How Solar Sails Work... Photon PressureCosmos-1 can articulate its solar-sail blades. For example, when Cosmos-1's blades are all configured flat, and oriented face-on to the Sun, then sunlight exerts the most pressure on the whole spacecraft. When Cosmos-1 has twisted all its blades so they're edge-on to the Sun, then it receives its minimum push from sunlight. How Solar Sails Don't WorkHave you ever seen the radiometer from Edmund Scientific? It's a glass bulb containing some blades, painted black and white, that can rotate on a needle bearing. The air has been evacuated from the bulb so the blades can rotate freely without a lot of air resistance. While it does illustrate a form of motion caused by radiation, it works on a different principle than photon pressure (Cosmos-1 uses photon pressure). In the radiometer, light warms up the black sides of the blades. These then radiate their warmth as infra-red light, and the reaction from that radiation moves the blade. Also, don't confuse photon pressure with the solar wind. The Sun constantly throws particles outward through the solar system. These particles, mostly protons and electrons, are called the solar wind. But these particles mostly pass right through Cosmos-1's sails. Cosmos-1 does not rely on the solar wind.
On to the Next Topic...BACK TO THE SCALE MODEL HOME PAGE
|

This file was encoded by the Zend Guard. In order to run it, please install the Zend Optimizer (available without charge), version 3.0.0 or later.
The Zend Optimizer is one of the most popular PHP plugins for performance-improvement, and has been available without charge, since the early days of PHP 4. It improves performance by scanning PHP's intermediate code and passing it through multiple Optimization Passes to replace inefficient code patterns with more efficient code blocks. The replaced code blocks perform exactly the same operations as the original code, only faster.
In addition to improving performance, the Zend Optimizer also enables PHP to transparently load files encoded by the Zend Guard.
The Zend Optimizer is a free product available for download from Zend Technologies. Zend Technologies also developed the PHP scripting engine, known as the Zend Engine.