UNIVERSITY PARK, Pa. — Objects and events in space emit electromagnetic radiation, ranging from low-energy radio waves through visible and ultraviolet (UV) light and up to higher energy X-rays and gamma rays. Astronomers use unfathomably precise optics and sensors to dissect the radiation into individual wavelengths, allowing them to decipher the information it carries about its cosmic sources. Developing and testing these optics for X-rays and ultraviolet light is one of the focuses of Penn State astronomers Fabien Grisé and Jake McCoy, who have each been recently been awarded new NASA grants totaling over $4 million.
Grisé is an associate research professor and McCoy is an assistant research professor working with Randy McEntaffer, department head and professor of astronomy and astrophysics. They will use the grants to develop and test improved UV and X-ray diffraction gratings. These optical devices are a key component of spectrometers that can be integrated into telescopes. They function similar to the way a prism can split visible light into its constituent colors but are much more precise and can be tuned to specific wavelengths of electromagnetic radiation like UV or X-rays. The spectrometer can then identify specific wavelengths of UV or X-rays that are signatures of the presence of certain elements or other characteristics of objects or events in space.
The improved gratings will allow astronomers to observe and learn about objects that are farther away or fainter in the universe. In addition, the researchers said, these gratings may help answer questions about the universe, including identifying habitable planets outside of our solar system, how galaxies evolve, and how much and what types of matter makes up objects in space and how that matter is recycled.
“In our research, we are trying to learn about the universe by designing and fabricating gratings that improve the resolution and specificity of the data we collect,” Grisé said. “You can imagine these gratings sort of like CDs or DVDs. When you hold a CD in the light, the light bounces around in the grooves on the CD and we can see the colors of the rainbow. For the gratings, we etch tiny groves, much smaller than those on a CD, into a material so we can separate UV and X-ray radiation into separate wavelengths, which give us information about the object in space we are observing. We test the devices on small rockets that only spend a few minutes in space, but they could eventually be incorporated in the next-generation of large X-ray or UV space telescopes.”
Typically, X-rays are produced by hotter events with temperatures that are over one million degrees, whereas UV wavelengths represent slightly lower temperatures.
“As NASA continues to push to increase our technological readiness for big future projects like the Habitable World Observatory, a concept mission designed to search for and characterize habitable planets beyond our solar system, we will use these funds to advance and define what cutting edge technology looks like,” McCoy said.
With the two grants, Grisé and McCoy aim to increase the technological readiness of the gratings for future NASA missions. The first grant will support research to improve UV-wavelength diffraction gratings, while the second will focus on X-ray wavelength diffraction gratings.
“These grants, led by Grisé and McCoy, provide support for two independent, interdisciplinary, multi-institutional, collaborative research programs being led by two research professors in my group,” McEntaffer said. “Each of their programs just received a NASA grant to study nanofabrication of diffraction optics for space telescopes that are designed to expand the boundaries of what we can learn about our universe through UV and X-ray radiation.”
Both of the projects will make use of the Nanofabrication Laboratory, which is part of the Materials Research Institute at Penn State. The Nanofabrication Lab is a state-of-the-art facility with the tools and expert staff to facilitate the research and development of the gratings led by Grisé and McCoy.
“The equipment, staff and resources make the Nanofabrication Lab a fantastic space for our work,” McCoy said. “At most other institutions, our projects would have to be outsourced, but we are fortunate here at Penn State to do all our work in house.”
The McEntaffer Group has perennially been one of the largest users of the Nanofabrication Lab since moving to Penn State in 2016.
“Being able to go into the lab ourselves to run our experiments is a huge part of our project,” Grisé said. “The lab itself has almost every tool we could need to do our research and the staff is incredibly knowledgeable and helpful to our work.”
“Our faculty, students, researchers and Nanofabrication Lab staff have teamed up to take design concepts and drive them into large scale X-ray and UV gratings with complex designs that require extremely precise tolerances. This type of accomplishment can only be realized with dedicated partnerships and open innovation with a commitment to leading excellence,” said Clive Randall, director of the Materials Research Institute and distinguished professor of materials science and engineering.
The technology and expertise available in the Nanofabrication Lab will allow McEntaffer’s group to improve these gratings for future NASA missions and beyond, the researchers said.
“It is fascinating that by using all of these tools and chemical processes to fabricate nanoscopic patterns in the laboratory, we are able to probe further into the universe at the largest scales,” Grisé said. “As a scientist, being part of an ecosystem that tries to improve astronomical instruments and perform at a higher level will hopefully one day help us to understand the universe that we all live in better.”