Back | Next
Contents

Fading Into Blackness

The previous science speculation chapter, "Starships", discussed a number of possible techniques for building a starship that is literally capable of traveling between the stars. In the many years that I have thought about the problems of interstellar flight, most of my effort has been on finding technical solutions to the propulsion problem. But there is another major factor in the feasibility of interstellar flight that has nothing to do with technology—it is economics—specifically the exponential growth implicit in interest rates compounded over many decades of time. The exponential growth of debt at compound interest is just as deadly to a mission as the exponential growth of mass ratio in a rocket.

  

Nearly all the ideas for interstellar flight involve the construction of some expensive high power propulsion system that drives the space vehicle to the speeds necessary to accomplish the mission. The vehicle and its propulsion system must be built and paid for at the start of the mission, while the payoff in knowledge does not come about until decades or centuries later. With luck, the payoff will be knowledge with such an astronomically high value that it will produce a net return on the up-front investment that is greater than if the money had been invested in a savings account at an interest rate greater than inflation. Realistically, however, the probability of a large payoff is low. Even governments cannot ignore the "laws" of capitalism for long, or they will fall by the wayside—as witness the USSR and other communist governments.

  

What is needed is an interstellar flight concept that is both technologically feasible and financially feasible—in that it either does not involve a high up-front cost, or produces a reliable and adequate return for the investor during the mission, with the promise of a much higher payoff if the mission is successful.

  

The best candidate is my "Starwisp" concept. It is a beamed power propulsion and power system that requires the construction of a large and expensive sunlight-to-microwave power station in space, and a large and expensive beaming dish. The vehicle itself is small, and although probably expensive per gram, its total cost would be insignificant compared to the beaming dish, which in turn would be insignificant compared to the microwave power station. Unlike an antimatter engine, or a interstellar ramjet engine, or a laser or pellet beaming device that must be operated for years during the mission, the microwave power station in the Starwisp system is only used for propulsion and power for a few weeks at the beginning and the end of the mission. In addition, while the other engines have no use other than as an interstellar propulsion system, Starwisp's microwave generator can be used as a power station during most of the mission, generating enough income to pay the investors back their initial investment plus a modest profit, while holding out the hope for a "killing" if the mission is successful.

  

In the following story, "Fading Into Blackness" I describe a possible scenario that would send Starwisp on its way into interstellar space without violating the "laws" of either physics or economics. The story was first published in the July 1988 issue of Analog Science Fiction/Science Fact, Volume 108, Number 7, pages 60-69.  

 

 

 

"You are absolutely crazy!" James exploded. He hunched forward to sit perched on the edge of the plush sofa, his voice echoing in the cavernous office of his boss.

Michael Lord, media magnate, was leaning far back in his chair behind his desk, grinning like a student who has just thought of a great prank to pull. In back of him was a huge flatscreen showing a sunlit view of the whole Earth. The living image came directly from one of the dozen geostationary direct broadcast television stations that Michael Lord owned. Despite his annoyance, James's gaze was drawn once again to that brown and blue globe covered with clouds of wispy white. A fragile globe that was home to billions of humans.

This particular picture came from Station North America One that hovered over Canada, one of Michael Lord's first customers. It was near noon in Canada, so that particular full sunlight view of the Earth was being broadcast during every station break over every station around the globe. For the station breaks, the living image of the Earth was surrounded by the words, "LORD WORLD BROADCAST NETWORK LIMITED", the always varying, never-the-same logo of the Michael Lord empire.

Michael Lord had made his billions by finding a way around the International Telecommunication Treaty that controlled access to the geostationary orbit. He had realized that if he built broadcast stations that used a large solar sail to get constant thrust from sunlight, then the stations could be placed in artificial orbits that were many hundreds of kilometers north or south of the equatorial geostationary orbit, yet still only rotated around the Earth once a day. Since they were not in a natural orbit controlled solely by the Earth's gravity, his lawyers had successfully argued that his "stations" were not "satellites", and therefore were not regulated by the treaty.

