“I don’t want to hear that we’re going to be grounded again or that we need a delay…” Mildred paused, mid-sentence, as Lori’s words caught up to her. “I can go… you mean… wait… but…” Mildred paused again, this time speechless. She had worked on this project for years, working tirelessly to ensure that every little detail was perfect. As the operations manager for the crawler, she was in charge for making sure that they could deliver a product that was spaceworthy and safe. An engineer by training and a scientist by nature, Mildred had not spent many hours dreaming about what it would actually be like to travel in the machine she was building.
“You are to report for flight training tomorrow morning. I’ve read your report about the crawler and I accept that it is now ready for launch. We will move it into position by the end of the week. I’ll expect you to be fully certified to travel as an officer on board the crawler,” said Lori, a wide smile breaking across her face.
“I have a hundred things I have to check on the crawler before I let it go. I had better get back to rechecking the final simulations to make sure everything is ready for the launch. I’ll be ready by tomorrow. I can’t thank you enough. I don’t know what to say. Thank you so much. Never in a million years did I expect…” Mildred started to ramble from the excitement rising from deep within her. Abruptly, she grabbed Lori’s hand, gave it a firm shake, turned on her heel and disappeared down the hallway. Within a few minutes, she was deep in the bowels of the Materials Science Division, running yet more simulations and making her preparations for flight certification.
The crawler that Mildred had designed was a giant cylinder, roughly the size of a six story apartment building. From the outside, it looked like a gigantic steel structure, perfectly symmetric and perfectly smooth. There were no breaks, no windows, no obvious doors, no welds, and no tiles. This outer core was made of a completely solid carbon nanofiber lattice mixed with a fluorinated ceramic composite and set in an inner solid steel mold. The result was a strong, stiff, and heat-resistant outer capsule that could easily survive the high thermal gradients a flight into space and its return to Earth would experience. This outer shell also had the benefit of being a very good insulator, thereby protecting the occupants from both the high heat of travel to space and the cold temperatures once they arrived at their destination. Embedded on the outside of this composite material was a thin layer of a photodynamic protein-based photodetector (PPBD), itself covered by a super high performance fused silica glass composite for protection. This detector array would communicate to the occupants inside, through which they would be able to see everything happening outside the craft.
Inside the craft, an inner shell composed of two separate layers provided significant protection from high energy cosmic radiation to the occupants, including alpha, beta, and gamma rays. The outside part of the inner shell was a thin layer of lead, designed to stop the majority of alpha and beta rays that somehow made it through the outer shell and also to stop a significant percentage of gamma rays and other high energy cosmic rays. The inner portion was an organic and metallic composite embedded in a mixture of polyvinylchloride and polyurethane. The metallic ions were on the higher side of atomic table, while the organic compounds were specially designed to absorb high energy radiation. A one inch thick layer of this material was equivalent to nearly a foot thick layer of lead with regard to its protection from radiation. It was lighter than lead, had a rubbery and pliable texture, was malleable, and performed better than lead. A small company that had made this material, once known as Demron, had been acquired by Kent’s group to further support research into this important field. It was only a matter of time before this layer could be integrated into the carbon nanofiber lattice to provide protection from heat and radiation while sealing the spaceship from the vacuum as a single layer.
This inner core was sealed and covered with a stacked polymer light-emitting diode, thereby creating a gigantic screen that spanned the entire vessel. No matter what structure stood between the occupants and the outside of the ship, as long as there was a PPBD at that location on the outside of the ship, the same image would be conveyed inside. It was as if the walls were made of glass, and was it not for the temperate climate inside the crawler, its occupants would not have been able to tell that they were inside a spaceship. This unique characteristic permitted the occupants of the crawler a complete view of the surrounding heavens. If they so desired, the floor could be turned into a screen and they could see the Earth dropping away from them while they ascended the elevator. They could see the transition between sky and space as they passed through the atmosphere. They could see stars in any direction once they got past the mesosphere.
The crawler had six floors, each one with roughly 2,500 square feet. Each floor was composed of a series of modular components that could be switched out depending on the particular transportation needs and how long the crawler would spend in space. Maximum passenger capacity, if only seating modules were used, could be increased to 1500 people. For early voyages to geosynchronous orbit, roomy modules organized like living rooms were used. These early voyagers could sit back on a comfortable sofa and watch the outer wall turn into a giant screen showing their transit up through the atmosphere. The entire way people thought about traveling had changed.
The matter of how the crawlers would access space was solved relatively quickly using existing technology. With the proven success of magnetic levitation used in the train system now being deployed around the world, it was only natural to adapt this technology for use with the space elevator. Magnets were used throughout the length of the space elevator - more at the base and apex, and somewhat more in the atmosphere. More magnets were required at the base and apex to permit a gradual acceleration and deceleration, and also because this is where the most force would need to be generated to begin moving the crawlers. More magnets were used in the atmospheric section of the cable due to the increased friction from air resistance. An electric current generated at the apex using solar power was carried down through the length of the tether and used to power the entire apparatus. It was more appropriate to call them gliders, instead of crawlers.
