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Sattelites

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Owen Marshall

on 18 May 2010

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Transcript of Sattelites

Satellites. A pres Satellites A presentation by Owen Marshall Have you ever wondered what 's up there in outer space? Well you're not the only one. Throughout all of history, mankind has sat and stared at the vast
wonders of space wondering what it was truly like up there. For so long we had no idea what there was. But on October 4th 1957, all of that changed. The Russian Federation launched Sputnik 1, the earths first artificial satellite. Sputnik means "little traveller" and that's EXACTLY what it was.
It was transmitting data from space to earth via radio for 21 days
until its radios stopped, but the actual satellite orbited for 96 days
until it burnt up in the atmosphere on re-entry. The Sputnik 1 was put in space
to observe and report on things
like the temperature in the outer
atmosphere. Seeing all the Russian space activity, the Americans got a little jealous. They wanted their own. And so the Americans got to work, and by January 31 1958,
they were ready to launch their satellite. And so January 31st marks the birthday
of the first North American satellite. The Explorer 1 The Explorer sent the earth info about cosmic rays, and
meteors that orbit the earth for about 4 months... ...but it stayed in space for 12 years! But technology has been improving like crazy since the 50s... ...and so have our satellites. There are now man made satellites orbiting more than just earth, for example, there's the Galileo which is orbiting Jupiter
and the Magellen which orbits Venus. There's SOO much to discover in the world of satellites! So lets Dive in and find out!
Now that you know and thoroughly understand the various orbits, I'm going to explain the various types. By definition, a satellite is anything that is in an orbit. Such as... One of those really lame helicopter
toys that just "fly" in circles
while attached to a string. So when you just say satellite, you're not being very specific.
Satellites will always fall under two categories. Natural, or Artificial. (and its just as simple as it sounds) Natural Satellites are satellites that occour naturally such as the Moon around the Earth. These are not the kind of satellites I will be presenting to you today. I am going to be talking about Artificial satellites. Artificial satellites are, you guessed it, made by us on the earth and than sent into orbit by us. But even just saying artificial satellite is pretty vague. There are actually six main types of artificial satellites!
All with a different purpose. The types are... Weather

Navigation

Observation

Communication

Research

Military So to start off, let me explain weather satellites. Without Weather satallites, reporting on weather would be alot harder. Weather satellites study weather patterns so that we can make accurate weather predictions. So every time you watch the weather network, you can say a big thank you to weather satellites. Weather satellites will often travel in sun synchronus polar orbits, so that they can cover the entire surface of the earth.
Due to their orbit, they can moniter the earths surface at the same local time of day wherever they go. This makes it much easier for scientists to compare data. Some weather satellites are put in much higher orbits. These Satellites have an even broader veiw of the planet.

They can view over half of the earths surface! Next on our list would be the navigation satellites. Navigation sattelites help us out a great deal when it comes to travelling. For example, a GPS system could not function without a navigation satellite. GPS works by sending info to and from earth, via navigation satellites and pinpointing
your exact latitude and longitude. Then the little computer will figure out whatever road your on and show you a map of the area. But this doesn't work only on cars. GPS are used on Jets, boats or can even just be handheld for pedestrians! If you're anywhere on the surface of the planet, GPS can figure out your position. Another interesting type of satellite would be the observation satellite. Can you guess what it does? If you guessed observe the earth, your right. Some observation satellites map out and moniter things such as our natural resources and the planets changing chemical life cycles. They will typically follow certain orbits so that they are constantly in the sunlight. They also take pictures in various colours of visible light, or in nonvisible radiation Computers will then combine and analyze these pitctures and use them to, find and figure out the size of
various fresh water supplies, to detect the spread of desease in crops and forests, To identify sources of pollution and study the effects, Now another super cool satellite on the list would be the research satellite. Once again, just saying research satellite is too vague. There are three MAIN things that research satellites will do. The first type gathers info on the composition and effects of space near earth. They can operate in any kind of orbit, it just depends on exactly what they're looking for. The second type records changes in the earths atmosphere.
This kind typically flies in a sun synchronus polar orbit. Lastly there are the satellites that observe planets and stars. Such as the hubble space telescope. They mostly fly in low orbit. And last but not least we have the military satellite. The military satellite can be any one of the other five types, it is just used for military purposes. Next up, is the communications satellite. Communications sattellites are essentially just relay stations in the sky. They recieve signals from one location and send them to another. So do any of you have satellite tv? Well, communications satellites make that possible. Alot of the time, comunications satellites are put in a geosyncronus orbit above a ground station. The ground station would be equiped with a large satellite dish for transmitting and receiving signals.

Sometimes Communication satellites will be be sent up in networks called constellations. These constellations will take info. from the ground and pass it along in between each other that send it down to earth. In order for a satellite to stay in space, or even be considered a satellite for that matter, it must be in an orbit. A satellite is kept in orbit, by the pushing and pulling of two different forces. Gravity and Inertia You should all know what gravity is, but just in case I will quickly recap. Gravity is the force that pulls down on you and holds you to the planet. Without gravity we would probably just be endlessly floating through space. Anyways, Inertia is the tendency of an object continue moving forward
until it is stopped by an outside force. So in order for something to stay in orbit there has to abalance between inertia and gravity. And as you get further into space the forces of gravity is less so therefore you do not need quite as much inertia or the satellite will hurtle into space indefinatley. Different satellites require different orbits to complete their goals in space. I've set up a little diagram to show you some of the different orbits. Here we are at a low orbit. This is only 610 km above the earth. This is the orbit that most deep space telescopes work at. The orbital period takes 97 minutes. This is the medium altitude. This is 20,400 km out from the earth At this altitude it has a 12 hour orbital period. Now this is the big leagues of satellite orbits. Here we are at a high altitude geosynchronus orbit. Boo Yeah. This is 35 900 km off of the ground. The cool thing about this orbit is that it is moving extremely fast. So fast that the satellite will constantly above the same place on the earth. You may be wondering why this is a line not a circle. Well I'll tell you. The Sun synchronus polar orbit actually orbits the earths latitude. Because it orbits latitude, the satellites can cover the full surface of the earth. This orbit is 705 km with an orbital period of 99 minutes. In dedication to Laika the space dog. No I'm not making that up. Sadly, this is the end of my prezi. But am I done? No way. Lets take a look at a 3-D model I have for you.
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