Do you know all those acronyms used in the space industry? Probably not, so what about if we take a closer look at them? So, let’s start with the acronym of the day. Today we’ll explain LEO. Do you have any idea what this acronym stands for? Here’s a little hint, it’s not an animal. Let’s find out.
The acronym LEO stands for Low Earth Orbit. But what is a Low Earth Orbit? Let’s take it apart – back to front.
What is an orbit?
Before we dive any deeper, we are talking about an orbit as used in celestial mechanics. So, what is the definition of an orbit? It’s the curved trajectory of an object around another object or position in space. Alright, so we have an object, which can for example be a rock, a spacecraft, or a planet. The object is moving on a curved course around another object or position in space. Why is it moving on a curved course? Because gravity is pulling it into the curved course. Without the gravity, it would simply move straight on. The source of the gravity is the other object.
But wait a second, how can a position in space create gravity? Well, the position is not the source of the gravity. Instead, two other objects, for example a planet and the sun, are creating it. Those points are called Lagrange points. I wrote about them in a previous post. Check it out for more details. To sum it up, the gravity of two objects is creating a position in space, where another object can orbit.
Earth
The second word is Earth. I guess you know what the Earth is. So, by saying Earth orbit, we are talking about a curved trajectory around our plant Earth.
Low
This leaves the first word – low – to explain. Low in this case describes a high above the center of Earth. This can be as low as 160 km and as high as 2000 km. Objects in these obits take 128 minutes or less for one trip around Earth. So, we have two definitions, what a Low Earth orbit is – by height or by the time it takes for one round.
Aside from Low Earth Orbits, there are also Medium Earth Orbits, High Earth Orbits and more. But we’ll take a look at them another time.
What is using a Low Earth Orbit?
Satellites and crewed space stations are using Low Earth Orbits. Currently, the International Space Station (ISS) and the Chinese Space Station are in Low Earth Orbits. In fact, all crewed space stations to date have been within Low Earth Orbits. Until now, only the Apollo mission send humans beyond Low Earth Orbit.
Aside from space stations, satellites are in Low Earth Orbits. Especially satellites for imaging the Earth surface. Being closer to the surface allows for a higher resolution of the images. Recently, satellite constellations for communication stated using Low Earth Orbits. One example for such a constellation is Starlink by SpaceX.
To sum it up, Low Earth Orbits are pretty common and useful for the space industry. And we’ll see many more satellites launch into Low Earth Orbit.
Acronym of the day will become a series of post. Check them out!