Satellites collect and transmit information as they orbit Earth.
How do satellites work? :
A satellite is lounched to a specific altitude. This position is maintained by Earth's gravity. Gravity pulls the satellite down just enough to keep the satellite travelling in a circular orbit instead of flying away into space.
The body or frame of a satellite is made of metal or a combination of materials and is
called the bus. The different parts of the satellite are attached to this frame. The bus provides protection during the lounch and when the satellite is in orbit.
The Sun provides the satellite with power. Arrays of solar cells on the satellite convert sunlight into electrical energy which provides power to rechargeable batteries on the satellite. The batteries store power for times when the Sun is not visible.
Nearly all satellites have a radio transmitter / receiver and an antenna. This allows them to transmit or downlink data to command centres on Earth. It also means that command
centres can send or uplink messages to the satellite. These command centres request
information from the satellite, send adjustments to its course and can reprogram the
instruments on the satellite.
Amazing Facts about Space :
Before people ventured into spoce, scientists sent animals, so they could observe how the animals coped with being in spoce. The dog, Laika, was the first mammal from Earth to orbit the planet. Laika died from stress and overheating during her 1957 space mission in the Russian spacecraft Sputnik 2.
As telescopes have become more powerful, they have allowed us to observe planets, galaxies and nebulae in greater detail. In 1990 the Hubble telescope was sent into orbit
Galileo discovered four moons orbiting Jupiter in January 1610.
The Indian Astronomical Observatory which sits 4517 metres above sea level, in Hanle,
India, is the world's highest observatory telescope.
Amateur astronomers use refracting telescopes The earliest telescopes were all refracting
telescopes including the famous and very simple telescope used by Galileo Galilei in the early 1600s.
The Keck telescopes, the world's largest optical telescopes, are located on the dormant Mauna Kea volcano on the island of Hawaii.
Hubble is the size of a large school bus. It fits inside the cargo bay of a space shuttle.
The Hubble Space Telescope spotted young brown dwarfs for the first time in the Orion Nebula. Brown dwarfs are so-called failed stars because they are too small to be ordinary stars — they cannot sustain nuclear fusion in their cores the way our Sun does.
Hubble is serviced and newer technology is installed by astronouts on space walks. This
means that Hubble can benefit from the same advances as ground-based telescopes.
The Hubble Space Telescope completes one full orbit of Earth every 97 minutes.
A three-stage rocket, Saturn V, was used to take astronauts to the Moon in the Apollo
spacecraft. Stage 1 burnt its fuel over 2 minutes and 30 seconds - then separated from the rest of the rocket ond fell back to Earth. Stage 2 then fired and lifted the astronauts into space. It too fell away. Finally, Stage 3 fired for 2 minutes and 30 seconds and sent Apollo into orbit around Earth. Stage 3 fired again for over five minutes to send Apollo
towards the Moon. It then fell away from the spacecraft. All spacecraft and satellites are taken into space by rockets.
The largest and most powerful rocket ever built was the Saturn V rocket.
The Mariner probes were designed to investigate Mars, Venus and Mercury. In 1962, Mariner 2 became the first spacecraft to fly by another planet when it passed Venus.
The Viking landers conducted experiments on Martian soil to see if any form of life existed. Decades later, scientists are still arguing over the results.
The Halley Multicolor Camera on the Giotto probe was destroyed when it veered too close to the tail of Halley's Comet. Before it was shattered, it took some spectacular
pictures of the comet's nucleus.
In 1959, the Soviet Luna 2 mission successfully crashed into the Moon. It made history by being the first man-made object to reach another world.
Communications industries, such as Internet, TV and telephones, use satellites to transmit
Satellites also have an Attitude Control System which keeps the satellite pointing in the right direction.
The Soviet Union was the first country to launch a satellite. The Soviets launched Sputnik 1 on 4 October 1957. This was to be the beginning of the space race between
the Soviet Union and the USA.
If a satellite doesn't reach a suitable altitude, it can be affected by the drag of
Earth's atmosphere and fall back into the atmosphere where it burns up.
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