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                               CATALYSIS

                           BY POUL ANDERSON

                  _Man is a kind of turtle. Wherever
                    he goes, he will always carry a
                   shell holding warmth and air--and
                   with them his human failings...._

           [Transcriber's Note: This etext was produced from
             Worlds of If Science Fiction, February 1956.
         Extensive research did not uncover any evidence that
         the U.S. copyright on this publication was renewed.]


When you looked outside, it was into darkness.

Going out yourself, you could let your eyes accommodate. At high noon,
the sun was a sharp spark in a dusky heaven, and its light amounted to
about one-ninth of one percent of what Earth gets. The great fields
of ice and frozen gases reflected enough to help vision, but upthrust
crags and cliffs of naked rock were like blackened teeth.

Seventy hours later, when Triton was on the other side of the primary
that it always faced, there was a midnight thick enough to choke you.
The stars flashed and glittered, a steely twinkle through a gaunt
atmosphere mostly hydrogen--strange, to see the old lost constellations
of Earth, here on the edge of the deep. Neptune was at the full, a
giant sprawling across eight degrees of sky, bluish gray and smoky
banded, but it caught so little sunlight that men groped in blindness.
They set up floodlights, or had lamps glaring from their tracs, to work
at all.

But nearly everything went on indoors. Tunnels connected the various
buildings on the Hill, instruments were of necessity designed to
operate in the open without needing human care, men rarely had occasion
to go out any more. Which was just as well, for it takes considerable
power and insulation to keep a man alive when the temperature hovers
around 60 degrees Kelvin.

And so you stood at a meter-thick port of insulglas, and looked out,
and saw only night.

Thomas Gilchrist turned away from the view with a shudder. He had
always hated cold, and it was as if the bitterness beyond the lab-dome
had seeped in to touch him. The cluttered gleam of instruments in the
room, desk piled high with papers and microspools, the subdued chatter
of a computer chewing a problem, were comforting.

He remembered his purpose and went with a long low-gravity stride to
check the mineralogical unit. It was busily breaking down materials
fetched in by the robosamplers, stones never found on Earth--because
Earth is not the Mercury-sized satellite of an outer planet, nor has
it seen some mysterious catastrophe in an unknown time back near
the beginning of things. Recording meters wavered needles across
their dials, data tapes clicked out, he would soon have the basic
information. Then he would try to figure out how the mineral could have
been formed, and give his hypothesis to the computer for mathematical
analysis of possibility, and start on some other sample.

For a while Gilchrist stood watching the machine. A cigaret smoldered
forgotten between his fingers. He was a short, pudgy young man,
with unkempt hair above homely features. Pale-blue eyes blinked
nearsightedly behind contact lenses, his myopia was not enough to
justify surgery. Tunic and slacks were rumpled beneath the gray smock.

_Behold the bold pioneer!_ he thought. His self-deprecating sarcasm
was mildly nonsane, he knew, but he couldn't stop--it was like biting
an aching tooth. Only a dentist could fix the tooth in an hour, while
a scarred soul took years to heal. It was like his eyes, the trouble
wasn't bad enough to require long expensive repair, so he limped
through life.

Rafael Alemán came in, small and dark and cheerful. "'Allo," he said.
"How goes it?" He was one of the Hill's organic chemists, as Gilchrist
was the chief physical chemist, but his researches into low-temperature
properties were turning out so disappointingly that he had plenty of
time to annoy others. Nevertheless, Gilchrist liked him, as he liked
most people.

"So-so. It takes time."

"Time we have enough of, _mi amigo_," said Alemán. "Two years we 'ave
been here, and three years more it will be before the ship comes to
relieve us." He grimaced. "Ah, when I am back to Durango Unit, how fast
my savings will disappear!"

"You didn't have to join the Corps, and you didn't have to volunteer
for Triton Station," Gilchrist pointed out.

The little man shrugged, spreading slender hands. "Confidential, I will
tell you. I had heard such colorful tales of outpost life. But the only
result is that I am now a married man--not that I have anything but
praise for my dear Mei-Hua, but it is not the abandonment one had hoped
for."

Gilchrist chuckled. Outer-planet stations did have a slightly lurid
reputation, and no doubt it had been justified several years ago.

After all--The voyage was so long and costly that it could not be
made often. You established a self-sufficient colony of scientists
and left it there to carry on its researches for years at a time.
But self-sufficiency includes psychic elements, recreation, alcohol,
entertainment, the opposite sex. A returning party always took several
children home.

Scientists tended to be more objective about morals, or at least more
tolerant of the other fellow's, than most; so when a hundred or so
people were completely isolated, and ordinary amusements had palled, it
followed that there would be a good deal of what some would call sin.

"Not Triton," said Gilchrist. "You forget that there's been another
cultural shift in the past generation--more emphasis on the stable
family. And I imagine the Old Man picked his gang with an eye to such
attitudes. Result--the would-be rounders find themselves so small a
minority that it has a dampening effect."

