Southgate News reports on an AMSAT and ARISS initiative to get amateur involvement in the next NASA visits to the moon. They calculate path losses will be about 30dB higher than low earth orbit stations.
See http://southgatearc.org/news/2019/august/amsat-and-ariss-designing-amateur-radio-system-for-lunar-gateway.htm
4 Aug 2019
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2 comments:
Interesting development.
Is 30dB path loss considered to be a huge challenge? Certainly, you couldn't use an HT and you'd need a dish. But the Moon moves across the sky very slowly (relative to those here on Earth), and a dish wouldn't need to be moved during the course of a QSO. Along with that, Doppler shift shouldn't be an issue, as with LEO sats. Unlike EME, a signal isn't being *reflected* off the Moon -- it's a one-way trip.
The article doesn't describe the details of the proposal (FM, SSB, digital modes, bands, or how much TX power). Hopefully, it won't be microwave.
The deeper issue is that this station will be in orbit around the Moon, meaning that the Moon will block access to the station for long periods. And the Moon isn't always visible in the sky. But when the Moon is up and the station is on the Earth side, nearly hemisphere-wide communication should be possible.
A Chinese HF (15/10M) satellite will be going up in late autumn. Things are changing rapidly, creating new options for amateur operation independent of the solar cycle. It remains to be seen if the amateur community is adaptable enough to embrace these new options, or if it is truly hidebound and immovably planted in the 1950's.
Interesting.
Todd: If the station is orbiting the Moon, there will be considerable Doppler shifts involved. Some years ago I was listening to the carrier of the Lunar Reconnaissance Orbiter on 2.2GHz, and the Doppler shift was probably around 10kHz or more.
Actually, I would expect this to be a microwave set-up, because there it is possible to work with lower power and higher antenna gain. Just look at what people use for EME: On 2m CW, 4 yagis and 1kW is a common, on 10GHz people use 30 - 50W and a dish of 2 - 2.5m
I expect the path loss to be considerably less than via EME.
I would not be surprised if the band used will be 2.4GHz, possibly 10GHz.
In any case, getting on 2.4GHz is now not too difficult, and I have the intention to do so, also for the QO100 geostationary transponder.
It looks like an interesting experiment.
Vy 73 de OZ9QV, Jan
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