Brob
Bob looked forward to his sessions with the little people. They stood barely up to his knees, their squeaky voices made intelligible by the communicator. They had raised him from birth and built a habitat for him similar to their own, but on a larger scale, of course. He enjoyed taking virtual tours of their home planet, which he could never visit physically because of the crushing gravity. Still, being the only one of his kind could get to be rather lonely.
* * *
Tom had almost completed his preparations for his visit with his cousin Susan on Luna. The lunar colony was in the midst of its bicentennial celebration of the first landing on the moon.
Tom decided to give Susan a call. After dialing her number, it took about a minute for a communication link to become available. After communication was established, he saw a three-dimensional image of Susan seated at her desk.
“Hi Susan,” Tom said and waited for Susan to respond. He had grown accustomed to the three-second delay.
“How are things?” Susan asked.
“I’ll be leaving tomorrow morning and should arrive at Luna on the first of August if all goes according to plan.”
“See you then,” said Susan.
“Bye for now,” said Tom.
“Bye,” said Susan.
The next morning, Tom went through his checklist; everything had been taken care of. He went to his car in the garage and unplugged it from the charger and watched as the cord retracted into the vehicle. He grabbed the door handle while placing his thumb on the window of the biometric scanner and heard the click as the door unlocked.
After loading the car, Tom placed his thumb on the scanner window on the dashboard to activate the car. The viewscreen on the dashboard then displayed the message “Where to?”
“Airport,” said Tom.
The screen showed a map of the proposed route as well as the ETA. Tom decided to let the car do the driving.
“Drive,” said Tom.
The trip to the airport proved to be uneventful. Once at the airport, Tom boarded the flight destined for Conveyor Island that he had booked. Conveyor Island, so named for being the site of the space conveyor, is an island on the Equator.
After arriving at the airport on Conveyor Island, Tom took the maglev to the space conveyor. The space conveyor consists of a ground station connected to a top station by a conveyor belt moving along rollers on both of the stations. The top station, as well as the conveyor belt to which it is attached, is held aloft by the centrifugal force resulting from Earth’s rotation. The illustration below shows the space conveyor, followed by a close-up of the ground station.
The conveyor belt is powered by motors connected to the rollers at the ground station. In order to attach to the conveyor belt, the conveyor car is accelerated along a track using magnetic levitation and catches up with and hooks onto an attachment site moving along the bottom of the conveyor belt. Conveyor cars arriving from the top station unhook themselves when they reach the bottom of the conveyor belt. The track leads to a holding area (not shown), where the conveyor cars are loaded and unloaded. A similar procedure is used to attach and detach the conveyor cars at the top station, except that the conveyor cars are taken into the interior of the top station for loading and unloading. The space conveyor was responsible for reducing the cost of space travel to the point where it was affordable to the general public, a feat that could never have been accomplished using rockets alone.
[Readers who wish to skip the detailed description of the space conveyor can do so by going to RESUME HERE.]
The space conveyor extends 144 thousand kilometers (89 thousand miles) into space, that height chosen so that the gravitational force acting on the mass of either side of the conveyor belt is exactly balanced by the centrifugal force due to Earth’s rotation pulling the belt upward. The result is that there is no net force on the rollers of the ground station due to the weight of the conveyor belt and the attached conveyor cars, even in the presence of the net upward flow of mass resulting from humanity leaving Earth to explore and colonize the solar system. Thus, the only power required to operate the conveyor belt is that which is necessary to replace the relatively small amount of energy lost due to the friction from the bearings supporting the rollers as well as the air resistance along the tiny fraction of the conveyor belt that lies within Earth’s atmosphere, that power being supplied by an array of solar panels along with batteries to store the surplus energy for nighttime operation.
So how is it possible for the space conveyor to provide a net upward flow of material from the ground to well above Earth’s surface using only the energy necessary to overcome friction and air resistance? To answer that question, we must first recognize that the space conveyor lies in a rotating frame of reference, namely rotating Earth. Newton’s laws of motion can be applied in a uniformly rotating frame of reference provided we introduce what physicists refer to as fictitious forces, one of which is centrifugal force, which we have already considered. The second so-called fictitious force is the Coriolis force.
