How are satellites useful?
Satellites allow us to send information further. All around the world if we want. TV signals or mobile phone signals are transferred using a kind of light called radio waves. These signals can only go in a straight line. They can’t go far if sent from near the ground because they can’t follow the curve of the Earth. They disappear off into space. Instead, they are sent straight up to a satellite and the satellite sends the signal back down to different locations on the Earth. Satellite phones, satellite radio, and satellite internet are especially useful in remote areas that don’t have ground-based systems.
You’ve probably used GPS (Global Positioning System) on a mobile phone to find your way. You can do that because of a Global Navigation Satellite System (GNSS). This is a group of satellites working together as one system. A map app on a mobile phone uses signals from the GNSS to measure the distances between a receiver (your phone), and the network of satellites. By combining these distances, it tells you where you are.
Satellites can monitor Earth and look for changes.
Over 70% of the Earth’s surface is covered by oceans. Satellites can measure sea level rise, water surface temperatures, wave heights, and ocean winds.
Satellites can tell us about pollutants, greenhouse gases, and ozone in the atmosphere. They can also monitor changes in air quality. These changes could be due to smoke from fires, volcanic ash, or dust from large deserts.
Satellites can look for changes in the Earth’s land cover. For example, satellite images can show changes in the amount of land covered in forests; the amount of barren ground; or the amount covered by human-made structures. Google Earth was created through the use of Earth observation satellites.
Weather & Climate
The weather has a big impact on our lives and so we need reliable forecasts. In cases of extreme weather, accurate weather forecasts can save lives.
Forecasters use supercomputers and numerical data to predict the weather. The forecast is only as good as the data that is put into the supercomputer. This means we need accurate knowledge of the state of Earth’s atmosphere and surface. Satellites give us this accurate information and it is put into the supercomputer. Data from satellites is combined with ground-based networks of weather stations and ocean monitoring instruments. The first weather satellite was Tiros 1. It launched on 1st April 1960.
Climate is different from weather. It is large-scale and long-term. When we talk about climate, we are thinking globally, rather than locally.
Changes to the Earth’s climate can be due to natural processes (the Sun, volcanic eruptions) or to human-caused changes to the atmosphere. There is strong scientific agreement that the global climate is changing and that human activity is significantly contributing to this trend. Satellites collect a range of climate measurements including temperature, volume of greenhouse gases, snow, sea ice and vegetation cover, humidity, and winds. These measurements help scientists monitor and predict changes to the Earth’s climate.
Any industry that is affected by the weather relies on satellites for accurate forecasts. Industries like farming, fishing, construction, and tourism.
Aviation and shipping industries rely on accurate satellite navigation systems.
Even the finance industry needs satellites. The GNSS is like a giant invisible clock in space – each satellite contains a high precision atomic clock. Financial systems need single, precise times for each transaction. Satellites help machines all over the world agree on exactly what time it is. This helps keep banking secure and prevent fraud.
Did you know?
Clocks on satellites orbiting the Earth run more quickly than those on the Earth's surface? This is explained by Albert Einstein's Theory of Special Relativity. The Global Navigation Satellite Systems has to take this into account.