Satellites and Probes
We don't always send people into space when we run space missions. Most of the time we are sending up satellites to go into orbit around the Earth.
What is a satellite?
A satellite is just an object which orbits another object. The Moon is a satellite of the Earth, the Earth is a satellite of the Sun.
In conversation, the term satellite usually refers to artificial satellites orbiting the Earth which have been put there by man-kind. We have been putting objects into orbit around the Earth since 1957 when the USSR launched Sputnik 1 into orbit.
The Hubble Space Telescope, an artificial satellite used by NASA
What do satellites do?
Satellites can be used for all sorts of things! From the satellites that bounce phone signals across the world, to satellites that track your location for GPS. From satellites that spy on rogue nations and terrorist organisations, to satellites that watch the weather to give us accurate forecasting. Satellite technology have revolutionised so many fields.
What is a probe?
A probe is a robot which we send into space to do experiments instead of astronauts. These are cheaper to send into space than people and can travel further as they only need electricity (rather than food, water, etc.).
We currently have lots of probes in space such as Curiosity, a Mars rover searching for life, and Voyagers 1 & 2 which are pushing the boundaries of our furthest exploration ever further into space.
A Voyager space probe, used for exploring the planets further out.