Radiation-Hardened Detector System Advances MKIDs for Future Space Telescope Missions

The next generation of space telescopes, including the ambitious Habitable Worlds Observatory, demand increasingly sophisticated detector technology capable of capturing faint light from distant planets and unlocking the secrets of their atmospheres. Tracee Jamison-1, Lynn Miles, Sanetra Newman, and their colleagues at Arizona State University and NASA’s Goddard Space Flight Center are pioneering a new generation of signal processing electronics to meet this challenge. Their work focuses on Microwave Kinetic Inductance Detectors, a technology already proven in balloon-borne experiments, but requiring significant advancements for the harsh environment of space. This team is developing a radiation-hardened system, building on the technical groundwork of the PRIMA mission, to handle the massive data streams and on-board processing needed for future observatories and ultimately, the search for life beyond Earth.

This system is being rigorously tested and refined through the PRIMA mission, serving as a vital stepping stone towards the more ambitious requirements of the Habitable Worlds Observatory. The system relies on a high-speed digital signal processor built around a radiation-hardened computer chip, ensuring reliable operation in the harsh environment of space. This processor analyzes the signals from each detector, converting them into data that reveals the presence and energy of incoming photons.

The system achieves exceptional precision, capable of distinguishing frequency shifts as small as 10 kHz within a detector bandwidth of 30 kHz, a level of accuracy essential for characterizing the faint signals from Earth-like planets. A key innovation lies in the system’s ability to process a massive number of detector signals, over 1400 individual tones, without sacrificing performance. This is accomplished through a technique called frequency-division multiplexing, where each detector is assigned a unique frequency, allowing the system to isolate and analyze signals from each one. The signal processing algorithms are implemented on reprogrammable hardware, providing flexibility and allowing for future upgrades and improvements.

The system’s performance has been validated through extensive testing, demonstrating its ability to accurately measure the phase and amplitude of the detector signals. By precisely tracking these parameters, researchers can determine the energy and arrival time of each photon, providing a detailed picture of the incoming light. The method involves converting incoming photon signals into measurable changes in resonant frequency, achieved through precise monitoring of in-phase and quadrature components of the detector response. The research establishes critical parameters for MKID signal processing, including a required sampling frequency of at least 5 GHz and a minimum observation window of 219 samples to accurately resolve individual detector tones.

This ensures the system can distinguish between signals from the 1400 resonators within the MKID array, spanning a frequency range of 2. 4 to 4. 9 GHz. While the current implementation focuses on meeting the specifications for PRIMA, the algorithms for pulse detection and tone-tracking are intended for use in the more ambitious Habitable Worlds Observatory mission.