MOMENTUM

                            By Charles Dye

                       (author of "Time Killer")

                Just because an event "has to" happen,
                 some people think that, of course, it
                 will happen. It ain't necessarily so!

                 Ballard had but a few hours to solve
                   the problem, and he knew that the
                 answer was there, before his eyes--if
                       he could see it in time!

           [Transcriber's Note: This etext was produced from
        Future combined with Science Fiction Stories July 1951.
         Extensive research did not uncover any evidence that
         the U.S. copyright on this publication was renewed.]


Asteroid 1207 came spinning into the auxiliary ship's viewplate like a
glittering black mirage. The eight-mile chunk of rock was the last link
in a chain of nine asteroid navigational-markers still needing blinker
equipment installation. Minutes later, the _Minnow_ lay neatly berthed
in the deepest hollow of the asteroid, the shining wires of its drill
grapples anchoring it firmly to the jagged rock. The airlock opened
and two men in spacesuits stepped out. They climbed to the top of the
nearest hill dragging a platform of tools and equipment; the ragged,
close horizons of the asteroid made a hostile background for them as
they worked in silence.

Ballard leaned far over the rough edge of a circular pit, directing
the heat radiation beam that melted the foundation plastic smoothly
over the walls. He couldn't spare the time to turn his head and watch
Walton, but he could follow the other's progress in welding the
framework of the blinker tower by the irregular breathing and clanks
and buzzes coming through his earphones. He listened to Walton's
motions with an automatic alertness developed over six long weeks of
tension--ever since the finding of the rotenite nuggets on the second
of the light-marker asteroids. The rotenite represented enough wealth
to make them among the richest men in the solar system. Or one of
them--_the_ richest. That was what Ballard was afraid of.

Suddenly the clanks and rustles stopped, and Walton's voice muttered:
"Must have left the number three flux; better go back for it."

"What?" Ballard caught himself asking rhetorically, apprehension
flooding through him.

"I said I left something. Have to go back and get it." There was a
faint tremor in Walton's voice.

With a hard calm he wouldn't have recognized six weeks ago, Ballard
considered the consequences of making an excuse to go with Walton.
But the excuse would destroy the pose of innocence he'd so carefully
acted since his first suspicions of Walton's intention. And he could be
wrong. No sense in antagonizing Walton, particularly with the frayed
condition both their nerves were in. "Ok," he grunted. "Bring back
another 5R bit; this one I've been using chitters."

There were the sounds of Walton bounding down towards the ship in the
peculiar dancing glide demanded by the low gravity. Methodically,
without looking up, Ballard continued his job, following Walton with
his earphones. Only when the foundation fill was laid would it seem
natural for him to stop working for a moment and go to the ship.

Gradually, layer on layer, the plastic melted, coated the walls and
hardened. He heard Walton reach the ship, then there was a slight
ringing noise as the man touched his key-magnet to the airlock. As
Walton entered the lock, his mike registered the pressure of air by
suddenly picking up all the sounds of the ship; the throbbing of the
generators, the intermittent rush and sigh of the air conditioner, and
the close curved walls echoing back the scrape of his shoes on the
locker room floor.

Four minutes to go. Ballard finished melting the plastic onto the
walls, resisting the urge to hurry and risk botching the work. Walton
had no reason to kill him--except for the rotenite. And since its
discovery, Walton had shown nothing but a surface friendship covering a
hidden hatred and fear that was growing into surreptitious maneuverings
towards murder. But with a pretense at normality, Ballard hoped Walton
would get over his obsession and forget it, never knowing that he'd
seen anything suspicious. And meanwhile Ballard had only to stay out of
the way of accidents without seeming suspiciously careful.

He added the last necessary layer of plastic, switched off the heat
beam and stood up. There was no sign of motion around the _Minnow_.
Walton had not come out, but Ballard's earphones continued to pick up
Walton's nervous, irregular breathing.

       *       *       *       *       *

Ballard started down the hill in long, low floating bounds. The
_Minnow_ expanded up at him, a ship etched in black and white against
a jagged mass of black and grey ores. Just before landing on his
second bound, his earphones picked up a sharp metallic ringing note he
couldn't identify. Suddenly the ship expanded up directly in front of
him; he'd overshot his landing. He thudded into the ship, slid down to
the ground and landed facing the lock, his key-magnet in hand.

Again he heard the familiar tuning-fork note, this time ringing faintly
up from the magnet in his own hand as he put it against the circle of
lighter metal that was the lock. The circle turned, with the magnet
rotating out into a handle. He grabbed it and yanked to slide back the
airlock panel. The yank pulled him off his feet. For an instant he
couldn't orientate; then he realized that _he_ had moved because the
panel had not. It was a case of action or reaction. The panel had not
budged, seeming to be one with the flawless sweep of the hull.

