The Coupled Dark State Magnetometer (CDSM) aboard Macau Science Satellite #1 (MSS-1) is an optical scalar magnetometer, which is developed by the cooperation between Harbin Institute of Technology (Shenzhen) and Space Research Institute of the Austrian Academy of Sciences. This instrument consists of a sensor unit and a electronics unit. It can measure the magnetic field strength with the lowest absolute error of the instruments aboard MSS-1. Therefore, it serves as the reference instrument and ensures the instantaneous calibration of magnetic field detected by the two fluxgate magnetometers.

The CDSM is designed by a quantum effect named as coherent population trapping (CPT). The magnetic field measurement is based on the Zeeman effect. And CPT which could lead the rubidium atoms to a non-absorbing dark state, enables a more precise measurement of the magnetic field. CDSM measurements don’t depend on the sensor temperature, which make it an excellent performance during the in-orbit magnetic field detection.