James lowered his glance from the screen to find Michael Lord still grinning at him. "I won't let you do it! You can fire me if you want—I'm sure I can find lots of jobs at a million per year—but I won't let you throw away a hundred billion on this crazy scheme . . . this 'wisp' of glittering nothing."

"You just earned yourself a lifetime pension at a million per, Jamey," said Michael Lord, who had heard all this many times before from his old college roommate and fanatically faithful right-hand man. "But I hope you'll stay on at two million per in addition to make sure it's done right."

"Sure I can make sure—with your money I can make sure of anything. But to spend your entire net worth on this will-o'-the-wisp doesn't make sense to me. It won't get to Alpha Centauri for twenty years, long after we both are doddering old wrecks, if not dead. Then all it will do is send back pictures, which won't arrive back here for another four years or so. I also don't see why you are going to interrogate it on the trip out. All you'll get will be pictures of nothing.

"Exactly."

 

James did his job—as no one else could—nearly perfectly. One billion of Michael Lord's money went into design studies.

First was the design for the large solar power satellite, ten times larger than any that had ever been designed before. It would generate the fifty thousand megawatts of microwave power that would be needed to accelerate the interstellar probe up to twenty percent of the speed of light.

Second was the design for the radar dish that was to focus the microwaves into a far-reaching beam. It was ultralarge, four times larger than the diameter of the Earth, and ultralight, made out of a thin disk of fine wire mesh. The wire mesh disk was to shaped into a nearly perfect parabola by centrifugal acceleration from a slow rotation of the disk combined with a linear acceleration from a million electric ion thrusters spaced around the periphery of the disk.

Finally, there was the interstellar probe itself, a wisp of ultrafine wire woven into a hexagonal mesh that was a kilometer in diameter, yet had a total mass of only sixteen grams. At each six-wire intersection of the mesh was a microcircuit, so tiny that all one hundred billion of the microcircuits had a total mass of only four grams. Its name was to be—"Starwisp".

 

"Fascinating," said Michael Lord, staring at the thin shred of black veil floating in the center of the large glass globe that James had placed on his desk. "It's so light it just floats there."

"Actually, it's levitated," said James. "There's a small battery-powered microwave generator built into the base of the globe. It produces a beam of microwaves directed upward. The microwaves bounce off the wire mesh with enough force to lift it against gravity.

"Open the globe and let me feel the mesh," said Michael Lord.

"I'm afraid I can't do that," said James. "In the first place, the wires are so fine that the mesh would tear at the slightest touch. Second, the globe is evacuated. The minute any air got to the mesh, it would be eaten away and all you'd have left would be a drifting cloud of microcircuit dust."

"Fascinating," said Michael Lord again. He had found the power control to the microwave generator in the base, and was pushing the miniature model of the Starwisp probe up to the top of the globe, then letting it fall. He stopped for a second and looked up at James.

"Let's proceed with the next phase."

"If you insist," said James reluctantly, and started the long walk across the office. At the door he stopped and turned to look back at his boss. Michael Lord's gaze was again on the globe, watching the nearly invisible wisp as it rose and fell inside.

While James waited politely for Michael Lord to look in his direction, his attention was drawn once again to the constantly changing view of the living Earth on the flatscreen. This view was from Station South Pacific Two. On one side of the Earth he could see Hawaii, where they were. On the other side he could see the huge monsoon that was savaging the lower part of India. The news being broadcast that very minute over Michael Lord's worldwide news network was showing terrible scenes of havoc and human suffering. Like many others who had seen pictures of Earth from space, James was struck yet again by the thought of all mankind being just space travelers, wandering through the galaxy in a fragile blue globular spacecraft.

"Yet still we squabble," he thought.

James shook his head and lowered his glance from the image of the Earth and continued waiting. Michael Lord finally stopped playing with the microwave controls and looked up.

"I still think you are absolutely crazy!" James said vehemently, and slammed out the door.

