> Yes. See
> Lunar Orbital Evolution: A Synthesis of Recent Results
> The paper cites
> other papers for the rate of change of the lunar
> orbit, that rate of change is based on the
> measurements from the retroreflectors (which are
> not directly cited in this paper, but are cited in
> the papers cited).
Thanks! I'll take a look.
Edited later to add:
I’ve read your link, and as you say, it doesn’t mention the retroreflectors, which are merely the means to measure the moon’s distance.
The paper deals with how the rate of recession has speeded up due to tidal friction caused by changes in the geographical location of the continental masses (plate tectonic movement). In the far distant past, when landmasses were different shapes and in different locations, tidal friction was less, hence the rate of recession was slower too.
The distance between earth and moon, given by the history of readings from the reflectors, if extrapolated backwards without taking the changes due to landmasses influencing tidal friction, would give us an impossibly close orbit of the moon – one almost touching the earth’s surface!
As an aside on the retroreflectors, I was reading yesterday about the precision of the readings, a precision “equivalent in accuracy to determining the distance between Los Angeles and New York to 0.25 mm (0.0098 in)”, according to Wiki. That’s some accuracy!
It also mentions the fact that the reflectors are degrading with age. Hopefully, it won’t be another fifty years before astronauts return to replace them with superior modern technology!
Edited 1 time(s). Last edit at 08-Mar-18 19:11 by carolb.