Satellite Technology and Applications

- Overview

Satellite technology includes a wide range of applications like communication (internet, TV, phone), navigation (GPS), remote sensing for environmental monitoring, and disaster management. 

Emerging applications include space-based solar power, asteroid mining, and more advanced broadband internet access. 

These technologies work by using different types of satellites in various orbits (like geostationary or low Earth orbit) to send and receive signals, collect data, and perform tasks that support both commercial and public-good services.  

1. Key applications:

• Communication: Satellites enable global telecommunications, including internet access (especially for remote areas), television broadcasting, and phone services. 
• Navigation and Positioning: Systems like GPS, Galileo, and GLONASS provide precise location, navigation, and timing services for a vast array of applications, from car navigation to synchronizing cell phone towers. 
• Environmental and Disaster Management: Satellites monitor weather patterns, track storms, and provide data for managing natural disasters, crop health, deforestation, and climate change. 
• Military and Security: They are used for intelligence gathering, surveillance, and border monitoring to support national security. 
• Commercial and Industrial: Satellites support industries like energy (managing smart grids, monitoring infrastructure), agriculture (crop monitoring), logistics (tracking shipments), and finance (risk assessment). 

2. Technology and infrastructure:

• Orbits: Satellites are placed in different orbits based on their function. Geostationary orbits are used for applications needing to stay over a fixed point, like some weather and communication satellites, while low Earth orbits are common for Earth observation satellites to get higher resolution data. 
• Sensors: Satellites are equipped with instruments that can capture data across the electromagnetic spectrum, including optical and radar sensors. Radar, for instance, can penetrate clouds to get imagery. 
• Signal Frequencies: Various frequency bands are used for different satellite services. Higher frequencies (like Ku-band and Ka-band) allow for smaller antennas and are ideal for direct-to-home broadcasting and broadband internet. 
• Regulation: Organizations like the International Telecommunication Union (ITU) regulate orbital slots and assign frequencies to ensure orderly use of the radio spectrum. 

Please refer to the following for more information:

• Wikipedia: Applications Technology Satellites
• Wikipedia: List of Orbits

- Satellite Technology: Past, Present, and Future

Satellite technology has advanced from the first communications satellite, Telstar 1, in 1962 to today's complex systems that enable global connectivity, precise navigation, and Earth observation. 

The future will be shaped by technologies like AI, quantum computing, and new satellite constellations, which are entering a new era of global connectivity through advancements in areas like the Internet of Things (IoT) and 5G. 

1. Past:

• Telstar 1: Launched in 1962, this was the first active communications satellite, enabling live global television and telephone calls across the Atlantic. 
• Early limitations: Initial satellite communication speeds and latency were much higher than today's standards. 
• Evolution: Over time, advancements like moving satellites into higher orbits allowed for continuous communication and greatly simplified ground systems. 

2. Present:

• Ubiquitous connectivity: Thousands of satellites now provide internet, mobile connectivity, and television services to both populated and remote areas. 
• Multiple applications: Satellites are used for communications, precise positioning and navigation, and Earth observation. 
• Speed and accessibility: Modern satellite internet can offer speeds up to 100 Mbps, and lower launch costs are making satellite deployment more accessible. 

3. Future:

• New constellations: The development of new satellite constellations like OneWeb is a major trend.
• Advanced technologies: Future systems will incorporate AI for data processing, quantum computing for secure communication, and automation and robotics for operations.
• Enhanced services: The evolution of 5G and the Internet of Things (IoT) will be enabled by and integrate with satellite technology, leading to more sophisticated global connectivity. 

- Orbits

An orbit is the curved path that an object in space (such as a star, planet, moon, asteroid or spacecraft) takes around another object due to gravity.

Gravity causes objects in space that have mass to be attracted to other nearby objects. If this attraction brings them together with enough momentum, they can sometimes begin to orbit each other.

An orbit is a regular, repeating path in space that an object takes around another object. Objects in orbit around a planet are called satellites. According to the height of the satellite from the earth, satellite orbits can be divided into high earth orbit, medium earth orbit and low earth orbit.

