Elastic Particle Swarm Optimization for MarSCoDe Spectral Calibration on Tianwen-1 Mars Rover

Area of Science:

• Planetary Science
• Spectroscopy
• Robotics Engineering

Background:

• China's Tianwen-1 Mars rover utilizes the MarSCoDe laser-induced breakdown spectroscopy (LIBS) instrument for mineral and rock analysis.
• MarSCoDe faces extreme temperature variations (approx. 100 °C range) on Mars, causing significant spectral shifts and calibration line inconsistencies.

Purpose of the Study:

• To develop and validate an on-board spectral calibration method for MarSCoDe capable of handling harsh Martian environmental conditions.
• To address spectral shifts and spectral line number mismatches caused by temperature fluctuations and environmental changes.

Main Methods:

• An elastic particle swarm optimization (PSO) algorithm was employed for spectral calibration.
• A standard wavelength set (SWS) and particle wavelength sets (PWS) were established, with elastic selection from PWS for comparison with SWS.
• Testing was conducted using standard lamps and a Titanium (Ti) target within a Mars simulation environment chamber (MSEC) across a 70 °C temperature range.

Main Results:

• The PSO approach effectively corrected spectral shifts, reducing them to within 0.015 nm.
• A specific spectral line shift of 8.09 nm was corrected to approximately 0 nm.
• The method successfully addressed both spectral shift and spectral line number mismatch issues.

Conclusions:

• The elastic PSO-based approach provides robust on-board spectral calibration for MarSCoDe under challenging Martian conditions.
• This method enhances the accuracy of mineral and rock composition analysis by the rover.
• The technique is adaptable for calibrating other spectral payloads in deep space exploration missions.