Boundary: Chapter Twenty Three

    Ken Hathaway's eyes widened a bit. "A radius of one hundred and forty-six meters—almost a thousand feet across?"

    "Or more," Dr. Gupta said, nodding. "Half again as far across if we assume a rotation of once per minute. And farther across, much farther across, if we also wish to generate Earth gravity instead of merely something close to Martian."

    The Air Force colonel scratched his head, looking doubtful. "A rotation of once every forty seconds or so still seems awfully slow. I'm sure we could spin up to considerably more than that and remain well within tensile safety limits. Look at what we can do with suspension bridges and all."

    Gupta let Jackie field that one. "If it was just a matter of engineering, Ken, we could build it to be any size you want it to be. We could put you in what amounts to a washing machine or one of those carnival rotor things. But the problem is that a lot of people run into disorientation problems when they hit rotation over about two or three RPMs. For flights with small handpicked crews, you can ignore that problem to some extent. But our crew is much larger and is being selected for a much wider range of functions. Some of the members will be only marginally 'space-worthy.'"

    "Tell me about it," Hathaway grunted, smiling rather crookedly. As an officer accustomed to the rigorous selection procedures of the military, he was still trying to get accustomed to the much wider latitudes being applied to picking the Nike's crew. No one who suffered from really critical medical problems was being accepted, true. But Ken felt the definition of "critical" had been stretched to the breaking point. There was one member of the crew who was sixty-three years old, and another who was at least forty pounds overweight.

    Both of them, however, were also universally considered to be among the world's half-dozen top specialists at deciphering languages—and they were the only two who were willing to make the trip. So, aboard the Nike they would go, when the time came, whether the ship's captain was happy about it or not.

    Jackie continued her explanation. "Now, we're not taking anyone who's a complete groundhog—they're going to have to be able to take acceleration and no-gravity and all that—but Dr. Wu is firmly of the opinion that if we don't use slower rotation for our artificial gravity we will have problems with a significant portion of the crew. On the bright side, he's also firmly of the opinion that one-third gravity will be sufficient to maintain bone mass and prevent the other problems associated with long-term null-g situations. Ten years ago, we wouldn't have been able to be sure, but he says the most recent experiments have been consistent and clear and he's comfortable with a one-third gravity setting."

    "Okay, okay. I agree, there's a lot to be said for a big ship. We should be able to make her pretty roomy, which God knows we're going to want. Still, even if I stop her from spinning, that's a hell of a lever arm I'm trying to turn with. Wouldn't want to break 'em off."

    Jackie laughed. "Don't worry. The supports are designed to take anything you'll be able to dish out, even with the engines we're giving you. Here, take a look at our first main design model of Nike."

    The 3-D imaging view lit up and, suspended in space, a model of Earth's first interplanetary ship materialized.

    "Thank God for modern design technology." Ken mused, staring at the image before him.

    "No kidding. Without state-of-the-art automatic modeling and simulation testing and expert design packages, plus actual years of in-orbit construction experience, we'd need years to reach a workable design."

    Ken knew the truth of that. Many people didn't realize how difficult it was to design a new machine of any type. In the days before computers offered Computer Aided Design/Computer Assisted Modeling packages, design was a matter of physical construction of prototypes, testing of configurations, and iterations of these processes that could take years.

    Even after the start of CAD/CAM in the late part of the twentieth century, the designs still had to be built multiple times and tested physically for a number of purposes. The computers back then simply weren't capable of modeling the full range of complex interactions the real world would throw at a device in a high-stress environment. That applied twice over to spacecraft, which would have no safe harbor, no "side of the road" to pull over to, and which would be entering and exiting Earth's atmosphere under the greatest "environmental stress" imaginable. There was insufficient experience in the design of multiple types of space-suitable devices, in the assembly of spaceworthy habitats and vehicles, and related problems to permit the designers to make any useful assumptions.

    In the past two decades, however, things had changed. Just as an old-style CAD/CAM package had permitted one person to equal the design production of a dozen or more old-style designers, modern CDM (Computer Design and Modeling) packages made one person trained in their use equal to a department of old CAD/CAM users, plus an entire testing lab. The modern CDM packages integrated modeling software equally advanced from its predecessors like MATLAB—capable of modeling and testing a designed part to a degree never before possible. Components were automatically checked for their capability to endure the stresses inherent in the design intent, while the designer continued the main design work based on broad conceptual designs. The specifics could be modified at will, and the entire design reworked to fit new specifications, all in a small fraction of the time earlier generations would have needed. With the firm empirical knowledge derived from thirty years' of the ISS and its successors in orbit, such CDM packages now routinely produced new satellite designs, new living modules, and so on for space use in mere days—designs that worked.

