ELI5: Explain Like I'm 5

Hohmann transfer orbit

Imagine you and your friend are playing a game of catch, but you are on opposite sides of the playground. To get the ball to your friend, you have to throw it in a certain way so that it curves just right and lands in their hands. This is kind of like what a Hohmann transfer orbit is.

In space, there are planets and other objects that orbit around the sun. If we want to send a spacecraft from Earth to Mars, for example, we have to figure out how to get it there without using up too much fuel or taking too long. That's where the Hohmann transfer orbit comes in.

Basically, a Hohmann transfer orbit is a special kind of trajectory (or path) that a spacecraft can follow from one planet to another. It's named after a German engineer named Walter Hohmann, who figured out this method back in 1925.

To follow a Hohmann transfer orbit, the spacecraft will first launch from Earth and enter an elliptical orbit around the sun. This orbit will be carefully calculated so that it passes by the target planet (like Mars) at just the right time.

When the spacecraft gets close to the target planet, it will fire its engines to slow down and enter orbit around the planet. This part is like catching the ball when it comes towards you - the spacecraft has to slow down just enough so that it's captured by the planet's gravity and can enter orbit.

The great thing about a Hohmann transfer orbit is that it's a very efficient way to travel through space. It saves fuel because the spacecraft doesn't have to use much energy to change direction or speed up or slow down along the way. It also takes less time than some other methods of traveling between planets.

Of course, there are other factors that can affect a Hohmann transfer orbit - like the positions of the planets in their orbits, for example. But that's the basic idea: it's a special kind of trajectory that gets a spacecraft from one planet to another with minimal fuel use and travel time.