"_Sí._ I know. But you 'ave never told me your real reason for coming
here, Thomas."

Gilchrist felt his face grow warm. "Research," he answered shortly.
"There are a lot of interesting problems connected with Neptune."

Alemán cocked a mildly skeptical eyebrow but said nothing. Gilchrist
wondered how much he guessed.

That was the trouble with being shy. In your youth, you acquired
bookish tastes; only a similarly oriented wife would do for you, so
you didn't meet many women and didn't know how to behave with them
anyhow. Gilchrist, who was honest with himself, admitted he'd had
wistful thoughts about encountering the right girl here, under informal
conditions where--

He had. And he was still helpless.

Suddenly he grinned. "I'll tell you what," he said. "I also came
because I don't like cold weather."

"Came to _Neptune_?"

"Sure. On Earth, you can stand even a winter day, so you have to. Here,
since the local climate would kill you in a second or two, you're
always well protected from it." Gilchrist waved at the viewport. "Only
I wish they didn't have that bloody window in my lab. Every time I look
out, it reminds me that just beyond the wall nitrogen is a solid."

"_Yo comprendo_," said Alemán. "The power of suggestion. Even now, at
your words, I feel a chill."

Gilchrist started with surprise. "You know, somehow I have the
same--Just a minute." He went over to a workbench. His inframicrometer
had an air thermometer attached to make temperature corrections.

"What the devil," he muttered. "It _is_ cooled off. Only 18 degrees in
here. It's supposed to be 21."

"Some fluctuation, in temperature as in ozone content and humidity,"
reminded Alemán. "That is required for optimum health."

"Not this time of day, it shouldn't be varying." Gilchrist was reminded
of his cigaret as it nearly burned his fingers. He stubbed it out and
took another and inhaled to light it.

"I'm going to raise Jahangir and complain," he said. "This could play
merry hell with exact measurements."

Alemán trotted after him as he went to the door. It was manually
operated, and the intercoms were at particular points instead of every
room. You had to forego a number of Earthside comforts here.

There was a murmuring around him as he hurried down the corridor.
Some doors stood open, showing the various chemical and biological
sections. The physicists had their own dome, on the other side of the
Hill, and even so were apt to curse the stray fields generated here. If
they had come this far to get away from solar radiations, it was only
reasonable, as anyone but a chemist could see, that--

The screen stood at the end of the hall, next to the tunnel stairs.
Gilchrist checked himself and stood with a swift wild pulse in his
throat. Catherine Bardas was using it.

He had often thought that the modern fashion of outbreeding yielded
humans more handsome than any pure racial type could be. When a girl
was half Greek and half Amerind, and a gifted biosynthesizer on top of
it, a man like him could only stare.

Mohammed Jahangir's brown, bearded face registered more annoyance
than admiration as he spoke out of the screen. "Yes. Dr. Bardas," he
said with strained courtesy. "I know. My office is being swamped with
complaints."

"Well, what's the trouble?" asked the girl. Her voice was low and
gentle, even at this moment.

"I'm not sure," said the engineer. "The domes' temperature is dropping,
that's all. We haven't located the trouble yet, but it can't be
serious."

"All I'm asking," said Catherine Bardas patiently, "is how much longer
this will go on and how much lower it's going to get. I'm trying to
synthesize a cell, and it takes precisely controlled conditions. If the
air temperature drops another five degrees, my thermostat won't be able
to compensate."

"Oh, well ... I'm sure you can count on repair being complete before
that happens."

"All right," said Catherine sweetly. "If not, though, I'll personally
bung you out the main air-lock _sans_ spacesuit."

Jahangir laughed and cut off. The light of fluorotubes slid blue-black
off the girl's shoulder-length hair as she turned around. Her face was
smooth and dark, with high cheekbones and a lovely molding of lips and
nose and chin.

"Oh--hello, Tom," she smiled. "All through here."

"Th-th-th--Never mind," he fumbled. "I was only g-going to ask about it
myself."

"Well--" She yawned and stretched with breathtaking effect. "I suppose
I'd better get back and--"

"Ah, why so, señorita?" replied Alemán. "If the work does not need your
personal attention just now, come join me in a leetle drink. It is near
dinnertime anyhow."

"All right," she said. "How about you, Tom?"

He merely nodded, for fear of stuttering, and accompanied them down the
stairs and into the tunnel. Half of him raged at his own timidity--why
hadn't he made that suggestion?

The passages connecting the domes were all alike, straight featureless
holes lined with plastic. Behind lay insulation and the pipes of the
common heating system, then more insulation, finally the Hill itself.
That was mostly porous iron, surprisingly pure though it held small
amounts of potassium and aluminum oxides. The entire place was a spongy
ferrous outcropping. But then, Triton was full of geological freaks.

"How goes your work?" asked Alemán sociably.

