Space satellites: from man-made wonders to emerging Industry and start-ups

Space satellites have come a long way from the initial days of novel scientific research and prototype development. Then, it was mostly a race for defence and space supremacy in the cold war era. Now, over the decades, wide range of applications have emerged in addition to the defence and strategic needs of a country. From the government funded institutions like NASA, European Space agency or ISRO, the private industry players like SpaceX, Blue Origin have also emerged as the formidable players. Various startups in India have also find foothold in this emerging eco-system.

Civil Applications of Satellites

There are a number of civil applications of satellites, which include:
1. Weather forecasting: Satellites equipped with sensors can gather data on weather patterns, such as temperature, precipitation, and wind speeds. This data can be used to create accurate weather forecasts and help people prepare for severe weather events.
2. Telecommunications: Satellites are used to provide communication services, such as telephone and internet, to remote or underserved areas where terrestrial infrastructure may not be present or economical.
3. Television and radio broadcasting: Satellites can be used to transmit television and radio signals to large areas, allowing people in remote or underserved areas to access these services.
4. Navigation: Satellites are used in the Global Positioning System (GPS) to provide location and time information to users, which can be used for navigation and for tracking vehicles, ships, and aircraft.
5. Search and rescue: Satellites can be used to detect and locate distress signals from emergency beacons, which can help in search and rescue operations.
6. Environmental monitoring: Satellites equipped with sensors can be used to gather data on environmental conditions, such as air and water quality, deforestation, and land use.
7. Disaster management: Satellites can be used to provide real-time information on natural disasters, such as floods, landslides, and fires, which can help emergency responders and relief workers to respond more effectively.
8. Agriculture and Forestry: Satellites can be used to monitor crop health, yields and soil conditions, and to detect signs of pests and diseases. Additionally, it can be used to measure the growth of forests, and detect logging and poaching activities.
9. Urban planning: Satellites can be used to gather data on urban areas, such as population density, land use, and infrastructure, which can help in urban planning and development.
10. Air and maritime traffic control: Satellites can be used to track the location of aircraft and ships, providing real-time information for air and maritime traffic control.

How many types of satellites? – Application based categories

There are several ways to classify satellites, but one common method is based on their function or purpose. Here are some of the main types or categories of satellites:

1. Communication satellites: These satellites are used to transmit and receive signals for telecommunications and broadcasting, such as telephone and internet, and television and radio signals.
2. Earth observation satellites: These satellites are equipped with cameras and sensors to gather data on the Earth’s surface and atmosphere, such as weather patterns, land use, and environmental conditions.
3. Navigation satellites: These satellites are used in the Global Positioning System (GPS) to provide location and time information to users, which can be used for navigation and for tracking vehicles, ships, and aircraft.
4. Weather satellites: These satellites are equipped with sensors to gather data on weather patterns, such as temperature, precipitation, and wind speeds, which is used for weather forecasting.
5. Scientific research satellites: These satellites are used for scientific research, such as studying the Earth’s atmosphere, the solar system and universe.
6. Military satellites: These satellites are used for military purposes, such as reconnaissance, early warning, and communication.
7. Reconnaissance satellites: These satellites are used for surveillance, intelligence gathering, and reconnaissance.
8. Astronomical satellites: These satellites are used for astronomical observation and research, such as studying the stars, galaxies, and other celestial bodies.
9. Geological survey satellite: These satellites are used for studying the Earth’s geology and mineral resources.
10. Humanitarian and Disaster management satellite: These satellites are used to provide real-time information on natural disasters, such as floods, landslides, and fires, which can help emergency responders and relief workers to respond more effectively.

It’s important to note that some satellites can perform multiple functions or purpose, and can be classified into multiple categories.

Altitude based satellite categories

Another way to classify satellites is based on their altitude or distance from the Earth’s surface. Here are some of the main altitude-based categories of satellites:

1. Low Earth orbit (LEO) satellites: These satellites orbit the Earth at an altitude of about 160-2000 km. They have a relatively low orbital period (about 90-120 minutes) and provide coverage for a specific area of the Earth’s surface. They are mainly used for communication, navigation, and Earth observation purposes.
2. Medium Earth orbit (MEO) satellites: These satellites orbit the Earth at an altitude of about 8,000 km to 12,000 km. They have an orbital period of about 12-24 hours, and provide coverage for larger areas of the Earth’s surface. They are mainly used for navigation and communication purposes.
3. Geostationary orbit (GEO) satellites: These satellites orbit the Earth at an altitude of about 36,000 km. They have an orbital period of 24 hours, which matches the Earth’s rotation, so they appear to be in a fixed position in the sky. They are mainly used for communication and television broadcasting purposes.
4. High Earth orbit (HEO) satellites: These satellites orbit the Earth at an altitude above 20,000 km, they have an orbital period of several weeks to several months. They are mainly used for scientific research, military and reconnaissance purposes.
5. Deep space satellites: These satellites are placed in orbits far beyond the Earth’s orbit, they are mainly used for interplanetary missions, space exploration and astronomical observations.

