At that point, the other major source for the campaign, the GURPS Transhuman Space series of sourcebooks, comes into play. That provides me with quite detailed background for the game, most of it not specific to scenarios.
Copper wire is a commonplace industrial material, and when they were faced with the problem of ships with different performance, the characters were at a naval base in Earth orbit. So if they needed ordinary cabling, for a purpose in accordance with the mission the Navy had given them, the base would be willing and able to supply it. If it was very unusual cable, getting it would take longer, because the Navy would have to get it manufactured, but provided the PCs had a sensible reason for needing it, they'd get it. Their successes over the course of the campaign have made the Navy look good, so it is quite helpful to them.