How are satellites launched into space in groups?

In one line

The rule

Satellites can be launched together using a single launch vehicle, which carries multiple satellites and deploys them into space at different times or positions.

There is no single formula, but the process uses physics of motion and gravity to place each satellite in its correct orbit.

Let's understand it simply

Imagine you want to send several cricket balls to friends standing at different spots in a big field. Instead of running back and forth, you carry all the balls in a bag, walk to the middle, and throw each ball towards the right friend. In the same way, a rocket carries many satellites together. Once in space, it releases each satellite at the right spot, so each one goes to its own place around Earth.

This is like a delivery truck dropping off packages at different houses in one trip. It saves time, money, and fuel.

How it works

1. Satellites are packed together inside the rocket, often using special holders called dispensers.
2. The rocket is launched from Earth, carrying all the satellites together.
3. Once the rocket reaches space, it follows a planned path (trajectory) to the right height (altitude).
4. The rocket's upper stage opens, and a mechanism gently pushes out the first satellite.
5. The rocket moves a bit, then releases the next satellite, and so on, until all are out.
6. Each satellite uses small engines (thrusters) to adjust itself into its exact orbit.

The story behind it

Launching satellites in groups became popular as space technology improved. Earlier, rockets were expensive and could carry only one satellite. In 1981, India launched the Rohini Satellite Series one by one. But as demand grew, scientists wanted to save money and time. The Indian Space Research Organisation (ISRO) became famous for launching many satellites at once. In 2017, ISRO set a world record by launching 104 satellites in one go using the PSLV-C37 rocket. One fun detail: the satellites came from different countries, like a bus dropping off passengers at many stops.

Where you see it in real life

• ISRO's PSLV launches: India’s PSLV rockets often carry 20, 30, or even 100+ satellites in one trip.
• Communication satellites: Companies launch groups of satellites to create networks for internet or TV, like Starlink.
• Weather satellites: Sometimes, several weather satellites are launched together to cover different parts of the world.
• Earth observation: Many small satellites are sent together to take pictures of Earth for farming, disaster management, or mapping.
• Student satellites: Universities build tiny satellites (CubeSats) and send them together to save costs.
• International launches: Rockets from the USA, Russia, and Europe also launch satellites for many countries in one go.

Why it matters

• Saves money: Sharing a rocket is cheaper than sending each satellite alone.
• Saves time: More satellites can be put in space quickly, helping projects start faster.
• Boosts technology: Makes it possible for small companies and students to send their own satellites.
• Helps science and business: More satellites mean better weather forecasts, faster internet, and more data for research.

Worked example

Let’s see how ISRO launched 104 satellites in 2017:

Given: 104 satellites, one rocket (PSLV-C37)
Step 1: All satellites packed inside rocket using special holders
Step 2: Rocket launched from Sriharikota, India
Step 3: Rocket reaches 505 km above Earth (sun-synchronous orbit)
Step 4: Main satellite (Cartosat-2D) released first
Step 5: Each of the 103 smaller satellites released one by one, every few seconds
Step 6: Each satellite uses its own thrusters to move into its planned orbit
Result: All 104 satellites successfully placed in space

Common mistakes

• Thinking satellites are just dropped out together: They are released one by one, not all at once, to avoid crashing into each other.
• Believing only big satellites can be launched in groups: Even tiny satellites (as small as a lunchbox) are launched this way.
• Assuming all satellites go to the same orbit: Sometimes, the rocket changes direction or height to put satellites in different orbits.
• Forgetting about international cooperation: Many launches carry satellites from different countries.

Remember it

Think of a rocket as a school bus dropping students at different stops—one trip, many deliveries!