A Free Template from Joomlashack

A Free Template from Joomlashack

แบบสำรวจ

ท่านกำลังใช้ระบบปฏิบัติการ (OS) อะไรอยู่ ?
 

Search

ผู้เข้าเว็บขณะนี้

เรามี 70 บุคคลทั่วไป ออนไลน์
The Satellite Story PDF พิมพ์ อีเมล
เขียนโดย Administrator   
วันอังคารที่ 07 มีนาคม 2017 เวลา 05:29 น.

The Satellite Story
 
 
 
 




The Satellite Story (Part 1)

 

 

 

           Fifty years ago Sputnik was launched by the Russians, and the space age dawned. Starting with the jubilation, fear and panic that accompanied the launch of "The Red Moon", this documentary explores how satellites have now affected almost every aspect of our lives.
 
 
Spy satellites and GPS (global positioning system) have transformed the military. Communications have been revolutionised, with Telstar, the first commercially-launch satellite, even becoming an international celebrity. Satellites have revolutionised our understanding of our climate, saving countless lives. Hubble, so nearly a disaster, went on to change the way we understand our universe. Thanks to satellites, the world is now a smaller, safer, and better understood place.
 
 
The programme explores the technological milestones that have made all this possible but ends with a warning. Our civilisation is now dependent on satellites, making us vulnerable were something to go wrong. Recent events in China have revealed just how vulnerable we might be, for they suggest we might be on the verge of another new age - of satellite terrorism.


 

Sputnik 1

 Sputnik 1: The first artificial satellite to orbit Earth.

 

          Sputnik 1 was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957. It was a 58 cm (23 in) diameter polished metal sphere, with four external radio antennae to broadcast radio pulses. It was visible all around the Earth and its radio pulses were detectable. This surprise success precipitated the American Sputnik crisis and triggered the Space Race, a part of the larger Cold War. The launch ushered in new political, military, technological, and scientific developments.
 
 
 
Tracking and studying Sputnik 1 from Earth provided scientists with valuable information, even though the satellite itself wasn't equipped with sensors. The density of the upper atmosphere could be deduced from its drag on the orbit, and the propagation of its radio signals gave information about the ionosphere.
 
 
 
 
Sputnik 1 was launched during the International Geophysical Year from Site No.1/5, at the 5th Tyuratam range, in Kazakh SSR (now known as the Baikonur Cosmodrome). The satellite travelled at about 29,000 kilometres per hour (18,000 mph; 8,100 m/s), taking 96.2 minutes to complete each orbit. It transmitted on 20.005 and 40.002 MHz, which were monitored by amateur radio operators throughout the world. The signals continued for 21 days until the transmitter batteries ran out on 26 October 1957. Sputnik burned up on 4 January 1958 while reentering Earth's atmosphere, after travelling about 70 million km (43 million mi) and spending three months in orbit.

 

 Sputnik Model in the Boeing Milestones of Flight Hall

Sputnik Model in the Boeing Milestones of Flight Hall

 

           The first artificial satellite was Sputnik 1, launched by the Soviet Union on October 4, 1957, and initiating the Soviet Sputnik program, with Sergei Korolev as chief designer (there is a crater on the lunar far side which bears his name). This in turn triggered the Space Race between the Soviet Union and the United States.
 
 
Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War.
 
 
Sputnik 2 was launched on November 3, 1957 and carried the first living passenger into orbit, a dog named Laika.
 
 
In May, 1946, Project RAND had released the Preliminary Design of an Experimental World-Circling Spaceship, which stated, "A satellite vehicle with appropriate instrumentation can be expected to be one of the most potent scientific tools of the Twentieth Century." The United States had been considering launching orbital satellites since 1945 under the Bureau of Aeronautics of the United States Navy. The United States Air Force's Project RAND eventually released the report, but considered the satellite to be a tool for science, politics, and propaganda, rather than a potential military weapon. In 1954, the Secretary of Defense stated, "I know of no American satellite program." In February 1954 Project RAND released "Scientific Uses for a Satellite Vehicle," written by R.R. Carhart. This expanded on potential scientific uses for satellite vehicles and was followed in June 1955 with "The Scientific Use of an Artificial Satellite," by H.K. Kallmann and W.W. Kellogg.
 