The Coriolis force is interesting in the way it operates. It doesn’t affect any object at rest relative to the rotating frame. An object in motion relative to the rotating frame will experience a Coriolis force perpendicular to both its direction of motion and the axis of rotation of that frame, in this case, Earth’s axis of rotation. Thus, the upward-moving (west) side of the conveyor belt will experience a Coriolis force in the westward direction, causing it to bulge slightly outward in that direction, while the downward-moving (east) side of the conveyor belt will experience a Coriolis force in the eastward direction.
A net upward flow of mass results in a net westward force on the space conveyor, which in turn exerts a torque about Earth’s axis of rotation in the direction opposite to that of Earth’s rotation, causing Earth’s rotation to slow down. We have thus identified the source of energy enabling a net upward flow of mass: the energy of Earth’s rotation!
Since the mass of the conveyor cars is only a tiny fraction of Earth’s mass, the resulting slowing down of Earth’s rotation is so small that it requires the accuracy of atomic clocks in order to measure it. Furthermore, even this tiny effect will vanish after several centuries, when the solar system has been colonized to the point where the flow of traffic leaving Earth is essentially equal to the flow of traffic arriving at Earth. In any case, Earth’s rotation is already slowing down due to the tidal drag caused by the moon and to a lesser extent by the sun; scientists correct for this effect by adding a second to the day every so often in order to keep the atomic clocks in sync with Earth’s period of rotation. The tiny addition to this rate of slowing down caused by the operation of the space conveyor is accommodated by adding a second to the day slightly sooner than would otherwise be necessary.
Before the space conveyor could be constructed, the space surrounding Earth had to be cleared of any satellites and debris that could possibly hit the space conveyor. The only satellites that could safely coexist with the space conveyor were those in geostationary orbit; even those satellites had to be carefully monitored to ensure that they didn’t drift into the space conveyor.
The conveyor belt was fabricated from carbon nanotubes, the only known material having sufficient tensile strength to enable the conveyor belt to support its own weight plus the weight of the attached conveyor cars. The carbon was obtained from coal, which was in plentiful supply since it was no longer used to generate power. It took the flooding of the coastal areas of the industrialized countries in the latter part of the 21st century in order to provide those countries with sufficient motivation for them to curb their burning of fossil fuels.
The space conveyor was constructed by first placing a space station in geostationary orbit by conventional means (i.e., rockets). A cable fabricated from carbon nanotubes was wound around a pulley, which was lowered to Earth directly above what would become the ground station. The cable was unwound from spools on the space station. The pulley was given an initial boost to get it going on its downward journey. After the pulley was some distance from the space station, Earth’s gravity pulled it down the rest of the way. When the pulley reached the ground, it was hooked onto an anchor point. The space station then moved into a higher orbit in order to put some tension on the cable at ground level. The two ends of the cable were then spliced at the space station to form a continuous loop and wrapped around a second pulley. The pulley at ground level was attached to a motor and the moving cable was used to transport supplies from the ground to the space station in order to construct the space conveyor.
Two space conveyors are currently under construction on Mars. The two Martian moons are in the process of being converted into top stations for those space conveyors as those moons are slowly being moved into areostationary orbit, the Martian equivalent of geostationary orbit.
Those passengers traveling to a destination in either the outer solar system — Mars and beyond — or the inner solar system are first transported to the top station in a conveyor car and from there board a conventional (i.e., rocket-propelled) spacecraft, which is released from an opening in the top of the top station to take them to their final destination.
To explore the solar system outside of Earth’s orbit, the spacecraft is released from the top station when Earth is between the sun and the top station, giving the spacecraft an initial speed with respect to the sun equal to the sum of Earth’s orbital speed and the speed of the top station relative to Earth, thus giving the spacecraft a boost on its journey to a destination in the outer solar system. When the destination of the spacecraft is somewhere inside of Earth’s orbit, the spacecraft is released when the top station is between Earth and the sun, thereby causing the spacecraft to initially fall toward the sun in an elliptical orbit. In the case of travel to the moon, however, being released from the top station isn’t practical because it would impart to the spacecraft a high speed relative to the moon, requiring it to expend a substantial amount of precious rocket fuel in order to reduce its speed to the point where it could safely land on the moon.