"Oh, pretty well," said Catherine. "I suppose you know we've
synthesized virus which can live outside. Now we're trying to build
bacteria to do the same."

On a professional level, Gilchrist was not a bad conversationalist.
His trouble was that not everyone likes to talk shop all the time. "Is
there any purpose in that, other than pure research to see if you can
do it?" he inquired. "I can't imagine any attempt ever being made to
colonize this moon."

"Well, you never know," she answered. "If there's ever any reason for
it, oxide-reducing germs will be needed."

"As well as a nuclear heating system for the whole world, and--What
do your life forms use for energy, though? Hardly enough sunlight, I
should think."

"Oh, but there is, for the right biochemistry with the right
catalysts--analogous to our own enzymes. It makes a pretty feeble type
of life, of course, but I hope to get bacteria which can live off the
local ores and frozen gases by exothermic reactions. Don't forget, when
it's really cold a thermal engine can have a very high efficiency; and
all living organisms are thermal engines of a sort."

They took the stairs leading up into the main dome: apartments,
refectories, social centers, and offices. Another stair led downward
to the central heating plant in the body of the Hill. Gilchrist saw an
engineer going that way with a metering kit and a worried look.

The bar was crowded, this was cocktail hour for the swing shift
and--popular opinion to the contrary--a scientist likes his meals
regular and only lives off sandwiches brought to the lab when he must.
They found a table and sat down. Nobody had installed dial units, so
junior technicians earned extra money as waiters. One of them took
their orders and chits.

The ventilators struggled gallantly with the smoke. It hazed the murals
with which some homesick soul had tried to remember the green Earth. A
couple of astronomers at the next table were noisily disputing theories.

"--Dammit, Pluto's got to be an escaped satellite of Neptune. Look at
their orbits ... and Pluto is where Neptune should be according to
Bode's Law."

"I know. I've heard that song before. I suppose you favor the Invader
theory?"

"What else will account for the facts? A big planet comes wandering in,
yanks Neptune sunward and frees Pluto; but Neptune captures a satellite
of the Invader. Triton's got to be a captured body, with this screwy
retrograde orbit. And Nereid--"

"Have you ever analyzed the mechanics of that implausible proposition?
Look here--" A pencil came out and began scribbling on the
long-suffering table top.

Catherine chuckled. "I wonder if we'll ever find out," she murmured.

Gilchrist rubbed chilled fingers together. Blast it, the air was still
cooling off! "It'd be interesting to land a ship on Nep himself and
check the geology," he said. "A catastrophe like that would leave
traces."

"When they can build a ship capable of landing on a major planet
without being squeezed flat by the air pressure, that'll be the day. I
think we'll have to settle for telescopes and spectroscopes for a long,
long time to come--"

The girl's voice trailed off, and her dark fine head poised. The
loudspeaker was like thunder.

"DR. VESEY! DR. VESEY! PLEASE CONTACT ENGINEERING OFFICE! DR. VESEY,
PLEASE CONTACT DR. JAHANGIR! OVER."

For a moment, there was silence in the bar.

"I wonder what the trouble is," said Alemán.

"Something to do with the heating plant, I suppose--" Again
Catherine's tones died, and they stared at each other.

The station was a magnificent machine; it represented an engineering
achievement which would have been impossible even fifty years ago. It
kept a hundred human creatures warm and moist, it replenished their air
and synthesized their food and raised a wall of light against darkness.
But it had not the equipment to call across nearly four and a half
billion kilometers of vacuum. It had no ship of its own, and the great
Corps vessel would not be back for three years.

It was a long way to Earth.

       *       *       *       *       *

Dinner was a silent affair that period. There were a few low-voiced
exchanges, but they only seemed to deepen the waiting stillness.

And the cold grew apace. You could see your breath, and your thin
garments were of little help.

The meal was over, and the groups of friends were beginning to drift
out of the refectory, when the intercoms woke up again. This chamber
had a vision screen. Not an eye stirred from Director Samuel Vesey as
he looked out of it.

His lips were firm and his voice steady, but there was a gleam of sweat
on the ebony skin--despite the cold. He stared directly before him and
spoke:

"Attention, all personnel. Emergency situation. Your attention, please."

After a moment, he seemed to relax formality and spoke as if face to
face. "You've all noticed our trouble. Something has gone wrong with
the heating plant, and Dr. Jahangir's crew haven't located the trouble
so far.

"Now there's no reason for panic. The extrapolated curve of temperature
decline indicates that, at worst, it'll level off at about zero
Centigrade. That won't be fun, but we can stand it till the difficulty
has been found. Everyone is advised to dress as warmly as possible.
Food and air plant crews are going on emergency status. All projects
requiring energy sources are cancelled till further notice.

"According to the meters, there's nothing wrong with the pile. It's
still putting out as much heat as it always has. But somehow, that heat
isn't getting to us as it should. The engineers are checking the pipes
now.

