International Geomagnetic Reference Field (IGRF)
Earth has its own magnet which is about tilted by about 11 degrees from the axis passing through the north and south poles. It is made of molten metals and it is changing continuously but slowly that’s why IGRF model is updated in every five years. IGRF model is created by International Association of Geomagnetism and Aeronomy (IAGA using satellites and some observatories. The cool fact about the Earth’s magnetic field is that because of it, we are alive. Yeah! This shield blocks the dangerous cosmic radiation (energetic protons) coming from the Sun. HOW?
The IGRF model provides magnetic field vector in NED (North East Down) frame at any given latitude, longitude and altitude.
Position of the satellite can be taken from the propagator model and fed into the IGRF model (appropriate conversion is required from ECI to NED frame) and the IGRF model will give magnetic field vector. Magnetic field vector is important for magnetometer sensor and magneto-torquer actuator.
Other than IGRF, there are some other models such as World Magnetic Model (WMM).[1] The difference between WMM and IGRF[2] is that WMM is valid for less number of years but more accurate as it is produced by dedicated agencies like NCEI and BGS for US and UK defense purposes.
If you are done reading this page, you can go back to Attitude Determination and Control Subsystem.
