"The thrust, Snow, that's why. If that weight were suddenly removed
from the ship--boys of Space Scout age usually run to an average
weight of one hundred pounds, or, in this case, a total of about
fifteen hundred pounds--if that weight had suddenly become missing,
then Anders' fuel consumption, remaining the same but with less mass
to thrust, would have made him overshoot Earth. This, however, did not
happen. In fact, the gauges in the pilot's compartment plainly show
that the ship's mass was, on landing, within a fraction of an ounce of
its takeoff mass. Therefore, no mass at all was lost in space except
that expended by the consumption of fuel."
Snow shook her head, bewildered. "But that doesn't make sense!" she
cried. "If they weren't taken off the ship in space, and they weren't
aboard her when she landed, then--" All at once, she got it, and sat
back with a sharp gasp.
"Exactly," I said. "They never even left Mars."
"But you said that this man Anders had seen to it that they were all
aboard before takeoff."
"Which I have no doubt he did. But the civilian mind skips a few
details when it thinks over his report. They see him look at the boys,
nod, then go up front and press the starter button. It doesn't happen
quite that simply. There are a lot of other things to be done. Anders
had to go into the pilot's cabin, strap himself in place, check the
guages which showed his course, mass, fuel supply, thrust control,
oxygen-nitrogen mixture, and a million and one other things. He had to
check the last and most important dial examined before takeoff; the one
which told him that each of the fifteen takeoff racks in the ship were
occupied."
"But--" Snow cut in, bewildered, leaning forward.
"Let me finish." She set her mouth and sat back again. "He had to know
that, because takeoff thrust on a human being _not_ snugly in his
padded rack would probably squash him to pieces against a bulkhead. So
there had to be something in those racks in order to fool Anders into
thinking that the scouts were still aboard; something which, by the
time Anders had maneuvered the ship into its flight vector, would be
gone without leaving a trace, or not much of a trace, unless one were
actually looking for it."
"What?" asked Snow, fascinated.
"Ice," I said. "Hunks of ice in every one of the fifteen bunks. Ice
which the temperature control unit would commence to melt immediately."
"But that would mean ice blocks of hundred-pound weights! They couldn't
melt so fast. Wouldn't Anders be likely to come back to the racks and
find them still there?"
"Not," I said, "with the efficiency of the temperature control system.
Sharp deviations from comfortable levels in a spaceship can be
disastrous. So the thermostat in the ship is set for a rigid fifty-five
degrees, and it's built to keep the interior heat at that level. Put
fifteen-hundred pounds of ice on board, and the heat in the rack cabin
goes up, trying to get the temperature back to its correct level. The
ice, lying there melting, absorbs the heat swiftly. So more heat is
pumped into the room. Well, figure fifteen minutes before all the ice
was liquified. More than enough of a margin of safety."
"Safety for whom?" Snow asked.
"For whoever didn't want Anders finding any evidence of how the
disappearance was accomplished. About an hour passed between takeoff
and the time he checked the cabin. You must remember that Anders had to
maneuver the ship free of Mars' gravity, set his course for Earth, and
then make a final check of all his equipment before going back into the
ship proper. That takes plenty of time."
"But how could you figure this out?" Snow asked, her eyes wide with
interest. "And where did the ice come from?"
"From the night side of Mars," I said. "Where the temperature drops
below zero as soon as the sun has gone down. Remember, the ship was
in a landing berth, and had just been prepared for a takeoff. The
technicians would have moved away to be clear of the blast. In fact,
they'd all be inside their shacks, having coffee against the chilly
weather they'd been exposed to. All it took was someone bright enough
to get hold of the water tank, and to spray the water into any handy
container where it would freeze solid in a few seconds. Then the chunks
of ice were substituted for the boys in the bunks, and Anders took off
with no one but himself on board."
"You reasoned this out?" Snow said, incredulously. "How?"
"My gift for spotting, which I told you about. Once I knew that the
boys could not have been kidnapped from space, and that something had
to be making up for their mass aboard the _Phobos II_, I tried to think
of _where_ this something could be kept. It wasn't in the open, nor in
any of the storage space. Therefore, it had to be within the bulkheads.
But what could go within the bulkheads? Only water which had been taken
from the air to keep the humidity down. And yet this water had to
remain--without a container, mind you--in the fifteen racks at takeoff
time so that Anders' dial would register them as all being securely in
place before he pressed the starter. So in what form could water sit on
a bunk without a container?"
Snow smiled helplessly, "Ice, of course. You make it sound almost
idiotically simple." Then her face fell. "But it's only a theory, isn't
it! Or is it?"
I shrugged. "It seems borne out by a few things, Snow. When I entered
the _Phobos_, I checked beneath the canvas covering on one of the
takeoff racks. There was grit there, which is a little unusual on a
military vessel, with their one-track-mindedness about things being
spic and span. And water running through canvas, taking along the dirt
that even a military white-glove inspection can't find, leaves behind a
residue of grit."
"It still doesn't seem enough," she said wistfully, as if begging me to
prove my theory correct for her peace of mind. I was glad to oblige.
"There's more. Water weighs in at 62.4 pounds per cubic foot. So,
fifteen hundred pounds of water would occupy approximately twenty four
cubic feet; the exact surplus found aboard the _Phobos II_, in the
bulkhead tubing."
Snow looked startled, but still unconvinced. "To kidnap fifteen
boys, without Anders noting even the slightest sign of a struggle or
disturbance...."
I nodded. "Right. It is odd, isn't it! This bothered me, too, until I
checked the contents of those storage lockers."
"Oh. I'd forgotten about that!" she exclaimed. "What did you find?"
"Roughly, without going into precise itemization, there were bottles of
space sickness capsules, clean handkerchiefs, toothbrushes, packets of
soap and the like."
"And the like?" Snow remarked. "What likeness is there between those
things?"
I smiled happily, and told her, simply, the clinker I'd spotted at once
on seeing those items: "They're all items which small boys hate with
almost apocalyptic fury. But I did not find such things as jackknives,
candy, chewing gum--Shall I go on?"
"You mean that whoever kidnapped the boys took along the things which
the boys wanted?" she asked, her lovely voice making an unbelieving
squeak on the last word.
"I mean," I said softly, "that I believe the Space Scouts left the
_Phobos II_ of their own free will."
7
By evening of the following day we were in descent toward Marsport; a
slow planet-circling downward spiral with a steady braking by the nose
jets, lest we hit the atmosphere too fast and burn up. Even a thin
atmosphere like that of Mars was no fun to enter at interplanetary
speeds.
Snow, looking through the viewport beside her chair in the lounge,
sighed gently and turned her lovely gaze back to my face. "I wish--"
she began softly.
I laid my hand upon hers. "We've been over that, Snow. You must return
to Earth. You haven't a chance of finding those boys. Hell, if you
had, the Brain would have picked you. And I, with the Amnesty, can go
anywhere, do anything, get results in a hurry."
"But if I came with you...." she pleaded in a tense whisper.
I shook my head, with finality. "I've told you over and over. You wreck
my spotter's instinct, Snow. If you're with me, I'll never be able to
locate those boys. I'll miss even obvious clues."
"You weren't so fuddleheaded yesterday when you told me how you'd
reasoned out the real facts about the disappearance," she accused.
"Hell, your presence affects my thinking, not my memory! Come on, now,
see it my way, will you?"