"I'll have a stat of the findings made up and issued. Suggestions are
welcome, but please take them to my office--the engineers have their
own work to do. Above all, don't panic! This is a nuisance, I know, but
there's no reason to be afraid.

"All personnel not needed at once, stand by. The following specialists
please report to me--"

He read off the list, all physicists, and closed his talk with a forced
grin and thumbs up.

As if it had broken a dam, the message released a babble of words.
Gilchrist saw Catherine striding out of the room and hastened after her.

"Where are you going?" he asked.

"Where do you think?" she replied. "To put on six layers of clothes."

He nodded. "Best thing. I'll come along, if I may--my room's near
yours."

A woman, still in her smock, was trying to comfort a child that
shivered and cried. A Malayan geologist stood with teeth clattering in
his jaws. An engineer snarled when someone tried to question him and
ran on down the corridor.

"What do you think?" asked Gilchrist inanely.

"I don't have any thoughts about the heating plant," said Catherine.
Her voice held a thin edge. "I'm too busy worrying about food and air."

Gilchrist's tongue was thick and dry in his mouth. The biochemistry of
food creation and oxygen renewal died when it got even chilly.

       *       *       *       *       *

Finished dressing, they looked at each other in helplessness. Now what?

The temperature approached its minimum in a nosedive. There had
always been a delicate equilibrium; it couldn't be otherwise, when
the interior of the domes was kept at nearly 240 degrees above the
surrounding world. The nuclear pile devoted most of its output to
maintaining that balance, with only a fraction going to the electric
generators.

Gilchrist thrust hands which were mottled blue with cold into his
pockets. Breath smoked white before him. Already a thin layer of
hoarfrost was on ceiling and furniture.

"How long can we stand this?" he asked.

"I don't know," said Catherine. "Not too long, I should think, since
nobody has adequate clothes. The children should ... suffer ... pretty
quickly. Too much drain on body energy." She clamped her lips together.
"Use your mental training. You can ignore this till it begins actually
breaking down your physique."

Gilchrist made an effort, but couldn't do it. He could stop shivering,
but the chill dank on his skin, and the cold sucked in by his nose,
were still there in his consciousness, like a nightmare riding him.

"They'll be dehumidifying the air," said Catherine. "That'll help
some." She began walking down the hall. "I want to see what they're
doing about the food and oxy sections."

A small mob had had the same idea. It swirled and mumbled in the hall
outside the service rooms. A pair of hard-looking young engineers armed
with monkey wrenches stood guard.

Catherine wormed her way through the crowd and smiled at them. Their
exasperation dissolved, and one of them, a thickset red-head by the
name of O'Mallory, actually grinned. Gilchrist, standing moodily behind
the girl, could hardly blame him.

"How's it going in there?" she asked.

"Well, now, I suppose the Old Man _is_ being sort of slow about his
bulletins," said O'Mallory. "It's under control here."

"But what are they doing?"

"Rigging electric heaters, of course. It'll take all the juice we have
to maintain these rooms at the right temperature, so I'm afraid they'll
be cutting off light and power to the rest of the Hill."

She frowned. "It's the only thing, I suppose. But what about the
people?"

"They'll have to jam together in the refectories and clubrooms. That'll
help keep 'em warm."

"Any idea what the trouble is?"

O'Mallory scowled. "We'll get it fixed," he said.

"That means you don't know." She spoke it calmly.

"The pile's all right," he said. "We telemetered it. I'd'a done that
myself, but you know how it is--" He puffed himself up a trifle. "They
need a couple husky chaps to keep the crowd orderly. Anyhow, the pile's
still putting out just as it should, still at 500 degrees like it ought
to be. In fact, it's even a bit warmer than that; why, I don't know."

Gilchrist cleared his throat. "Th-th-then the trouble is with the ...
heating pipes," he faltered.

"How did you ever guess?" asked O'Mallory with elaborate sarcasm.

"Lay off him," said Catherine. "We're all having a tough time."

Gilchrist bit his lip. It wasn't enough to be a tongue-tied idiot, he
seemed to need a woman's protection.

"Trouble is, of course," said O'Mallory, "the pipes are buried in
insulation, behind good solid plastic. They'll be hard to get at."

"Whoever designed this farce ought to have to live in it," said his
companion savagely.

"The same design's worked on Titan with no trouble at all," declared
O'Mallory.

Catherine's face took on a grimness. "There never was much point in
making these outer-planet domes capable of quick repair," she said. "If
something goes wrong, the personnel are likely to be dead before they
can fix it."

"Now, now, that's no way to talk," smiled O'Mallory. "Look, I get off
duty at 0800. Care to have a drink with me then?"

Catherine smiled back. "If the bar's operating, sure."

Gilchrist wandered numbly after her as she left.

The cold gnawed at him. He rubbed his ears, unsure about frostbite. Odd
how fast you got tired--It was hard to think.

"I'd better get back to my lab and put things away before they turn off
the electricity to it," he said.

