Satellites are objects in orbit around Earth, other planets, or the Sun.
There are hundreds of satellites in the universe.
Two Basic Satellites
The two types of satellites are artificial and natural satellites. Natural
satellites are objects like the Moon, Earth, comets, etc. They are satellites
because they orbit around another object in space. For example, the Moon is a
satellite because it revolves around Earth.
Artificial satellites are man-made and are very important to Earth. Without
them we would not know what the universe look like. There are six different
types of artificial satellites: communication, resource, navigation, military,
scientific, and weather.
Communication Satellites
The communication satellites capture different radio waves and send them to
different spots in the world. Over 300 communication satellites help us
communicate around the world and beam satellite television into our homes.
NASA launched the first telephone and television satellite in 1962.
Resource Satellites
Resource satellites help scientists monitor natural resources by taking
pictures. The camera looks at the target and takes the picture. The pictures are
sent to scientists who study them, and then they turn the pictures into maps.
The maps show things like underground oil and foggy air.
Navigation Satellites
Pilots and sailors use navigation satellites to help them know where they are
and where they are headed. When they are in trouble, they will send distress
signals. The satellites will capture the signals and send them to emergency
resource stations. This allows the emergency crew to find and rescue the ones in
need of help.
The U.S. Navy launched the first navigation satellite in 1960. The U.S. Air
Force operates the NAVSTAR Global Positioning System (GPS) which can tell you
exactly where you are located to within 1 cm!
Military Satellites
These satellites help the armed forces to navigate, communicate, and spy on
other countries. They take pictures and pick up the radio waves that are sent by
other countries.
Scientific Satellites
Scientific satellites help scientists study Earth and outer space. Satellites
study planets, the Sun, other solar systems, and deep space. They help find
asteroids, comets, and black holes. The Hubble Space Telescope and space probes
are two examples of scientific satellites.
Weather Satellites
Weather Satellites help scientists study different types of weather patterns.
The satellite has a camera (like a resource satellite) that takes pictures of
places on Earth to figure out where rain, snow, sleet and hail are falling. It
can also see what kinds of clouds are in the air. These satellites are also used
to help predict the weather and track severe storms.
NASA launched the first weather satellite in 1960.
The Launch
It takes a lot of energy to put a satellite in orbit. They need to reach at
least 120 miles (200 km) above the earth at a speed of over 18,000 mph (29,000
km/h) to get in to orbit. Multistage rockets are used to do this.
The first stage of a multistage rocket contains engines that provide a huge
amount of force. This stage lifts the entire launch vehicle—the satellite, the
rocket body, and its fuel—into Earth’s atmosphere. After the engines run out
of fuel, the first stage separates from the rest of the rocket. Then the second
stage starts. It provides the
energy to lift the satellite in its orbit. Then it also separates from the
satellite.
Another
way people launch satellites is by having astronauts launch them from the U.S.
space shuttle. They carry the satellites in the cargo bay. The shuttle can also
bring satellites back to Earth for any repairs needed.