[RESUME HERE]
After Tom checked in at the ground station, he boarded one of the compact spacecraft lined up on the track waiting for the daily launch window. The spacecraft were the size of conveyor cars and, like the latter, had two hooks on top to hook onto the bar of the attachment site. The spacecraft would ride the conveyor belt part of the way up to the top station and then detach themselves, at which point they would go into a long elliptical orbit around Earth, calculated to rendezvous with the moon at a relatively low speed.
Tom entered the small cabin that he had been assigned along with his belongings. The announcement directed the passengers to secure any loose items and strap themselves into the padded recliners that had been provided before launch. Tom did as directed and waited.
When the launch began, Tom was thrust back in his seat by the acceleration of the vehicle as the latter matched speed with the attachment site. When they locked onto the attachment site, the acceleration ceased, but the passengers were told to remain secure in their seats. A few seconds later, Tom was forced deep into his seat by the centrifugal force as their vehicle swung around the second roller. After they passed the second roller, the announcer informed them that they were free to leave their seats.
Tom found the food and accommodations to be adequate, given that he had chosen to travel economy class. He kept himself occupied with the ebooks and videos he brought along. It’s amazing how much information can be stored on a 64 terabyte flash drive.
Over the next few days, Tom noticed that his weight gradually decreased as he continued his upward journey. On the fourth day, they reached the height of geostationary orbit; Tom was weightless except for the tiny amount of weight caused by the Coriolis force resulting from their upward motion.
Over the next two days, Tom slowly regained a small fraction of his weight, as the spacecraft swung around on its hooks to be suspended upward. On the second day, the captain announced that they would be detaching from the conveyor belt, alerting the passengers that they would then be weightless.
Tom looked out the window as they slowly moved away from the space conveyor. It would be another six days before they reached the moon.
As they neared the moon, the captain directed the passengers to strap themselves into their chairs, as he was about to make the final course adjustment maneuvers.
To conserve rocket fuel, spacecraft would, whenever possible, not take off and land vertically. Rather, the spacecraft would be launched by being accelerated along a long track by magnetic levitation until they reached sufficient speed to escape lunar gravity. The power was supplied by banks of solar cells lining both sides of the track, along with storage batteries to accommodate nighttime operation. Incoming spacecraft were decelerated along that track by regenerative magnetic braking, thus recovering some of their kinetic energy.
The captain carefully guided the spacecraft onto the launching and landing track. When the spacecraft locked onto the magnetic field of the track, Tom was thrust forward in his seat as the spacecraft began to decelerate. After five minutes of deceleration, the spacecraft turned off of the main track and stopped at the Luna station.
The passenger boarding bridge used to connect the spacecraft to the station is similar to the moveable corridor that commonly extends from an airport terminal gate to an airplane. After the bridge was maneuvered into position, workers outside in spacesuits locked the end of the bridge to the hatch of the spacecraft to form an airtight seal. The hatch at the station was then opened, filling the corridor with air. Finally, the hatch of the spacecraft was opened to allow the passengers to exit.
As Tom entered the station, he was met by Susan. “Welcome to Luna,” she said, as she gave him a hug.
“Good to see you,” Tom replied.
As Tom walked with Susan, he noticed that he was bouncing up and down with every step he took, in spite of the luggage he was carrying. Susan noticed it too. “Lunar gravity takes some getting used to,” she said.
Tom observed how the other people were walking. They took slow loping strides, giving the appearance of running in slow motion. Tom tried to emulate that gait, with some success.
As they continued walking, they passed near a woman with two children who were both jumping up and down, reaching heights of ten feet or more. She told them to stop, which they did. However, one of the children then ran off. When the woman loudly called his name, the child attempted to stop, but fell head over heels and began to tumble, nearly knocking over a man with whom he collided. For safety reasons, running and jumping were prohibited, except in designated recreation areas.
Susan led them to the station of the maglev train. They arrived just as the train was boarding. When they entered the train, Susan put her thumb on the scanner window to pay for both of them. “Gives new meaning to thumbing a ride,” Tom chuckled to himself.
Five minutes later, Susan indicated that their stop was next. When they left the train, they walked to where Susan’s car was parked. Her car resembled a golf cart. It had a windshield but was otherwise open. It had two seats in front and a hatchback for storage. Tom deposited his luggage in the back while Susan unplugged the car from the charger.