"Good idea. Might as well tidy up in my own place." Something flickered
darkly in the girl's eyes. "It'll take our minds off--"

Off gloom, and cold, and the domes turned to blocks of ice, and a final
night gaping before all men. Off the chasm of loneliness between the
Hill and the Earth.

They were back in the chemical section when Alemán came out of his lab.
The little man's olive skin had turned a dirty gray.

"What is it?" Gilchrist stopped, and something knotted hard in his guts.

"_Madre de Díos--_" Alemán licked sandy lips. "We are finished."

"It's not that bad," said Catherine.

"You do not understand!" he shrieked. "Come here!"

They followed him into his laboratory. He mumbled words about having
checked a hunch, but it was his hands they watched. Those picked up a
Geiger counter and brought it over to a wall and traced the path of a
buried heating pipe.

The clicking roared out.

       *       *       *       *       *

"Beta emission," said Gilchrist. His mouth felt cottony.

"How intense?" whispered Catherine.

Gilchrist set up an integrating counter and let it run for a while.
"Low," he said. "But the dosage is cumulative. A week of this, and
we'll begin to show the effects. A month, and we're dead."

"There's always some small beta emission from the pipes," said the
girl. "A little tritium gets formed down in the pile room.
It's ... never been enough to matter."

"Somehow, the pile's beginning to make more H-3, then." Gilchrist sat
down on a bench and stared blankly at the floor.

"The laws of nature--" Alemán had calmed down a bit, but his eyes were
rimmed with white.

"Yes?" asked Catherine when he stopped. She spoke mostly to fend off
the silence.

"I 'ave sometimes thought ... what we know in science is so leetle. It
may be the whole universe, it has been in a ... a most improbable state
for the past few billion years." Alemán met her gaze as if pleading
to be called a liar. "It may be that what we thought to be the laws of
nature, those were only a leetle statistical fluctuation."

"And now we're going back onto the probability curve?" muttered
Gilchrist. He shook himself. "No, damn it. I won't accept that till I
must. There's got to be some rational explanation."

"Leakage in the pipes?" ventured Catherine.

"We'd know that. Nor does it account for the radiation. No, it's--" His
voice twisted up on him, and he groped out a cigaret. "It's something
natural."

"What is natural?" said Alemán. "How do we know, leetle creeping things
as we are, living only by the grace of God? We 'ave come one long way
from home." His vision strayed to the viewport with a kind of horror.

_Yes_, thought Gilchrist in the chilled darkness of his mind, _yes, we
have come far. Four and a half billion kilometers further out from the
sun. The planet-sized moon of a world which could swallow ours whole
without noticing. A thin hydrogen atmosphere, glaciers of nitrogen
which turn to rivers when it warms up, ammonia snow, and a temperature
not far above absolute zero. What do we know? What is this arrogance of
ours which insists that the truth on Earth is also the truth on the rim
of space?_

No!

He stood up, shuddering with cold, and said slowly: "We'd better go see
Dr. Vesey. He has to know, and maybe they haven't thought to check the
radiation. And then--"

Catherine stood waiting.

"Then we have to think our way out of this mess," he finished lamely.
"Let's, uh, start from the beginning. Think back how th-th-the heating
plant works."

       *       *       *       *       *

Down in the bowels of the Hill was a great man-made cave. It had been
carved out of the native iron, with rough pillars left to support the
roof; walls and ceiling were lined with impermeable metal, but the
floor was in its native state--who cared if there was seepage downward?

The pile sat there, heart and life of the station.

It was not a big one, just sufficient to maintain man on Triton.
Part of its energy was diverted to the mercury-vapor turbines which
furnished electricity. The rest went to heat the domes above.

Now travel across trans-Jovian spaces is long and costly; even the
smallest saving means much. Very heavy insulation against the haze of
neutrons which the pile emitted could scarcely be hauled from Earth,
nor had there been any reason to spend time and labor manufacturing it
on Triton.

Instead, pumps sucked in the hydrogen air and compressed it to about
600 atmospheres. There is no better shield against high-energy
neutrons; they bounce off the light molecules and slow down to a speed
which makes them perfectly harmless laggards which don't travel far
before decaying into hydrogen themselves. This, as well as the direct
radiation of the pile, turned the room hot--some 500 degrees.

So what was more natural than that the same hydrogen should be
circulated through pipes of chrome-vanadium steel, which is relatively
impenetrable even at such temperatures, and heat the domes?

There was, of course, considerable loss of energy as the compressed gas
seeped through the Hill and back into the satellite's atmosphere. But
the pumps maintained the pressure. It was not the most efficient system
which could have been devised; it would have been ludicrous on Earth.
But on Triton, terminal of nowhere, men had necessarily sacrificed some
engineering excellence to the stiff requirements of transportation and
labor.

