A new reconfigurable structure could be used to make space habitats

Even some fields that seem fully settled will occasionally have breakthrough ideas that have reverberated impacts on the rest of the fields of science and technology. Mechanics is one of those relatively settled fields—it is primarily understood at the macroscopic level, and relatively few new breakthroughs have occurred in it recently.

Until a few years ago, when a group of Harvard engineers developed what they called a totimorphic structure, and a recent paper posted to the arXiv preprint server by researchers at ESA’s Advanced Concepts Team dives into detail about how they can be utilized to create megastructures, such as telescope mirrors and human habitats in space.

First, it’s worth understanding what a totimorphic structure is. It is a series of triangular structures with a beam, a lever, and two elastic bands acting as springs. Given the proper configuration, the elastic bands can hold the lever at a set position in what mechanics researchers call “neutral”—i.e., without any external force being applied.

One important aspect is that the lever can be held at any position, essentially making it an analog positioning system that doesn’t have any set points where it must necessarily rest. Another important aspect is that two or more can be combined in an hourglass-looking shape, allowing the structure to take on literally any form in either 2D or 3D space and be stable in that form.

That second part is the critical feature that the researchers at ESA were interested in. Such a flexible structure would be useful in several applications, including building domed habitats or creating a telescope with an adjustable focal length that doesn’t rely on complex actuators. So, they developed a method for simulating these structures and applying them to those two use cases.

Since these modular units are physical structures, they must still abide by some rules. The three rules of these structures are that the beam and lever both have fixed lengths and that the lever must be connected on one of its ends to the midpoint of the beam. It would be interesting to see how these structures could use different types of materials for the lever or beam that would potentially allow them to change, but that’s still on the to-do list for researchers somewhere.

With those requirements in mind, the researchers set up a series of Python scripts that solve optimization problems associated with both configurable structures. The optimized features are different for either the habitat or the mirror. Still, both use the fact that the totimorphic structure is “analog,”—meaning it can continuously and stably move from one state to another without having to “jump” between them.

The results were promising, though they show that physically realizing this system would be difficult. They also point out that an AI would be well-placed to understand the properties of the structures created by combining loads of these modular units, similar to how it is possible for AI to fold proteins in innumerable ways without ever physically experiencing them.

A lot of work will still be done with this novel technology, though putting these systems to the test in an actual experimental environment is probably pretty close. If the ESA or another team can build a functional variable focal point mirror out of this new structure, that would be a breakthrough worthy of celebration.