Dana floated down to the Inertial Measuring Unit. The guidance device was a metal sphere the size of a beach ball. Inside the casing a platform was maintained in position by three nested spheres. The whole thing was like a table on a boat, gimbaled to remain level regardless of the boat’s heeling. The system was the spacecraft’s way of being able to sense where it was relative to a reference trajectory.

Checking the alignment was a routine chore; it was a checklist item on every flight. But there was a big fear that the pogoing and wild gyrations Apollo-N had suffered during the launch might have thrown the platform out of line.

To align the platform Dana had to take sightings on various stars through a small optical telescope and sextant. The idea was to pick a couple of stars from a standard list, then tell the spacecraft to find them. If the star wasn’t exactly centered in the crosshairs of the telescope, Dana would make an adjustment to correct it, and the computer would enter the adjustment into the platform, which would then reset itself.

He selected the constellation of Orion, with its distinctive three-star belt across the middle. He shielded his eyes more carefully from the glare of the Earth and the cabin lights, and he pointed the ’scope where he knew Orion ought to be. At last he made out the three faint dots, and bright Sirius nearby, right where they were supposed to be…

He grinned. The alignment was fine. Maybe the worst was over, and the rest of the flight was going to work out.

After all, the first objective of the flight test had already been achieved: to prove that the S-NB could loft itself, and a crewed spacecraft, into orbit. From here on out the mission was to show that NERVA could safely be restarted several times. During the week-long flight Apollo-N would be sent on thin, elliptical orbits, looping a hundred thousand miles into space — halfway to the Moon.

There would be plenty of science to do, with an extreme ultraviolet telescope, helium observations, high-altitude atmospheric studies, and Earth observation and photography; there was equipment inside the Command Module, and various external experiments and sensors stored in an instrument bay in the Service Module. But the science was nominal, Dana knew. The real purpose of this mission was simple: make sure the damn NERVA works, and can be controlled from the spacecraft, without smearing nuclear waste all over everything.

When he’d taken his star readings, he used the sextant to measure the angle between two fixed stars. It was a check of the platform’s memory; Dana had to get his calculations to agree to within a ten-thousandth of a percentage point: the goal, in fact, was to get five balls, a perfect reading of .00000 on the star angle comparison.

Dana scored .00003: four balls and change.