    Ken's hand reached out, tracing the ghostly outline of Nike. The main ship's body was one and a half times as long as her fully-opened span—about fourteen hundred feet. From slightly forward of the halfway point, a great wheel-like ring encircled the ship, glittering with hints of both metal and transparent windows.

    "That's the habitat area, of course," Ken said, pointing. "Do you realize how huge this thing is? I mean, good God, it must be nearly three thousand feet around!"

    "We certainly do. And we'll all be discussing the logistics with everyone later. It can be done, though, with the priority that the government's put on it. The size is pretty much necessary, to give us room to operate in as well as to give us the gravity we need. We may be living in Nike for a year or more."

    Jackie circled one area of the hab ring and a separate view zoomed up. As it did so, the ring seemed to fragment into multiple identical segments with the profile of a sort of squarish croissant pastry that was being slightly bent in the middle.

    "The main structural elements here, and in the main body, are standardized units that lock together. The internals can be customized almost limitlessly around a set of standardized modular connection points. You'll have hallway sections that basically have nothing but empty space, and habitable sections that are in the center of a bunch of supplies like water which help with shielding. The same, as a rule, with labs, dining or rec areas—and all of them based on the same support and maintenance structure. The main body has its own standardized assembly parts. This allows us to crank out a lot of the ship from a relatively few assembly designs, then fill it up with what we need. The fuel areas, of course, are basically subdivided tanks."

    Ken nodded, continuing his visual tour. To the rear of Nike, six great blocky assemblies, arranged in a pentagonal rosette with the sixth in the center, ended in the unmistakable vents of nuclear rockets. Front and back ended in smooth curves, the forward end coming to a graceful point. Colored areas indicated windows and sensor mountings.

    "You've streamlined things along the front to back contours," Ken remarked absently. "Why? She's not going into atmosphere."

    "Are you objecting to her appearance, Major?" Gupta's voice was slightly nettled. "Can an engineer not also have some appreciation of aesthetics?"

    "Oh, no, no, not at all. She's beautiful. It's just..."

    Gupta accepted Ken's backpedal with a gracious nod. "Still, it cannot be argued that there is effort involved in such design and manufacture. Perhaps making the ship streamlined would be cheaper and more swift. Yet, there are other considerations."

    He nodded once more, to tell Jackie to continue. Gupta liked to distribute explanations among all his engineers, rather than be the sole source of information.

    "Publicity," Jackie said. "This project is going to get rammed through no matter what people think, but the better we can make it look, the better it will go over. And the ship itself is going to be one of our biggest advertisements. We want everyone who's got a shred of imagination to be able to visualize themselves aboard her. And... well, some of them would balk at a spaceship that looked like it was put together with an Erector set, even if it was perfectly safe and practical."

    Ken looked up. "Believe me, I'm not complaining. That, my friends, is a ship. We've been sending out little rowboats up until now, but this time we are going in style. Does she have to be quite that large, and can she be that large—that is, can she be built that large fast enough?"

    "Well, like we said, diameter-wise the living quarters have to go out that far. The rest of the body is actually—relatively speaking—easy to build. It's going to be mostly storage space for equipment and consumables, and of course the main drive systems. Currently we have plans for one reusable orbiter/lander to be carried along, depending on our cargo capacity—we're going to want to bring a hell of a lot of instrumentation and analysis equipment to Phobos, so I don't know how much spare capacity we'll have."

    She pointed to another part of the image. "The habitat ring will have some small attitude drives on it. The leverage advantage will allow you to adjust direction, or spin up the ship, efficiently from that point. But most of the drives, both main and secondary, will be on the main body. It's not something you can whip up in your garage, no, but the real complexities will be in designing the living spaces to hold the people, give us all lots of flexibility in what we see and do and where we can go during months in space. Even after we get to Phobos, it's going to be quite a while before we can live there. So I figure we've got to have living space that'll be comfortable for at least a year or two. Even with the rotation shuttle idea."

