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"I thought I was still hunting. Lucky I wasn't, or I'd be dragon meat.
Sorry to shock you like that. I injured my arm yesterday. It's still sore."
"My apologies Sir. You said anyone should wake you if they found
something. It looks like I've got the start of a trace. If you'd like to come to
my screen I'll show you."
"Can we get a coffee first? My throat feels parched."
"This way Sir."
Although it's morning, the light in the communications centre is dim. Hector
and the engineer who woke him walk past a line of men, who look like they could
be sleeping, except that the screens they stare at, change and move under the
control of invisible threads which link man to machine. At the end of the row
are some coffee jugs which are permanently full. Hector takes two cups for
himself, and follows the engineer back to his console drinking as he walks.
"What's your name?"
"ComsWatchman Auberon Sir."
"Well ComsWatchman Auberon, what have you found?"
"I was assigned to the initial contact trace Sir. Using the range of
times you gave me for the arrival of the alien, I searched back through the
archives to try and find a physical trace. I couldn't get anything on the normal
sensors."
"No, that's one of the mysteries. We know Carlos landed, and we know he
must have come from a ship. But it was never spotted at the time."
"As I said Sir, I couldn't find anything, so if they did make physical
contact they were well cloaked. If you look at the screen you'll see the kind of
thing that our sensors pick up."
The screen is a mass of random spots.
"I can't see anything."
"No Sir. No matter how you process this data, you can't get a
discernable trace. But, I thought to myself there must be one. It's just a
question of looking harder."
"Is it possible they were cloaked so well that we wouldn't pick up any
trace at all?"
"No, Sir. Although, whatever they use it's better than anything we've
got. If their ship was still it would be impossible to find. But a ship on the
move has to make a disturbance. It's against the laws of physics otherwise.
Anyway I tried to superimpose the data from other sensors, at different parts of
the spectrum, infra-red, ultra-violet, gravitronic. This is what I got."
The next screen looks very similar to the previous one, but has a higher
density of random dots. Hector strains his eyes at the screen.
"I still don't see a trace."
"No Sir. I was still unable to get a trace using this method. The dots
are still random, even when you superimpose all the frequencies. And then I had
an idea."
Hector watches the screen fascinated at an animated time sequence that looks
at first like the trace like a leaf being blown in the wind. As it progresses it
shows the unmistakable deliberate approach of a bright dot close to Scythia.
Then it parts into two dots. The two dots blow around their different ways, one
of them glancing into the atmosphere. The lurching of the dots continues, but
when they join up again into one dot and move away together, it clear that what
he has seen is the trace of a man made object. The alien ship. The trace stops.
"That's all I've got so far Sir. It took me an hour or so to figure out
what they were doing, and I didn't have much data. Is that what you were looking
for?"
"How did they do it? Why couldn't we see them before?"
"Well it's quite clever really, and it would have taken me a lot longer
if I had to look at more data. It was very lucky that you had a good guess at
when they arrived. I don't understand the technology of how they do it Sir, but
what they seem to have is the ability to control the emission of radiation at
all frequencies from an envelope around their ship. They can't stop radiation
getting out altogether, because even a black hole emits gravitrons, but what
they can do is control the wavelengths of the leakage. They move in a random
sequence of short jumps. So if we look at any particular part of the spectrum,
there's nothing to correlate into a recognizable motion. But if we assume they
are shifting through the wavebands at regular intervals, then this is the sort
of thing you start to see at first."
The screen starts to show short groups of dots that grow and shrink
independently like worms stretching and shrinking all over the screen. When the
worms join up, most of them disappear and leave a single tangled line, of a
superworm that's tied in a knot.
"Once I saw a group of dots appearing, I realized what they were doing
so I ran a search algorithm to try out different frequencies and maximize the
length of the traces. It looks like they can rechannel their emissions into any
part of the spectrum about a hundred times a second. Now as you know, Sir, our
space sensors need to integrate a signal for quite a while to filter out
background noise before they'll give you a reliable signal. So the frequency
hopping makes it harder to spot them because we only get a weak signal to start
off with in any given band."
"Let me see if I understand it. Not only are they moving randomly in
space which makes an extrapolated trace difficult, but they control the colour
of the spectrum we see them in at any time. So we never see them moving in a
straight line at any frequency, before they've changed direction again. Hence
they're invisible."
"That's it Sir."
"That's very clever. Is it a technique that we could reproduce?"
"I'm not a technologist Sir. I didn't even know it was possible. But
if we know someone else has done it, I'm sure that our technologists can repeat
it. It could be a useful technique, if no-one else knew about it. It would be
better if they used a random timing but there may be a technical obstacle that
makes it more difficult."
"That trace we're looking at, how long is that in real-time from end to
end?"
"That's a good question Sir. I don't know. Let me check."
The ComsWatchman's fingers scrabble around the desk.
"It looks like it's most of the data segment I requested. And I was
working on a dump going back over the last week."
"So they were actually in our system for quite a while before they
introduced themselves. And if they hadn't, we wouldn't have detected them at
all."
"It seems not Sir. Yes, I would say my trace is at least a week long. I
would have to download more data and work backwards to give you the exact
answer."
"Don't worry about that for the moment. I'm more interested in finding
out where they are now, rather than where they were last week. How long will it
take to find them, now that you've got a starting point?"
"It will be more difficult, because it involves looking at a larger
area, so I'd have to correlate sensor data from several sources. If I was doing
it on my own, and had a good CPU priority..."
"What if everyone was working on it? and all CPU time was dedicated?"
The ComsWatchman's eyes widened. "Sorry Sir. I didn't think of that.
In that case, it shouldn't take more than about five or six hours. Assuming
that they're still somewhere in the system."
Hector smiled. "I'm sure they will be. If they managed to spend a week
practically on our doorstep without being seen, they'll be quite confident. And
we know that the signal sent to their ship won't get very far. Congratulations
Senior ComsWatchman, I think you've found our prey. It will be
interesting to see how sharp their claws are, once we've got them cornerered." |