 

It took five years and a good deal of Mr. Lord's money to start construction of the solar power satellite. But, even James had to admit it was a good investment. New scientific advances in methods for the direct conversion of sunlight to microwaves gave the solar power satellite an energy conversion efficiency of seventy-five percent. That was many times the efficiency of solar cells and twice that of ground-based power plants. The advent of room temperature superconducting power transmission lines had allowed the microwave receiving stations on the ground to be placed in uninhabitable deserts, oceans, and frozen wastelands far from the cities that needed the power. The customer list for the first five thousand megawatt section was oversubscribed even before it was completed, but Michael Lord insisted on reserving the first month of output for preliminary tests on a tenth-scale prototype Starwisp.

 

James sat back in the sofa, holding the remote control for the flatscreen on the wall. Michael Lord came out from behind his desk and joined him. The living Earth on the screen now came from Station South Africa One. James pushed the button on the remote control and the picture of the Earth was replaced by a picture of Powersat Alpha, the flagship of Lord Powersat Limited.

"Nothing much to show you here," said James. "I'm sure you have been monitoring construction progress yourself."

"I notice the microwave transmitter array in the center is no longer pointing at Earth," said Michael Lord.

"The engineers wanted to get maximum efficiency for this test," said James. "So they rotated the antenna array so that it points to the microwave dish in its high orbit over the South Pole. Once Powersat Alpha is up to full power the transmitting array will stay pointed at Earth. Using standard phased array techniques, it can feed power beams to a dozen Earth stations, while at the same time it's sending a beam out to the interstellar probe." He pushed a button on the control. All that could be seen on the screen were a few stars and a thin ellipse of pinkish-blue lights.

"This is the microwave dish that will turn the broad microwave beam from Powersat Alpha into a narrow beam. This tenth-scale model can form a beam that will reach halfway to Mars. The full scale model will form a beam that can reach Jupiter. You can't see the mesh, but you can see the exhaust from the ring of xenon ion engines around the rim."

James referred to a sheet of paper, then pushed the button for another channel. The long vertical ellipse of glowing electric rocket engines was replace by a smaller horizontal oval of rocket lights.

"This is the flat mesh mirror that collects the microwave beam from Powersat Alpha and directs it down the axis of the beaming dish. The beaming dish stays pointed in the direction the probe is supposed to go, while the flat mirror wobbles slightly once a day to track Powersat Alpha below as it rotates around the Earth.

"It's a shame that the mesh structures are too fine to see," said Michael Lord. "Fortunately the electric rockets give us their outline. I presume you are not going to even bother trying to show me the scale-model Starwisp."

"Since I knew you would be interested, I had the engineers take out some video equipment and give it a try. They were actually pretty successful. By aligning things so the camera is on one side of the sail and the Sun on the other, they were able to get enough forward-scattered light to see the mesh. It's the same technique that they used during the Voyager flybys to take a picture of the rings around Jupiter." James gave the button another push and a bright oval of light appeared on the screen.

"There's 'Lord's Folly'," said James. "All two hundred milligrams of it. It's sitting out about half-way between the Earth and Moon, lined up between the beaming dish and Mars."

Michael Lord winced. "I thought 'Starwisp Prototype 0.1' was its name."

"That's its official name," said James. "But it's much too long for daily use. Since you didn't make up a name, I did . . ." He paused, "I still think you are absolutely crazy!"

Michael Lord smiled determinedly. "Let's see what . . . 'Lord's Folly' can do!" he said.

James took out a beeper-type communicator and held it up. "The microwave beam will be triggered at Powersat Alpha as soon as this signal gets transmitted through the earthcomm links," said James, "but it will take about a second for the beam to make it out to the beaming dish above the south pole, then almost another second before the microwaves reach the sail." He pushed the button and they both watched the illuminated oval on the screen as James counted.

"One-thousand one. One-thousand . . . There it goes! My God, Mickey, it's really working!!"

The glowing oval of mesh billowed slightly, then started moving off, slowly at first, then faster and faster as the constant ten gravity acceleration built up its velocity. The camera swiveled to follow it. The oval shrank, changed into a circle, then faded into blackness.

