Flight results of Redundant MEMS IMU (MARIN) on satellite and launch vehicle

Abstract

Along with the improved accuracy of MEMS gyroscopes and accelerometers in recent years, JAXA has been studying a navigation-grade Inertial Measurement Unit (IMU) using MEMS gyroscopes and accelerometers for spacecraft and for launch vehicles. Since spacecraft and launch vehicles fly in a special environment that entails high vibration, a wide temperature range, and a severe radiation environment, the IMU for spacecraft and launch vehicles needs to be resistant to such a severe environment and must maintain highly accurate inertial measurements. The technical issues for a spacecraft and launch vehicle’s IMU are as follows: (1) Highly accurate inertial measurements for navigation and guidance (2) Maintaining accuracy for a wide temperature range (3) Maintaining accuracy for a high vibration environment (4) Ensuring normal operation in a severe radiation environment To evaluate accuracy and environmental resistance of high aciculate MEMS gyroscopes and accelerometers in the IMU configuration for spacecraft and launch vehicles, we developed a redundant MEMS IMU whose name is MARIN (MEMS Advanced Redundant Inertial Navigation system). Main characteristics of MARIN are as follows. (1)Using high accuracy MEMS gyroscopes and MEMS accelerometers for non-space applications (2)Two redundant IMU units configuration with mutual data transfer (3)Two redundant MPUs in each IMU unit with mutual monitoring of MPU calculation (4) One fault operative system as IMU (5) Low cost IMU using commercial electrical parts with radiation mitigation techniques include redundant electronic circuits, redundant modules and current monitoring The specifications of MARIN are as follows. Weight: 1.24 +0.06/-0.09 (kg) Size: 152(W)mm × 105(L)mm × 80(H)mm Power ConsumptionLess than 5W Angle Increment Measurement: Range: 400deg/s Gyro Bias Instability: less than 0.2deg/h(Max) Velocity Increment MeasurementRange: ±30G Acceleration Bias Instability: less than: 0.09 mg(Max) To evaluate MARIN’s functions and performances on severe spacecraft and launch vehicles, we did qualification tests of MARIN both for satellite and launch vehicle on ground and MARIN passed all items of the qualification tests. We did the on-orbit flight experience of MARIN by “Rapid Innovative payload demonstration SatellitE-2” (RAISE-2) which was launched on November 22, 2021. The MARIN installed on RAISE-2 has been worked normally on-orbit more than one year. We also did the flight experience during launch phase by Epsilon rocket F6 launched on October 12, 2022. The MARIN installed on the second stage of Epsilon rocket F6 worked normally and performed inertial measurements within the required accuracy during the launch. Another MARIN will be tested on H3 rocket first flight, H3TF#1, which will be launched in February 2023. After these flight tests of MARIN, MARIN will be used on Japanese flagship rockets, H3 rocket and Epsilon S rocket. This paper shows the issues of the MEMS IMU for spacecraft and launch vehicles and specifications and design of MARIN first. Then this paper presents the on-orbit flight experience results of MARIN on RAISE-2 and the flight experience results during launch phase by Epsilon rocket F6.