"This is the Mars Environmental Protection Organization telling the people of Earth that it is wrong to bombard other planets with disaster from space. We will show you what it is like!" Johnny's face was bloodied and there were several bodies lying lifeless on the bridge of the Prometheus. Several other men and women were standing around Johnny with automatic weapons. How they had gotten those weapons on board is still a mystery to this day.
"Johnny! What are you doing?" I cried, neglecting bridge protocol. The captain just eyed me with his peripheral vision. We were friends and he had trusted me for years.
"Ah, my sweet Tamara. You have been corrupted by the expansionist nature of the evil capitalists and will have to learn that what you are doing to Mars is wrong!"
"You're nuts!" I screamed and then the Boy's Life listed and lurched and I knew that Johnny had burned us loose from the NEO as well. The low-mass solar sail spacecraft had been cut loose and was beginning to pitch forward. Of course it was pitching very slowly and it would take days for the two -hundred—kilometer-diameter disk to pitch through ninety degrees. I jumped into my helmsman seat and began counteracting the unexpected forces or lack thereof. Then I set the automated correction algorithms to full control of the pitch-correction controls. The computer would make the minor adjustments to the control sail vanes and solar light pressure would remove the unwanted pitch in a few hours.
With two of the sailing ships now untethered from the NEO it only made sense for the third ship to let go as well. The NEO was on its outbound leg and now had odd perturbations to its orbit. There is no way that the slight perturbations would push the sail into Earth in short term. Even if its orbit were modified enough that it would impact Earth in a few orbits or so, we could simply come out and catch it with another sail formation and fly it out of the way. I didn't understand what these so-called Mars Environmental Protection Organization nuts had in mind.
"Captain," I asked, "are there protocols for dealing with this type of thing?"
"Well, there probably are but I've never heard of them," Captain Billy replied.
"Yeah, this has never happened before to my knowledge and I've been flying sail tugs for years." What should we do? The sail tethers would have to be reconnected before we could grab the asteroid and it would take hours to do that.
The navigator, Carol "Jelly" Wilson, looked up from her computer system. "Captain, I think I understand what they have in mind."
"Well, don't keep us hanging, Jelly," he said.
"The orbit of the NEO now tracks right over the Belt, sir."
"So what, Jelly? It will go over the Belt not hitting anything," I responded.
"Well, yeah, Tami, but . . . they only need a few meters per second of delta-V to bring the inclination down. If they bring the inclination down just a few degrees then the NEO will plow right through the top of the Belt."
"I see," Captain Billy said. "They want to play bumper pool with the Belt and scatter rocks throughout the system!"
"That's right, sir. And with that nuke tug they have more than enough delta-V to do just that." Jelly frowned and shook her head.
"With that many collisions I don't know if we could stop all of the newly created NEOs," I said. "The Earth could be totally devastated!"
"Then it's settled. We can't let them push down the inclination of that rock." The captain ordered, "Jelly, see if we can plot a course that will allow us to catch them and drag it back up out of harm's way."
"Yes, sir!"
Jelly worked on the course trajectory for about an hour or so. There was no big hurry; the Belt was weeks away and she had calculated that the nuke tug would have to push the NEO continuously for four or five days to move it down enough into the ecliptic to cause problems. We had time. What we didn't have was speed or maneuverability.
By the time Jelly had finished her calculations, the nuke tug had positioned itself against the NEO and had started pushing it. Captain Billy had discussed options with the other sail tug drivers and with headquarters but nobody had come up with a solution. We were far enough from other vessels that nobody could catch us in time to help. All we could do was to sit and watch. So all three of the sail tugs floated along behind the asteroid in loose formation just in case we came up with an idea.
Jelly did believe that we could net the NEO and pull it up and over the Belt since the solar sail propulsion ships don't run out of fuel this close to the Sun, because sunlight is the fuel. The nuke tug, on the other hand, would run out of reaction mass if it ran continuously in just eight or nine days and there would be no way it could push the NEO all the way to the Belt. We were more than two weeks from the Belt and had many kilometers of tether, so we could just hook up the tethers, catch the NEO again, and pull it up against the nuke tug until it ran out of fuel. We would prevail because we had an endless fuel supply and the nuke tug didn't. So we had figured out a plan.
We suited up and took the long ride from the control room, located in the hoop on the circumference of the sail tug, down one of the radial support beams to the central hub of the sail. The tether system is located in the middle of the sail on the central hub so the force from dragging the NEO is in the center of pressure and mass of the sail. You see, the sail is really a giant hula-hoop two hundred meters in diameter. The hoop itself is two stories thick and this is where the crew lives. There are also three support booms (one every hundred and twenty degrees) that run radially from the hoop inward to the central hub where the tether mechanisms are. The hoop and booms are made of carbon-nanotube-reinforced polymers and titanium struts. The sail material itself is a carbon-carbon nanotube fiber mesh. There are heavier-duty compartments spread about the hoop to offer crew protection in case of solar flares, but the ship is mostly super-lightweight stuff.
