These great hollow globes of artificial super-metals, and artificial transparent adamant, ranged in size from the earliest and smallest structures, which were no bigger than a very small asteroid, to spheres considerably larger than the Earth. (Olaf Stapledon, STAR MAKER)
Sunday, June 17, 2018
The concept of an orbital tugboat and/or taxi has been around for a long time. Here's a diagram showing one recent concept (the claim is that it would significantly cut orbital transfer costs).