Tag satellites

satellite

Satellite Orbits

Satellites orbit around celestial bodies, such as planets or stars, under the influence of gravity. The specific characteristics of a satellite’s orbit depend on various factors, including its altitude, velocity, and the mass of the celestial body it is orbiting. Here are some key concepts related to satellite orbits:

  1. Orbital Altitude: The altitude or distance above the Earth’s surface at which a satellite orbits is a crucial factor. Satellites in low Earth orbit (LEO) are closer to the Earth and typically orbit at altitudes ranging from about 160 kilometers (100 miles) to around 2,000 kilometers (1,240 miles). Medium Earth orbit (MEO) and geostationary orbit (GEO) satellites are positioned at higher altitudes, with GEO satellites orbiting at approximately 35,786 kilometers (22,236 miles) above the equator.
  2. Orbital Velocity: The speed at which a satellite orbits its parent body is called its orbital velocity. The orbital velocity depends on the altitude and the mass of the celestial body. Satellites in lower orbits must travel faster to maintain their orbits, while those in higher orbits can move more slowly.
  3. Orbital Period: The time it takes for a satellite to complete one orbit around its parent body is called its orbital period. This period is determined by the satellite’s altitude and orbital velocity. Satellites in lower orbits have shorter orbital periods than those in higher orbits.
  4. Types of Orbits:
    • Low Earth Orbit (LEO): Satellites in LEO are positioned relatively close to the Earth’s surface. They are often used for purposes such as Earth observation, communication, and scientific research. The International Space Station (ISS) is an example of a satellite in LEO.
    • Medium Earth Orbit (MEO): Satellites in MEO are positioned at intermediate altitudes. Navigation satellites like those in the Global Positioning System (GPS) are located in MEO to provide global coverage.
    • Geostationary Orbit (GEO): Satellites in GEO orbit at the same speed as the Earth’s rotation, making them appear stationary relative to the Earth’s surface. This characteristic makes them ideal for communication and weather observation satellites.
    • Polar Orbit: Satellites in polar orbits pass over the Earth’s poles, providing global coverage as the Earth rotates beneath them. These orbits are commonly used for Earth observation and scientific missions.
  5. Orbital Decay: Satellites in low orbits can experience orbital decay due to atmospheric drag. Over time, they lose altitude and eventually re-enter the Earth’s atmosphere. To counteract this, they may need periodic boosts to maintain their orbits.
  6. Kepler’s Laws: Johannes Kepler formulated three laws of planetary motion, which also apply to satellites. These laws describe the elliptical nature of orbits, the relationship between orbital radius and orbital period, and the equal area law, which governs the speed of a satellite as it moves along its orbit.
  7. Two-Body Problem: The motion of a satellite is typically described using the two-body problem, which simplifies the interaction between the satellite and the celestial body to just two objects: the satellite and the celestial body.

In summary, satellite orbits are determined by a combination of factors, including altitude, velocity, and the gravitational pull of the celestial body they are orbiting. Different types of orbits are used for various purposes, ranging from Earth observation and communication to navigation and scientific research.

Links: https://craigjohnmiles.com

Connecting the World

Connecting the World

Connecting the world is a moral imperative, in our opinion.

Recent figures suggest that less than half the world has internet access.

Connectivity brings economic and cultural benefits.

Connectivity also empowers women and girls, who currently have less access to the internet.

Without the internet, they are kept at a disadvantage.

Disadvantage in terms of education and empowerment.

Disadvantage in terms of work opportunities.

The Traditional Problem

The traditional problem that faces telecommunications providers, is an economic one.

Installing the necessary telecommunications infrastructure, is not economic in less populated areas.

A typical cell tower, which provides the link between the mobile (cell) phone, and the network, only has a fairly short communications range.

That is why there has to be many towers, spaced fairly close together.

At the relatively high radio frequencies that are used (typically 900Mhz & 1800MHz, in UK), the range is short.

This isn’t a problem in the UK, and other areas of high population density, but is in sparsely populated areas of the world.

When a telecommunications provider installs equipment, there are a number of cost factors.

In the case of a mobile phone system, there is the cell tower, and associated infrastructure.

The Space Solution

Satellites can cover large geographic areas of the earths surface, from Space.

Traditionally however, there was a problem.

The problem is called ‘Latency

Latency is the delay in the signal reaching the receiver, after being transmitted.

Radio waves are travelling at 186,000 miles per second.

This sounds fast, but does mean signal delay.

For data communications over the Internet, this isn’t desirable.

Imagine trying to have a two-way live Zoom conversation, with delay in the data moving back and forth, between the participants.

The Latency issue, can be vastly improved, by having satellites in Low Earth Orbit (LEO).

This is because there is less distance for the radio waves to travel.

Solution, well Kind of

So why don’t we switch to using satellites for all of our Internet connectivity.

Capacity and Bandwidth!

LEO Satellites now provide worldwide coverage.

However they could not handle all the required data of the Internet.

That is why we need both terrestrial (earth based), and also Space based communications infrastructure.

Connecting the world, is an imperative, as recognised by International bodies, such as the ITU.