"Let's see the pictures it's sending back," said Michael Lord.

James looked down at the remote control and selected another channel. A high resolution picture of the Moon showed up on the left hand side of the screen. It was moving noticeably toward the edge of the screen as the prototype Starwisp accelerated in a direction to one side of it.

"At this distance from the transmitter there is more than enough microwave power impinging on the sail to power the microcircuits," said James. "The real test will be when the distance between them is lightyears, not Earth radii."

"Any engineer can calculate that," said Michael Lord, "and even you will have to admit that with the full-sized dish directing the microwave beam, that there will be plenty of microwave power flooding the Alpha Centauri star system to power the mesh circuits. What I was really worried about was the ability of all those billions of microcircuits to work together as an image processing computer. Look at that picture!"

"I've got to admit it's high quality," said James. "Better than the video cameras on your broadcast stations. In full color too."

"With a billion microcircuits, each with a photosensitive detector looking in a different direction and sensitive to a different color, you have everything you need to make a picture. It's just a matter of each microcircuit working with its neighbors to unscramble the billions of bits of data to make an image."

"We'll find out how well it performs tomorrow, when the sail approaches Mars," said James. "The engineers will lower the microwave power in the beam until it's as weak as it would be if it had to travel from the solar system to Alpha Centauri. The probe will only have one watt of power reaching it. And with that one watt the probe has to power a billion microcircuits with a billion photodetectors, and carry out a billion billion calculations for each picture."

"I'm looking forward to seeing Mars up close," said Michael Lord. "What time does . . . 'Lord's Folly' get to Mars?"

James chewed his lower lip as he consulted a schedule. For once Mickey might be right and he was wrong. "Lord's F . . . Starwisp Prototype 0.1 arrives within imaging distance of Mars tomorrow morning at 0920," he said. "It will be traveling at almost two percent of the speed of light. At that speed, it'll shoot past the orbit of Mars in just a few minutes."

"I certainly don't want to miss it," said Michael Lord. "I'll see you promptly at nine-fifteen and we can watch it together."

"I'll be here," said James. "And I'll bring a written apology along with my letter of resignation." He put the remote control for the flatscreen on the table in front of the sofa and left the office.

"And I'll file them the same place I filed all your other letters of resignation, Jamey," said Michael Lord to the closed door. He walked over to the table in front of the sofa and picked up the remote control. He pushed the button for one of the higher numbered channels that was used for calibration of the probe's imaging system. This channel used the photons coming from the backside of the probe that had managed to penetrate through the back of the thin microcircuits to reach the photodetectors from behind. It formed an image of objects in the direction that the probe had come from. It wasn't as good as the image from the front side, but it was still better than a standard high resolution video camera.

As Michael Lord switched on the channel, a picture of the Earth as seen from the probe appeared on the screen. The Earth was three-quarters full and flanked by the Moon, also three-quarters full. He watched for a few minutes as they shrank slowly on the screen. He smiled with satisfaction, then switched the flatscreen back to its normal full Earth living picture from one of his broadcast stations. It was from Station South Africa One, and if it was nearly midday in South Africa, it must be time for him to go to bed. He yawned and went through the door behind his office to his apartment.

 

The images of Mars were fantastic, even after the engineers had lowered the microwave power shining on the minuscule spacecraft to less than a tenth of a watt. There was now no question the technology worked. A large enough microwave dish could send a beam that could push a lightweight spacecraft to speeds approaching the speed of light. The same microwave dish could supply power to that same spacecraft over interstellar distances. And that same microwave dish could also receive return signals from the spacecraft many years later that contained real-time, high-resolution, color television pictures of the planets in that new star system as the high-speed sail sped through it. Now all that it was necessary to do was to spend the money to build it.