    Ares' engineers, following up on their own designs, had pointed out that once they got several return modules sitting on Mars, they could easily set them up to return to Phobos and then continue to Earth. That would make it possible to literally keep up a rotation of people on Phobos base, with people spending a few months to a year on Phobos and then ending up back on Earth in a few months. The returning launches of supplies could be alternated with replacement personnel, keeping the Phobos base fully staffed.

    This was a far preferable alternative than to have to use Nike to go back and forth. Nike's vast power and resources were much more likely to be needed at Phobos. NASA had agreed with the basic concept, but added that the proper design approach should allow them to have reusable vessels which could act as orbital ferries. The first of these would be produced for Nike to take with her to Phobos; others would follow.

    "Six engines? Are we talking about six like the prototype? Six million pounds of thrust?"

    "And with a delta-vee of about twelve KPS."

    "Holy..."

    "That makes her mass ratio about four to one—3.89 and a smidge, actually," Jackie continued smugly. "Basically, if we take the trajectory we intend to, you'll be starting with about two KPS extra delta-vee. We wanted a lot of safety margin in there. Until we get safely established and the Ares processes kick in, there's no refueling for us."

    "But, why the hell so overpowered? I'd think a tenth that thrust would be enough. More than enough."

    "Oh, undoubtedly." Jackie laughed. "It's overkill, sure—if our purpose was simply to move Nike from Point A to Point B. But this is also another political maneuver to satisfy at least three different purposes."

    "Three..." Ken studied the design. "I get it. The five exterior engines and reactors can be unshipped, can't they?"

    "Give the man a cookie. Exactly. Take them all off and Nike still has one big-ass engine that's a bit of overkill, but a little extra power never hurt anyone. The NERVA fanboys and fangirls, of which I confess to being one, wanted to play around with possible nuclear rocket landers. With Mars' weaker gravity and no real environment to worry about, it's an ideal test location for things like that. More importantly, separate nuclear reactors of that size offer the chance to have a lot of power—and even redundant power—available on Mars or Phobos. It's also a showoff maneuver. Nike will be a powerful ship, and we can design the ship to take that level of stress."

    "In addition," Gupta chimed in, "if one such engine is sufficient for a vessel such as Nike, consider. We have here the chance to get several such engines built and sent into space. But only now—only now. The political winds are fickle, are they not? If we already have the engines—nuclear engines, which are the sort most likely to cause fear and caution to delay the launch—it makes it much, much more likely that additional large interplanetary vessels will be built. Would it not be desirable to have several Nikes, several large research and exploration vessels, while we indeed have the chance?"

    "I see. Very clever, Doctors. Build a really impressive ship and put in incentives to build more just like her." A broad grin spread across Ken's face as he contemplated the possibilities.

    "Sooo... If I floor her, am I going to make everyone black out?"

    Gupta's rich laugh rolled out. "Alas, I feel that this is extremely unlikely. We are using nuclear reactors, which have so very much shielding, and must have multiple redundancies and failsafes, and are taking so very, very many people and equipment... Were we using Orion, ah, then we could promise to give you accelerations of such magnitude. But I do not believe, even with our best efforts, that we could give you much more than a gravity or so, even when the vessel is nearly empty. Still, when you do, as you say, 'floor her,' I guarantee that it will be felt by all aboard, and felt for quite some time.."

    To a space engineer or astronaut, these were numbers that weren't seen in real life; they were fantasies. Oh, Ken knew that any science fiction buff could dream of a "reactionless" drive that allowed one to tool about the solar system as if driving a car. But in real life a "burn"—the firing of an engine—was measured in seconds, the change in speed in a few hundred meters per second, and the transition from one planet to another measured in many, many months.

    To save weight and space, energy and thrust budgets were worked out to the greatest precision possible. A spacecraft was generally hoped to arrive at its destination with just a tiny bit of reserve left in its fuel tanks for final positioning, as every ounce of fuel taken to the destination was an ounce of payload wasted.

    The "mass ratio" was perhaps the most telling statistic. It was the ratio of the mass of the fuelled ship compared to the mass of the "dry," or unfueled, ship. By way of comparison, a chemical-fueled ship with the same "delta-vee"—which meant the potential to change the velocity of the ship, the power to speed up and slow down, measured in absolute total speed change—of twelve kilometers per second would have a mass ratio of fourteen or more.

    Colonel Hathaway was pretty sure his face now looked like that of a child at Christmas. Jackie and Gupta both smiled back at him.

    "You seem to approve," Jackie said finally. "Then would you like to get into details? We've got a lot to cover in this overview."

    "Yes, please!"