Sally said: “Dear me! You must read the newspapers!”
“The odds figure out, the odds are even that the Platform won’t get an actual meteor puncture in the first twenty thousand years it’s floating round the Earth.”
“Twenty thousand two seventy, Joe,” said Sally. She was trying to tease him, but her face showed a little of the strain. “I read the magazine articles too. In fact I sometimes show the tame article writers around, when they’re cleared to see the Platform.”
Joe winced a little. Then he grinned wryly.
“That cuts me down to size, eh?”
She smiled at him. But they both felt queer. They went on into the interior of the huge space ship.
“Lots of space,” said Joe. “This could’ve been smaller.”
“It’ll be nine-tenths empty when it goes up,” said Sally. “But you know about that, don’t you?”
Joe did know. The reasons for the streamlining of rockets to be fired from the ground didn’t apply to the Platform. Not with the same urgency, anyhow. Rockets had to burn their fuel fast to get up out of the dense air near the ground. They had to be streamlined to pierce the thick, resisting part of the atmosphere. The Platform didn’t. It wouldn’t climb by itself. It would be carried necessarily at slow speed up to the point where jet motors were most efficient, and then it would be carried higher until they ceased to be efficient. Only when it was up where air resistance was a very small fraction of ground-level drag would its own rockets fire. It wouldn’t gain much by being shaped to cut thin air, and it would lose a lot. For one thing, the launching process planned for the Platform allowed it to be built complete so far as its hull was concerned. Once it got out into its orbit there would be no more worries. There wouldn’t be any gamble on the practicability of assembling a great structure in a weightless “world.”
The two of them—and the way they both felt, it seemed natural for Joe to be helping Sally very carefully through the corridors of the Platform—the two of them came to the engine room. This wasn’t the place where the drive of the Platform was centered. It was where the service motors and the air-circulation system and the fluid pumps were powered. Off the engine room the main gyros were already installed. They waited only for the pilot gyros to control them as a steering engine controls an Earth ship’s rudder. Joe looked very thoughtfully at the gyro assembly. That was familiar, from the working drawings. But he let Sally guide him on without trying to stop and look closely.