And after all, it had worked without a hitch for many years on Saturn's
largest moon. It had worked for two years on Neptune's--

       *       *       *       *       *

Samuel Vesey drummed on his desk with nervous fingers. His dark
countenance was already haggard, the eyes sunken and feverish.

"Yes," he said. "Yes, it was news to me."

Jahangir put down the counter. The office was very quiet for a while.

"Don't spread the word," said Vesey. "We'll confine it to the
engineers. Conditions are bad enough without a riot breaking loose. We
can take several days of this radiation without harm, but you know how
some people are about it."

"You've not been very candid so far," snapped Catherine. "Just exactly
what have you learned?"

Jahangir shrugged. There was a white frost rimming his beard. "There've
been no bulletins because there's no news," he replied. "We checked the
pile. It's still putting out as it should. The neutron flux density is
the same as ever. It's the gas there and in our pipes which has gotten
cold and ... radioactive."

"Have you looked directly in the pile room--actually entered?" demanded
Alemán.

Jahangir lifted his shoulders again. "My dear old chap," he murmured.
"At a temperature of 500 and a pressure of 600?" After a moment, he
frowned. "I do have some men modifying a trac so it could be driven
in there for a short time. But I don't expect to find anything. It's
mostly to keep them busy."

"How about the pipes, then?" asked Gilchrist.

"Internal gas pressure and velocity of circulation is just about what
it always has been. According to the meters, anyway, which I don't
think are lying. I don't want to block off a section and rip it out
except as a last resort. It would just be wasted effort, I'm sure."
Jahangir shook his turbanned head. "No, this is some phenomenon which
we'll have to think our way through, not bull through."

Vesey nodded curtly. "I suggest you three go back to the common rooms,"
he said. "We'll be shunting all the power to food and oxy soon. If you
have any further suggestions, pass them on ... otherwise, sit tight."

It was dismissal.

       *       *       *       *       *

The rooms stank.

Some ninety human beings were jammed together in three long chambers
and an adjacent kitchen. The ventilators could not quite handle that
load.

They stood huddled together, children to the inside, while those on
the rim of the pack hugged their shoulders and clenched teeth between
blue lips. Little was said. So far there was calm of a sort--enough
personnel had had intensive mind training to be a steadying influence;
but it was a thin membrane stretched near breaking.

As he came in, Gilchrist thought of a scene from Dante's hell.
Somewhere in that dense mass, a child was sobbing. The lights were
dim--he wondered why--and distorted faces were whittled out of thick
shadow.

"G-g-get inside ... in front of me," he said to Catherine.

"I'll be all right," answered the girl. "It's a fact that women can
stand cold better than men."

Alemán chuckled thinly. "But our Thomas is well padded against it," he
said.

Gilchrist winced. He himself made jokes about his figure, but it was
a cover-up. Then he wondered why he should care; they'd all be dead
anyway, before long.

A colleague, Danton, turned empty eyes on them as they joined the rest.
"Any word?" he asked.

"They're working on it," said Catherine shortly.

"God! Won't they hurry up? I've got a wife and kid. And we can't even
sleep, it's so cold."

Yes, thought Gilchrist, that would be another angle. Weariness to eat
away strength and hope ... radiation would work fast on people in a
depressed state.

"They could at least give us a heater in here!" exclaimed Danton. His
tone was raw. Shadows muffled his face and body.

"All the juice we can spare is going to the food and air plants. No use
being warm if you starve or suffocate," said Catherine.

"I know, I know. But--Well, why aren't we getting more light? There
ought to be enough current to heat the plants and still furnish a
decent glow in here."

"Something else--" Gilchrist hesitated. "Something else is operating,
then, and sucking a lot of power. I don't know what."

"They say the pile itself is as hot as ever. Why can't we run a pipe
directly from it?"

"And get a mess of fast neutrons?" Catherine's voice died. After
all ... they were being irradiated as they stood here and trembled.

"We've got batteries!" It was almost a snarl from Danton's throat.
"Batteries enough to keep us going comfortably for days. Why not use
them?"

"And suppose the trouble hasn't been fixed by the time they're
drained?" challenged Gilchrist.

"Don't say that!"

"Take it easy," advised another man.

Danton bit his lip and faced away, mumbling to himself.

A baby began to cry. There seemed no way of quieting it.

"Turn that bloody brat off!" The tone came saw-toothed from somewhere
in the pack.

"Shut up!" A woman's voice, close to hysteria.

Gilchrist realized that his teeth were rattling. He forced them to
stop. The air was foul in his nostrils.

He thought of beaches under a flooding sun, of summer meadows and a
long sweaty walk down dusty roads, he thought of birds and blue sky.
But it was no good. None of it was real.

The reality was here, just beyond the walls, where Neptune hung ashen
above glittering snow that was not snow, where a thin poisonous wind
whimpered between barren snags, where the dark and the cold flowed
triumphantly close. The reality would be a block of solid gas, a
hundred human corpses locked in it like flies in amber, it would be
death and the end of all things.