He tried again, yanking it with the same futile results. Apprehension
flooded through him. "Walton!" he called. "Walton, the panel's stuck!
Open it from the inside!"

For an instant he was aware of Walton's nervous breathing, then it
stopped--there was a low chuckle. "Listen, Ballard! I'd be crazy to
let you in. Don't you think I've seen you watching me like a hawk ever
since we found the rotenite, just waiting for a chance to catch me off
guard! I should have done this weeks ago, but it didn't occur to me how
clean and easy it would be until I thought of the airlock jamming with
you outside. So--the lock is jammed and you have left little over two
hours of suit oxygen. And while you're out there suffocating to death,
I'll be waiting in my sleep-tank on a nice euphoriac jag. It's going to
be nice being the richest man in the--"

"Wait! Walton, listen! You're all wrong! I--"

Walton had cut his radio. For a moment, Ballard dumbly stood there,
his mind racing around like a pin-wheel. Slowly it stopped, as numbing
fear coursed through his nervous system. He'd under-concealed his
suspicions, after all; Walton had suspected him of the very same thing
he'd suspected Walton of.

Suddenly, in spite of his predicament, in spite of death waiting for
him only a few hours in the future, Ballard smiled. He really couldn't
hate Walton for what he'd done; it was the old cliche again of too much
greed and suspicion.

He realized that this didn't alter the fact that he was going to
die--unless he could think of something fast. Ballard looked at his
chronometer; he now had less than two hours.

In spite of this, his mind suddenly calmed and became clear. First he'd
have to think of all the possibilities of getting into the _Minnow_,
then allot only so much time to each possibility. There was the welding
torch, the heat-beam, a pneumatic jackhammer, and miscellaneous hand
tools. Surely with that assortment he could knock or burn a hole in the
ship. All the air would swish out, but there were enough suit cylinders
to allow him to take the ship back if he didn't damage it too badly
getting in. And Walton would be safe in his sleep-tank; Ballard would
see to that by disconnecting the awakener.

       *       *       *       *       *

Ballard smiled at the stars as he bounded back to the hill where the
tools lay. Walton had been a fool to lock him out here with cutting,
burning, and pounding equipment--and almost two hours in which to use
them. Things weren't so bad after all.

He decided to try the welding torch first. He crossed over to the
almost-completed blinker tower and picked up the torch and power-pack,
then from a tool box he selected a cutting nozzle.

Carefully, so not to exert himself and waste oxygen, he glided down
with his gear to the aft section of the _Minnow's_ hull just forward
of the tubes where the skin was thinnest. As he ignited the torch, he
was aware of what a temptation it was to drain off all the oxygen
contained in the power-pack into his own cylinder. Quickly he went
ahead and applied the torch to the skin of the ship. Ballard glanced at
his chronometer: An hour and a half to go. Good. Fifteen minutes would
be long enough to tell whether the torch would cut through the skin or
not. If it would, then he could use the rest of the time in cutting the
hole.

After the first five minutes he turned the nozzle away and examined the
spot where it had been applied. Not a mark.

Six minutes went by. Then seven, eight, nine--

Again he looked at the skin; still no change.

Three more minutes went by. Ballard felt sweat break out on his face
as he pulled the torch away for a third time. For a moment--his eyes
still blinded by the glare--he could see nothing. His heart sank. Then
he detected a faint red spot with a whitish center. _It was working._
Three more minutes and the hole would be started. He turned back the
nozzle to the glowing spot. Then with dismay he watched the torch
sputter and go dead. Frantically he pushed the activator button--

Stunned, he finally noticed that the power-pack read empty. Walton had
nearly exhausted it on the blinker tower.

Ballard glanced at his wrist. He still had an hour and fourteen minutes.

He didn't smile at the stars this time as he went back up the hill.
Things didn't seem ironic any more, merely dangerous. He loaded the
heat-beam with its larger power-pack onto the equipment platform and
slowly dragged it behind him down to the ship.

An hour and two minutes left. He went to work adjusting the beam to its
maximum intensity; then, moving it as close to the hull as possible, he
turned it on full force.

Time seemed to have stopped. Twice in one minute Ballard glanced at his
wrist, expecting to see a lapse of ten or fifteen minutes. Only five
minutes had dragged by; he now had just fifty-seven left. His spacesuit
suddenly began reminding him of a coffin. With superhuman effort he
jerked his thoughts away from suffocation and back to the job.

Forty-five minutes to go. _The beam wasn't going to work._ The sudden
realization cut into Ballard like a knife. He should have known that in
the first place; a beam meant for plastic wasn't intense enough for the
skin of a spaceship.

