Folding solar panels for satellites

Satellites need electricity to run electronics, mostly for communications and control systems, but also, if they're up there for scientific purposes, for whatever experiments they're doing. Most - not all - of these satellites use solar panels as power sources. You probably know that the Voyager spacecraft used nuclear cells for power. That's because they were travelling out of the solar system and sunlight out there is very weak.

Space agencies have to transport large solar sails into orbit. Clearly, these can't be sent up all in one piece. The solar sail has to be broken down into components, the largest part being small enough to fit into a small capsule. But the real complication is figuring out how to assemble all these small parts using the very least amount of work. 

If the panel is going to the ISS, some of the work can be done by astronauts, but even then, their time is very precious and work done outside is very difficult and dangerous.

But most panels are destined for smaller satellites that have no humans nearby. So laboriously unfolding complex shapes, or assembling individual components is not the ideal way of doing it.

A Japanese scientist called Koryo Miura came up with a method of folding panels so that all the satellite needs to do is extend the panel in one direction - diagonally. The fold is called the Miura-ori, and is based on parallelograms. The whole panel folds down into a rectangle, which can be long or short, depending on the shape of the parallelograms.

I've made two out of paper. One has nearly rectangular parallelograms, and the other has nearly diamond-shaped ones. The nearly square one folds into a very compact shape. The other one folds into a long rectangular bundle.

Autonomous satellites can now deploy large solar panels using a simple mechanism that extends or retracts things.

I find these patterns and the technique fascinating and enormously aesthetic. What's more, it's something you can try at home during a lockdown.