Tuesday, August 13, 2019

LO-94 Lunar-Orbiting Satellite Crashes Into Moon, But Not Before "Photographing" HF Radio Spectrum

Space.com and amateur radio science/technology blogger Daniel Estévez, EA4GPZ/M0HXM, are reporting that the lunar-orbiting LO-94 satellite has been intentionally crashed into the far side of the moon by its controllers. The reports indicate that the crash was long-planned as the satellite had completed its primary mission and exceeded its life expectancy, and controllers did not want to leave it in orbit as space debris.

The satellite, built by China's Harbin Institute of Technology, achieved many firsts. It was the first lunar-orbiting amateur satellite; amateurs on Earth were able to command it to shoot and send back photos from the dark side of the Moon; it recorded a total solar eclipse back on Earth and served as the platform for the first-ever repeater QSO made from lunar orbit (see July 9, 2019 CQ Newsroom post).

One of LO-94's final accomplishments, reported on the HamSci reflector, was to take a spectral "photograph" of RF energy emanating from Earth on the MF/HF spectrum. The graph published by Chinese media showed peaks just below the AM broadcast band and at roughly 9, 12 and 17 MHz. Propagation expert Carl Luetzelschwab, K9LA, added notations to the chart for the HF amateur and shortwave broadcast bands, plus WWV/WWVH, showing that most of the peaks match up with the major shortwave broadcast bands. It was noted by one member of the HamSci group that it would have been interesting to see what the graph looked like if the readings were made during a major DX contest weekend. Carl's chart is posted below.
Graph of RF energy emitted from Earth between 1 and 30 MHz, as measured by the LO-94 satellite from lunar
orbit, with notations of amateur radio and shortwave broadcast bands, as well as WWV/WWVH frequencies
added by Carl Luetzelschwab, K9LA. (Tnx HamSci reflector)