Under the temporary command of Commodore Theodore Wilson the space
squadron sped out into the uncharted wastes of the sky on the true line
toward Castor. Slowly, as the squadron flew, its component spacecraft
diverged in a narrow cone so that the volume of space to be covered
would fall within the scope of the detection equipment aboard each
ship. Computers flicked complex functions in variables of the laws of
probability, and came up with a long series of "and-or-if" results.
Toby Manning, Master Computer for the squadron, sympathized when Wilson
showed the latest sheaf.
Wilson grunted, "This is no damn good at all. It sort of says that the
lifeships will be wherever we find them."
Manning nodded. "Like the problem of catching a lion on the Sahara
Desert. You get a lion cage with an open door, electronically triggered
to close at the press of a distant button. Then the laws of probability
state that at any instant there exists a mathematical probability the
lion is in the region of the cage. At this instant you shut the door.
The lion lies within the cage, trapped."
"Stop goofing off. This is no picnic. Have you any idea of how many
square light years we have to comb?"
"Cubic light years, Commodore Wilson."
"Cubic. So I'm sloppy in my speech, too? Look, Manning, all we really
want from you is the overall conic volume in which the lifeships must
lie. You know the course of Flight Seventy-nine. You know the standard
take-off velocity of a lifeship. The forward motion plus the sidewise,
escape velocity, produces a vector angle which falls in the volume of
a cone because we don't know which escape angle they may have used. We
can pinpoint the place of escape fairly close."
"Yeah, within a light year. Maybe two."
"And we know that the lifeship will reduce its velocity below light as
soon as possible."
"Naturally."
"So somewhere on that vector cone, or within it, is a lifeship--two
lifeships--traveling on some unknown course at some velocity
considerably lower than the speed of light."
"We've located 'em before. We'll locate 'em again."
Wilson shook his head worriedly. "That's a lot of vacant space out
there. Even admitting that we have the place pinpointed, the pinpoint
is a couple of light years in diameter, and will grow larger as time
and the lifeship course continues. Or," he added crisply, "shall we
take a certain volume of space and assert that a definite mathematical
probability exists that the survivors lie within that volume?"
"Sorry, Commodore. I didn't mean to be scornful."
"Well, then, you'd better set up your space grid in the coordinate tank
and we'll start combing it cube by cube."
"Correct," said Toby Manning.
The "tank" was not really a tank. It was a stereo projection against a
flat glass wall at one end of the big Information Center Room below the
bridge section of the flagship. Wilson went there some time later to
watch the bustle as the tank was set up to cover the segment of space
they intended to comb.
Even looking at the thing required some training. The plotters and
watchers wore polaroid glasses to provide the stereo effect. Through
the special glasses, the tank looked like a small scale model of this
section of the sky. Castor and Pollux and other nearby stars were no
longer pinpoints on a flat black surface, but tiny points of light that
seemed to hang in space, some in front of and some behind the position
of the screen itself.
Behind the glass screen, a technician was carefully laying a curve down
on a drawing table with a pantagraph instrument. As he moved the pencil
point along the curve, a thin green line appeared in stereo, starting
close by and abruptly, and leading towards the dot labeled Castor.
The loud-speaker said, "This green line is the computed course of
Spaceflight Seventy-nine."
* * * * *
A red knot was placed on the line.
"This is the approximate point of explosion."