US standards body proposes atomic clocks in lunar orbit to keep Moon time Researchers at the US National Institute of Standards and Technology (NIST) have come up with a proposal for keeping track of time on the Moon – an essential for lunar navigation tools. While the Apollo-era astronauts rarely ventured far from their Lunar Module during the precious few days they spent on the lunar surface, NASA …
There are going to be some interesting decisions to be made on orbits of any LPS (I vote for LPS) system as there are no radiation belts or atmosphere which gives more choices but the moon has a messy mass distribution which means that more stationkeeping tweaks are going to be required as the orbit gets lower and magnetorquers wont work so there will be a increased fuel burn to maintain orientation. I suspect the answer would be proportionally higher orbits where each one can be seen from more of the moons surface. This is good for reducing the number of satellites and improving orbital stability plus do you really need a 20 satellite fix on the moon? Being between skyscrapers is wont be a issue for a while.
some type of LPS would help with landings for sure. Everyone (nations and corps) seem to be having issues with P+N... getting accurate 't' would help with PNT issues like not being sure how fast you're moving/navigating along the surface and where exactly your pre-mapped landing position is and getting your correction burns in on Time. (PNT!)
I don’t think GPS time does leap seconds?
They may not need to worry about days, and also I think the lunar month is actually shorter than the lunar day?
As in sunrise to sunset to sunrise is about 1 earth month, and the position cycle of earth in the lunar sky from full earth to new earth to full earth is about 1 earth day.
GPS doesn't use leap seconds. I think it may keep a running tally of the offset from UTC, but this isn't used for any of the position calculations.
The moon raises tides in the earth's oceans. This has the dual effect of slowing down the earth's rotation and moving the moon further from the earth. You could argue that they are the same effect.
So the moon's orbit around the earth is getting bigger and taking longer.
The moon is tidally locked to the earth, so, if one orbit around the earth is taking longer, its equivalent of a sidereal day (actually about a month in earth terms) is getting longer.
So they will need leap seconds, even if LPS doesn't use them.
Once the earth is tidally locked to the moon we can stop all of this silly leap seconds nonsense.
The Moon is tidally locked to the Earth. Does this mean that a clock on the surface of the Moon closest to the Earth would keep ever so slightly different time to a clock on the surface furthest from the Earth, and if so, do we have atomic clocks accurate enough to measure the difference? el Reg's Boffins please advise.
The Moon is tidally locked to the Earth. Does this mean that a clock on the surface of the Moon closest to the Earth would keep ever so slightly different time to a clock on the surface furthest from the Earth, and if so, do we have atomic clocks accurate enough to measure the difference? el Reg's Boffins please advise.
While not the full bottle on relativity (a pretty empty one I suspect) I would note that the moon is in free fall in its orbit around the earth (equivalently the earth around the moon.)
To my mind that means the moon is in an inertial frame with respect to earth's gravity so leaving tidal forces arising from the differences between two points of how space-time is bent by the masses involved.
So my take is that the clocks shouldn't vary from the variation of the proximity of earth to the moon.
Brings to mind Arthur Dent's regret that he wished he had paid greater attention in one of his school classes and when asked by Ford Prefect what he had missed - Arthur responded that he didn't know because he hadn't paid attention - similarly I feel I ought to have paid more attention in Physics classes. ;)
First there would need to be a luna-wide need for time coordination. For landings, a radio beacon or even RADAR targets would be more than sufficient. Setting up a GPS network of sats around the moon is the sort of brute force way of doing what's needed. In other words, how I usually go about designing something the first time around. Yes, I'm sure there are dreams of having a mining station near the south pole, a scientific station around the equator and field teams roaming about in rovers, but there's so much to do and almost no funding to do any one thing beyond flags/footprints, again.
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