"Glance at that, Dona! See? A magnetometer to record the strength of the magnetic field on a new planet. It recorded the ship's own field in the absence of any other. And the ship's field dropped to zero! Do you see? Do you?"
"I'm afraid not," admitted Dona. But she smiled at the expression on Kim's face.
"It's the answer!" said Kim zestfully. "Still I don't know how that blasted field is made, but I know now how it works. Neutrons have no magnetic field, but this thing turns them aside. Alpha and beta and gamma radiation do have magnetic fields, but this thing turns them aside, too. And the point is that it neutralizes their magnetic fields, because otherwise it couldn't start to turn them aside. So if we make a magnetic field too strong for the field to counter, it won't be able to turn aside anything in that magnetic area. The maximum force-field strength needed for the planet is simply equal to the top magnetic field the sun may project so far. If we can bury the Starshine in magnetic flux that the force-field can't handle—" He grinned. He hugged her.
"And there's a loop around the Starshine's hull for space-radio use," he cried. "I'll run a really big current through that loop and we'll try again. We should be able to put quite a lot of juice through a six-turn loop and get a flux-density that will curl your hair!"
He set to work, beaming. It took him less than half an hour to set up a series-wound generator in the airlock, couple in a thermo-cell to the loop, so it would cool the generator as the current flowed and thereby reduce its internal resistance.
"Now!" he said. "We'll try once more. The more juice that goes through the outfit, the colder the generator will get and the less its resistance will be, and the more current it will make and the stronger the magnetic field will be."
He flipped a switch. There was a tiny humming noise. A meter-needle swayed over, and stayed.
The Starshine ventured into the black globe below.
Nothing happened. Nothing happened at all.
"The stars are blotted out, Kim," Dona at last said uneasily.