With the entire perimeter of the crawlers a sealed unit, the matter of where to load and unload people, cargo, and modules became a design issue. It was elected to load the modules from the top, so that the entire bottom and perimeter could be one sealed and enclosed unit. This decision was based on the increased heat generated during decent as the crawlers passed through the atmosphere. The crawlers would climb up the tether at a slower rate, and thereby generate significantly less heat from friction. As a result, a design taking advantage of the magnets was utilized. The entire top of the crawler assembly could be lifted free and entirely separated from the crawler. This can-opener style design made loading and unloading the crawler extremely efficient. The entire area of the circle at the top of cylinder was available for loading and unloading operations. At the Nexus, people could simply embark onto the crawler and take escalators or elevators to whatever floor or compartment they wished to go to inside the crawler. At the orbiting platform, the top of the crawler would simply be peeled off and people could disembark easily. The entire process took advantage of magnets and energy gathered from the solar panels.
These enormous assemblies were also used to ferry cargo to and from the orbital platform. With an overall volume greater than 150,000 cubic feet, there was enough space to hold over a million gallons of water. To handle this enormous cargo, both the Nexus and the orbital platform were built to have separate levels dedicated to people and the loading and unloading of cargo. Crawlers carrying cargo would stop at the lowest level of the Nexus, while those carrying people would be the next level up.
The crawlers were also designed to permit survival in outer space for extended periods of time. Their enormous volume alone would permit a small group of people to survive for over a year with minimal artificial life support. With the addition of advanced modules such as carbon dioxide scrubbers, water purifiers, waste processors, hydroponics bays with aquatic bioregeneration capability, and portable power plants, the amount of time a decent group of people could survive bordered on nearly a decade.
The matter of weightlessness was also handled. For crawlers that traveled beyond the orbital platform and deeper into space, their entire layout was modified. The cylinders were capable of rotating around their central axis, thereby using centripetal force to generate an artificial sort of gravity. The smaller crawlers with only a 25 foot radius made this rotation somewhat disconcerting, but later crawlers with a larger radius made it nearly imperceptible.
…
Mildred’s training on the operation of the crawler was entirely straightforward. The entire control of the crawler was coordinated by the Nexus and the orbital platform. Both parties shared master control and the assent of both was needed before the crawler could depart the Nexus. This was done to ensure that no accidents would happen with crawlers headed in opposite directions, or a crawler that had not yet cleared the loading platform. There was actually very little involved in direct operation of the crawler from the machine itself. Much of the training was centered on the operation of various modules, what to do for local emergencies within the crawler, first aid certification, fire fighting certification, and containing dangerous or unexpected situations by isolating modules. There were no explosives on board the crawler, no potential for sudden decompression, and only a marginal danger of insufficient life support resources such as a paucity of oxygen. Training was completed in two days, and Mildred spent the next several days waiting for the crawler to be certified for flight.
The crawler had been built directly around the tether in a fabrication plant located in one of the deeper levels of the Nexus. The modules were developed and loaded at this point, and the entire crawler rigged for its first journey.
Mildred got little sleep the night before the unveiling ceremony. She had not even dared to think about this moment, and yet it was already upon her. She brushed her hair in the morning, put on her best dress, and went to the Nexus. As soon as she stepped off the shuttle to the Nexus, she knew that this was going to be a special day. There was already an escort waiting for her, and she was ushered to a special area for the passengers. There were about a hundred people gathered for the maiden voyage, including various heads of departments, senior members of Kent’s operations, and other VIPs from within the organization. She saw only familiar faces - not one VIP from outside the company was in this special section, and she smiled privately to herself. Kent had worked them all very hard for many years, but he had a reputation for rewarding people. What greater reward than to be the first to experience such a wondrous journey?
A large crowd had gathered at the loading deck of the Nexus. Every person on the island must have shown up for this ceremony. On the next level up, VIPs from all around the world were present, having journeyed to the Nexus that very morning on the now operational rapid transit system. Kent had set up a small platform next to the opening into the crawler that they would be using today, and he looked as excited as could be. He was flanked by his launch commander, Lori Jennings, and his executive board - the people who controlled the entire operation that had created all of this.
As Mildred walked to the loading area, she was simply overtaken by the sheer beauty of this part of the Nexus. They were at the central axis, the part of the Nexus that sailed straight up in a continuous unbroken line to the stars. This was the part that the tether was at, hanging straight down from thousands of miles in space. The weather was beautiful - bright, sunny, and with nary a cloud. The light mixed well with the solar lighting that spread across all of the floors. She could just barely make out the point where the Nexus ended and sky began, over 3,000 feet into the air. Streamers hung at multiple points, carried by air currents within the enormous facility of the Nexus. Flashing signs, video monitors, decorations, even a holographic light show were all coordinated. The thrill was palpable.
