AMARETTO - Optically pumped Magnetometers for Earth Observation

The AMARETTO study set out to evaluate the feasibility of a self calibrating vector alkali vapor magnetometer for Earth Observation, focusing on the integration of scalar and vector techniques. The work involved defining instrument level requirements for Earth Observation missions, assessing calibration strategies and analysing how deadtime affects data quality. It also included developing a high level sensor design that meets size, weight, and power constraints, and establishing a technology development plan suitable for space qualification.

The study used a combined approach of requirement analysis, sensor operation modelling, and high level hardware design to evaluate the performance, feasibility, and risks of the proposed concept. The work was informed by a review of current technologies and Earth Observation mission scenarios. It included modelling the effects of calibration deadtime, analysing field homogeneity and bias error contributions, and designing a concept based on a custom rubidium based MEMS vapor cell with a single laser source and three axis coils. Computer aided design provided estimates for mass, volume, and power consumption.The concept relies on dual scalar and vector functionality, using free induction decay for scalar measurements and zero field nulling for vector measurements within the same vapor cell. Both continuous and interleaved calibration strategies were examined to assess long term performance.The analysis showed that a calibration deadtime of 100 milliseconds introduced errors below 0.2 nanotesla. The estimated size was 0.24 liters, the mass 120 grams, and the power consumption 1.75 watts. The high level validation confirmed the feasibility of the concept, although further work is required to address space compatibility and optimize calibration.