We spent hours outside in pressure suits repairing the tether release mechanisms and setting them up for a NEO catch. Normally we just let go of the tether and if we want to hook up again we just reel out more tether and the super-small coffee-can-sized satellite or picosatellite on the end of the tether flies to meet the picosatellites from the other two sail tugs. The problem here was that when the tethers are usually released there is an automatic tension placed on the tether reel to avoid a backlash or "bird's nest" to spring backward into the tether reel. If the reel is let free with no tension on the tether, the entire tether tries to unwind itself while still on the spool. So we had a knotted-up and tangled-up mess that we had to unwind while in spacesuits. That was not an easy task and it took hours. But once we got the "bird's nest" loose and unwound, we spooled the tether tight and hooked up the next picosatellite in the hopper. Our counterpart sail tugs had to go through the same process. We were all real tired after this and I was expecting to put in for extra class hazard pay for the unscheduled EVA.
Unfortunately, the nuke tugs can be somewhat maneuverable and once we had netted the NEO, Johnny simply stopped pushing the NEO and burned through the tethers with his exhaust plasma again. The tether backlash on one of the other sail tugs, the Tsander, was reported to be so bad that it would take weeks to fix. The Boy's Life and the Tsiolkovsky were in good shape and could be fixed with another tiring EVA. But we could no longer drag the NEO with just two sail tugs; there just wasn't enough delta-V. So the plan was no good.
Three days had passed and we still had no idea what to do. We had fixed the tethers that were fixable, but what could we do with them? Captain Billy had told us that he wanted the ship in proper order because you never know what you can use during a crisis. This was most definitely a crisis since one more day of the Prometheus pushing the NEO and it would be enough to cause serious problems in the Belt. Jelly had also figured out that the mining facility would be totally destroyed as the NEO passed through the Belt. We had to do something. But what?
I was on break and so I planned to spend some time in my quarters resting and thinking and cursing Johnny. It turns out that he used me as a reference to get on the nuke tug crew. Having told them that I would vouch f
or him got him through a lot of hoops. He must have been setting this terrorist thing up for some time and had been planning to use me. That's why he suddenly came back into my life and wouldn't leave. He needed me for his plan to work. That sack of shit!
The hoop is so large that you can barely feel the curvature as you walk it. It is two stories wide and the sail is rolled slightly to give a light artificial gravity field. I was "moonwalking," as we call it, to my quarters when the fire alarm went off. The automated alarm said there was smoke detected in Floor One, Degree Nineteen. This meant that the fire was in a room on the outer floor and at nineteen degrees clockwise from the command center. In other words, about a half of a degree from my present location, so I went from a "moonwalk" to a "moonrun." I beat the fire team to the fire. One of the new crew members had left a makeup mirror out with the curved side facing the window. As we listed forward and the window let sunlight into the room, it hit the makeup mirror, which in turn focused the sunlight onto the bed across the room. The bedspread had begun to smolder and the smoke set off the alarm. The fire marshal presently chewed out the rookie, but I wanted to kiss her!
I turned back toward the command center direction and "moontrotted" down the hoop. I was out of breath when I got there so I had to relax a second before I could speak.
"Captain . . . huff puff . . . I've got it!" I said.
"What've you got, Tami?" Jelly asked.
"We burn the nuke tug up!" I panted some more.
"How do you propose we do that?" Jelly asked sarcastically.
"Let her finish, Jelly," Captain Billy scolded her.
"We tether the center of one of the sails to another sail tug and have them sail in opposite directions. The tension of the tether pulling on the center of the sail and the resistance of the sail's support booms to the tension will cause the sails to be curved toward each other just like when we pull a NEO. Then we point one of the sails concave side toward the Sun at an angle that will reflect the light and focus it on the nuke tug. We will burn them by focusing the light with the sail just like you can burn ants with a magnifying lens or bedspreads with a makeup mirror!"
"Would that be enough energy to burn a spaceship hull?" Jelly asked.
"Well," the captain said, "the sail is one hundred thousand meters in radius. Square that and multiply by pi and you get a surface area of nearly thirty-two billion square meters! Our distance from the Sun is about one-point-two astronomical units so there is about a kilowatt per square meter of sunlight here. Multiply the two and you get more than 3x1013 watts of sunlight that can be collected and focused. Even if the sail is only thirty-percent efficient at reflecting light to the target we would still have 1x1013 watts on target. I would say that is plenty!"
"Johnny," I stared him down through the video screen. "You are an idiot and a bastard and you can't just use people this way. Also, how does killing millions of people on Earth help your case, hunh? You're stupid and it's time you saw the light!" I had timed my hail to them with the moment that the sail tug pitched at the right angle. And then more than 1x1013 watts of focused sunlight swept across the NEO onto the nuke tug. As the intense beam of sunlight swung through the dust cloud surrounding the NEO, sparkles and flashes from the tiny grains of asteroid vaporizing tracked with the beam. The focused beam burned across the NEO, leaving a scorched mark, and then the light settled onto Johnny's hijacked tug. The tug vaporized almost immediately and out-gassed into space.
