Enlarge / SEM image of a 3D-printed microscopic version of the USS Voyager , a fictional Intrepid class starship from the Star Trek franchise. Studying such objects could lead to tiny robots for targeted drug delivery, among other applications. (credit: R.P. Doherty et al/Soft Matter)

Physicists at Leiden University in the Netherlands have created a 3D-printed microscopic version of the USS Voyager from the Star Trek franchise, according to a recent paper in the journal Soft Matter. These kinds of synthetic "microswimmers" are of great interest to scientists because they could one day lead to tiny swimming robots for autonomous drug delivery through the bloodstream, or for cleaning wastewater, among other potential applications. Such studies could also shed light on how natural "microswimmers" like sperm and bacteria travel through the human body.

Because of their small size, microswimmers face unique challenges when they move through fluids. As we've reported previously in the context of different research, biological microorganisms live in environments with a low so-called Reynolds number —a number that predicts how a fluid will behave based on the variables viscosity, length, and speed. Named after the 19th-century physicist Osborne Reynolds , the concept is especially useful for predicting when a fluid will transition to turbulent flow.

In practical terms, it means that inertial forces (e.g., pushing against the water to propel yourself forward while swimming) are largely irrelevant at very low Reynolds numbers, where viscous forces dominate instead. So because bacteria or sperm swim at low Reynolds numbers, they can barely coast any distance at all if you push them to set them in motion. It's akin to a human trying to swim in molasses.

Enlarge / Scientists mixed chitin—an organic polymer found in abundance in arthropods, as well as fish scales—with a mineral that mimics the properties of Martian soil to create a viable new material for building tools and shelters on Mars. (credit: Javier G. Fernandez )

Space aficionados who dream of one day colonizing Mars must grapple with the stark reality of the planet's limited natural resources, particularly when it comes to building materials. A team of scientists from the Singapore University of Technology and Design discovered that, using simple chemistry, the organic polymer chitin —contained in the exoskeletons of insects and crustaceans—can easily be transformed into a viable building material for basic tools and habitats. This would require minimal energy and no need for transporting specialized equipment. The scientists described their experiments in a recent paper published in the journal PLOS ONE.

"The technology was originally developed to create circular ecosystems in urban environments," said co-author Javier Fernandez . "But due to its efficiency, it is also the most efficient and scalable method to produce materials in a closed artificial ecosystem in the extremely scarce environment of a lifeless planet or satellite."

As we previously reported , NASA has announced an ambitious plan to return American astronauts to the Moon and establish a permanent base there, with an eye toward eventually placing astronauts on Mars. Materials science will be crucial to the Artemis Moon Program's success, particularly when it comes to the materials needed to construct a viable lunar (or Martian) base. Concrete, for instance, requires a substantial amount of added water in order to be usable in situ , and there is a pronounced short supply of water on both the Moon and Mars. And transport costs would be prohibitively high. NASA estimates that it costs around $10,000 to transport just one pound of material into orbit.