History of Mirrors- Published on: 15/04/2009 19:29:01
It’s a ritual we humans perform on a daily basis; it’s so instinctive we almost don’t notice it. But every morning there we are - looking into the mirror. Sometimes it’s while shaving, or combing our hair or just checking we look presentable for the day ahead. We programme ourselves to do this from an early age once we become self aware and conscious of how we look.
Mirrors have fascinated mankind since prehistoric times .The Ancient Mayans, Aztecs, Indians, Chinese, Incas and Egyptians all buried there dead with in there eyes magical stone or metal reflectors, to ward off evil spirits or catch the soul or even to make sure they were presentable in the afterlife. Early round mirrors mimicked the sun due to their similar round shape.
Mirrors were even back then used to apply war paint or simple cosmetics just like today. Mirrors have always been believed to be magical throughout the ages and even back in the Middle Ages people used them to see into the future as Scryers
Mirrors have always played a part in history-The great Archimedes used mirrors to set fire to Roman ships in the harbour during the siege of Syracuse according to ancient legend. People debate whether this ever happened but either way it lead on to how mirrors have shaped our past and future.
Another ancient legend where a mirror of sorts is used is in Greek mythology where the Greek goddess of wisdom daughter of Zeus- Athena- gave a young Perseus a magic highly polished reflection/mirrored shield so he could fight Medusa who would turn anyone to stone if they stared directly into her eyes.
The most amazing mirror in modern times being the Hubble space telescope –a mirror Archimedes would be impressed with no doubt.
The Hubble mirror
Construction of the Perkin-Elmer (who were the main contractor) mirror began in 1979, starting with a blank manufactured by Corning from their ultra-low expansion glass. To keep the mirror's weight to an absolute minimum it consisted of inch-thick top and bottom plates sandwiching an intricate honeycomb lattice. Perkin-Elmer simulated zero-g by supporting the mirror on both sides with 138 rods that exerted varying amounts of force. This ensured that the mirror's final shape would be correct and to detailed specification when finally deployed. Mirror polishing continued until May 1981. Perkin-Elmer's managerial structure was brought into question, and the polishing began to slip behind schedule and over budget. To save money, NASA halted work on the back-up mirror and put the launch date of the telescope back to October 1984. The mirror was completed by the end of 1981; it was washed using 2,400 gallons of hot, deionised water and then received a reflective coating of aluminium 65 nm-thick and a protective coating of magnesium fluoride 25 nm-thick.
NASA was forced to postpone the launch date until first March and then September 1986. By this time the total project budget had risen to US$1.175 billion .
In fact after launch it was found that the mirror and telescop did not work properly as it was flawed.It took a few years and lots of work but finally a solution was found and STS-61 Space shuttle Endevour in December 1993 was launched to begin the complicated repiar procedure to fix the flawed mirror.The mission involved installation of several instruments and other essential eqipment over a total of 10 days. Finally on January 13, 1994, NASA declared the mission a complete success and showed the first of many much sharper images.