"He can do anything any space skipper has ever done, and more," said Sue Eagen, and her face glowed. "But it isn't easy. Right this minute he's working over the computer—a small, simple, ship-board computer—working out orbital and positional and blast-intensity data that would be a hard nut for the giant calculators on Earth to crack. And he's doing it in half the time—or less—than it would take the average mathematician, because he has to; because it's a life-and-death matter if he makes a mistake or takes too long."
"But—but—"
"But what?" Miss Eagen's composure seemed to have been blasted to shreds by the powerful currents of her indignation. Her eyes flashed. "You mean, but why doesn't he just work the ship while it's spinning the same way he does when it isn't?"
Through a growing fear, Marcia nodded mutely.
"He'll spin the ship on its long axis," said the stewardess with exaggerated patience. "That means that the steering jet tubes in the nose and tail are spinning, too. You don't just turn with a blast on one tube or another. The blasts have to be let off in hundreds of short bursts, timed to the hundredth of a second, to be able to make even a slight course correction. The sighting instruments are wheeling round and round while you're checking your position. Your fuel has to be calculated to the last ounce—because enough fuel for a Moon flight, with hours of fuelless free-fall, and enough fuel for a power spin and course corrections while spinning, are two very different things. Captain McHenry won't be able to maneuver to a landing on the Moon. He'll do it exactly right the first time, or not at all."
Marcia was white and still. "I—I never—"
"But I haven't told you the toughest part of it yet," Miss Eagen went on inexorably. "A ship as massive as this, spinning on its long axis, is a pretty fair gyroscope. It doesn't want to turn. Any force that tries to make it turn is resisted at right angles to the force applied. When that force is applied momentarily from jets, as they swing into position and away again, the firing formulas get—well, complex. And the ship's course and landing approach are completely new. Instead of letting the ship fall to the Moon, turning over and approaching tail-first with the main jets as brakes, Captain McHenry is going to have to start the spin first and go almost the whole way nose-first. He'll come up on the Moon obliquely, pass it, stop the spin, turn over once to check the speed of the ship, and once again to put the tail down when the Moon's gravity begins to draw us in. There'll be two short periods of free-fall there, but they won't be long enough to bother you much. And if we can do all that with the fuel we've got, it will be a miracle. A miracle from the brain of Captain McHenry."
Marcia forced herself away from the bulkhead with a small whimper of hurt and hatred—hatred of the stars, of this knowledgeable, inspired girl, and—even more so—of herself. She darted toward the door.
Miss Eagen was beside her in an instant, a hard small hand on her arm. "Where are you going?"