Adapting laser heterodyne radiometry for space-based greenhouse gas monitoring

Laser Heterodyne Radiometry (LHR) is a spectroscopy technique known for its high spectral resolution and strong radiometric sensitivity, making it a promising tool for monitoring atmospheric composition. However, conventional LHR instruments require minutes of signal acquisition, limiting their applicability for space-based Earth observation, where rapid measurements are essential. This work presents advancements in LHR technology that reduce acquisition time to the millisecond scale, enabling a nadir-facing orbital configuration and expanding its potential for greenhouse gas (GHG) monitoring.

This adaptation enables detection of gases that are otherwise challenging to measure remotely, such as nitrous oxide (N20) at low atmospheric concentrations and methane isotopologues like 13CH4 that can be used for source fingerprinting and attribution. Both gases are critical to emissions attribution, climate modelling, and regulatory frameworks.
To demonstrate these capabilities, a prototype LHR system has been developed and tested. The results demonstrate a substantial reduction in signal acquisition time. The system's ability to collect high spectral resolution data rapidly supports its integration into future spaceborne and airborne platforms for atmospheric monitoring.

This development represents an important step in expanding the capabilities of remote sensing for greenhouse gas monitoring. By addressing the limitations of conventional LHR, this work opens new opportunities for high-precision, space-based measurements that support climate science, policy, and emissions accountability.