How low can a satellite go to stay in orbit?

I was listening to a hip-hop song, oh yeah I like hip hop, How Low, while I was thinking of satellites.
How low can a satellite go to stay in orbit?

A satellite is usually the word for that man-made equipment or machine that orbits the planet. But those are the artificial satellites. The moon, earth, etc. are natural satellites. The earth is the natural satellite of the sun; it orbits the sun. The other things in the solar system orbit the sun such the asteroids. comets, planets, etc.

The earth's moon is the natural satellite of the Earth; it orbits the earth.

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We need the artificial satellites in space for a lot of reasons. One of which is for communication such as phone calls, TVs and global positioning system (GPS), etc.

Currently, the GPS satellites alone has 31 satellites in orbit; this figure includes the decommissioned and those in reserve. For an excellent GPS sync, a total of 4 active satellites should be in available, and for the earth coverage a total of 24 active satellites.

If we look up above the sky appears all free and calm.

But according to the United Nations Office for Outer Space Affairs, UNOOSA website, a total of 8086 satellites was launched into outer space since 1957. With a total of 4788 currently orbiting in space. This amount is an increase of 3.3% from last year's number.

James Yorder was kind enough to make a 3D visualisation in real time of the various satellites, rocket bodies and debris currently floating around in the space. It is a delightful interactive website which you may like to check out here. There are a bunch of information of each satellite too if you click on it such as altitude, velocity inclination, type, date of launch, etc.

So when next you look up the sky take a moment and take in the fact that there are thousands of human-made machines floating around in orbit.

What is an orbit and how does it occur?

The celestial body such as the plant has an area where the gravitational force can pull anything that is in proximity towards it.

But if an object can "escape" this region of gravitational force, it will not experience a continuous free fall.

Orbit is the outcome of a perfect balance between a planet's gravitational tug and the forward momentum of the body in space. The gravitational force is usually from the more prominent body in space such as a star or a planet.

The body manages to stay in orbit and move in circles as the tug-of-war between the forward momentum of the object and the gravity continues as seen in this image here.

The two forces (inertia and gravity) has to be perfectly balanced for this orbit to be in place. If the forward momentum is too strong, the object will speed past the orbit, if too weak, the gravity will pull the object to the body exuding the gravitational pull.

The gravitatational pull of earth can still be felt more than 238,855 miles (384,000 km) from earth. This distance is the closest approach (perigee) the moon's elliptical orbit from earth happens to be.

The orbit around the earth is in various categories which are dependent on the distance of the satellite from it. There are four broad categories of classification by altitude. These are the Low Earth Orbit (LEO) such as the orbit of the international space station (ISS). The LEO is also for monitoring the earth's surface and in military use for spying. The medium earth orbit (MEO) finds application in GPS used in sat. navs.

The Geosynchronous Orbit (GEO) such as the earth observatory, used mainly for communication purposes, e.g. satellite tv

The last is the High earth orbit (HEO) satellites. An example is the Intersetllar Boundary Explorer (IBEX) used by the NASA for scientific observation. It is the most suitable since its high orbit allows it to move out of the earth's magnetosphere

Name	Color	Distance above earth(km)
Earth	Blue/brown	0
Low Earth Orbit(LEO)	Cyan area	160 to 2,000
Medium Earth Orbit(MEO)	Yellow area	2,000 to 34,780
International Space Station(ISS)	Red dotted line	370
Global Positioning System	Green dash-dot line	20,230
Geostationary Orbit	Black dashed line	35794
High Earth Orbit	Not shown in drawing	above 35,794km

So to answer the question, how low can you go to stay in orbit is 160km which is in the low earth orbit (LEO) region. If an object gets below 160km, it will experience an orbital decay, that is it will lose altitude due to the pull of gravity.

The LEO is an essential aspect of the space program since it is where the ISS is located. Also, all astronauts have to conduct their affairs at LEO except for the crew of the Apollo program between 1968 to 1972.

Now that I know this, all I require is a spaceship capable of catapulting me to a distance of 160km to hit that orbit and start orbiting the earth at a period of between 84 to 127 minutes.

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^References

• ^Satellite
• ^{How many satellites are orbiting the Earth in 2017?}
• ^{3D Visualization of Satelittes in Space}
• ^{How Far is the Moon}
• ^{Low Earth Orbit}

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