The ferry was a sausage-shaped structure of thin metal and plastic with an airlock at the front and a small reaction motor at the rear. It had been modified to hold either solid or liquid cargo and to operate off the monopropellant fuel instead of the lox and kerosene used when the station was built. There was even a plastic pipe between the cargo tank and its fuel tank to save separate filling, and no further modification was needed.
Blane took it out after checking the stowage of the mercury cans. He was slightly rusty, but he steadied down as he jockeyed into position beside one of the three lunar ships. He'd picked a balloon on the sunward side, and the warm fuel was soon flowing into his tank, forced through a long tube by a tiny, built-in pump. When he took off again, the ferry was overloaded and sluggish, but it showed no evidence of weakness. Of course, if they ran into a meteoroid of any size, they'd be ruined—but the chances of that were very slight.
Peal was already outside the hub, dressed in space suit and clinging to a convenient handhold. He came through the lock, carrying his computations, a small telescope, and an extra spacesuit for Blane. "May need this," he suggested. "Our front end probably won't fit the seal on their hub."
Blane nodded. He should have thought of it. But his chief interest was in the orbit. It had been figured so that they would accelerate away from the station and up from Earth at low thrust, well within the limits of his power. There was a table of times and star angles to locate his correct course. Peal had done an excellent job, far better than Blane had expected.
"I spent two years on the Island," the scientist explained. "I learned a little about astrogation, though I'm no navigator. But this is a simple problem."
Essentially, it was; to make it simpler, it was always possible to make minor corrections, since they had more than enough fuel.
"If the stations were run properly, there'd be a regular service between them," Peal suggested when they were coasting along in their orbit. "It would be cheaper to exchange supplies than to rush up a sudden emergency shipment from Earth. In fact, if a private company had built the first one, there would probably be a dozen stations by now, all connected. And we'd take over the television relay business, too."