The ISS' new sensors will help to make radio waves travel better than ever

The Naval Research Laboratory intends to start testing a pair of ionospheric sensors on the International Space Station this spring. If the tests are successful, they could result in a constellation of monitoring satellites that would improve high-frequency radio communications for the Department of Defense (DoD).

In an interview with Breaking Defense, Andrew Nicholas, one of the project's primary researchers, said the "Experiment for Characterizing the Lower Ionosphere and Prediction of Sporadic-E" (ECLIPSE) Sensors are scheduled to launch to the ISS via the DoD Space Test Program in March.

According to Nicholas, the DoD needs to understand the ionosphere (53 miles (85 km) and 373 miles (600 km) above the Earth's surface) because it affects how radio waves travel or are reflected.

All three branches of the military—Navy, Army, and Air Force—use HF radio communications for long-distance communications. Still, over the past two decades, satellite communications have become increasingly important to them, particularly for the Navy's high-speed, high-data-rate communications with ships in the open ocean.

Since Russia and China have learned how to disable or destroy US satellites, worries are growing about how vulnerable they are. So, HF radio is getting a second chance as a backup in case military SATCOM channels go down during a war.

The two ECLIPSE instruments were based on the "Coordinated Ionospheric Reconstruction CubeSat Experiment" (CIRCE), a project by NRL and the UK Defense Science and Technology Laboratory. Two tiny CubeSats that were part of the CIRCE project each with various sensors to explore the ionosphere were destroyed in the Virgin Orbit launch attempt that failed on January 10 from Cornwall.

The "Triple Tiny Ionospheric Photometer" (Tri-TIP), a sensor made by NRL for the CIRCE satellites, was intended to measure radiation-induced "airglow" in the nocturnal atmosphere.

To measure the glow from nightside oxygen ions (O+), NRL developed a low size, weight, and power (10 x 10 x 10 cm, 890 g, 14 W) ionospheric remote sensing equipment with the help of the CIRCE development. Nicholas says that the Tri-TIP design was changed and used as a baseline configuration to track magnesium ions (Mg+).

Nicholas said that the Tri-MIP magnesium sensor was made possible by the Defense Advanced Research Projects Agency and the Office of Naval Research. Both will operate "in tandem" on board the International Space Station.

Also, according to Nicholas, the goal is to measure the number of particles in the ionosphere, which affects how radio waves travel through it.

If the experiment works, Nicholas added, the data can be used to improve ionospheric monitoring models. They could even lead to the creation of dedicated satellites to monitor changes in the ionosphere that could keep HF communications from working.