A plane is a 2D face. You need a terrain. You can make one with gigantic resolution 4096 which has ample detail to make really huge in the scene. You can make the preview in the TE larger so you can better place the craters.
The other option is tiling. Once you have found a terrain you like, place it. Do not resize it yet. Put camera from above. Copy (ctrl-c, ctrl-v) the terrain and place it north. Hold down the shift key and hit the up arrow 4 times.
Go back to the terrain editor (TE) and switch off Random Extent, Random Position and Random Character. If you hold down the Shift key while clicking on any one, all 3 get deselected. Now enable Tile North and click on Fractal. This creates a new terrain from the same random seed that tiles neatly north of the previous one. Exit the TE.
Copy the new terrain again and paste it north again, this is the third terrain. In the TE, just click on Fractal and the terrain changes so it tiles again.
It is important that you follow a line, otherwise the terrains won’t tile. To create a 3 x 3 terrain, go twice north, once east, twice south, once east, twice north. You can proceed west (left) instead of east (right).
Once you have your terrains, select them all and make them very slightly larger to make the gaps disappear. There are other methods to fill the gaps but this one works also. Then group the terrains and make the combined terrain as large as required. You can always access each individual terrain and put a crater in it. Just don’t go too far to any edge.
If you are very patient, you can create a large sphere and put the individual terrains on the surface. You’ll have to nudge each terrain so they make up a sphere, or part of it, without noticable gaps.
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