       *       *       *       *       *

This time as Ballard once more climbed the hill, the stars seemed to be
smiling at him. But not with friendliness. They seemed to smile _death_.

He got the jackhammer all the way down to the ship before a devastating
thought struck him. He'd forgotten that the hammer had a cracked 5R
bit; it would fly to pieces on the diamond hardness of the hull.

He sat down, stunned at the fact that he'd run out of things to try.
The ship lay before him like some impenetrable fortress. Several
precious minutes dragged by before Ballard could again calm his
spinning brain. He still had forty minutes. Had he overlooked any other
possibility of getting into the ship?

Slowly he walked around the _Minnow_, concentrating as he'd never
concentrated before. Then as he stepped in front of the drive tubes
something clicked: _The main tube was large enough for him to crawl
into. If he could remove the recoil plate and hydraulic mechanism,
he might be able to burn a hole through the ordinary steel bulkhead
beyond._

Half-bounding and half-running, he returned from the hill with the
tool box. After selecting several likely wrench sizes, he grabbed a
flashlight and crawled up the tube. He wasted five minutes unscrewing
the first bolt holding the plate in place. The second bolt was so
corroded he couldn't budge it. Cursing he crawled out and dragged in
the jackhammer, hoping the cracked 5R bit would hold until the bolt
was knocked out.

It almost held, flying to pieces just as there was a quarter inch to
go. Frantically he somehow managed to knock the remainder out with the
chuck of the hammer. But it had taken Ballard five more minutes. _Only
twenty-five left._

He went out and grabbed a crowbar and pried the plate off, recoil
cylinder and hydraulic fluid following like a jack-in-the-box.
After cleaning out the drive tube he almost lost his reason when he
discovered the cable connecting the beam to the power-pack wasn't long
enough to reach the bulkhead. Fortunately he found an extension in the
bottom of the tool box.

_Fifteen minutes to go._

That should be just long enough. He switched on the beam. Now time
seemed to race by. At ten minutes to go the bulkhead turned a
cherry-red. At five minutes it was almost white. At four, the steel
started to buckle. At three--the heat-beam suddenly went dead. The
power-pack was empty.

Ballard's reason reeled. He grabbed the crowbar and jabbed at the fast
cooling metal.

_Too late._

In the one minute he had left to live, Ballard suddenly became calm,
reconciling himself to his end. Wearily he crawled out of the tube.
At least Walton would be in for a nasty surprise, with the main drive
recoil plate gone. And to make sure, he would push it off into space.
With one last surge of fury he dragged up the foot thick plate he
could never have lifted back on Earth, and started shoving to give it
momentum.

_Momentum equals velocity times mass._ Suddenly he stopped, the plate
drifting on ahead of him. Now why had he thought of that? Something
from his school days--he tried hard to remember--something about
mass....

_Mass is a constant. Weight is a variable, but mass is what knocks
holes in things--spaceships, for instance._

Just one thing could save him now--momentum. Ballard glanced at his
wrist. Twenty seconds to go. Then maybe another twenty from the oxygen
in the connecting tube. Not much time--

He bounded off after the still-drifting plate, then began forcing
it around in a semi-circle back toward the ship. The recoil plate
sluggishly began to move faster as it gained momentum. It started
getting ahead of him so he gave it one last push, and it slowly crept
away heading straight for the hull. It floated edge-wise into the aft
section--and kept on going. A three foot stream of light poured out
from the side of the ship.

Ballard started crawling into the hull and the light wavered and
brightened. He couldn't understand it. Then it dimmed altogether--

_The last of his oxygen was gone._

Dizzily he tried to squeeze through the rip. He kept slipping back ...
back. There was a roaring darkness all around him, but he could still
crawl.

For ages he seemed to be crawling over polished glass--His head crashed
into something that clanged hollowly. Some fading portion of his
consciousness told him he was inside the ship--and the clang had been
the spacelocker. Automatically, as though by instinct, he reached up
and fumbled with the handle--Then he was clumsily trying to fit a new
oxygen cylinder into place....

       *       *       *       *       *

Ballard awoke feeling cramped and tired, as though he'd slept all
night in a bird cage. He looked at his chronometer, then at his
suit air-gauge. No. He'd been out only a few minutes. He got up and
crawled into the sleep-tank compartment and disconnected Walton's
awakener. Then he went into the control room and looked up the nearest
space-freighter lane in the radio call book, and set up an automatic
distress signal. He felt as if he were going to pass out again--this
time from sheer fatigue. There was still one thing more he wanted to do.

Out of the nose compartment he hauled a small case containing what had
caused all the trouble--

Then he crawled back out through the torn hull skin, opened the case
and flung every single one of the rotenite nuggets far out into space.