Reaching into space
Space exploration means investigating outer space using technology. To leave Earth we must overcome gravity, and for that we use rockets. A rocket burns fuel to push hot gas downwards, and the gas pushes the rocket upwards with an equal force. This action-and-reaction thrust is strong enough to carry spacecraft beyond the atmosphere.
Key idea
A rocket rises because it throws gas backwards, and the gas pushes the rocket forwards with an equal and opposite force. This is how a spacecraft escapes Earth's gravity.
Satellites, probes and stations
A satellite is an object placed in orbit around Earth. Communication satellites relay television, telephone and internet signals across the world. Weather satellites photograph clouds and storms to help forecasting. The Global Positioning System (GPS) uses satellites so that phones and cars can find their position.
A space probe is an uncrewed spacecraft sent to explore distant planets, moons and comets, sending data back to Earth. A space station, such as the International Space Station, is a large craft where astronauts live and carry out experiments for long periods.
Example
The first artificial satellite, Sputnik 1, was launched in 1957. It began the space age and led to the many satellites we depend on today.
Everyday benefits
Space technology also produces spin-off inventions used on Earth, such as improved water-filtering methods, lightweight materials and better weather warnings. So exploring space improves life at home too.
Remember
- Rockets use thrust to escape Earth's gravity.
- Satellites help with communication, weather and navigation (GPS).
- Space probes are uncrewed; space stations carry astronauts.