On Thursday, August 11, 2022, 01:16:02 PM EDT, Tarsala, Jan A (US 337C) via AMSAT-BB amsat-bb@amsat.org wrote:

You may want to examine NASA’s SunRISE project, led by Jim, W6RMK. We are temperature testing the first three instruments today, with delivery to spacecraft integration within the month.

Very interesting... But I am also curious about the extent to which terrestrial HF signals can be heard well outside the bounds of the ionosphere. My guess is that if much of the long-distance terrestrial propagation we experience on HF is due to ionospheric absorption and re-radiation (i.e. setting ions in motion at an RF rate), then it might be much more transparent than we have been led to believe.

I seem to recall a story about a Chinese satellite that traveled to the vicinity of the Moon and carried with it an HF receiver. A spectrum plot made by the satellite showed it was filled with HF signals originating from the Earth.

73 de John, KD2BD