“Ladies and Gentleman,” cried Kent, “Welcome to the grand unveiling of the first crawler carrying human life into outer space. This momentous day has been years in the making, and it represents a turning point in how all of humanity will look upon travel to the stars. Never before have so many people ventured into space simultaneously, all at a fraction of the cost and resources used in conventional space travel. With this maiden voyage to the stars, travel to realms beyond our planet are now within reach, accessible to all humans on Earth. Let these words ring true - we are no longer prisoners of our planet, but sailors free to voyage among the stars!”
Before Mildred could finish clapping, the line was already in motion. Already they were being ushered to the entrance to the crawler and guided to their various modules. They were about to be voyagers, leaving this planet to become astronauts. Gasps were audible in the audience outside, as the video monitors on the lid, which had previously been showing what was occurring on the other side, suddenly became opaque. The great deception was striking - people had been enjoying what they thought was sunshine and streamers - and those things were really happening, just on the other side of a massive solid carbon and steel composite now being lowered onto the crawler. A thousand seals silently moved into place, anchoring the lid seamlessly into the top of the crawler.
And to the beat of the drums and great fanfare, the six story tall crawler silently started its ascent to geosynchronous orbit. A million magnets were quietly coming to life as electricity converted from sunlight was streaming down the enormous tether.
Inside the crawler, massive screens were coming online, showing the thousands of people gathered outside clapping and shouting, watching the massive craft slowly sail upwards. Their ceilings were transparent, and the floor translucent. The monitors were intelligent enough to keep up the appearance of a solid floor directly beneath them, but the rest of the room was slowly fading away. If it wasn’t for the furniture in the room, it almost gave one the impression that a small platform was hoisting them up into the heavens.
Mildred was simply ecstatic. The slow travel through the Nexus was amazing - the beautiful symmetry of the structure, the detail that went into the design - it was a masterpiece of architecture and art. When she looked up, the sky was drawing closer and closer, getting larger and larger. The people below her were now the size of ants, barely perceptible. The acceleration in the crawler was barely noticeable at this stage - the more powerful magnets that would propel them spaceward were still to come, located several miles above the Nexus. They continued on this gradual journey, now leaving the Nexus itself. Light splashed all around them - but not enough to blind them as the intelligent monitors immediately corrected the brightness and contrast to make it comfortable for the occupants. The ocean stretched out around them, nearly unbroken. The coast of Africa was now coming into view. The island of Sao Tome visible in the distance. The sun was high in the sky, its rays reflecting off the enormous waves of the Atlantic Ocean.
They were nearing the primary magnetic complex now. This is where they would start to accelerate towards the stars. They had left the thickest atmosphere behind, with the resistance ahead of them dropping off almost exponentially. Their rate of ascent was now increasing, but it was barely noticeable to the occupants. The slow rate of increase in acceleration for the passenger crawlers was intended to keep their occupants comfortable. It was right around this moment that Mildred began to feel a little overwhelmed. The vast Earth was stretching out below them - Principe becoming a but a speck in the blue ocean and even the details of Africa becoming lost. The monitors, sensing her rise in blood pressure and heart rate, automatically made the floor more opaque. Lights turned on in the room, highlighting the furniture and helping to reorient her senses. Mildred’s nausea disappeared as fast as it had come, and her momentary discomfort was quickly forgotten.
Upwards they continued. Higher and higher, until even the vast blue beneath them was slowly losing its dimensions. Mildred’s attention was now focused around her and upward, as she thought to herself “So beautiful. No one has ever seen this ascent into space like this before. No one has ever truly marveled at the beauty of our world, and no one has ever appreciated our small our planet really is. I am leaving my planet, my home - the home for our entire civilization. Everyone needs to see this - to experience this - and to finally understand what it means to be human, and to finally understand where humanity’s next purpose lies. This cradle of civilization has helped us grow to reach this place in life - the bountiful planet has nurtured us, the brilliant sunlight has awoken us every morning - but now it is time to leave the comforts of home and journey into the adventure that awaits.”
And so the crawler ascended the tether, guided silently by the power of the sun and the fruits of the Earth. Like father and mother, they guided their sons and daughters to leave the cradle and finally learn to take the first steps.
The flimsy spider - a prototype test vehicle that looked like a motorized bo’sun’s chair - had already made a dozen ascents to twenty kilometers, with twice the load it would be carrying now. There had been the usual teething problems, but nothing serious; the last five runs had been completely trouble-free. And what could go wrong? If there was a power failure - almost unthinkable in such a simple battery-operated system - gravity would bring Duval safely home, the automatic brakes limiting the speed of descent.
- Arthur C. Clarke, Fountains of Paradise
