Pillar to the Sky (7 page)

“I use to promise him that when I grew up,” she finally continued, voice a bit husky, “I’d find a way for him to run and fly again. A little girl’s promise. He’d hug me, laugh, I still remember the feel of his whiskers on my cheeks when he hugged me and how the nurses at the hospital treated him with such respect. He always wore his medals on his hospital bathrobe and…”

She cleared her throat, coughing a bit nervously, her eyes bright with emotion, and then she looked back at the whiteboard, filled now with her diagrams and formulas.

Neither of the men spoke, Erich just looking at her with a knowing smile, Gary averting his eyes and then noticing the framed Victoria Cross on the bookcase behind his mentor. Hero of the Soviet Union, Victoria Cross, both the equivalent to the Medal of Honor in America … He felt humbled.

“It will make the rocket propulsion system obsolete,” she announced, swiftly but not too adroitly changing topics, “as obsolete as steam power for trains or piston engines for long-distance flight.”

“In other words, your proposal would put a lot of people working at Kennedy Space Center and Houston out of business,” Erich said dryly, and Gary could see that the old man had been touched by her personal moment and was glad they had shifted back to this proposal. “I still do have a few friends working there.”

She did not reply for a moment.

“Should we have stuck with steam-powered trains, sir?” she finally replied.

He chuckled and shook his head no, then looked over at Gary. It was time for the “gladiator games” to begin again.

“Now, Mr. Morgan, I’ll give you the first shot at the questions.”

Gary hesitated, still touched by the comment about her grandfather. His own grandfather had flown B-17s during the war, and he had gone to many an air show and several reunions as a boy. It had triggered his own fascination with aviation and that of his father as well. A father who had been a naval aviator, flown in the early days of the Vietnam War, then died in a senseless civilian aviation accident. No heroic medals—as was true for so many in that war and the one his grandfather had been in—for men who fought with utmost bravery, in conflicts where heroism was commonplace. Growing up, Gary and his father would go along with Granddad to air shows. The old man would always puff up with pride whenever he was near a B-17, and anyone within hearing distance, especially a fellow vet, would know he had flown one through twenty-five missions. On the other hand, there were at times long silences, and sometimes Gary heard him waking up in the middle of the night, crying out for a comrade to bail out, bail out …

Gary wondered for a moment what had compelled Eva to go into aerospace engineering besides the memory of her grandfather. But then again, what had compelled him as well? Perhaps it really was the wonder of it all, the idea that a frontier still awaited.

“Mr. Morgan, any comments, or are you so captivated by Miss Eva’s arguments that you fully agree and believe we should start construction tomorrow after I put in the hundred-billion-dollar budget proposal, which, of course, will pass without comment?”

Gary looked over at her, made eye contact, and tried to smile, then saw that she was still a bit off-balance from a public recollection of what were obviously very private memories.

“What are you proposing it be built out of?” Gary asked, going straight to the core problem.

“We don’t have the material yet,” she answered openly, obviously having been hit by this question before, “but…”

Erich chuckled as he tapped the ashes out of his pipe, refilled it, and lit it. Both looked at him.

“We all know there is a ratio between compression strength, tensile strength, and width of the foundation. Cathedrals are a good example. As they strove for height, the width of the foundation had to become bigger. They solved it, at least to the limits of their ability, with the flying buttress support, but even then the practical limit for stone buildings was only several hundred feet before the foundation became cumbersome to the point of absurdity.

“If you want an interesting example go, take a look at the highest stone tower in England, at Salisbury, at over four hundred feet high. The support beams inside the cathedral bulge outward more than a meter from the stress. A sharp eye by a full-time structural engineer assigned to that wonder, and high-tech lasers monitoring the bulges in the support columns, keep constant watch on it, because someday the stress overload will cause it to collapse. The same is true with any tower: the more weight compressing downward due to gravity, the wider the foundation. If we tried to build this tower with tungsten steel, for example, the foundation would be scores of miles in diameter, clearly an absurd proposition.

“So, Miss Eva, your answer?”

She nodded in agreement.

“Steel gave us the skyscraper,” Erich continued, “but above a few thousand meters, you start to run into the same problem, though you could just keep expanding the support base and make the building wider—but then, that adds more weight and more foundation.

“You could build this tower of steel, even a Tower of Babel of bricks, but the foundation?”

She smiled, sensing he was playing with her a bit, but Gary did know this point was true. You could build anything you wanted to any height if you kept broadening the foundation to bear the tremendous weight, but that, of course, did not take in a number of other factors that would tear a steel tower apart long before they even got a fraction of the height desired.

“Even if you built it of diamonds,” Gary interjected, “I doubt if it would met all the stress demands.”

“There’s promising research in carbon fibers,” she replied. “It is already revolutionizing aviation design, and the Japanese apparently are doing a lot of behind-the-scenes research on this.”

Erich nodded.

“To what percent of usability?” he asked.

“I’m not sure, sir. That’s classified by them, and that fact alone should tell us they are onto something big. But the published literature is saying it’s moving along a lot further than anyone predicted five years ago.”

Erich stood up and sighed as he stretched. For the first time Gary saw him walking and noticed a slight limp—a memento, he’d learn later, of a commando attempt to capture Rommel and the source of the Victoria Cross.

The old man opened up his briefcase and, of all things, pulled out a pack of paper soda straws, then opened it up, drawing out several. Limping over to the whiteboard, he took the blue marker from Eva and drew three arrows alongside the line representing the tower.

“Whatever it is built with has to be able to withstand three stresses. The first is compression, the weight of the object itself, which increases, of course, the higher up you go. You could actually build this tower out of soda straws, but at some point the weight of the straws above will cause the bottom ones to buckle unless you add more and more to the base until they cover half the planet.”

