Satellite observations indicate a correlation between anomalies observed in the ionosphere and stratosphere and the occurrence of earthquakes. These anomalies include changes in electric and magnetic field components, variations in electron density, ions, ionic compositions, and their temperatures in the ionosphere, as well as changes in stratospheric temperature. This article investigates these space-based precursors and the payloads used to measure these anomalies. For each payload, its components, operation method, mass, power budget, and installation considerations are described. Additionally, analysis results of several earthquakes in Iran and recent global earthquakes using data from these payloads have been examined.
The study of these payloads shows that the electric field detector instrument in the ULF range is one of the best for earthquake precursor detection. A double standard deviation index was considered for identifying anomalies in several earthquakes in Iran, and ULF signal amplification was observed during satellite passage over the earthquake epicenters for earthquakes larger than 5.8. Several earthquakes in Iran were also analyzed using data from the TIMED satellite's 10-channel radiometer payload, with a 1.5 standard deviation index considered for identifying anomalies. Examination of average and maximum temperatures over a one-month period showed that anomalies were observable one week before the earthquake occurrence, and for strong earthquakes above magnitude 7, a clear anomaly effect in this parameter was observed 14 to 16 days before the earthquake.
Finally, after various assessments, the electric field detector payload in the ULF range, the search coil magnetometer, the tri-band beacon, and the 10-channel radiometer payload measuring stratospheric temperature were introduced as suitable payloads for earthquake precursor detection in Iran. A native platform was considered, and its subsystems were introduced. Given the mass budget, power, and stabilization and attitude control system of this native satellite, the tri-band beacon was proposed as the final payload for this platform, and its specifications were stated. It is worth noting that the electric field detector payload requires four booms longer than four meters, making it impossible to use on a platform using a gravity gradient boom for stabilization. The search coil magnetometer also requires one boom. In the native platform, due to the gravity gradient boom, using the search coil magnetometer was not possible unless used as a boom tip mass, which is feasible in composite booms but not applicable to this platform. The 10-channel radiometer also required high power and mass, which was not possible given the native platform requirements. Therefore, the tri-band beacon was ultimately specified as the satellite's final payload. This payload transmits three in-phase signals in VHF, UHF, and L-band. These signals undergo Faraday rotation and group delay while passing through the ionosphere. On Earth, these signals are received by a chain of receivers, their phase differences are processed, and based on that, a vertical profile or two-dimensional image of ionospheric electron density can be extracted. The use of the satellite’s store and forward capacity for transferring data from new ground-based seismological stations was also proposed.