Space has been characterized by exploration, specially of other heavenly bodies. But, our lives are constantly in touch with satellites, the workhouses of space equipment. They furnish TV, Direct Satellite Broadcasts, Telephone service, and other messaging services. Satellites are the most interesting part of space usage world wide.
The Hubble Space Telescope, originally called the Large Space Telescope, which was released from the Space Shuttle Discovery on April 19, 1990. This satellite which has a mirror that is 22.4 meters in diameter, and orbits the earth at an altitude of over 600 kilometers does not have the atmosphere distortion problems of land based telescopes. Despite years of planning the Hubble Telescope suffered from a misground mirror that was too flat. To correct this NASA deployed COSTAR (Corrective Optics Space Telescope Axial Replacement) in December of 1993 which contains small mirrors that bounces incomplete light off their partners. These excessively concave mirrors compensate for the primary mirror's convexness. The Optic problems that COSTAR fixed were able to temporally be compensated with software although it did not provide an image as clear as it should be. NASA also replaced the solar panels on Hubble due to a design flaw that made them shutter when passing from light to darkness. Although NASA touted the success of this retrofit saying that it exceeded the original specifications for the Hubble, for political reasons, it did not provide Hubble with the original specifications. The major short loss versus the original specifications is that the field of view on all of the instruments was reduced by up to three-fourths of what it originally was planned to be.
Space has always offered a vacuum which scientists have been interested in growing crystals in because the reduced gravity and lack of air flow have provided ideal conditions to grow crystals. These crystals are useful because they could be used for many things including making computers run faster. In early 1994 the Space Shuttle Discovery grew gallium-arsenide films on the Wake Shield, a 13.5 million dollar, twelve foot diameter stainless steel disk, which provides a pure vacuum. The Wake Shield should have produced a vacuum 100,000 time purer than one could be created on Earth, but due to malfunctioning circuitry on the shield it was not released, but only tethered on the Space Shuttle's robotic arm. This reduced the vacuum to levels that can be created on Earth. This caused the quality of the films to fall because of the reduced vacuum and water vapor from the shuttle contaminated the films.
Satellite images have been traditionally restricted to governments, specifically the intelligence agencies of governments. In March of 1994 President Clinton changed this by easing restrictions by lowering the resolution maximum from three meters per pixel to one meter per pixel, which is sharp enough to see cars from four hundred miles above the Earth. While companies such as Earthwatch, Space Imaging, Orbital Imaging, and Lockheed are just starting to get into this business, governments have been selling satellite images for years. For example a Russian Spy Satellite Photo of an Officially-Non-Existent Air Base located near Rachel, Nevada appears in the March 1994 issue of Popular Science on page 55. Companies launching imaging satellites have not only been sparked to life because of the easing of restrictions, they are also more eager to enter the satellite imaging business because advances in technology, including better mirrors, make imaging more feasible. EarthWatch, a startup company, has plans to launch the first non-government imaging satellite which will have a three meter resolution. Satellite imaging companies are aiming to increase their business from a 100 million dollar a year industry to at least two billion dollars a year industry, by marketing the images to real estate agents, cities, foreign nations, utilities, farmers, and others who use plane based photography. The satellite photography industry requires this kind of growth due to the costly nature of launching satellites. Lockheed plans to spend 500 million dollars for a satellite while Earthwatch by producing smaller, cheaper satellites with Star Wars Technology wants to launch four satellites for 200 million dollars. This area of space is still developing, within two years Earthwatch, Space Imaging, Orbital Imaging are launching one meter resolution satellites, which will circle the planet in a polar orbit.
Cell Phones have become a part of many people's lives. Their main fault is though they are wireless, they are tied to a specific geographic area. Due the localized nature of cell phones, each major area has its own providers of cellular service, unlike a corded phone switching from Ameritech to Cellular One when you move is not just a matter of unplugging the phone and plugging it back in at different locations, but a matter of reprogramming the phone and obtaining a new number, a considerable hassle considering most people only make short trips to different areas. Cell phones are also unusable in airplanes and other conditions. The solution to this problem is a system of satellites. Motorola's 66-satellite Iridium satellite system, which was named after the element with 77 orbiting electrons before the amount of satellites was reduced from 77, Motorola has not renamed the system Dysprosium, the element with 66 orbiting electrons. Instead of having the Iridium satellites orbiting at thousands of miles like most satellites they orbit at only hundreds on miles. This allows the phones to be handheld because of the lower amount of energy required to transmit the shorter distance. These satellites will orbit in optimally phased polar orbits, which will provide coverage to the whole planet, including the North and South Poles. The major problem with this technology is maintaining the satellites which have complex circuitry to switch phone calls from one satellite to another, and there is the problem of having to replace failed satellites. While Iridium is an innovative technology, as many space related products it is not cheap, the telephones to be used with Iridium cost $3,000 and phone time is billed at three dollars a minute.
While voice transmissions are the most preferred transmission method of communications a small company called Orbital Sciences is developing system that will transmit short messages for twenty-five cents using twenty-six low earth orbit satellites. The company envisions this system being useful for emergency services, monitoring on large farms, and general communications. By making their satellites small and inexpensive, they greatly reduce the capital needed to launch such a system.
While designing and maintaing satellites is a major part of any satellite system, moving a satellite from the grip of Earth's gravity into orbit is also a major part of providing a satellite service. Companies that launch satellites have the major task of competing with countries for launches and launch services. China, Japan, and India are becoming major space players. China consistently underbids US companies for satellite launches by at least thirty percent. While most satellites are launched with traditional multi-stage disposable rockets several other methods are in testing, including a tethered satellite release and a vertical launch and landing vehicle. In March 1993 a tethered launch system was tested as an alternative to a second stage to launch satellites into higher orbits. A 12.4 mile polyethylene string was unreeled by the momentum given to the payload satellite by the springs that released it from its housing. Near the end of the tether brakes slowed the payload satellite down and with the payload swinging back and forth a blade cut the cord at a precise moment to direct the satellite along a precise path. Another method involves a pyramid shaped rocket called the DC-X which launches, stops it self mid-air at a predetermined height, moves itself over to a landing pad and lands vertically. This system was damaged in late June 1994. The accident that damaged the DC-x was caused by Hydrogen venting from the fuel tanks exploded seventeen seconds into the normal flight, the emergency mode was activated by a mission controller, and the ship safely returned to the ground in a repairable state.
Space Satellites like many immature technologies still has several interesting and controversial systems, including systems for lighting and advertising to the Earth. Engineers have proposed a system to beam light to proto-planktion at night. The Russians have launched a solar wail with a 65 ft in diameter of reflective Mylar what sent a 2.5 mile wide beam light at 17,000 mph across the Atlantic, Europe, and Russia. This beam could be seen from the Earth. Space Marketing Inc. has also announced plans to launch satellites of large Mylar billboards featuring a symbol visible from the Earth. This satellite would burn up after two weeks. It has been denounced by consumer groups, astronomers, and environmentalists, but the company claims the ads would provide a platform for scientific research. A 140 mile high Japanese and American satellite split into a mother and daughter ship and transmitted 832 of microwave power to recennas about 36¾” square inches. This was the first wireless transmission of power in space and it paves the way for transmission of electricity to ground based receivers.
With all of these new communications technologies especially cell phones and satellite communications it interferes with Radio telescopes that sense radio waves from other galaxies.
Satellites defiantly affect our lives in several ways including, television, communications and observations of the land.
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