Origami Universe: Corrugation: A Mini-Solar Array

Background: Spacecraft
A solar array is a group of solar panels that captures energy from our Sun to generate electricity as a system. Many spacecraft have solar panels to convert sunlight into the electrical power to help run the spacecraft. Ideally, solar arrays have a lot of surface area in which to be pointed towards the Sun to gather all the energy needed.

NASA’s Chandra X-ray Observatory, for example, travels about a third of the way to the moon at its farthest point from Earth, in order to observe the X-ray Universe. Chandra generates the electrical power needed to function from its solar arrays. The power is then stored in three banks of batteries, and eventually distributed in a carefully regulated manner to its parts. Chandra’s two 3-panel solar arrays produce about two kilowatts of power (roughly the same power as a hair dryer!) for the heaters, science instruments, computers, transmitters, etc. on board.

Chandra’s arrays were unfolded like an accordion. With its solar arrays deployed, Chandra measures 19.5 meters (64 ft) wide. It’s about as long as a school bus, and was the largest spacecraft to ever fit inside the bay of the Space Shuttle. In order to fit inside the Shuttle, Chandra’s solar panels had to be folded up, and then unfolded after it was deployed and made its way to its orbit.

Researchers from NASA’s Jet Propulsion Laboratory (JPL), however, have also been designing ways to fold up solar panels into more efficient origami-like packages, instead of using accordion-style folding. As larger solar panels are needed for newer kinds of spacecraft, accordion-style deployment can become riskier, and more liable to fail with each layer of expansion. Creating an origami-packaged solar panel system requires innovation in both the solar array materials and its “packaging,” as solar panels can’t be made paper thin. As you’ll see in the activity below, each fold or bend increases the overall thickness of the object you’re making. Engineers have to take such increases into account when creating solar arrays or other expandable parts of a spacecraft.

The following activity will use a corrugation style of folding to create a mini-solar array.

Objectives:

1. Show that a simple model that can be folded by a novice folder gives a process for significant compression.
2. Teach students a method for compact folding. This is a simple four-step origami model that is effective in greatly reducing the area and/or volume of the folding medium. It follows on the conclusions from the introductory exercises about the compact-ability of paper through folding.
3. Show the relationship between this corrugation and items used in space, such as a solar array. Also, there are similar, but more complex folding methods, such as the Miura-ori folding process.

Materials:

• One piece of copy paper (or something similar) for each student. The paper can be any shape rectangle, including square, but needs to be the same size.
• If old calendar pages are available, they make an interesting look that could be folded for a second model

Ages: Ages 10 and up

Time Needed: 1 hour

Process:

• Fan fold the paper into 8 equal portions length-wise.
• Using the directions/diagrams/video instruction provided, each student will fold a chevron corrugation.
• Calculate the surface area of the folded version of the model vs the surface area of the paper before folding. What fraction of the starting paper is the folded model?
• Is it important in this case to talk about volume?

Thought Questions:

• What is different about the corrugation folding process/result than just fan folding the paper? Is it more effective (i.e., does corrugating decrease the “footprint” of the paper more than just fan folding it)? If so, in what way?
• Can you think of other ways of pleat folding/corrugating paper that would produce a significantly different result?
• Art Connection: Two-color the model so that you see only one color when look at it from the left, and only the other color when looking at it from the right. Can you color it in other interesting ways?

Presenter: Charlene Morrow, PhD, OrigamiUSA & Mt. Holyoke