MEMS Microgravity Measurement Module with Nano-g/Hz Noise Floor for Spaceborne Higher-Level Microgravity Scientific Experiment Applications

Most spaceborne scientific experiment applications require a microgravity environment. The current high-precision accelerometers used for the spaceborne vibration isolation system generally have a noise floor of sub-μg/√Hz, which cannot meet the demand of higher-level microgravity measurements. This article introduces a micro-electromechanical system (MEMS) acceleration sensor that has a noise floor of 2–5 ng/√Hz and an input range of more than ±2 mg. Its three-component version, the MEMS microgravity measurement module (MEMS-M3), is designed to measure accelerations in the space microgravity environment and might be used in the active vibration isolation system for higher-level microgravity scientific experiments in the future. The MEMS-M3 has a volume of 105 × 90 × 115 mm3, a weight of 1.2 kg, and power consumption of 3 W. The performance of the MEMS-M3 has been characterized on the ground and a series of preflight reliability experiments have been conducted. Then, the MEMS-M3 installed inside the test spacecraft has been carried by the Long March 5B rocket (CZ-5B) to the low Earth orbit at 10:00 on May 5, 2020, and returned to Earth ground at 5:00 on May 8, 2020, both in UTC time. During the on-orbit period, the MEMS-M3 has been switched on for 11 h. After data processing, the transient, periodic, and steady accelerations can be observed by the MEMS-M3 and a much noisier shelf product IMU STIM300, verifying the functionality of the MEMS-M3. Apart from application in active vibration isolation systems for spaceborne scientific experiments, it can also be used for drag-free control of satellites and other space applications.