Design and Characterization of the Engineering Model of the Spectrometer Onboard LuSEE‐Night.

The Lunar Surface Electromagnetics Explorer—Night, LuSEE‐Night, is a low‐frequency radio astronomy experiment that will explore the cosmic Dark Ages signal on the radio‐quiet farside of the Moon. The LuSEE‐Night carries a radio frequency spectrometer consisting of a set of antennas, analog and digital processing electronics, and will be launched by NASA's Commercial Lunar Payload Services in 2025. The spectrometer is designed to observe the spectrum of the radio sky in the 0.5−50 MHz band. The engineering model (EM) of the four‐channel spectrometer has been developed. The EM has been characterized for linearity, gain, noise, and their temperature dependence, confirming that the EM meets all the requirements for LuSEE‐Night. Three mitigation techniques have been implemented and verified to suppress self‐induced electromagnetic interference. The flight model of the spectrometer is currently being developed and is scheduled to be shipped to the integration site in early 2024. Plain Language Summary: LuSEE‐Night is a four‐channel radio spectrometer scheduled for delivery to the lunar farside in 2025. The 0.5−50 MHz instrument is a pathfinder intended to explore the feasibility of searching the 21 cm global spectrum from the Dark Ages epoch of the early Universe. The engineering model of the LuSEE‐Night spectrometer was evaluated for gain, bandwidth, and noise and confirmed to meet the mission requirements. Its temperature dependence was measured and found to be within the requirements. Three mitigation techniques have been implemented to suppress electromagnetic interference; all switching waveforms must be limited to multiples of the system frequency of 100 kHz, the differential sensing of the input signals in the analog signal chain, and the notch filter of the field‐programmable gate array spectral engine. These techniques can be verified to effectively remove the artificial switching noise. The flight model of the spectrometer is being developed. Key Points: The engineering model of the spectrometer developed for the LuSEE‐Night mission meets all mission requirementsThree mitigation techniques have been successfully implemented to suppress electromagnetic interferenceThe flight model is currently being developed and will be delivered to the integration site in early 2024 [ABSTRACT FROM AUTHOR]