Warfighters depend on high-frequency (HF) radio transmissions to operate military systems across the space, air, ground, and maritime domains. Current understanding of how HF waves propagate through the electromagnetically noisy ionosphere typically depends on ground-based methods. To more accurately understand HF propagation in space requires scientific measurements taken from within the ionosphere itself.
DARPA’s new Ouija program aims to use sensors on low-orbiting satellites to provide new insights into HF radio wave propagation in the ionosphere, which spans the upper edges of the Earth’s atmosphere to the lower regions of space. The program seeks to quantify the space HF noise environment and improve characterization of the ionosphere to support warfighter capabilities.
“Ouija will augment ground-based measurements with in-situ measurements from space, in very low- Earth orbit (VLEO), to develop and validate accurate, near real-time HF propagation predictions,” said Jeff Rogers, Ouija Program Manager in DARPA’s Strategic Technology Office. “The VLEO altitude regime, approximately 200 km – 300 km above Earth, is of particular interest due to its information-rich environment where ionospheric electron density is at a maximum. Fine-grained knowledge of the spatial-temporal characteristics of electron density at these altitudes is required for accurate HF propagation prediction.”