Susan activated the car by placing her thumb on the scanner window. As the car slowly accelerated, Tom noticed a sign indicating that the speed limit was ten meters per second and mentally did the conversion — 22 miles per hour. “Why such a low speed limit?” he asked.
“Traction on the moon is one-sixth of that on Earth for equivalent road conditions,” Susan explained. “It wouldn’t be safe to drive any faster.”
It was a short trip to Susan’s apartment complex. She parked the car in her reserved space in the underground garage and they both took the elevator to Susan’s apartment.
Tom found Susan’s apartment to be similar to his own, including the clock on the wall. The Lunans scheduled their activities around the 24 hour Earth day to which the human circadian rhythm was adapted by evolution. They also used the Earth calendar for convenience in coordinating scheduling with those on Earth.
Susan directed Tom to deposit his luggage in the guest room. When Tom left the room, he rose from the floor and lightly bumped his head on the ceiling. Tom made a mental note that until he became accustomed to lunar gravity, he would have to watch his step — literally.
While Susan prepared dinner, Tom used Susan’s computer to obtain some information about Luna. The colony consists of three geodesic domes connected pairwise by passageways. This design ensured that if one of the domes was struck by a meteor of sufficient size to depressurize it before the hole could be patched, the inhabitants of that dome could be evacuated to the other domes until the damage was repaired. Both sides of the passageways could be closed with airtight hatches, enabling the passageways to function as airlocks between the domes. A fourth dome is under construction to accommodate the growing population.
Of necessity, recycling is extensively practiced. The unavoidable loss of material is replaced by that obtained from mining operations as well as imports from Earth. Power is supplied by a vast array of solar panels that track the sun during the lunar day and store the excess power in batteries for use during the lunar night.
Luna’s main export to Earth is electronic components that are normally produced in cleanrooms on Earth. The lunar vacuum has less dust than is present in any cleanroom, enabling Luna to manufacture these components at a higher quality and lower cost than is possible on Earth. Luna imports heavy metals and other minerals in which the moon is deficient, much of which is used in the manufacture of the aforementioned electronic components.
Food is obtained from plants grown hydroponically in greenhouses, those plants also serving to recycle the carbon dioxide back into oxygen to maintain breathable air. It was decided that feeding plants to animals and using those animals as a food source was an inefficient use of resources. All meat and dairy products are imported from Earth and are thus rather expensive compared to the homegrown food.
After dinner, Tom went to the guest room and unpacked. As he prepared for bed, he noticed a scale in the bathroom and was curious to see what he weighed on the moon. When he stood on the scale, the display showed 74.2. Back on Earth, Tom weighed 163 pounds the last time he checked. On the moon, he should weigh one-sixth of that, namely — he did the mental calculation — 27 pounds. He made a mental note to ask Susan about that.
The next morning at breakfast, Tom asked Susan, “Does your scale measure Earth pounds or lunar pounds?”
“Kilograms,” Susan replied. She wondered why the United States remained the only country that hadn’t converted to the metric system.
After breakfast, Susan informed Tom that she had arranged for them to go to a basketball game. The layout of the basketball court was similar to those on Earth, except for the height of the hoops, which Tom estimated to be about 30 feet. During play, the players would jump up and down, often passing to each other in midair. The low lunar gravity literally added another dimension to the game.
After the game, Susan asked Tom if he ever wished that he could fly like a bird.
“What do you have in mind?” Tom asked.
“I’ve arranged for us to take a flying lesson,” Susan replied.
Susan led the way to the flight center. Once there, the flight instructor assisted them in strapping on the flying apparatus. Pumping the foot pedals as on a bicycle would cause the wings to flap, providing sufficient lift in the low lunar gravity for the wearer to remain airborne. Steering is done by shifting one’s weight, similar to the method used with a hang glider. Takeoff is accomplished by jumping and while off the ground placing one’s feet on the pedals and pumping them to flap the wings. The flight instructor advised them to keep a safe distance from the other flyers, several of whom were currently in the air, in order to avoid midair collisions.
