A new type of gamma-ray sensor developed by NASA, called AstroPix, will take part in a robotic arm demonstration on the agency’s upcoming Fly Foundational Robots mission, set to launch in late 2027.

Gamma rays are the highest-energy form of light. Scientists observe them coming from events like lightning in Earth’s atmosphere, powerful solar flares from our Sun, and cosmic collisions in distant galaxies. The sensors on the AstroPix technology demonstration are designed to measure gamma rays between 20,000 and 700,000 electron volts. For comparison, visible light’s energy falls between 2 and 3 electron volts.

Current NASA missions, including the Fermi Gamma-ray Space Telescope and Neil Gehrels Swift Observatory, also observe gamma rays, including those with even higher energies.

But for energies between 500,000 to 1 million electron volts, existing detectors are less sensitive. This range is where many powerful explosions called gamma-ray bursts shine the brightest. It’s also where astronomers expect to see the strongest glow from the most massive and distant active galaxies powered by black holes. By stacking AstroPix detectors in future missions, scientists could bridge this gap and improve observations of these cosmic objects to better understand the processes that create and drive them.

“The Fly Foundational Robots spacecraft is also a technology demonstration, so the projects were a good fit for each other,” said Dan Violette, an AstroPix team member and post-doctoral fellow at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We need to thoroughly test AstroPix’s performance before we can use the sensors in future science missions. We’ve flown comparable technologies on a scientific balloon mission, and the current prototype eventually will be part of a sounding rocket payload. Many of those flight opportunities only reach near space, though. It’s not often that technology demonstrations like ours can find a ride into orbit.”

Each AstroPix chip contains four silicon pixel gamma-ray detectors, and each detector incorporates 1,225 pixels. The chips function similarly to the sensors in cell phone cameras.

The AstroPix Satellite Technology dEmonstration Payload, also known as A-STEP, will be hosted within the Fly Foundational Robots mission’s Orbital Replacement Unit, a movable module built by Rocket Lab Robotics. Rocket Lab Robotics also will provide a robotic arm that will pick up and reposition the unit during flight and perform in-orbit operations as part of a robotic servicing demonstration. The A-STEP payload will collect its data following the repositioning. Astro Digital will provide the spacecraft.

The Orbital Replacement Unit was designed to support power and data interfaces for a payload, but the original plan called for the robotic arm to reposition the module without one. As mission development progressed, however, the Fly Foundational Robots team identified an opportunity to further maximize the mission’s value by integrating an additional technology demonstration that could fit 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, In-space Servicing, Assembly, and Manufacturing in the Space Technology Mission Directorate at NASA Headquarters in Washington. “One of our major goals with Fly Foundational Robots is to demonstrate robotic changeout of payloads in orbit, enabling 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 Orbital Replacement Unit will hold the chips and all the associated electronics needed to provide power, and collect and transmit data during flight.

NASA’s Fly Foundational Robots mission is funded through the Space Technology Mission Directorate’s ISAM portfolio, managed at NASA Goddard. Rocket Lab Robotics will supply the mission’s robotic arm system through a NASA Small Business Innovation Research Phase III award. Astro Digital will host the orbital flight test of the arm through NASA’s Flight Opportunities program, managed at NASA’s Armstrong Flight Research Center in Edwards, California. The development of AstroPix was supported by NASA’s Astrophysics Division in the Science Mission Directorate at NASA Headquarters, through the agency’s Astrophysics Research and Analysis Program, and funded through the Nancy Grace Roman Technology Fellowship.

To learn more, visit:

https://go.nasa.gov/3R28tWE

By Jeanette Kazmierczak
Goddard Space Flight Center, Greenbelt, Md.