At 09:04 AM 12/5/2006 +0000, Graham Shirville wrote:
Uum but if the moonbase is at the south pole then it wont even be line of site to the earth for >50% of the time.
Hence this idea of three satellites in elliptical lunar orbit
http://science.nasa.gov/headlines/y2006/30nov_highorbit.htm?list140623
Or maybe it would be cheaper/simpler just to have a nice big telescopic tower to see over the horizon or even some lunar repeaters on nearby hilltops which have been delivered and placed by unmanned rovers which would help with base to mobile comms on the lunar surface and have moon<-> earth comms capability as well.
Sounds like they really need some ham "experts" to work on these issues:)
cheers
Graham G3VZV
The article I read mentioned that the base was destined for a location "near: the southern pole which received 100% sunlight throughout the lunar month...but that doesnot imply 100% earthview (very astute observation by Graham). From that I would surmise that solar power is considered (plus it avoids the deep cold temps of lunar night).
All the discussion so far "assumes" a fixed pointed antenna pointed toward earth. I would suggest that with the kind of infrastructure a manned base implies, that a steared dish is reasonable. Thus it can be larger than 5 WL and just compensate for apparent earth movement (libration, etc.). In my private reply to Pat, I suggested that the digital signal (aka CC-rider ACP) might have a contant pilot carrier for locking a tracking system (and AFC as well). This would imply at least three command stations located on earth.
The over Moon-horizon issue is a good one. For NASA comms they may use orbiting relay sats like used for the Mars rovers. But it would be prudent to have direct comms, as well. So either the remote hill-top dish linked back to the Moon-Base as suggested...or just accept that direct comms is only available for part of the lunar month that earth is visible (not an acceptible choice for NASA but certainly one for hams). I think ham radio on the Lunar orbiting sats is a long shot...forget it.
In the artists rendition I viewed, it showed manned rovers. So, in time, there would be the means for setting up a remote Moon ham station. Justification would likely be the same as ARISS (emergency back-up + personal comms for Lunarnauts).
Hope I am arround to see this happen (c. 2020). 73's Ed - KL7UW ========================================= BP40iq, Nikiski, AK http://www.qsl.net/al7eb 50-144-222*-432-927-1296-2304*/2400-3456* -10368-24192* MHz *Under construction USA Rep. for Dubus Magazine: dubususa@hotmail.com =========================================