over a large distance.
Things to think about
- 1.Imagine you are aiming at a target 20 m away. If your aim could vary 5 degrees left or right, how much could you miss the target by? Hint: draw a diagram to form two right-angled triangles.
- 2.How does Dr Ben Greene suggest his team can reduce, by 70 per cent, the number of manoeuvres a satellite makes? Note the figures that reporter Eleni Psaltis uses to explain the improvement in accuracy between traditional radar systems and the laser surveillance system.
- 3.Let's say the radar beam had an accuracy of 1 degree and a target was 200 km away. Two right-angled triangles could be drawn, each with a base of 200 km and an angle of 0.5 degrees. The spread of the beam at 200 km would be: 2 x 200 tan(0.5) = 3.4907 km. Laser beams may have an accuracy of 0.002 degrees. What would the spread of the laser beam be (in metres) at 200 km? The answer is one of the following: 6.98 m, 13.96 m, 3.49 m.
- 4.How accurate are you? Find a wall and draw a target on it in chalk. Stand 20 m away and throw a wet tennis ball at the target. Measure the horizontal and vertical distances of spread. Use trigonometry to find your own degree of accuracy horizontally and vertically. Ask others to do the same, and compare your accuracy.
Date of broadcast: 25 Aug 2010
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