• High Earth orbit starts about one-tenth of the way to the moon. Many types of weather and some communications satellites tend to have higher Earth orbits, furthest from the surface.
• Satellites operating in medium Earth orbit include navigation satellites, designed to monitor a specific area.
• Most scientific satellites, including NASA's Earth Observing System satellites, have low-Earth orbits.

- Satellite Orbits

Satellite orbits are the paths satellites take around Earth, balanced between the satellite's velocity and Earth's gravity. 

Different orbits, categorized as low, medium, and high Earth orbits, are used for various purposes like communications, weather monitoring, and Earth observation. Common types include geostationary orbit (GEO), which remains over the same spot on Earth, and polar orbit, which circles the globe from pole to pole.  

Common types of satellite orbits: 

1. Low Earth Orbit (LEO):

• Altitude: 160 to 2,000 km.
• Characteristics: Satellites complete an orbit in 90 to 120 minutes.
• Uses: Earth observation, reconnaissance, and scientific research. The International Space Station is in LEO.

2. Medium Earth Orbit (MEO):

• Altitude: Between LEO and GEO.
• Uses: Navigation systems like GPS.
• Geostationary Orbit (GEO):
• Altitude: Approximately 35,790 km.
• Characteristics: Orbits in the same direction and at the same rate as Earth's rotation, so the satellite appears stationary from the ground.
• Uses: Communications and weather monitoring.

3. Polar Orbit: 

• Characteristics: Travels from north to south, over the poles. As Earth rotates underneath, the satellite can scan the entire globe over time.
• Uses: Weather and environmental monitoring.
• Highly Elliptical Orbit (HEO):
• Characteristics: An elliptical path that takes the satellite to a high altitude for a period and then brings it close to Earth for another period.
• Uses: Communications for specific, high-latitude regions.

- Trends in Future Satellite Technology

The space industry is using emerging technologies like 5G, 3D printing, big data, and quantum computing to upgrade and scale operations in space. The future of satellite services may see satellite services begin to compete directly with terrestrial services.

The use of automation and robotics in future satellite technology has the potential to revolutionize the industry. Automation and robotics can lead to more efficient and cost-effective production and maintenance processes. It can also improve satellite communications and provide more precise data.

Here are some trends in future satellite technology, including:

• Small satellites: It is expected that 370 small satellites will be deployed in low or medium orbits for communication services and earth observation images.
• Satellite Internet of Things: The development of the Internet of Things is entering a new era of global connectivity.
• Advanced ground systems: Advanced ground systems are a trend in satellite communications.
• Artificial Intelligence: Artificial intelligence can be used in automatic learning systems for satellite management.
• Automation and Robotics: Automation and robotics can lead to more efficient and cost-effective production and maintenance processes.

Other future satellite technology trends include:

• Quantum satellites
• In-orbit and On-orbit service
• Advanced payload system
• Spacecraft propulsion
• Very High Throughput Satellite (VHTS)
• Low-Earth orbiting (LEO) satellites 
• Reusable rocket launch vehicles 
• Satellites with all-electric propulsion New use cases for 5G and Beyond,  and the Internet of Things (IoT)
• Miniaturization 
• Smart propulsion 
• Data analytics 
• Cybersecurity

[New York City, New York - Civil Engineering Discoveries]

- Quantum Satellites

Quantum satellites use quantum principles to establish secure communication channels between ground stations and satellites. Quantum satellites use quantum physics to entangle photons to communicate with ground stations.

Satellite-based quantum key distribution (QKD) can:

• Enables secure communication channels between ground stations and satellites
• Create secure encryption keys that are resistant to interception
• Connecting local terrestrial quantum networks over long distances
• Building a network of networks, much like the Internet is today

A quantum satellite uses photons that are inextricably linked or “entangled” by quantum physics, to communicate with a ground station. The satellite transmits pairs of entangled photons to two receivers in the access segment. The satellite creates a single quantum channel between two receivers.

Satellites are seen as a major opportunity for quantum secure communications because:

• They play an important role in long-distance, long-distance communications and data transmission.
• Architectures that move data through many different points can be compromised.

China is developing a quantum communications satellite that will carry a 600 mm diameter telescope for photon transmission. Satellites in higher orbits will allow the creation of a global, all-sky quantum communications network.

[More to come ...]