Satellites are celestial bodies that orbit around a planet or any other celestial body in space. They are used for various purposes, from communication to scientific research, weather forecasting, and navigation. People often wonder whether satellites can change orbit.
Satellites can change their orbit by altering their altitude or inclination. The process requires careful planning and execution, considering factors such as thrust, fuel, time, space debris, and weather. Changing a satellite’s orbit can be useful in various applications, including communication, weather forecasting, and scientific research.
This article will explore how satellites can change orbit and the factors that affect this process.
What is an Orbit?
An orbit is a path that an object in space takes around another object due to the force of gravity. The object being orbited is called the primary, while the object in orbit is called the satellite. The orbit of a satellite is determined by its velocity and altitude.
Satellites orbiting the Earth are subject to the Earth’s gravity, which pulls them towards the center of the Earth. However, the satellite’s velocity allows it to maintain its altitude and avoid crashing into the Earth’s surface.
Types of Orbits
Satellites can take several types of orbits, depending on their purpose. The most common types of orbits are the following:
- The geostationary orbit
- The low Earth orbit
- The polar orbit
The satellite remains fixed above the Earth’s equator in a geostationary orbit. This type of orbit is used for communication and broadcasting, as it allows for continuous coverage of a specific region on the Earth’s surface.
A low Earth orbit is an orbit that is closer to the Earth’s surface, with an altitude of fewer than 2,000 kilometers. Satellites in this type of orbit are used for navigation, imaging, and scientific research.
A polar orbit is the one in which a satellite passes over the Earth’s poles. This orbit type is used to observe and map the Earth’s surface.
Watch these different types of satellites in this video:
Can Satellites Change Orbit?
The short answer is yes, satellites can change their orbit. Satellites are designed to have the ability to change their orbit to adapt to their mission requirements.
There are several reasons why a satellite may need to change its orbit, including:
- End of Mission – When a satellite’s mission is over, it may need to be moved to a different orbit or de-orbited to avoid collisions with other objects in space.
- Change in Mission Requirements – If a satellite’s mission requirements change, it may need to be moved to a different orbit to meet those requirements.
- Collision Avoidance – Satellites may need to change their orbit to avoid collisions with other space objects, such as other satellites, debris, or meteoroids.
- Maintenance – Satellites may need to change their orbit to facilitate maintenance, repair, or refueling.
How is Orbit Changed?
There are several ways to change a satellite’s orbit, including:
- Propulsion Systems – Satellites are equipped with propulsion systems that can be used to change their orbit. The propulsion systems can provide thrust in the opposite direction to the satellite’s velocity, which can increase or decrease the satellite’s speed.
- Gravity – Satellites can also use the gravity of other planets or moons to change their orbit. This technique is known as a gravity assist, and interplanetary missions commonly use it.
- Aerobraking – Satellites can also use the Earth’s atmosphere to change their orbit. This technique, known as aerobraking, involves using the atmosphere’s friction to slow down the satellite and reduce its altitude.
1. Propulsion Systems
Satellites are equipped with propulsion systems that use various fuels, including liquid, solid, and electric. The propulsion systems can change the satellite’s velocity by providing thrust in the opposite direction to the satellite’s motion.
The thrust can increase or decrease the satellite’s speed, which can change its orbit. There are several types of propulsion systems used in satellites, including:
- Chemical Propulsion – Chemical propulsion systems use liquid or solid fuels for thrust. They are commonly used in satellites that require high thrust for short periods.
- Electric Propulsion – Electric propulsion systems use electric or magnetic fields to accelerate charged particles and provide thrust. They are commonly used in satellites that require low thrust for long periods.
- Solar Sails – Solar sails use the pressure of sunlight to provide thrust. They are commonly used in small satellites requiring low thrust and a large surface area.
2. Gravity Assists
Gravity assists are used by interplanetary missions to change their trajectory and speed. The spacecraft uses the gravity of a planet or moon to accelerate or decelerate and change its orbit.
The spacecraft needs to be precisely positioned so that it can use gravity to assist in achieving the desired change in trajectory.
The gravity assist can also change the spacecraft’s direction, allowing it to fly by multiple planets or moons.
3. Aerobraking
Aerobraking is a technique that uses the Earth’s atmosphere to slow down a satellite and reduce its altitude. The satellite is placed in a low orbit that intersects the Earth’s upper atmosphere.
The atmosphere’s friction slows down the satellite, reducing its velocity and altitude. The process is repeated several times until the satellite reaches the desired orbit.
Aerobraking is commonly used by interplanetary missions to reduce the spacecraft’s velocity before it enters the planet’s atmosphere. The technique is also used to dispose of satellites at the end of their mission.
The satellite is placed in a low orbit that intersects the Earth’s atmosphere, and the atmosphere’s friction causes the satellite to burn up.
Challenges of Changing Orbit
Changing a satellite’s orbit is not a simple process, and several challenges must be overcome. One of the main challenges is the limited amount of fuel a satellite can carry. The limited fuel means the satellite must use its propulsion system efficiently to achieve the desired change in orbit.
Another challenge is the precision required to change a satellite’s orbit. The satellite must be precisely positioned and oriented to achieve the desired change in orbit. The satellite must also be able to monitor its position and velocity accurately to ensure it is on the correct trajectory.
Conclusion
Satellites can change their orbit to adapt to their mission requirements. They are equipped with propulsion systems that can change their velocity and altitude. However, changing a satellite’s orbit is not a simple process, and several challenges must be overcome, including limited fuel and the precision required to achieve the desired change in orbit.