 

Fortunately, James was up to the task. Nearly eighty billion more went into the completion of the fifty gigawatt solar power satellite, but it started generating a net cash flow before it was completed. Another fifteen billion went into the full scale beaming dish, in a far orbit that took it high over the South Pole, guided by its electric ion rockets as the engineers tuned the millions of components so they would work as a whole. Then, finally, a kilometer wide sheet of thick plastic was unrolled far out in space in the southern skies of Earth. Printed on the plastic was Starwisp. First were the multitude of ultrathin wires that formed the body of Starwisp. At each intersection of six wires were the multitude of multilayered microcircuits that formed the brain of Starwisp. In each microcircuit were the multitude of photodetectors that formed the retina of Starwisp.

After baking for two days in the intense ultraviolet glare of the light from the Sun, the plastic backing decomposed. Starwisp now floated in space, naively looking at the light sources around it, and waiting for the first of the microwaves from Earth that would fling it outward to the stars.

 

"It's taken five years and 122 billion," said James. "Instead of holding a majority interest in your properties, you are a minor stockholder. I hope you're satisfied."

"Of course I'm satisfied, Jamey" said Michael Lord. "I've always been satisfied with everything you have ever done for me. Haven't you arranged it so that I am still CEO of Lord Broadcasting Network Limited, even if I don't own it?"

James frowned in annoyance and begrudging acknowledgement.

"Besides," continued Michael Lord. "What is the use of making money if you don't spend it? I certainly can't take it with me."

"The one who dies with the most toys wins?" said James. "I never thought you were that type, Mickey. But you certainly have bought the most expensive toy ever made."

"Some toys are purely for fun," said Michael Lord, "Others are designed to educate . . ." He drew a deep breath. "It's time to launch Starwisp on its way. Push the button."

"That's your job," said James bruskly, handing him the special beeper with a single button.

Michael Lord shrugged and pushed the button.

 

Ten full minutes dragged on as the microwave beam shot out from Powersat Alpha around the Earth, flashed southward to the deflector mirror, bounced off the beaming dish, and shot across interplanetary space to Starwisp waiting patiently in the southern skies. Starwisp billowed slightly as the leading portion of the microwave beam struck it, then straightened out and started accelerating toward Alpha Centauri. Five minutes later, the billowing was seen on the flatscreen in Michael Lord's office on Earth as well as billions of video screens around the globe.

Starwisp accelerated at more than one hundred times Earth gravity, and was beyond the range of the monitor cameras within a few minutes. The news broadcasters, having nothing on their screens, switched to interviews of people around the world.

 

"Mr. Lord is daft, spending all his money like that. I certainly would have saved a little fer me kids and me old age."

"With millions of hungry people starving in Bangladesh and Ethiopia, it is criminal to throw away money on an egotistical whim!"

"Eh bein . . . I do not see the good of this."

"Dinkum nonsense!"

 

At the closing of the broadcast, Michael Lord had the living Earth logo for his network changed to an image of the Earth taken from the rapidly receding Starwisp. Even at the maximum magnification the mesh imaging system was able to supply, the Earth was noticeably smaller than the image the audience had been used to.

Starwisp continued to accelerate for ten hours under the powerful push of the microwave beam. By the time it had reached the limit of the beam, it had passed the orbit of Jupiter and was on its way out of the solar system at twenty percent of the speed of light. Some twenty-five years later, the human race would see pictures of new planets from its front side imaging system. Now, its back side imaging system was sending pictures of a familiar planet—Earth.

As the hours passed, the image of the Earth shrank on the screen. The hourly reminders of the shrinking blue-white globe during the day brought home to the human race the smallness of its triumphs, the pettiness of its squabbles, the frailness of its home. Soon many found themselves staring closely at their television screens, searching through the fluctuating pixels for the tiny dots that were the Earth-Moon system.

After just two days, Starwisp had passed out of the solar system, leaving Neptune and Pluto behind on its twenty year journey to the nearest stars. Even when the Sun started to appear at one side of the magnified image—the Sun itself was nothing but another star in the sky, lost among the multitudes of other stars.

Day by day, the world watched as the Earth faded into blackness . . .

And grew up.

 

Back | Next
Contents
Framed