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Very low Earth orbit. Very low Earth orbit is a range of orbital altitudes below 400 km (250 mi), and is of increasing commercial importance in a variety of scenarios and for multiple applications, in both private and government satellite operations. Applications include earth observation, radar, infrared, weather, telecommunications, and rural ...
A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. [ 1 ] Most of the artificial objects in outer space are in LEO, peaking in number at an altitude around 800 km (500 mi), [ 2 ] while the farthest in LEO, before medium Earth orbit (MEO ...
Oct 12, 2024 · News •. low Earth orbit (LEO), region of space where satellites orbit closest to Earth ’s surface. There is no official definition of this region, but it is usually considered to be between 160 and 1,600 km (about 100 and 1,000 miles) above Earth. Satellites do not orbit below 160 km because they are affected by atmospheric drag.
Sep 15, 2015 · Low Earth orbit is not very high. Yes, we think about LEO as being way up there in space—and it is indeed very high. The International Space Station orbits 400 km above the Earth’s surface.
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Just as different seats in a theater provide different perspectives on a performance, different Earth orbits give satellites varying perspectives, each valuable for different reasons. Some seem to hover over a single spot, providing a constant view of one face of the Earth, while others circle the planet, zipping over many different places in a day...
There are essentially three types of Earth orbits: high Earth orbit, medium Earth orbit, and low Earth orbit. Many weather and some communications satellites tend to have a high Earth orbit, farthest away from the surface. Satellites that orbit in a medium (mid) Earth orbit include navigation and specialty satellites, designed to monitor a particul...
Changing a satellites height will also change its orbital speed. This introduces a strange paradox. If a satellite operator wants to increase the satellites orbital speed, he cant simply fire the thrusters to accelerate the satellite. Doing so would boost the orbit (increase the altitude), which would slow the orbital speed. Instead, he must fire t...
Together, the satellites height, eccentricity, and inclination determine the satellites path and what view it will have of Earth.
A geostationary orbit is extremely valuable for weather monitoring because satellites in this orbit provide a constant view of the same surface area. When you log into your favorite weather web site and look at the satellite view of your hometown, the image you are seeing comes from a satellite in geostationary orbit. Every few minutes, geostationa...
Because geostationary satellites are always over a single location, they can also be useful for communication (phones, television, radio). Built and launched by NASA and operated by the National Oceanic and Atmospheric Administration (NOAA), the GOES satellites provide a search and rescue beacon used to help locate ships and airplanes in distress.
Finally, many high Earth orbiting satellites monitor solar activity. The GOES satellites carry a large contingent of space weather instruments that take images of the Sun and track magnetic and radiation levels in space around them. Most scientific satellites and many weather satellites are in a nearly circular, low Earth orbit. The satellites incl...
Of the five Lagrange points in the Sun-Earth system, only the last two, called L4 and L5, are stable. A satellite at the other three points is like a ball balanced at the peak of a steep hill: any slight perturbation will push the satellite out of the Lagrange point like the ball rolling down the hill. Satellites at these three points need constant...
The first Lagrange point is located between the Earth and the Sun, giving satellites at this point a constant view of the Sun. The Solar and Heliospheric Observatory (SOHO), a NASA and European Space Agency satellite tasked to monitor the Sun, orbits the first Lagrange point, about 1.5 million kilometers away from Earth. The second Lagrange point i...
Closer to the Earth, satellites in a medium Earth orbit move more quickly. Two medium Earth orbits are notable: the semi-synchronous orbit and the Molniya orbit. Atmospheric drag is stronger when the Sun is active. Just as the air in a balloon expands and rises when heated, the atmosphere rises and expands when the Sun adds extra energy to it. The ...
The semi-synchronous orbit is a near-circular orbit (low eccentricity) 26,560 kilometers from the center of the Earth (about 20,200 kilometers above the surface). A satellite at this height takes 12 hours to complete an orbit. As the satellite moves, the Earth rotates underneath it. In 24-hours, the satellite crosses over the same two spots on the ...
Just as the geosynchronous satellites have a sweet spot over the equator that lets them stay over one spot on Earth, the polar-orbiting satellites have a sweet spot that allows them to stay in one time. This orbit is a Sun-synchronous orbit, which means that whenever and wherever the satellite crosses the equator, the local solar time on the ground...
The Sun-synchronous orbit is necessary for science because it keeps the angle of sunlight on the surface of the Earth as consistent as possible, though the angle will change from season to season. This consistency means that scientists can compare images from the same season over several years without worrying too much about extreme changes in shad...
The path that a satellite has to travel to stay in a Sun-synchronous orbit is very narrow. If a satellite is at a height of 100 kilometers, it must have an orbital inclination of 96 degrees to maintain a Sun-synchronous orbit. Any deviation in height or inclination will take the satellite out of a Sun-synchronous orbit. Since the drag of the atmosp...
The amount of energy required to launch a satellite into orbit depends on the location of the launch site and how high and how inclined the orbit is. Satellites in high Earth orbit require the most energy to reach their destination. Satellites in a highly inclined orbit, such as a polar orbit, take more energy than a satellite that circles the Eart...
Satellites in a low Earth orbit are also pulled out of their orbit by drag from the atmosphere. Though satellites in low Earth orbit travel through the uppermost (thinnest) layers of the atmosphere, air resistance is still strong enough to tug at them, pulling them closer to the Earth. Earths gravity then causes the satellites to speed up. Over tim...
- Holli Riebeek
- 2009
Nov 30, 2017 · Figure 1: Popular Orbit Regimes. Low Earth Orbit (LEO) is shown in blue, Medium Earth Orbit (MEO) is in red, and Geosynchronous Orbit (GEO) is in yellow. Low Earth Orbit (LEO) The majority of satellites orbiting the Earth do so at altitudes between 160 and 2,000 kilometers. This orbital regime is called low Earth orbit, or LEO, due to the ...
Oct 1, 2024 · Within 30 degrees of the Earth’s poles, the polar orbit is used for satellites providing reconnaissance, weather tracking, measuring atmospheric conditions, and long-term Earth observation. Sun-Synchronous Orbit (SSO) A type of polar orbit, SSO objects are synchronous with the sun, such that they pass over an Earth region at the same local ...
