Part 1 of Essay
Centuries ago the Greek mathematician Archimedes used sunlight to set fire to invading ships. In the following paper you will read more about the wonders of its many uses and how it works. You may also find facts like why it was invented, how it started, how it is used today, and how it is hoped to be used in the future. ....

Part 2 of Essay
.... source of power was needed to be found that would have to function over a long period of time with a continuous source of electrical power. If these needs weren’t met future space activities would be limited. was eventually used. Once an unmanned space probe was on its way no one would be there to oil or repair it. Solar cells today are made out of one of the earth’s most common ingredients, silicon. Silicon used in producing solar cells is very carefully prepared. The flow of electricity takes place when the cel ....