To make his point, he held up a straw, then put a finger atop it and pressed down until it buckled.

He tossed the broken straw aside and now held up three straws and did the same, but this time they were bundled together in his hand and did not buckle.

“So tie three straws together but then you have to do perhaps two straws for the next ones atop the first three, and so on.”

He took two more straws, positioning them atop the three.

“We could play around with building a tower ten feet high now with these,” he said as he used a bit of tape to secure the three straws into a bundle, then did the same to the two atop the first three, and then the one atop the two. He set it on his desk and pressed down on the top straw with a finger until finally the structure collapsed.

It was obvious Erich had thought this little demonstration out the day before, and Gary inwardly smiled. It was more befitting of a high school science class, but it definitely illustrated the points he was making.

“Now, if my budget allowed for additional straws, I’d bundle six straws together, then put five on top of them, then four, and so on, and maybe we could build a tower fifty feet high of straws, but in the end it will collapse.

“Which definitely tells us we cannot build this tower of soda straws”—there was a bit of a playful smile—“unless we build a base inside the entire beltway around Washington and cover over the entire city.”

He paused.

“Actually, not a bad idea,” he muttered.

“So,” and he wrote a
C
next to the downward arrow, “first there is compression, which can be defeated only by expanding the base to an utterly absurd width.”

He then put a finger next to the arrow pointing up.

“So now we have our second problem, and that is vertical tensile strength. Not much of a problem for an earthbound tower a few miles high. But go out 23,000 miles?”

He shook his head.

“The centrifugal force imparted by the rotation of the earth will actually be trying to fling that tower up and away once you get out past…” He paused.

“Around 18,000 kilometers up,” Eva interjected, “but, yes, sir, that upper part will be imparting a tensile or extension pressure. But to a certain extent that relieves the compression. Also—and this is crucial—gravity decreasing at an inverse ratio becomes significant even when just a thousand kilometers up. This is where the entire formula gets very complex. The higher you go, the less the compression weight created by gravity and then eventually the tensile effect of it trying to pull itself apart from above. In part, this does cancel out the issue of compression once above a certain height.”

Erich smiled, as if pleased with an exceptional student, even as he fished a few more straws out of the pack and put all but one aside.

He held up the remaining straw, held one end, then pulled on the other, and it quickly stretched out and became distorted.

“So, even if you have something that can withstand the compression weight, it still has to hold up to the force that will try to stretch it out until it breaks and the upper part just goes flying off into space because of the momentum imparted by the earth’s rotation. That is one tough formula to play with, Miss Eva.”

She nodded without replying. It was obvious the old man had already prepared these responses and was a step ahead of any intern.

“Now, finally, the third force, which is lateral stress.”

This time he held up one straw and pushed at the midpoint: it buckled over.

“The difference in angular momentum the higher up you go and lower down within the atmosphere can be impacted even by terrestrial weather. You ever been up a tall building, like the World Trade Center towers in New York, during a storm? Those buildings are designed to sway as much as six feet, and they are only a thousand feet tall. Some people have to quit their jobs there because they keep getting motion sickness. In fact, NASA has helped more than one building designer with wind-tunnel testing.

“You figure out the square footage of a side of the tower: it gets hit by a hurricane all the way up through and beyond the stratosphere, and the lateral stress loads are enormous. Out in space you even have, of all things, the solar wind, minute but impacting during a major solar event. Along over 20,000 or more miles of structure, it would be noticeable, especially if there is a major solar storm or coronal mass ejection storm.

“Now let’s add in the fact that there are slight but noticeable anomalies in gravity, depending upon where you are above the earth’s surface. That really threw us off-balance when the first satellites were going up and their orbits seemed a bit odd because of that difference in gravity over different locations because the earth is not a perfect sphere. And then let’s add in the influence of the moon’s gravity, even the sun’s gravity. It all adds up to one heck of a calculation.”

He looked at the broken straws on his desk, sighed, and sat back down.

“What about meteors, space debris, and satellite impacts?” Gary now threw in, and he almost regretted asking the question, because it was obvious that Eva, who was looking at the straws, was more than a little crestfallen at the moment.

Erich nodded in agreement.

“There are something like 10,000-plus objects in orbit as we speak, ranging from fingernail-size fragments, to an astronaut’s glove, a rather expensive camera someone let float away, and satellites weighing several tons. All of them cross the equatorial plane twice in each orbit around the earth. On any given day, chances are one will come very close indeed to the tower. I’d guess that at least a few times a year, though we’ve yet to model it on a computer, a tower even a few centimeters wide would suffer an impact. And as Gary mentioned, meteor impacts are an unknown quantity but have to be anticipated, from something the size of a grain of sand to a darn big boulder tumbling along.”

Eva sighed and finally said softly, “So you think it is impossible, sir.”

Erich was silent for a moment, picked up one of the straws, twirled it around, then inserted a second one into it, then a third, and let the end drop into his empty coffee cup so the small tower leaned up and out at a drunken angle.

“No, I don’t think it impossible at all. If I believed in that word, Apollo never would have gone further than that whiteboard”—he smiled—“and you would not be my intern this summer.

“You just told me your research project for the summer. And amongst other things some Cray time to try to model how many impacts per year striking a one-centimeter-wide tower would give us a solid number beyond mere guesswork for now.”

She looked at him in surprise, a delighted grin creasing her features, green eyes sparkling.

“I’m running a lot of different things here, most of them crackpot, and I’m already late for my next group. We’ll meet here same time every morning to talk things over, and once a week I’ll want a written report from both of you as to the progress you’ve made. First things first: the latest data—declassified, of course—on carbon nanotube development, which will most likely be the only material that could withstand the forces involved.”

“‘We,’ sir?” Gary asked, a bit confused.