Why do you need 128-bit floats for storing solar system coordinates? 64-bit floats will give you millimeter precision on Pluto, if your coordinate system has an origin in the sun.
https://www.jpl.nasa.gov/edu/news/2016/3/16/how-many-decimal...
* JPL's highest accuracy calculations, which are for interplanetary navigation, we use 3.141592653589793.
* How many digits of pi would we need to calculate the circumference of a circle with a radius of 46 billion light years to an accuracy equal to the diameter of a hydrogen atom (the simplest atom)? The answer is that you would need 39 or 40 decimal places.
By 1596 Ludolph van Ceulen had 20 digits, and even more by the time he designed his tombstone: https://upload.wikimedia.org/wikipedia/commons/e/e8/Monument...
39 or 40 decimal places would have to wait until 1699.
https://en.wikipedia.org/wiki/Chronology_of_computation_of_π
If you are using a 64-bit float, then you have 53 bits of precision in 1D, 53 bits of precision in 2D, and 53 bits of precision in 3D. The precision doesn’t change as you add or remove dimensions.