Rocket scientists use X-rays to develop new spacecraft materials
Scientists at NASA and Berkeley are now able see how the microscopic structures of new spacecraft materials survive extreme conditions.
When it comes to launching some of the world’s most sophisticated rockets, scientists are required to explore all potential challenges a spacecraft could encounter when entering and landing on planets with extreme atmospheres.
Scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and NASA are using X-rays to ensure future spacecrafts survive in extreme environments.
Through 3D visualizations, the scientists are able to see how the microscopic structures of spacecraft heat shield and parachute materials survive extreme temperatures and pressures, including simulated atmospheric entry conditions on Mars.
In order for human exploration of Mars, scientists believe that a new type of heat shield would be required that is flexible and can easily be folded up when needed.
This is where x-ray science comes in handy. Candidate materials for this type of flexible heat shield, in addition to fabrics for Mars-mission parachutes deployed at supersonic speeds, are being tested with X-rays at Berkeley Lab’s Advanced Light Source (ALS).
“We are developing a system at the ALS that can simulate all material loads and stresses over the course of the atmospheric entry process,” said Harold Barnard, a scientist at Berkeley Lab’s ALS who is spearheading the Lab’s X-ray work with NASA.
The team is working towards establishing a toolbox of tests that will allow for rapid development of new materials with established performance and reliability. X-ray imaging is just one of the many tests that will be performed, yet is a new quality control option available to rocket scientists. Others include small laboratory experiments, computer-based analysis and simulation tools, as well as large-scale high-heat and wind-tunnel tests.
Scientists are now able to heat sample materials to thousands of degrees, subject them to a mixture of different gases found in other planets’ atmospheres, and with pistons stretch the material to its breaking point, all while imaging in real time their 3D behavior at the microstructure level.
Michael Barnhardt, a senior research scientist at NASA Ames Research Center (NASA ARC) and principal investigator of the Entry Systems Modeling Project, said the X-ray work opens a new window into the structure and strength properties of materials at the microscopic scale, and expands the tools and processes NASA uses to “test drive” spacecraft materials before launch.
“Before this collaboration, we didn’t understand what was happening at the microscale. We didn’t have a way to test it,” Barnhardt said. “X-rays gave us a way to peak inside the material and get a view we didn’t have before. With this understanding, we will be able to design new materials with properties tailored to a certain mission.”
Barnhardt explains that this method will help build the basis for more predictive models. The X-ray work could reduce risk and provide more assurance about a new material’s performance even at the drawing-board stage.
The X-ray experiments were done on a sample the size of a postage stamp. The experimental data is used to improve realistic computer simulations of heat shield and parachute systems.
“We need to use modern measurement techniques to improve our understanding of material response,” explains Francesco Panerai, a materials scientist with NASA contractor AMA Inc. and the X-ray experiments test lead for NASA ARC. These X-ray images have provided the best pictures yet of the behavior of the internal 3-D microstructure of spacecraft materials.
The experiments capture a sequence of images as a sample is rotated in front of an X-ray beam. These images, which provide views inside the samples and can resolve details less than 1 micron, or 1 millionth of a meter, can be compiled to form detailed 3D images and animations of samples.
This study technique is known as X-ray microtomography. “We have started developing computational tools based on these 3D images, and we want to try to apply this methodology to other research areas, too,” he said.
Video courtesy of Arnaud Borner, Tim Sandstrom/NASA Ames Research Center.