He spoke slowly, through numbed lips: "Why has man always supposed that
God cared?"

"We don't know if He does or not," said Catherine. "But man cares,
isn't that enough?"

"Not when the next nearest man is so far away," said Alemán, trying to
smile. "I will believe in God; man is too small."

Danton turned around again. "Then why won't He help us now?" he cried.
"Why won't He at least save the children?"

"I said God cared," answered Alemán quietly, "not that He will do our
work for us."

"Stow the theology, you two," said Catherine. "We're going to pieces in
here. Can't somebody start a song?"

Alemán nodded. "Who has a guitar?" When there was no response, he began
singing a capella:

    "_La cucaracha, la cucaracha,
    Ya no quiere caminar--_"

Voices joined in, self-consciously. They found themselves too few, and
the song died.

Catherine rubbed her fingers together. "Even my pockets are cold now,"
she said wryly.

Gilchrist surprised himself; he took her hands in his. "That may help,"
he said.

"Why, thank you, Sir Galahad," she laughed. "You--Oh. Hey, there!"

O'Mallory, off guard detail now that everyone was assembled here, came
over. He looked even bulkier than before in half a dozen layers of
clothing. Gilchrist, who had been prepared to stand impotently in the
background while the engineer distributed blarney, was almost relieved
to see the fear on him. _He_ knew!

"Any word?" asked Catherine.

"Not yet," he muttered.

"Why 'ave we so leetle light?" inquired Alemán. "What is it that draws
the current so much? Surely not the heaters."

"No. It's the pump. The air-intake pump down in the pile room."
O'Mallory's voice grew higher. "It's working overtime, sucking in more
hydrogen. Don't ask me why! I don't know! Nobody does!"

"Wait," said Catherine eagerly. "If the room's losing its warm gas, and
having to replace it from the cold stuff outside, would that account
for the trouble we're having?"

"No," said O'Mallory dully. "We can't figure out where the hydrogen's
disappearing to, and anyway it shouldn't make that much difference. The
energy output down there's about what it's supposed to be, you know."

Gilchrist stood trying to think. His brain felt gelid.

But damn it, damn it, damn it, there must be a rational answer. He
couldn't believe they had blundered into an ugly unknown facet of the
cosmos. Natural law was the same, here or in the farthest galaxy--it
had to be.

Item, he thought wearily. The pile was operating as usual, except that
somehow hydrogen was being lost abnormally fast and therefore the pump
had to bring in more from Triton's air. But--

--Item. That couldn't be due to a leak in the heating pipes, because
they were still at their ordinary pressure.

--Item. The gas in the pipes included some radioactive isotope.
Nevertheless--

--Item. It could not be hydrogen-3, because the pile was working
normally and its neutron leakage just wasn't enough to produce that
much. Therefore, some other element was involved.

Carbon? There was a little methane vapor in Triton's atmosphere. But
not enough. Anyway, carbon-13 was a stable isotope, and the pile-room
conditions wouldn't produce carbon-14. Unless--

_Wait a minute!_ Something flickered on the edge of awareness.

Danton had buttonholed O'Mallory. "We were talking about using the
battery banks," he said.

The engineer shrugged. "And what happens after they're used up? No,
we're keeping them as a last resort." His grin was hideous. "We could
get six or seven comfortable days out of them."

"Then let's have them! If you thumb-fingered idiots haven't fixed the
system by then, you deserve to die."

"And you'll die right along with us, laddybuck." O'Mallory bristled.
"Don't think the black gang's loafing. We're taking the cold and the
radiation as much as you are--"

"_Radiation?_"

Faces turned around. Gilchrist saw eyes gleam white. The word rose in a
roar, and a woman screamed.

"Shut up!" bawled O'Mallory frantically. "Shut up!"

Danton shouted and swung at him. The engineer shook his head and hit
back. As Danton lurched, a man rabbit-punched O'Mallory from behind.

Gilchrist yanked Catherine away. The mob spilled over, a sudden storm.
He heard a table splinter.

Someone leaped at him. He had been an educated man, a most scientific
and urbane man, but he had just been told that hard radiation was
pouring through his body and he ran about and howled. Gilchrist
had a glimpse of an unshaven face drawn into a long thin box with
terror, then he hit. The man came on, ignoring blows, his own fists
windmilling. Gilchrist lowered his head and tried clumsily to take the
fury on his arms. Catherine, he thought dizzily, Catherine was at least
behind him.

The man yelled. He sat down hard and gripped his stomach, retching.
Alemán laughed shortly. "A good kick is advisable in such unsporting
circumstances, _mi amigo_."

"Come on," gasped Catherine. "We've got to get help."

They fled down a tunnel of blackness. The riot noise faded behind, and
there was only the hollow slapping of their feet.

Lights burned ahead, Vesey's office. A pair of engineer guards tried to
halt them. Gilchrist choked out an explanation.