After that little incident, we realized that we should pay closer attention to security in our space fleet. A positive outcome of the incident was, we realized, that we could use the sail as a mirror, and push or vaporize the NEOs as we needed. We didn't even need to sail out to them. We would stay in near Earth's orbit and focus sunlight onto whatever we needed to with these gigantic mirrors. Oh, people had thought of it before but never knew how to implement the idea. I guess thanks to Johnny, we figured out how to do it. And also, the wackos sort of disappeared into the woodwork and we never heard from them much anymore.
Soon, I hear that an array of sail mirrors is going to be aimed at Mars to add even more energy to the ecosystem there. I hope to get a job steering one of those things so I can continue being a "cleaning lady." Of course the NEOs will still have to be pushed into Mars at least for a few more decades, but we all firmly believe that one day we will have a nice livable neighbor in Mars and a "clean neighborhood" to boot!
ARE WE THERE YET?
Here's a bit more background on "Doc" Taylor—he's earned his soubriquet the hard way: he has a doctorate in optical science and engineering, a master's degree in physics, a master's degree in aerospace engineering, all from the University of Alabama in Huntsville; a master's degree in astronomy from the University of Western Sydney, and a bachelor's degree in electrical engineering from Auburn University.
Dr. Taylor has worked on various programs for the Department of Defense and NASA for the past sixteen years. He's currently working on several advanced propulsion concepts, very large space telescopes, space-based beamed energy systems, and next-generation space launch concepts.
In his copious spare time, Doc Travis is also a black belt martial artist, a private pilot, a scuba diver, has raced mountain bikes, competed in triathlons, and has been the lead singer and rhythm guitarist of several hard rock bands. He currently lives with his wife Karen, two dogs, Stevie and Wesker, and his two cats, Neko and Kuro, in north Alabama.
Travis S. Taylor
With the advent of the recent mess in America's space program and inherent problems with the Space Shuttle and the cost overruns on the International Space Station (ISS), we begin to wonder if we are ever going to really get into space and have wonderful adventures like Tamara does in "Cleaning Lady." For the general public it must seem as though the evolution of space exploration came to screeching halt, or at least a slow crawl, after the Apollo program. Some of this "going nowhere" feeling is true, but there is a significant amount of research and engineering going on today in the aerospace community that will bring us closer to space. Of course, what we have mostly seen is the bad press and the disasters. What will be discussed here are the success stories and the hopeful outlook on getting us into space and enabling adventures worthy of science fiction.
To start with we have to be able to get off the planet. Tamara in "Cleaning Lady" rode a rocket into space to get out of Earth's gravity well. Heinlein said in various ways that once we get out of the Earth's gravity well you are halfway to anywhere you want to go. This implies that getting out of Earth's gravity well, or to orbit is half of space travel. Indeed it is. Presently our best way to get man and machines into orbit is with the Space Shuttle, but the Shuttle is limited to only about three hundred or so mile-high orbits. If we want to send people, or anything for that matter, to orbits higher than the ISS then we will have to build something new. Of course there are expendable launch vehicles that will lift satellites to much higher orbits. The Atlas V and the Delta IV Heavy boosters can lift nearly 15,000 kilograms to an elliptical orbit as high as 35,000 kilometers at the peak. But these rockets are not designed to carry people and since the Apollo days man has been limited to ISS-type low Earth orbits (LEOs).
The Russians and the Chinese also have rockets similar to the Apollo systems that can carry people into space (the Chinese have yet to fly humans but soon will) but they are also limited to LEO for the most part. The foreign rockets, Space Shuttle, and the American expendable rockets all use typical combustion engines that implement some sort of volatile like kerosene, liquid hydrogen or hydrazine. These are highly explosive materials and therefore make these Earth-to-orbit (ETO) rockets very dangerous. That is why they are so expensive; it takes a tremendous amount of engineering effort to make them even moderately safe for the crews who fly them.
NASA has plans to make these systems safer and more cost effective and to reach more useful orbits. This plan was previously the X program rocket systems and was hopefully going to lead to the Venture Star reusabl
e single stage to orbit spacecraft. The X-33 was to be the first demonstrator of this program but there were technical and programmatic issues that caused the program to be canceled a few years back. Recognizing the need and public outcry for a better manned initiative, NASA followed the defunct X-33 with the Space Launch Initiative (SLI).
SLI was to bring all of the aerospace industry together to develop a next-generation spacecraft to replace the aging and troubled Space Shuttle fleet and to fill the gap that the failed X program had caused. SLI was funded to the tune of several billion dollars for about three years and design concepts were beginning to be refined and "downselected" to. The NASA Advisory Council met at NASA Headquarters in Washington, D.C., in 2002 to discuss the progress of SLI and made the decision to change the direction of the program.
The Advisory Council expressed that they were concerned that billions of dollars had been spent for some very fancy view graphs and fun animations. This is a bit of a facetious and over-encompassing statement since there were many engineering trade studies that were undertaken in order to calculate the most likely designs for the SLI concept vehicles, but in the end pretty pictures are what make it to visual displays. Were the efforts and pretty pictures worth the billions that were spent? They would have been had we gone on to the next step and started building these designs. Due to the Advisory Council input and various other political influences, the SLI program was gutted and redesigned.
Cosmic Tales - Adventures in Sol System Page 9