 
In the context of activities planned for the International Geophysical Year (1957–58), the White House announced on July 29, 1955 that the U.S. intended to launch satellites by the spring of 1958. This became known as Project Vanguard. On July 31, the Soviets announced that they intended to launch a satellite by the fall of 1957.
 
 
Following pressure by the American Rocket Society, the National Science Foundation, and the International Geophysical Year, military interest picked up and in early 1955 the Army and Navy were working on Project Orbiter, two competing programs: the army's which involved using a Jupiter C rocket, and the civilian/Navy Vanguard Rocket, to launch a satellite. At first, they failed: initial preference was given to the Vanguard program, whose first attempt at orbiting a satellite resulted in the explosion of the launch vehicle on national television. But finally, three months after Sputnik 2, the project succeeded; Explorer 1 became the United States' first artificial satellite on January 31, 1958.
 
 
In June 1961, three-and-a-half years after the launch of Sputnik 1, the Air Force used resources of the United States Space Surveillance Network to catalog 115 Earth-orbiting satellites.
 
 
Early satellites were constructed as "one-off" designs. With growth in geosynchronous (GEO) satellite communication, multiple satellites began to be built on single model platforms called satellite buses. The first standardized satellite bus design was the HS-333 GEO commsat, launched in 1972.
 
 
The largest artificial satellite currently orbiting the Earth is the
International Space Station.

 



The Satellite Story (Part 2)

 

 

Satellites in geostationary orbit

Satellites in geostationary orbit, 36 000 km up, remain in the same position in the sky relative to Earth's surface. Geostationary orbit is such an economically valuable region that it is carefully regulated by the International Telecommunication Union, with nations assigned geostationary slots along the 265 000 km-long circle corresponding to their geographical territory, with positioning carefully worked out to avoid interference from overlapping signals.

 

 

The Satellite Story 

The Satellite 

 

In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as Earth's Moon.
 
 
 
 
In 1957 the Soviet Union launched the world's first artificial satellite, Sputnik 1. Since then, about 6,600 satellites from more than 40 countries have been launched. According to a 2013 estimate, 3,600 remained in orbit. Of those, about 1,000 were operational; the rest have lived out their useful lives and become space debris. Approximately 500 operational satellites are in low-Earth orbit, 50 are in medium-Earth orbit (at 20,000 km), and the rest are in geostationary orbit (at 36,000 km). A few large satellites have been launched in parts and assembled in orbit. Over a dozen space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, a few asteroids, and the Sun.
 
 
 
Satellites are used for many purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and space telescopes. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.
 
 
 
A launch vehicle is a rocket that throws a satellite into orbit. Usually it lifts off from a launch pad on land. Some are launched at sea from a submarine or a mobile maritime platform, or aboard a plane (see air launch to orbit).
 
 
 
Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control and orbit control.

 

  


The Satellite Story (Part 3)

 

 

European Weather Satellite Constellation to Debut in 2017

European Weather Satellite Constellation to Debut in 2017

 

 

The TELSTAR II communications satellite 

Telstar is the name of various communications satellites. The first two Telstar satellites were experimental and nearly identical. Telstar 1 launched on top of a Thor-Delta rocket on July 10, 1962. It successfully relayed through space the first television pictures, telephone calls, and fax images, and provided the first live transatlantic television feed. Telstar 2 launched May 7, 1963. Telstar 1 and 2—though no longer functional—still orbit the Earth.

 

 

 



 

แก้ไขล่าสุด ( วันอังคารที่ 07 มีนาคม 2017 เวลา 06:11 น. )
 

เพิ่มคอมเมนต์ใหม่

 


Joomla 1.5 Templates by Joomlashack