Using technology similar to that found in smartphone cameras, NASA scientists are developing new sensors to reveal more details about black hole flares and exploding stars – while also consuming less energy and easier to mass-produce than detectors in use today.

Research astrophysicist Dr. “When you think of black holes that are actively ripping stars apart, or neutron stars that explode and create really high-energy bursts of light, you’re looking at the most extreme events in the universe,” said Regina Caputo. “To observe these events, you have to look at the highest-energy form of light: gamma rays.”

Caputo is leading the effort to develop an instrument called the AstroPix at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The silicon pixel sensors in AstroPix, which is still in development and testing, are similar to the semiconductor sensors that make smartphone cameras so small.

A NASA postdoctoral researcher working with Caputo, Dr. “Measuring gamma rays is notoriously difficult because of how the incoming particle interacts with your detector,” said Amanda Steinhebel.

Gamma rays have wavelengths of light with more energy than ultraviolet and X-rays, and their photons behave more like particles than waves. “Instead of being absorbed by the sensor like visible light, gamma rays are reflected everywhere,” said Steinhebel.

NASA’s Fermi Gamma-ray Telescope, which has been studying the gamma-ray sky since 2008, has solved the “bounce” problem in its main instrument using strip-shaped sensor towers. This table-sized cube, the Large Fermi Telescope, was a breakthrough technology at the time the mission was launched.

Each strip reflects gamma radiation in one dimension, while layers of stripes oriented perpendicular to each other register the second dimension. Gamma rays create a series of energy shocks across multiple layers, creating a map showing the source.

According to Caputo, a space telescope instrument using AstroPix sensors the size of a golf bag would require half as many layers of Fermi strip detector technology.

“It’s easier to pinpoint exactly where the particles interact,” said Steinhebel, “because you identify the point on the grid where they interact. Then you use multiple layers to literally trace the paths the particles travel through.”

Steinhebel explained that AstroPix is ​​able to record lower-energy gamma rays than current technology because these photons tend to get lost as the stripe filters through the detector’s multiple layers. Catching them will provide more insight into what happens during short-lived, energetic events. “These low-energy gamma rays are most common at the flare’s peak brightness,” he explained.

Caputo said the pixel detectors use less electricity to operate, which is a huge advantage for future tasks that plan for power consumption. Pixel-based silicon detectors have been proven in experiments with particle accelerators, and their widespread use for cell phones and digital cameras makes them easier and cheaper to mass produce, he said.

Steinhebel said it has been exciting and immensely rewarding to develop various prototypes over several years and watch AstroPix produce accurate gamma-ray graphics. As the team continues to work on developing and refining their technology, Caputo said the next step will be to launch the technology on a short rocket flight for further testing over Earth’s atmosphere. They hope to take advantage of a future gamma-ray mission designed to further study high-energy events in the universe.

“We can do great science with this,” Caputo said. “I just want it to happen”