NASA’s next-generation gamma-ray sensor, named AstroPix, is set to be tested in space aboard the Fly Foundational Robots mission, scheduled for launch in late 2027. This technology demonstration aims to significantly advance gamma-ray measurements in space.
Gamma rays represent the most energetic form of light. Scientists observe gamma rays originating from various cosmic events, including lightning strikes on Earth, powerful solar flares, and collisions in distant galaxies. The AstroPix technology is designed to measure gamma rays within the energy range of 20,000 to 700,000 electron volts, a stark contrast to the 2 to 3 electron volts of visible light.
While current NASA missions like the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory detect higher-energy gamma rays, their sensitivity decreases in the 500,000 to 1 million electron volt range. This energy band is crucial as it’s where gamma-ray bursts are brightest and where the most intense glow is expected from the largest and most distant active galaxies fueled by black holes. By incorporating AstroPix detectors into future missions, scientists can fill this observational gap, enhancing the study of these cosmic phenomena and improving understanding of the processes that create and drive them.
“The Fly Foundational Robots spacecraft is also a technology demonstration, so the projects align well,” said Dan Violette, a postdoctoral researcher at NASA Goddard Space Flight Center and part of the AstroPix team. “We need to thoroughly test AstroPix’s performance before we can use it for scientific missions. We’ve flown similar technologies on a scientific balloon mission, and the current prototype will eventually be part of a sounding rocket payload. Many of these flight opportunities only reach near space. It’s not common for technology demonstrations like ours to find a ride to orbit.”
Each AstroPix chip contains four silicon pixel gamma-ray detectors, with each detector comprising 1,225 pixels. The chips operate similarly to sensors found in cellphone cameras.
This payload, also known as the AstroPix Satellite Technology dEmonstration Payload (A-STEP), will be housed within the Orbital Replacement Unit (ORU) of the Fly Foundational Robots mission. The ORU is a mobile module manufactured by Rocket Lab Robotics. Rocket Lab Robotics will also provide a robotic arm to retrieve and reposition the module during flight, performing in-orbit operations as part of the robotic servicing demonstration. The A-STEP payload will collect its data following this repositioning. Astro Digital will provide the spacecraft.
The ORU was designed to provide power and data interfaces to a payload, but the original plan anticipated the robotic arm repositioning the module independently. As mission development progressed, the Fly Foundational Robots team identified an opportunity to further enhance the mission’s value by integrating an additional technology demonstration capable of fitting within the 11.8-inch (30-centimeter) cube.
“The unit already had the volume, power, and data needed to support the AstroPix team’s design,” said Bo Naasz, senior technical lead for Servicing, Assembly, and Manufacturing in Space at NASA Headquarters’ Space Technology Mission Directorate in Washington. “One of our core goals with Fly Foundational Robots is to enable robotic servicing of payloads in orbit, allowing for upgrades or improvements to satellites and space instruments at a fraction of the cost of a full mission. Allowing AstroPix to complete its own technology demonstration in orbit is a bonus.”
The AstroPix team is working to deliver their hardware this September, and it will be integrated into the Fly Foundational Robots payload before final integration onto the spacecraft. The ORU will house all the necessary electronics for the chips, providing power, collecting data, and transmitting it during flight.
NASA’s Fly Foundational Robots mission is funded through the In-Space Servicing of Missions (ISAM) portfolio managed at NASA Goddard. Rocket Lab Robotics is providing the mission’s robotic arm system via a NASA Small Business Innovation Research Phase III award. Astro Digital will conduct the arm’s in-orbit flight test through NASA’s Flight Opportunities program, managed at NASA’s Armstrong Flight Research Center in Edwards, California. AstroPix’s development is supported by the Astrophysics Division of NASA Headquarters’ Science Mission Directorate, through the agency’s Astrophysics Research and Analysis Program, and funded via the Nancy Grace Roman Technology Fellowship.
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By Jeanette Kazmierczak
Goddard Space Flight Center, Greenbelt, Md.
