Very true! You don't need a datum unless you're measuring angles on the surface and elevations.
My point was more that the standard mapping tools allow non-Earth bodies just fine. E.g. here's a UTM-like projection for Mars using a simple ellipsoid in proj4: "+proj=tmerc +lat_0=0 +lon_0=0 +k=0.9996 +x_0=0 +y_0=0 +a=3396190 +b=3376200 +units=m +no_defs" You can happily define a simple sphere of the right general size and have things work correctly.
It's not overcomplicating the math to use existing libraries, it's avoiding rewriting a lot of fairly complex operations that are easy to get wrong.
You can use gdal, proj, org, et al quite well on other planets. It's a hell of a lot easier than writing everything from scratch. They're set up to do things like this.
Yes, I didn't mean to imply that the software wouldn't be useful. (Or for anyone to attempt to do all the math on their own.) Most people just don't realize you can define a generic coordinate system, and depending on the software, leave the projections/ datums blank (or set a generic/custom one), and still get good use out of many of the tools. (The danger is some tools that should only be used with projections might run error free without having one defined and return a meaningless answer.
Although admittedly I haven't kept up with the different capabilities for the last few years.
What method/format would even be used to generate points for an astroid? Radar? Lidar? Photogrammetry? From a "where do you start" perspective, knowing that would probably narrow down practical approaches...
My point was more that the standard mapping tools allow non-Earth bodies just fine. E.g. here's a UTM-like projection for Mars using a simple ellipsoid in proj4: "+proj=tmerc +lat_0=0 +lon_0=0 +k=0.9996 +x_0=0 +y_0=0 +a=3396190 +b=3376200 +units=m +no_defs" You can happily define a simple sphere of the right general size and have things work correctly.
It's not overcomplicating the math to use existing libraries, it's avoiding rewriting a lot of fairly complex operations that are easy to get wrong.
You can use gdal, proj, org, et al quite well on other planets. It's a hell of a lot easier than writing everything from scratch. They're set up to do things like this.