The point others are making, is that Columbia as the first space-going shuttle was not built to support a docking mechanism. The later shuttles were designed with docking in mind. Columbia could not be retrofitted without exorbitant costs.
The original designs for space shuttles were for a lighter smaller craft to achieve high orbit and docking with space stations, but the NASA engineers were over-ruled by military dictates for a larger shuttle to put big payloads into low Earth orbit (recon-satellites etc.). As built, it was too heavy to go beyond a few hundred miles up, and wasn't designed to dock.
They won't be using the shuttle for that much longer. Big satellites need big rockets, and the shuttle is about the biggest. The other big one is the Titan IV. A BDB based on shuttle hardware could be flying very quickly if they take that route.
The original designs for space shuttles were for a lighter smaller craft to achieve high orbit and docking with space stations
Wouldn't be surprising to see that idea implemented in the near future.