arXiv subjects

Michael Lembeck

Publications and source records attributed to Michael Lembeck.

6 recordsLinked to original sources

arXiv2026

X-ray characterization of fully-depleted p-channel Skipper-CCDs for the DarkNESS mission

The Dark matter Nanosatellite Equipped with Skipper Sensors (DarkNESS) mission is a 6U CubeSat designed to search for X-ray lines from decaying dark matter using Skipper-CCDs. Thick, fully-depleted p-channel Skipper-CCDs provide low readout noise and high quantum efficiency for 1-10 keV X-rays, but their X-ray performance has not yet been demonstrated in the space environment. DarkNESS will operate in low-Earth orbit, where trapped protons induce displacement damage in the sensor that increases charge-transfer inefficiency and degrades the X-ray energy resolution. This work measures the X-ray line response of Skipper-CCDs before and after proton irradiation and quantifies the associated degradation. A sensor was exposed to 217 MeV protons at a fluence of 8.4 x 10^10 protons cm^-2, corresponding to a displacement-damage dose more than an order of magnitude above the three-year expectation for representative mid-inclination and Sun-synchronous low-Earth orbits. A 55Fe source was used to compare the energy resolution of the beam-exposed quadrant to adjacent unexposed quadrants and a non-irradiated reference sensor. These measurements provide a quantitative assessment of radiation-induced spectral degradation in Skipper-CCDs and enable an estimate of the end-of-life X-ray energy resolution expected for DarkNESS operation in low-Earth orbit.

astro-ph.IM↗

arXiv2025

PULSE-A Mission Overview: Optical Communications for Undergraduate Students

Recent advances in the size, weight, and power (SWaP) requirements for space-based sensing have dramatically increased the demand for high-bandwidth downlink. However, high data rate RF transceivers still pose significant SWaP and cost restrictions, especially for university-class CubeSat missions. Optical communication may provide a solution to this challenge, enabling data transmission with order-of-magnitude rate increases over RF while being both secure and SWaP-efficient. The Polarization-modUlated Laser Satellite Experiment (PULSE-A) is a University of Chicago mission to demonstrate optical downlink at a data rate of up to 10 Mbps using circular polarization shift keying (CPolSK). PULSE-A comprises a <1.5U Optical Transmission Terminal, 3U CubeSat Bus, Optical Ground Station (OGS) employing an amateur telescope, and RF Ground Station (RFGS), all of which are being designed and integrated by a team of over 60 undergraduate students. The mission objective is threefold: (1) to provide hands-on educational experiences for undergraduate students, (2) to make hardware for optical communication systems more accessible via open-source design, and (3) to explore the viability and potential advantages of using CPolSK for optical downlink. In this work, we present an overview of the mission, and we describe the PULSE-A Team's learning-oriented approach to program management and engineering. We especially emphasize the importance of student leadership in PULSE-A's development process and the resulting benefits for the University of Chicago community. We also highlight takeaways from the experience of founding and operating an undergraduate student-led CubeSat program.

physics.ed-ph↗

arXiv2025

Development of an Open-Source Spacecraft Bus for the PULSE-A CubeSat

The undergraduate-led Polarization-modUlated Laser Satellite Experiment (PULSE-A) at the University of Chicago seeks to demonstrate the feasibility of circular polarization shift keyed satellite-to-ground laser communication. PULSE-A's low-cost open-source bus serves as the backbone of the mission and has been designed in tandem with the Payload, with design driven by strict requirements for pointing accuracy, component alignment, power demand, and thermal stability. This work presents the design and testing of the PULSE-A bus. The spacecraft bus was designed to fill two major needs: (1) to meet the requirements of the PULSE-A mission, and (2) to be easily configurable for future missions that desire enhanced capabilities over other low-cost open-source designs. At its core, the bus features dual BeagleBone Black Industrial compute units, selected for their flight heritage, integrated via a PC/104 header standard. PULSE-A implements Goddard Space Flight Center's core Flight System (cFS), which takes a modular software architecture approach and is built in C. The use of C as the primary language aligns with the expertise of the University of Chicago's Computer Science department, allowing for ease of development by PULSE-A's undergraduate flight software team. The CubeSat structure utilizes Gran Systems' 3U frame, modified to accommodate openings for various ports and deployable components. Inside, the avionics stack uses the PC/104 standard quad rails, which terminate in PULSE-A's custom-designed Payload Box that houses all of the Payload components and optical fiber runs. This work also covers the techniques and iterative engineering processes used to develop the thermal control and dissipation mechanisms for the specific requirements, under volume, mass, and temperature-range constraints.

physics.app-ph↗

arXiv2025

DarkNESS: A skipper-CCD NanoSatellite for Dark Matter Searches

The Dark matter Nanosatellite Equipped with Skipper Sensors (DarkNESS) deploys a recently developed skipper-CCD architecture with sub-electron readout noise in low Earth orbit (LEO) to investigate potential signatures of dark matter (DM). The mission addresses two interaction channels: electron recoils from strongly interacting sub-GeV DM and X-rays produced through decaying DM. Orbital observations avoid attenuation that limits ground-based measurements, extending sensitivity reach for both channels. The mission proceeds toward launch following laboratory validation of the instrument. A launch opportunity has been secured through Firefly Aerospace's DREAM 2.0 program, awarded to the University of Illinois Urbana-Champaign (UIUC). This will constitute the first use of skipper-CCDs in space and evaluate their suitability for low-noise X-ray and single-photon detection in future space observatories.

astro-ph.IM↗

arXiv2024

CubeSat single-photon detector module for investigating in-orbit laser annealing to heal radiation damage

Single-photon avalanche photodiodes (SPADs) based on silicon are widely considered for quantum satellite communications but suffer from an increasing dark count rate (DCR) due to displacement damage in their active areas induced by proton radiation. When the DCR of SPADs exceeds a certain threshold, they become unusable for quantum communication protocols. Previous laboratory experiments have demonstrated that laser annealing of SPADs' active area with about 1~W optical power can significantly reduce radiation-induced DCR of synthetically irradiated SPADs. To assess the feasibility of in-orbit laser annealing on constantly irradiated SPADs in low-Earth orbit, we developed a module with a CubeSat form factor capable of both laser and thermal annealing of four silicon SPADs. Here we report the design and ground testing of this module, investigating laser annealing in a simulated space environment. Our results pave the way for an in-orbit trial that may prove this technology useful for future satellite missions with quantum receivers on board.

physics.ins-det↗

arXiv2024

DarkNESS: developing a skipper-CCD instrument to search for Dark Matter from Low Earth Orbit

The DarkNESS (Dark Matter Nano-satellite Equipped with Skipper Sensors) mission aims to deploy a skipper-CCD CubeSat Observatory to search for dark matter (DM) from Low Earth Orbit. This mission will employ novel skipper-CCDs to investigate O(keV) X-rays from decaying DM, as well as electron recoils from strongly-interacting sub-GeV DM. The DarkNESS mission will be the first space deployment of skipper-CCDs, and the DarkNESS team is developing a skipper-CCD instrument that is compatible with the CubeSat platform. DarkNESS has recently progressed from laboratory validation to a Critical Design Review (CDR) phase, with a launch opportunity anticipated in late 2025. The implementation of the DarkNESS skipper-CCD payload on the CubeSat platform will pave the way for future demonstrators of space-based imagers for X-ray and single-electron counting applications.

astro-ph.IM↗