West of Nothing

32. Breaking Down a Leg

While Johnny was solving the puzzle of the X-Bot's DNA, the first results began to come in from the materials lab. In contrast to the bio-labs, the mat-lab was a get-right-down-to-business affair. Give them some piece of tech and they would tear it down, scan it inside and out, and tell you what it was made of. So long as there was a plump check involved, they didn't ask questions.

A single lab was handling all the work. There had been heated debate on this point. Wasn't that like putting all your eggs in one basket? But Goat and Doogie combined forces to win the argument. Whereas the interior tissue was more or less an undifferentiated blob, the leg was a functional unit. Chopping it up and sending pieces off to different labs would have diminished their chances of finding out how it functioned. Besides, a mechanical component, even a really clever one, was not likely to raise suspicion in the same way a strange new life-form might.

Still, it was a risk. What would the mat-lab make of any internal, cellular structures?

"Absolutely nothing," Goat assured them. "These are engineers we're talking about. They are highly intelligent but very focused and literal minded. You ask them to solve for X and they won't even think about looking at Y, much less Z. One time a honeybee found its way into a container being sent off for analysis. The lab did a full workup on the bee, over two hundred pages of scans and schematics down to the beat rate of its wings and the electrical conductance of its antennae. They called it a self-replicating, carbon-based pollen-vector device. They charged a handsome sum too. When the client refused to pay, they took them to court and won. After all, the bee was in the sample box. How were they to know it wasn't part of the work order?"

"Whoa, that's crazy," Mason said.

You know he's pulling your leg, right? Gabby private messaged him.

Of course, Mason lied.

When the first scans arrived, Mason could only sit and stare at them, gob smacked. Comparing these to the ones made on the Bridge was like comparing a Hubble image to one taken with a backyard telescope. Of course, the mat-lab didn't have to contend with kludged together equipment operating on a live specimen.

The different materials had been color-coded. The internal structure showed up as a blue webbing of criss-crossing struts that attenuated in the middle and finned out where they adhered to the shell. When he showed it to Gabby, she immediately recognized it as the product of a stress-optimized space-filling algorithm, similar to soft bone structure. By contrast, the red fibers were clearly tensors, muscle analogs for tugging the leg in various directions. The white fibers served as the sinews and ligaments. They came in two types: short, fat ones that bound the segments together at the joints and long, slender ones that attached to various interior points.

The scans showed that the X-Bot's leg was not just a fancy marionette manipulated by individual strings; movement required precise coordination across multiple segments and muscle groups. That demanded a sophisticated command and control system with near-instantaneous feedback. This was surely where the yellow threads came in. They ran the entire length of the leg, sprouting tendrils that reached out to the tensors and even penetrated into the stiff shell, which was shown in gray. Mason was no biologist, but the resemblance to human nerve fibers was striking. Perhaps there was an optimal design pattern to this sort of thing, regardless of whether it was a real spider or a robotic simulacrum.

He pulled up his own models, which were crude by comparison, and arranged them side by side. He had copied the outside with reasonable accuracy, but that was the visible portion after all. He could hardly blame himself for having conceived of such a simplistic interior design. Robots were the product of human engineers with an inborn preference for smooth surfaces and clean lines, and Mason was no less guilty of this sin. When was he going to stop underestimating the X-Bot?

While the CAD diagrams could be understood by the casual observer, the reports Goat received were inscrutable to anyone without an advanced physics degree. The listing of elements and compounds was the least obtuse part. There were pages of diagrams that, from a distance, looked like isometric dungeon maps. Blocks of small text referred to nucleated crystals, electron affinity levels and other arcane terms.

Mason would ask a question like, "What does this chart mean?" and Goat would patiently explain. "It's a spectogram. It shows how light scatters off atoms."

"And this one here?"

"It measures electrical resistance, or how freely electrons flow through a medium. At one extreme you have super-conductors and at the other, insulators. Silicon is famously somewhere in between, a semi-conductor."

And on it went. In this way, Mason learned the outer skin was indeed made of graphene but interleaved with other layers for insulation and shock absorption. Graphene, a bona fide miracle material, was in some ways too good. In pure form, it was so thin and durable that shocks and stresses were transferred undampened to the internal structure. In comic books, much ado was made over bulletproof skin with scant attention paid to the blunt force trauma to the guts of the guy underneath. In addition to compression forces, the X-Bot's shell also had to cope with lateral sheer. To this end, it contained what Goat referred to as zippers, microscopic seams that tore open and just as quickly resealed themselves. This allowed the leg segments to stretch and deform without putting undue strain on the joints and connecting fibers.

"This is interesting," Goat said, tracing his fingers down a series of bars in an appendix titled Isotope Distribution of Common Elements using Stochastic Sampling. "Are you seeing this?"

"What does it mean?" Mason asked. For all he could tell, the bars might represent a distribution of penis sizes by GPA for robotics undergrads.

"It tells us what types of isotopes are present in the sample and in what proportion."

"Isotope, that has something to do with the nucleus of an atom, right?"

Goat stared at him incredulously. He had a tendency to forget he wasn't speaking to one of his erudite colleagues in the Applied Materials department. "An isotope is an atom with a different number of neutrons in its nucleus. It doesn't change how the atom behaves chemically but it does affect its atomic weight."

"If it doesn't change how it behaves then why does it matter?"

"An isotope can tell us something about an atom's origin. For example, the inner planets have a higher concentration of heavy oxygen-18 because they don't get pushed around as easily by the solar wind. You can think of them as bigger pebbles in a stream. Different isotopes also have different decay rates so you can use them as a dating mechanism."

"What does that have to do with the X-Bot?"

"According to these readings, the X-Bot was made a billion years ago on Pluto." Now it was Mason's turn to look incredulous. Goat laughed. "I'm just kidding. At least about the made-on-Pluto part. But the isotope anomaly is strange. Normally I don't even bother looking at them. One piece of matter taken from the Earth's surface looks pretty much the same as any other, isotopically speaking. Unless it spent some time in a radiation zone or got chipped off a meteorite."