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
space, but some would be drawn back by the asteroid’s slight gravity. The
craters would be highly radioactive and some radioactive debris would 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 mental calculations. They would be exposed to
radiation 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 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.
Space ships blasted through space 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 space ship," 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 two bombs to kick the asteroid
into the orbit, then fire one 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. "And when we really have the sun’s gravity pulling
us, we’ll increase speed. We’ll lose a little after we pass the sun, but
by then we’ll be almost home."
It was just space 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 space 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, clumsy in his space suit. "Sir, I ask permission
to speak."
Rip hid a smile at the little Italian’s formal manner. In space, formality
was forgotten. "What is it, Dominico?"
"Sir, I think we not worry so much about this radiation, eh? You will
think of some ways to take care of it, sir. What I want to ask, sir, is
when do we let go the bombs? Radiation I do not know much about, but I can
set those bombs like you want them."
Rip was touched by the Italian 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 space with every step. Of course
the asteroid had some gravity, but it was so slight that it didn’t count.
Rip centered the top of the instrument’s vertical hair line 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. 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 through
the instrument 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.
Rip picked up the instrument and carried it to a point 90 degrees from the
line represented by Koa and Santos. He put the instrument down and zeroed
it on Messier 44, the Beehive star cluster in the constellation Cancer.
For the second sighting star he chose Beta Pyxis as being closest to the
line he wanted, made the slight adjustments necessary to set the line of
sight since Pyxis wasn’t exactly on it, then directed Trudeau into
position as he had Koa. Nunez took position behind the instrument and Rip
had the cross-fix he wanted.
He called for Dowst, then carried the instrument to the center of the
cross formed by the four men. Using the instrument, he rechecked the lines
from the center out. They were within a hair or two of being exactly on,
and a slight error wouldn’t hurt anyway. He knew he would have to correct
with rocket blasts once the asteroid was in the new orbit.
"X marks the spot," he told Dowst. He put his toe on the place where the
cross lines met.
Dowst took a spike from his belt and made an X in the metal ground.
"All set," Rip announced. "You four men can move now. Let’s have the
cutting equipment over here, Koa."
The Planeteers were all waiting for instructions now. In a few moments the
equipment was ready, fuel and oxygen bottles attached.
"Who’s the champion torchman?" Rip asked.