Vesey emerged and swore luridly, out of hurt and bewilderment at his
own people. "And we haven't a tear gas bomb or a needler in the place!"
He brooded a moment, then whirled on Jahangir, who had come out behind
him. "Get a tank of compressed ammonia gas from the chem section and
give 'em a few squirts if they're still kicking up when you arrive.
That ought to quiet them without doing any permanent damage."

The chief nodded and bounded off with his subordinates. In this
gravity, one man could carry a good-sized tank.

Vesey beat a fist into his palm. There was agony on his face.

Catherine laid a hand on his arm. "You've no choice," she said gently.
"Ammonia is rough stuff, but it would be worse if children started
getting trampled."

Gilchrist, leaning against the wall, straightened. It was as if a bolt
had snapped home within him. His shout hurt their eardrums.

"_Ammonia!_"

"Yes," said Vesey dully. "What about it?" Breath smoked from his mouth,
and his skin was rough with gooseflesh.

"I--I--I--It's your ... y-y-your _answer_!"

       *       *       *       *       *

They had set up a heater in his laboratory so he could work, but the
test was quickly made. Gilchrist turned from his apparatus and nodded,
grinning with victory. "That settles the matter. This sample from the
pile room proves it. The air down there is about half ammonia."

Vesey looked red-eyed at him. There hadn't been much harm done in the
riot, but there had been a bad few minutes. "How's it work?" he asked.
"I'm no chemist."

Alemán opened his mouth, then bowed grandly. "You tell him, Thomas. It
is your moment."

Gilchrist took out a cigaret. He would have liked to make a cavalier
performance of it, with Catherine watching, but his chilled fingers
were clumsy and he dropped the little cylinder. She laughed and picked
it up for him.

"Simple," he said. With technicalities to discuss, he could speak well
enough, even when his eyes kept straying to the girl. "What we have
down there is a Haber process chamber. It's a method for manufacturing
ammonia out of nitrogen and hydrogen--obsolete now, but still of
interest to physical chemists like myself.

"I haven't tested this sample for nitrogen yet, but there's got to be
some, because ammonia is NH_{3}. Obviously, there's a vein of solid
nitrogen down under the Hill. As the heat from the pile room penetrated
downward, this slowly warmed up. Some of it turned gaseous, generating
terrific pressure; and finally that pressure forced the gas up into the
pile room.

"Now, when you have a nitrogen-hydrogen mixture at 500 degrees and 600
atmospheres, in the presence of a suitable catalyst, you get about a 45
percent yield of ammonia--"

"You looked that up," said Catherine accusingly.

He chuckled. "My dear girl," he said, "there are two ways to know a
thing: you can know it, or you can know where to look it up. I prefer
the latter." After a moment: "Naturally, this combination decreases
the total volume of gas; so the pump has to pull in more hydrogen from
outside to satisfy its barystat, and more nitrogen is welling from
below all the time. We've been operating quite an efficient little
ammonia factory down there, though it should reach equilibrium as to
pressure and yield pretty soon.

"The Haber process catalyst, incidentally, is spongy iron with certain
promoters--potassium and aluminum oxides are excellent ones. In other
words, it so happened that the Hill is a natural Haber catalyst, which
is why we've had this trouble."

"And I suppose the reaction is endothermic and absorbs heat?" asked
Catherine.

"No ... as a matter of fact, it's exothermic, which is why the pile
is actually a little hotter than usual, and that in spite of having
to warm up all that outside air. But ammonia does have a considerably
higher specific heat than hydrogen. So, while the gas in our pipes has
the same caloric content, it has a lower temperature."

"Ummm--" Vesey rubbed his chin. "And the radiation?"

"Nitrogen plus neutrons gives carbon-14, a beta emitter."

"All right," said Catherine. "Now tell us how to repair the situation."

Her tone was light--after all, the answer was obvious--but it didn't
escape Gilchrist that she _had_ asked him to speak. Or was he thinking
wishfully?

"We turn off the pile, empty the pipes, and go into the room in
spacesuits," he said. "Probably the simplest thing would be to drill
an outlet for the nitrogen vein and drop a thermite bomb down
there ... that should flush it out in a hurry. Or maybe we can lay an
impermeable floor. In any event, it shouldn't take more than a few
days, which the batteries will see us through. Then we can go back to
operation as usual."

Vesey nodded. "I'll put Jahangir on it right away." He stood up and
extended his hand. "As for you, Dr. Gilchrist, you've saved all our
lives and--"

"Shucks." His cheeks felt hot. "It was my own neck too."

Before his self-confidence could evaporate, he turned to Catherine.
"Since we can't get back to work for a few days, how about going down
to the bar for a drink? I believe it'll soon be functioning again.
And, uh, there'll doubtless be a dance to celebrate later--"

"I didn't know you could dance," she said.

"I can't," he blurted.

They went out together. It is not merely inorganic reactions which
require a catalyst.