NASA has selected AstroPix, a new gamma-ray detection technology, for an orbital demonstration. This technology will fly aboard the Fly Foundational Robots mission, scheduled for 2027. The goal is to test a new generation of sensors in space that could significantly improve the study of some of the Universe’s most energetic phenomena.
Gamma rays are the most energetic form of electromagnetic radiation. They are produced in extreme events such as solar flares, lightning in Earth’s atmosphere, and cosmic explosions observed billions of light-years away. While NASA missions like Fermi and Swift already observe this radiation, there is an energy band where current instruments have limited sensitivity.
This specific energy range contains some of the most intriguing signals for astronomers, including those generated by gamma-ray bursts—among the most powerful explosions in the Universe—and active galactic nuclei powered by supermassive black holes. If the AstroPix technology proves its capabilities in orbit, it can be utilized in future scientific missions to observe these phenomena with greater precision and gather new insights into the physical processes that create them.
How AstroPix Works
AstroPix is a sensor based on silicon detectors designed to detect gamma rays with energies ranging from 20,000 to 700,000 electronvolts. For comparison, visible light perceived by the human eye has energies between approximately 2 and 3 electronvolts.
Each AstroPix chip contains four detectors, and each detector is composed of 1225 pixels, functioning similarly to the image sensors found in smartphones. When a gamma ray passes through the detector, the sensor records the deposited energy and allows for the reconstruction of the observed radiation’s characteristics.
This technology has previously been tested through flights on stratospheric balloons and will also be used in future suborbital rocket campaigns. However, these missions only reach high altitudes or have short durations in space. The flight on the Fly Foundational Robots mission will provide an opportunity to verify the sensors’ performance directly in orbit, a crucial step before deployment in dedicated gamma-ray astrophysics space observatories.
A Space Robotics Demonstration with a Scientific Payload
AstroPix will fly as a payload for the A-STEP (AstroPix Satellite Technology dEmonstration Payload) technological demonstration. This payload will be housed within the Orbital Replacement Unit, a mobile module developed by Rocket Lab Robotics. This module is designed to simulate an on-orbit replaceable instrument and will be manipulated by a robotic arm during the Fly Foundational Robots mission.
The robotic arm, provided by Rocket Lab Robotics, will grasp the module and reposition it in space as part of a satellite maintenance and servicing demonstration. Only after this operation will AstroPix begin its scientific activity, collecting gamma-ray data and verifying the sensors’ functionality in the orbital environment.
The Orbital Replacement Unit was initially conceived as a simple demonstration element to be moved by the robotic arm, with no experiment on board. However, during the mission’s development, the team saw an opportunity to utilize the available volume inside the module, a cube approximately 30 centimeters on each side, to host a secondary technological demonstration. AstroPix emerged as an ideal candidate, increasing the mission’s scientific value without altering its primary objectives.
In the coming months, the team will complete the construction of the flight hardware. The AstroPix chips and all the necessary electronics for powering them, collecting data, and transmitting it to Earth will be installed inside the Orbital Replacement Unit before final integration onto the spacecraft, which will be provided by Astro Digital.
