Comment by westurner
> optical frequency comb
"113 km absolute ranging with nanometer precision" (2024) https://arxiv.org/abs/2412.05542 :
> two-way dual-comb ranging (TWDCR) approach
> The advanced long-distance ranging technology is expected to have immediate implications for space research initiatives, such as the space telescope array and the satellite gravimetry
Note that the precision is very good, however the accuracy is nowhere near as close (fractions of a metre) in the atmosphere, due to the variable refractive index of air. Long term averages can help, of course.