Pictures Provided by NASA
The true definition of a satellite is an object than orbits another object (i.e. a moon orbiting a planet). A moon or other natural object that orbits a planet or other object are called natural satellites. Man-made satellites that are made on earth and launched into space to serve a purpose (i.e. weather, global positioning) are called artificial satellites. This page focuses on artificial satellites and the current Mars rovers.
How Satellites are Built and Launched-
When the need for a scientific satellite arises NASA appoints a team of experts to design the satellite. Their first job is to design what the satellite will look like and then build a small model of their idea. Their next task is to decide if the satellite will do what NASA wants it to do. If they think it will then they take their prototype to NASA to get the design approved. If the plan is approved then the team of experts and engineers go back and build the real thing. Then it is transported to NASA for some basic tests. If the satellite passes the tests, NASA’s job is to decide how to launch the satellite into space. Small satellites can be launched in a rocket that will deploy it and then fall back to earth. If it is a large satellite like, the Hubble Telescope, it is taken apart and sent to space on space shuttles. Once in space, the crews of the space shuttles use the shuttle’s robotic arm to deploy and assemble the satellite. Sometimes astronauts are required to leave the shuttle and work on the satellite.
If a satellite is needed by a certain group of people or company (i.e. Garmin GPS inc., meteorologists) then they submit the request for a satellite and sometimes even a design to NASA with some of their own aeronautics engineers. If NASA accepts the plans then it appoints a team of engineers to work with the engineers sent by the group. These satellites are built the same way (see above paragraph) but they are almost always launched by rockets.
What Satellites Do-
There are several types of satellites and they all have a different job. The armed forces have satellites for communication and tracking the movement of troops. Meteorologists use weather satellites for watching and predicting weather conditions. Several million outdoor enthusiasts use handheld GPS (Global Positioning Service) receivers to receive data about where they are from satellites. Cable television and long distance phone calls are transmitted through satellites. NASA use satellites for all different reasons from exploring the outer edges of the solar system to why Venus is so hot.
-Current Mars Rovers-
Picture of Oppurtunity Provided by NASA
Currently there are three (3) rovers exploring Mars. They are, the British Beagle, and NASA’s Spirit and Opportunity. Beagle landed on December 25, 2003, Spirit landed on January 4, 2004, and Opportunity landed on January 21, 2004. Their task is to search the Martian soil for water of other signs of life.
Very little information about Beagle could be found. Since landing on December 25, it has had no contact with British scientists controlling it on earth. They fear it may have been destroyed during landing.
Spirit and Opportunity-
NASA assigned a team of experts to work on these robots. Both identical rovers have panoramic cameras, robotic arms, microscopes, thermometers, atmospheric pressure sensors, and 6 individually controlled wheels. Once the prototypes were approved, the team made the full-scale rovers and two smaller ones that they could practice driving on earth. As of now both rovers seem to be fully operational although Spirit ran into some problems once it landed and had computer problems in the last week of January. It is said that Spirit has already found some miraculous things on the Martian soil that may prove that water once existed on Mars.
How Mars Rovers
Once the rockets are launched from earth, it travels a little over 8 months to get to the Red Planet. Once it gets close the rocket breaks apart and sends a smaller shuttle toward Mars. This smaller shuttle carries the rover. As soon as the shuttle gets caught in Mars’s gravitational field and begins to orbit, the shuttle drops a pyramid shaped box, which houses the rover. Once entering the atmosphere, the box deploys a parachute to slow the descent. When the box comes within 50 feet of the surface of Mars, airbags deploy and completely cover the pyramid. When the box is about 25 feet of the ground the rope connecting it to the parachute disconnects from the box and it drops to the Martian surface. The box will bounce for a while but when it comes to a complete stop the airbags deflate and the boxes opens to revel the rover.