AMPERE: Active Magnetosphere and Planetary Electrodynamics Response Experiment

Johns Hopkins University, Baltimore MD

Investigators

Abstract

This is a five year project led by the John Hopkins University Applied Physics Laboratory (JHU APL) to establish a facility to provide a global measurement of the field-aligned Birkeland electric currents that flow between the Earth?s magnetosphere and ionosphere. Field aligned currents are a fundamental aspect of the coupling between the magnetosphere and ionosphere but our current ability to measure these is severely limited by lack of adequate data coverage. This proposal will remedy this situation in a spectacular and highly efficient fashion. It will provide the first ever global, continuous observations of the Birkeland currents over both the northern and southern Polar Regions with sufficient time resolution Global coverage is provided by utilizing the existing Iridium constellation of more than 70 satellites in low altitude (780 km), polar (86 degree inclination) orbits evenly distributed among six equally spaced orbit planes. This commercial satellite network is operated to provide global communication services. It is owned by Iridium Satellite LLC (ISLLC) and is operated by Boeing Service Company (BSC) out of their Satellite Network Operations Center in Leesburg, VA. As part of their attitude control system the satellites all carry vector magnetometers that provide on-board magnetic field measurements of ~30nT accuracy at below second cadence. Currently, however, the magnetic field data are sub-sampled and bundled in a large engineering data packet for transmission to the ground only once every 200 seconds on average. This corresponds to latitude spacing between measurements of ~12 degrees and as a result data have to be collected for ~2hours to obtain global maps of field-aligned current estimates at ~1degree latitude resolution. This project will perform an upgrade to the Iridium satellites flight software and ground data systems that will send 10 to 100 times more magnetometer data to the ground to yield continuous, near real-time measurements of the global Birkeland currents with a latitude resolution of ~0.12 to ~1.2 degrees and a re-visit interval of just 9 minutes. In addition to the flight software modifications and development of an additional AMPERE satellite operations ground system that will be carried out in collaboration with BSC and ISLLC, an AMPERE science data center will be established at JHU APL for routine data processing, science product generation, providing community data services, and offering real-time monitoring. The new observational data set will enable investigation of a large number of important outstanding science questions and, thus, will transform the field of magnetosphere-ionosphere system science. The new facility will serve a wide section of the space physics community and will enable and enhance a wide range of space physics research project, both observational and theoretical. In addition, the project has broader societal benefit in that it provides a valuable observational asset for space weather monitoring and forecasting as well as for space weather model validation and data assimilation. The project exploits and expands a unique partnership between scientists and commercial satellite operators that is certain to inspire and open the door for similar initiatives in the future.