Meer asked the science teacher what geostationary satellites are. “Geo means Earth and stationary means not moving. The satellites that seem to be stationary but are actually moving at the same angular speed as that of the Earth are said to be in a geostationary orbit. They are about 36000 kilometres from the Earth over the equator. As the direction of rotation is the same as Earth’s (west to east), they appear at the same spot all the time,” said the teacher.
Rahul asked how they help us. “These satellites are useful in many ways. They help with communication as they transmit communication signals,” the teacher explained.
Determining the location on a navigation system through GPS (Global Positioning System) is very accurate and one can see and track one’s movement on the screen. The location can also be sent to others.
TV signals are also transmitted by the satellites and we receive signals through dish antennas said Swati. The satellites are also used to capture weather information. They can warn us of cyclones and rains. In the news they show weather reports and pictures taken by satellites added Alfred.
In recent times satellites were very useful in tracking the movement of the cyclones like OCKHI and are instrumental in saving thousands of lives. The met satellites are fitted with special equipments to study the weather conditions like temperature and pressure across the world and also alert the affecting areas if an alarming situation is seen. They are very useful for farmers. The information is also useful for air and sea navigation.
Navin asked about spy satellites. He said: “I read some countries have spy satellites to track enemy military movements. And these are also fitted with very powerful night vision cameras and sensors to capture the enemy movements in the dark.
“Yes, spy satellites are in use. They help the military with security functions. Aryabhatta was the first Indian satellite launched from Soviet Union while Rohini was the first satellite to be launched by India. Now we are not only capable of developing the satellites for various needs such as communication and weather but are highly capable of launching them too. After success of the Mangalyan ISRO is highly respected the world over.
(Writer is a mechanical engineer and runs a hands-on science activity centre at Margao)