The night is kind to radio. Free from the deadlock of rush-hour commercials, DJs can play with the format, delve into back catalogues, and mess around with B-sides. The night is also kind to radio listeners, especially those on the edge of service. When radio waves reach the ionosphere in the atmosphere, they can bounce down to earth, and on some nights where the ionosphere is dense with free electrons, that means radio signals can go farther.
The United States Air Force is interested in replicating this effect. While a more reliably dense ionosphere could help people trying to tune in a college radio station at the edge of its broadcast range, that's probably not the the Air Force's primary interest. Instead, an electron-rich ionosphere primarily means more range for the radios used by the military, and it might provide some protection for GPS signals against solar storms.
So how is the Air Force going to create that electron density? Tiny satellites, bombing the sky with plasma.
From New Scientist:
Now the USAF wants to do this more efficiently, with tiny cubesats, for example, carrying large volumes of ionised gas directly into the ionosphere. As well as increasing the range of radio signals, the USAF says it wants to smooth out the effects of solar winds, which can knock out GPS, and also investigate the possibility of blocking communication from enemy satellites.
There are at least two major challenges. One is building a plasma generator small enough to fit on a cubesat – roughly 10 centimetres cubed. Then there's the problem of controlling exactly how the plasma will disperse once it is released.
The project is in early stages, with three teams building different, cubesat-based approaches to this. The ultimate goal may be an on-demand fleet of cubesats that can strengthen the ionosphere when needed, but first the teams contracted by the Air Force has to prove the science works.
Then, and only then, can we begin bombing the ionosphere to save it.