Space-Age Leaves: Solar Panel Design Imitates Beech Leaves by Don DeYoung

How do you design a huge solar panel that can be folded up and stored in a tiny rocket? To find the answer, scientists looked inside the buds of the common beech tree.

Imagine the benefits of building large solar panels on earth and then launching them into space to collect energy from the sun. But there is a big problem. To be effective, solar panels require maximum surface area and lots of metal bracing for strength, yet somehow the panels must be folded compactly and stuffed into a rocket for the initial journey into space.

The design must be both lightweight and strong so that the panels will unfold without the need for a lot of motors or fear of damage. How can these design challenges be overcome?

The Japanese found a solution in God’s creation—in the buds of the common beech tree. The tree begins each growing season by constructing new leaves compactly folded within small buds. When it’s time for the plant to begin absorbing energy from the sun, the buds open, and the new leaves unfold like accordions.

The intricate folding of the beech leaf is an ingenious design. You can see it for yourself by doing a simple origami exercise (see sidebar below).

Japanese scientist Koryo Miura extended the origami concept of the beech leaf to a pattern called the miura-fold. In 1995 this design was put to the test. The Japanese built a massive solar array—80 feet (24 m) long with a surface area of 620 square feet (58 m²)—that they folded up and stored in a Japanese satellite called the Space Flyer Unit.

Engineers are looking at other amazing folding patterns in nature, too, such as the leaves of other trees and the wings of beetles and butterflies.

Folding examples from nature have a great range of potential applications. Consider highway maps that we struggle to refold after use. A folding design somewhat similar to the beech leaf has been used in a Tokyo subway map. A single pull extends the map to full size, and a downward push collapses the map once again.

The miura-fold, when made into a cylinder shape, is also useful as a design for heart stents that clear blocked arteries. There appears to be no end to origami applications, inspired by created designs like the leaf of the beech tree. Such practical folding patterns are clearly a gift from the Creator.

P. Forbes, Gecko’s Foot (New York: W.W. Norton & Company, 2005), pp. 181–183.

Sound complicated? Just view the video to see this fold in action.