It’s important to note that these categories of satellites are not mutually exclusive, and some of them can overlap. For example, LEO and MEO satellites are used for both navigation and communication purposes, and some GEO satellites are also used for Earth observation purposes.

How a satellite is made : major modules of a satellite?

Satellites are complex systems that consist of several modules or sub-systems that work together to perform their mission. Some of the major satellite sub-systems are:

1. Power Subsystem: This subsystem provides power to the satellite, typically through solar panels that convert sunlight into electricity and batteries that store the energy for use during periods when the satellite is not in direct sunlight.
2. Communications Subsystem: This subsystem enables the satellite to transmit and receive data, typically through antennas and transceivers.
3. Attitude and orbit control subsystem: This subsystem is responsible for controlling the satellite’s position and orientation in space, typically through reaction wheels, thrusters, and sensors.
4. Thermal control subsystem: This subsystem controls the temperature of the satellite, typically through heat dissipation, insulation, and thermal coatings.
5. Payload subsystem: This subsystem is the main equipment of the satellite that accomplishes the mission, for example, cameras, sensors or communication transponders
6. Structures and Mechanisms subsystem: This subsystem includes the physical structure of the satellite, such as the body, solar panels, and antenna, as well as any moving parts, such as deployable solar arrays, that are used to deploy and orient the payload.
7. Data Handling and Management subsystem: This subsystem manages the data collected by the satellite, including data storage, data compression, and data transmission.
8. Command and control subsystem: This subsystem allows ground-based controllers to command and control the satellite, typically through a ground station that communicates with the satellite via a radio frequency link.

It’s important to note that different types of satellites have different subsystems, and some subsystems are more critical than others depending on the mission of the satellite.

Satellite manufacturers

There are many companies and organizations that manufacture satellites around the world. Some of the major satellite manufacturers include:

1. Airbus Defence and Space: A European aerospace manufacturer that designs and manufactures a wide range of satellites for communication, Earth observation, and navigation.
2. Boeing: An American aerospace manufacturer that designs and manufactures satellites for communication, Earth observation, and navigation, as well as spacecraft for human spaceflight.
3. Lockheed Martin: An American aerospace manufacturer that designs and manufactures satellites for communication, Earth observation, and navigation, as well as spacecraft for human spaceflight.
4. Thales Alenia Space: A joint venture between French and Italian companies that designs and manufactures a wide range of satellites for communication, Earth observation, and navigation.
5. China Aerospace Science and Technology Corporation (CASC): A Chinese state-owned enterprise that designs and manufactures a wide range of satellites for communication, Earth observation, and navigation, as well as spacecraft for human spaceflight.
6. Mitsubishi Electric Corporation: A Japanese company that designs and manufactures a wide range of satellites for communication, Earth observation, and navigation.
7. Indian Space Research Organisation (ISRO): Indian government agency that designs and manufactures a wide range of satellites for communication, Earth observation, and navigation, as well as spacecraft for human spaceflight.
8. Space Systems Loral (SSL): A private American company that designs and manufactures a wide range of commercial satellites for communication, Earth observation, and navigation.
9. Surrey Satellite Technology Limited (SSTL): A British company that designs and manufactures a wide range of small and microsatellites for communication, Earth observation, and navigation.

It’s important to note that many of these companies also provide services such as satellite launches, ground equipment, and satellite operation and maintenance. Additionally, there are many smaller, specialized satellite manufacturers around the world that focus on specific types of satellites or specific markets.

Private satellite companies in India

There are several private satellite companies in India that design, manufacture and operate satellites for various applications. Some of the major private satellite companies in India include:

1. Antrix Corporation: This is the commercial arm of the Indian Space Research Organisation (ISRO) that provides launch services, satellite-based services, and technology transfer.
2. Aryan Satcom: This is a privately held Indian company that specializes in providing satellite-based communication services to the maritime, oil and gas, and media industries.
3. Exseed Space: This is a privately held Indian company that designs, manufactures, and operates small and microsatellites for communication, earth observation and remote sensing.
4. ISRO Inertial Systems Unit: This is a privately held Indian company that designs, manufactures and supplies high-precision navigation and guidance systems for aerospace and defense applications.
5. SatSure: This is a privately held Indian company that provides geospatial analytics and data services using satellite-based data.
6. SpaceKidz India: This is a privately held Indian company that focuses on promoting science, technology, engineering, and mathematics education among children, as well as developing and launching small satellites.
7. Pixxel: This is a privately held Indian startup that’s focused on building a constellation of earth-imaging microsatellites to provide near real-time, high-resolution data to businesses and governments.
8. Bellatrix Aerospace: This is a privately held Indian company that designs and develops electric propulsion systems and small satellite platforms
9. Agnikul Cosmos: It is a Start-up, building small rocket for satellite launch
10. Skyroot Aerospace : Another Indian start-up, which is building the satellite launch vehicle for small payloads
11. Dhruva Space: It is a full stack technology provider for satellite industry
12. Digantara: It provide end-to-end solution for satellite market. Recently, it has unveiled its large state-of-the-art satellite assembly facility.

It’s important to note that private companies in India are also working on developing their own satellite launch vehicles to reduce their dependency on foreign launchers, which in turn will reduce the cost of launching satellites.