"Get me the radiation detection instruments," he ordered.
Koa sensed the urgency in his voice and got the instruments himself. Rip switched them on and read the illuminated dial on the alpha counter.
Plenty high, as was natural. But no danger there--alpha particles couldn"t penetrate the s.p.a.ce suits. Then, his hand clammy inside the s.p.a.ce glove, he switched on the other meter. The gamma count was far below the alpha, but there were too many of the rays around for comfort.
Inside the helmet his face turned pale.
There was no immediate danger. It would take many days to build up a dose of gamma that could hurt them. But gamma was not the only radiation. They were in s.p.a.ce, fully exposed to equally dangerous cosmic radiation.
The Planeteers had gathered while he read the instruments. Now they stood watching him.
They knew the significance of what he had found.
"I ought to be busted to recruit," he told them. "I knew this asteroid was thorium and that thorium is radioactive. If I had used my head, I would have added nuc.l.i.te shielding to the list of supplies the _Scorpius_ provided. We could have had enough of it to protect us while around our base, even if we couldn"t be protected while working on the charges. That would at least have kept our dosage down enough for safety."
"No one else thought of it, either, sir," Koa reminded him.
"It was my job to think of it, and I didn"t. So I"ve put us in a time squeeze. If the _Scorpius_ gets back soon, we can get the shielding before our radiation dosage has built up very high. If the ship doesn"t come back, the dosage will mount."
He looked at them grimly. "It won"t kill us, and it won"t even make us very sick. I"ll have the ship take us off before we build up that much dosage."
Santos started. "But, sir! That means--"
"I know what it means," Rip stated bitterly. "It means the ship has got to return in time to give us some nuc.l.i.te shielding, or we"ll be the laughingstock of the Special Order Squadrons--the detachment that started a job the s.p.a.cemen had to finish!"
CHAPTER SEVEN
Earthbound!
There was something else that Rip didn"t add, although he knew the Planeteers would realize it in a few minutes. Probably some of them already had thought of it.
To move the asteroid into a new orbit, they were going to fire nuclear bombs. Most of the highly radioactive fission products would be blown into s.p.a.ce, but some would be drawn back by the asteroid"s slight gravity. The craters would be highly radioactive, and some radioactive debris was certain to be scattered around, too. Every particle would add to the problem.
"Is there anything we can do, sir?" Koa asked.
Rip shook his head inside the transparent bubble. "If you have a good luck charm in your pocket, you might talk to it. That"s about all."
Nuclear physics had been part of his training. He read the gamma meter again and did some quick calculations. They would be exposed for the entire trip, at a daily dosage of--
Koa interrupted his train of thought. Evidently the sergeant major had been doing some calculations of his own. "How long will we be on this rock, sir? You"ve never told us just how long the trip will take."
Rip said quietly, "With luck, it will take us a little more than three weeks."
He could see their faces faintly in the dim sunlight. They were shocked.
s.p.a.ceships blasted through s.p.a.ce between the inner planets in a matter of hours. The nuclear drive cruisers, which could approach almost half the speed of light, had brought even distant Pluto within easy reach.
The inner planets could be covered in a matter of minutes on a straight speed run, although to take off from one and land on the other meant considerable time used in acceleration and deceleration.
The Planeteers were used to such speed. Hearing that it would take over three weeks to reach Earth had jarred them.
"This piece of metal isn"t a s.p.a.ceship," Rip reminded them. "At the moment, our speed around the sun is just slightly more than ten miles a second. If we just shifted orbits and kept the same speed, it would take us months to reach Terra. But we"ll use one bomb for retrothrust, then fire two to increase speed. The estimate is that we"ll push up to about forty miles a second."
Koa spoke up. "That"s not bad when you think that Mercury is the fastest planet, and it only makes about thirty miles a second."
"Right," Rip agreed. "After the asteroid is kicked out of orbit, it will fall toward the sun. At our closest approach to the sun, we"ll have enough velocity to carry us past safely. Then we"ll lose speed constantly until we come into Earth"s gravitational field and have to brake."
It was just s.p.a.ce luck that Terra was on the other side of the sun from the asteroid"s present position. By the time they approached, it would be in a good place, just far enough from the line to the sun to avoid changing course. Of course, Rip"s planned orbit was not aiming the asteroid at Earth, but at where Earth would be at the end of the trip.
"That means more than three weeks of radiation, then," Corporal Santos observed. "Can we take it, sir?"
Rip shrugged, but the gesture couldn"t be seen inside his s.p.a.ce suit. "At the rate we"re getting radiation now, plus what I estimate we"ll get from the nuclear explosions, we"ll get the maximum safety limit in just three weeks. That leaves us no margin, even if we risk getting radiation sickness. So we have to get shielding pretty soon. If we do, we can last the trip."
Private Dominico saluted and moved forward. "Sir, may I ask a question?"
Rip turned to face the Planeteer, still worrying over the problem. He nodded and said, "What is it, Dominico?"
"Sir, I think we can"t worry too much about this radiation, eh? You will think of some way to take care of it. What I want to ask, sir, is when do we let go the bombs? I do not know much about radiation, but I can set those bombs like you want them."
Rip was touched by the Planeteer"s faith in his ability to solve the radiation problem. That was why being an officer in the Special Order Squadrons was so challenging. The men knew the kind of training their officers had, and they expected them to come up with technical solutions as the situation required.
"You"ll have a chance to set the bombs in just a short while," he said crisply. "Let"s get busy. Koa, load all bombs but one ten KT on the landing boat. Stake the rest of the equipment down. While you"re doing that, I"ll find the spots where we plant the charges. I"ll need two men now and more later."
He went back to his instrument, putting the radiation problem out of his mind--a rather hard thing to do with the colorimeter glowing pink next to his shoulder. Koa detailed men to load the nuclear bombs into the landing craft, left Pederson to supervise, and then brought Santos with him to help Rip.
"The bombs are being put on the boat, sir," Koa reported.
"Fine. There isn"t too much chance of the blasts setting them off, but we"ll take no chances at all. Koa, I"m going to shoot a line straight out toward Alpha Centauri. You walk that way and turn on your belt light.
I"ll tell you which way to move."
He adjusted his sighting rings while the sergeant major glided away.
Moving around on a no-weight world was more like skating than walking. A regular walk would have lifted Koa into s.p.a.ce with every step. Of course, the asteroid had some gravity, but so little that it hardly mattered.
Rip centered the top of the instrument"s vertical hairline on Alpha Centauri, then waited until Koa was almost out of sight over the asteroid"s horizon, which was only a few hundred yards away.
He turned up the volume on his helmet communicator. "Koa, move about ten feet to your left."
Koa did so. Rip sighted past the vertical hairline at the belt light.
"That"s a little too far. Take a small step to the right. That"s good ... just a few inches more ... hold it. You"re right in position.
Stand where you are."
"Yessir."
Rip turned to Santos. "Stand here, Corporal. Take a sight at Koa to get your bearings, then hold position."
Santos did so. Now the two lights gave Rip one of the lines he needed. He called for two more men, and Trudeau and Nunez joined him. "Follow me,"
he directed.