A mission at NASA is a task or group of tasks that help people learn about the Earth or something in space. The people who plan the mission might be engineers. They decide how the data gets back to the Earth from space. The planners could also be scientists, who will use the data. Many of the scientists work at a science center. The engineers work at a mission operations center or MOC.
The mission team chooses targets for the satellite to aim at for their mission. The targets may be things on the Earth like storms and forest fires. These targets may also be things in space like planets and galaxies. The mission team then makes a list of things they want the satellite to do. They decide what data the satellite will send back. They decide other things, too. How much fuel can the satellite carry? Will it be hot or cold inside the satellite?
Planning the path for a satellite in space is important. So is deciding which way the satellite is looking when it goes around the Earth. The Hubble Telescope looks at space so it can see stars and galaxies. The GOES satellite looks at the Earth so it can see hurricanes and storms.
When we want to study something that we don't understand, we need to collect facts about it. Those facts are called data. One way to collect data is through observation. Observation means watching something to see what it does, then writing down what you see. Using a telescope to look at the moon, then drawing or writing down the shape of the moon is observation. At NASA, we use satellites to observe and collect data about the Earth, planets, and other things in space.
Data are usually recorded in a computer inside the satellite. Most data are only pieces of facts or pictures that people cannot read. The computer sends the data back to Earth. Then more computers turn the data into numbers and pictures that people can read. The next time you see maps and charts in the weather forecast, you can tell your friends how those charts are made and how we got them.
Ground stations are places on Earth that send data to and receive data from satellites. Ground stations for NASA are all over the world. They use big satellite dishes to make sending and receiving data easy. Engineers and scientists work at ground stations to make sure satellites are still where they are supposed to be and doing the right things.
A network is a group of people and places that are connected to each other. NASA has three networks that use ground stations. The Space Network uses Data Relay satellites to help other nearby satellites in space. The Space Network has two stations in New Mexico and one in Guam. The Deep Space Network studies things in our solar system and all through the universe. The Deep Space Network has stations in California, Spain, and Australia. The Ground Network studies the Earth. It has stations in Norway, Antarctica, Alaska, Florida, and Virginia.
These places use different antennas to track satellites. The best kind of antenna to send and receive data is shaped like this one. The Deep Space Network uses satellite dishes that are almost as big as a football field.
When a satellite is flying around the Earth, it can only talk to a ground station when it can see it. Satellites can only see the ground station when they fly right over it. Many satellites are only right over the ground station for about 15 minutes each time they go around the Earth. For some missions, like the Space Shuttle and the International Space Station, the satellite needs to talk to the ground station all the time. To solve this problem, NASA created some special satellites called TDRSs. TDRS stands for Tracking and Data Relay Satellite.
TDRSs stay high up in the sky, and they stay connected with other TDRS satellites and the ground station all the time. The TDRS satellites are so high up in the sky, they can always see the other satellites. All the other satellites can just send their signals to the TDRS satellites. Then the TDRS satellites send the signals back to the ground any time. That is called data relaying.
One important thing to learn about in space is satellites. Satellites are objects that NASA workers and other people build. Hundreds of satellites are in space above us right now. Satellites get shot up into space, or launched. Out in space, they go around our planet and do science missions.
The satellites do lots of things on missions. What are some things that satellites do? They take pictures of other planets and galaxies. They take pictures of things on the Earth like mountains and crops. They track the weather, too. They can tell us where big storms are and where they are going. All this information is called data.
How does the data get to people down here on Earth? When satellites fly over special places called ground stations, they send them the data. A satellite can fly all the way around the world in an hour and a half. Each ground station can see a satellite and get data from it for about 15 minutes each time it goes around the world.
You may have heard of some of the satellites out in space today. The Hubble Space Telescope studies galaxies in outer space. The International Space Station is a big satellite where astronauts can live and work on missions for NASA. The GOES satellite studies weather patterns like storms and hurricanes. The Data Relay satellite is another important satellite. You can learn about it by clicking the Data Relay icon on the main menu.
If your teacher wants you to do something, she tells you how to do it. How do scientists tell a satellite to do something? Satellites have computers onboard. At NASA, scientists tell the satellites what to do by sending them commands on the computer.
A command is an instruction that tells the computer to do something. Satellites are thousands of miles away, so NASA scientists send remote commands to tell the satellites what to do. This works like the remote control for your TV. When you press a button on your TV's remote control, you send remote commands. You tell the TV to turn on or off, change channels, or make the sound louder. When you play with your remote control car, you are sending remote commands. You tell your car to turn left, turn right, go faster, or slow down. That is the same way that scientists tell satellites what to do.
An orbit is the path in which an object moves around another object. For example, the moon orbits around the Earth. The planets orbit around our Sun. An orbit usually looks like a circle. Some orbits look like a stretched circle, called an ellipse. An orbit is a lot like the track for play racecars, but you cannot see it.
To get the satellite into the right orbit, you have to shoot the satellite into space at just the right angle. How does the Space Shuttle get to the International Space Station? NASA engineers must aim, or point, the shuttle so that it will meet up with the space station. When the Space Shuttle gets into the right orbit, the astronauts can do their work.
Satellites fly in many kinds of orbits around the Earth. In a polar orbit, the satellite goes straight up and down around the Earth. This is the best kind of orbit to study the North and South Poles. Another type of orbit always goes around the equator of the Earth.
The point in the orbit that is the farthest away from the Earth is called the apogee. At the apogee, the satellite moves the slowest. The point in the orbit that is the closest to the Earth is called the perigee. At the perigee, the satellite is moving the fastest.