After a few minutes in flight, Tom decided to try a diving maneuver that he had seen one of the other flyers perform. He pedaled vigorously in order to gain altitude. When he was about 50 feet high, he shifted his weight forward to go into a dive. He descended slowly at first, then more rapidly. When he was about ten feet from the ground, he shifted his weight back to level off. Unfortunately, he misjudged the situation and hit the ground. The combination of the low lunar gravity and the heavily padded floor prevented him from being seriously injured, but he did get the wind knocked out of him.
After leaving the flight center, Tom decided that he had enough for one day.
The next morning, Susan announced, “I saved the best for last. Today, we are going to visit the Brob habitat.”
The size of a plant or animal is limited by the fact that while its weight increases with the cube of its linear size, the area available to support that weight increases only with the square of its size. On the moon, with one-sixth of Earth’s gravity, it should be possible, so the thinking went, for organisms to reach six times the size that was possible on Earth. When the technology made it possible to genetically engineer organisms to grow to six times their normal size, a habitat was established in Luna to be populated with such enlarged organisms. Such enlarged plants and animals would provide a bonanza for researchers studying biological processes. Thus, Project Brobdingnag was born.
Susan led the way to a door labeled “Brob Habitat.” As they entered, Tom was aware of the smell of flowers. The flowers looked familiar except for their enormous size, towering well above his head.
A sign near the entrance warned visitors to stay on the designated paths and that only authorized personnel were allowed to take samples of the flora.
As they continued along the path, Tom saw a bird the size of an eagle approach a flower. The bird hovered in place next to the flower and, upon closer inspection, revealed itself to be an enlarged hummingbird, with its wings visibly flapping as if in slow motion.
At the end of the path, they came to a door labeled “Bob’s Abode.”
The decision to apply the enlargement technique to a human was highly controversial. However, it had become a fait accompli before the opposition was able to become sufficiently organized to block the action. Bob, as he was named, was brought to term in an artificial uterus capable of accommodating his size.
In addition to Bob being six times the size of a normal person, his reaction time was six times slower due to the longer time it took for the nerve impulses to travel within his brain and between his brain and the other parts of his body. While this technically made him a slow learner, that was not due to his lack of intellect; his large brain endowed him with superior intelligence.
Bob was capable of comprehending human speech provided that the speech was slowed down by a factor of six, with a corresponding reduction in pitch. Likewise, Bob’s speech was made comprehensible to normal people by a sixfold increase in its speed. While Bob was sixty years old, his biological age was that of a ten-year-old.
As Tom and Susan entered Bob’s abode, Tom found himself in an enormous room; he estimated the ceiling to be 50 feet high. Susan approached a man seated behind a desk and announced, “We’re here to visit Bob.”
After Tom and Susan signed the visitor’s log, the man at the desk handed Susan a wireless microphone and said, “Press the button to talk to Bob and release the button when you are finished speaking.”
Susan handed the microphone to Tom and said, “Say hello to Bob.”
Bob was truly a giant. He was seated in an enormous chair befitting his size. Tom stood barely up to Bob’s knees.
Except for his size, Bob appeared to be a ten-year-old boy. He had on a headset with an attached microphone.
Tom pressed the button and spoke into the microphone. “Hi Bob,” he said and released the button.
There was no immediate response from Bob. After several seconds, Bob’s lips moved in what appeared to be slow motion. His speech was a low-pitched rumble. After about half a minute, Bob stopped speaking.
The “translation” came from a speaker on the desk: “Greetings to both of you. Do you have any questions for me?”
“Do you get lonely, being the only one of your kind?” Tom asked.
“At times,” replied Bob. “However, I have frequent visitors here as well as people on Earth with whom I communicate.”
* * *
When Bob was asked if he wanted to participate in the parade culminating the bicentennial celebration, he eagerly agreed. As he walked along with the parade, he waved to the people. To say that he stood out from the crowd would be an understatement.
When the parade reached its destination, the dignitaries were given an opportunity to speak. The master of ceremonies then asked Bob, who was wearing his headset, if he would like to say a few words.
As Bob spoke, the people eagerly waited for the “translation”: “Greetings to you all. I am honored to participate in the bicentennial parade. And I especially want to thank all the little people for their kind support.”
The reference to the “little people” drew roars of laughter from the assembled crowds as well as the viewers on Earth.