by Mike Combs, Copyright © 2004
‘Well, Dyson’s gone and topped himself again.’
‘Oh yeah,’ I replied, ‘So exactly how does one top spheres the size of solar systems and trees on comets?’
‘Actually, Keith, his newest idea kinda relates to the comet trees. Kinda sorta,’ Danny responded.
Danny Treece has the office next to mine here at the Wilcox Observatory. I’d made the mistake of poking my head in to say hi, and now it was starting to look like I might as well sit down. Danny had just gotten back from a conference at JPL where he’d heard the Princeton physicist Freeman Dyson give a lecture. Now it looks like he was on fire with yet another new space proposal, so I had a sermon in store.
I knew I should humor Danny, as he was doubtless my best friend here at the observatory. The proximity of our offices, combined with the similarity of our areas of work pretty much made a friendship inevitable. We both specialized in minor bodies; he in Near Earth Objects or NEOs, as well as Main Belt objects, I in Kuiper Belt Objects or KBOs in that more-distant ring of iceteroids. I’ve certainly found that Danny’s expertise in fixing orbital plots for objects with only two or three observations has helped me out on more than one occasion. He was also, so far as I could tell, the only dwarf working in the field of astronomy.
‘Dyson’s always thinking outside the box when it comes to the search for life beyond the Earth,’ Danny said while I settled in his spare chair. ‘While more pedestrian minds are saying to listen for radio waves, Dyson’s saying, ‘Forget radio, watch for infra-red. Be open-minded about freeze-dried European fish orbiting Jupiter.’ This new idea is more of his unconventional approach to the search for ET life.
‘He calls it ‘pit-lamping’. The term is borrowed from a Canadian nighttime hunting technique. It’s a technique so effective that it’s actually illegal. You tape a flashlight to the barrel of your gun. Now most of the time your prey is going to be too far away to see by the light of the flashlight, but guess what you see anyway?’
‘What, pray-tell?’
‘Two eyes, shining back at you from the dark. The optics of it are such that when the light shines into the eyes of the animal, a certain percentage of the light is reflected back; what we call ‘eye shine’.’
‘Yeah, I know what you mean,’ I said. ‘I see eye shine from my cat quite a bit.’
‘Right, but the very best positioning for seeing eye shine is with the light source directly behind your head from the point of view of the animal, or with the light on a direct line between you and the animal, as in this flashlight-on-the-gun-barrel setup.’
‘And this helps us find life beyond the Earth how?’
‘Well, first you have to stop and think about what life adapted for survival in space would be like.’
‘OK,’ I said, squinting up my eyes for dramatic effect. ‘I’m imagining a deer in a space suit. And I’m hungry for venison. So I’m putting a flashlight”
‘C’mon, be serious. Firstly, space-adapted life is going to be very plantlike, at least in structure and lifestyle. You have to assume that it’s using solar energy and recycling its own wastes. If it lives any distance from its sun at all, you need to assume a big parabolic concentrating reflector. Even if it wasn’t photosynthesizing, it might need something like that just to stay warm enough to function.
‘So, if there’s life like that in the outer solar system, say on Europa, or Jupiter’s Trojan asteroids (which are a lot icier than Main Belt bodies), or on your KBOs”
‘Life on iceteroids?’ I interrupted.
‘Dyson says planets may not be the best places to look for life. Think outside the box, man.
‘So anyway, the best way to observe it would be to wait until the sun was directly behind you. Just like with eye shine, when some of the light gets reflected back off of the reflector, it bounces back preferentially in the same direction the light’s coming from. So the best way to make these kinds of observations is when the sun is directly behind you when you’re facing your target. An interesting aspect of this is that it becomes more effective the further out you go.’
Suddenly Danny was looking at the wall of his office which was plastered with about a dozen pictures of orbiting space habitats. Maybe I ought to explain at this point that Danny was a relic from the old L-5 Society, and was still holding out hope that Gerry O’Neill’s enormous space colonies were going to get built someday. When discussing space, I’d learned long ago to avoid subjects like building cities on the moon or terraforming Mars. He’d sneer at me for my ‘planetary chauvinism’, point at his wall of Island One’s, Two’s and Three’s, and lecture me about freeing my mind from the ‘planetary paradigm’.
‘Oh my God. I’ve got that synergy thing going again,’ Danny announced. ‘Forget about space-adapted life! Pit-lamping is the ideal way to search for extraterrestrial intelligence.
‘If we assume there’s anything technological out there at all, we have to explain the Fermi Paradox. Y’know, why they haven’t already colonized Earth before we could even be here to talk about it. One possible explanation all along has been’ these babies,’ he said, gesturing at the artist’s conceptions of giant space habitats.
‘Maybe it’s presumptuous of us to assume that our solar system hasn’t already been colonized,’ Danny continued. ‘Even if ETs did come here to settle our system, who says they’d necessarily have any interest in planets? They’d just view them as awkwardly-steep gravity wells. Potholes in space best steered away from. Raw material inconveniently packaged in a way too uneconomical to extract. And planets aren’t mobile. What if you got bored with the orbit you’re in, and decided you’d rather orbit elsewhere? No, they’d stick with the kind of artificial free-space structures they’d traveled here in and were already used to, and would only mine small bodies; which means they’d be orbiting in the outer solar system where there’s plenty of volatiles. So how would we spot them?
‘Imagine that you’re floating around outside of a space habitat”
‘Which kind?’ I asked, looking at his wall. There were cylinders, spheres, tori.
‘Makes no difference,’ Danny insisted, waving a stubby hand in the air. ‘This argument would apply equally well to all of them. All of the peer-reviewed space habitat models involve enormous mirrors reflecting sunlight in through windows. The further from the sun, the bigger the mirrors. Now, imagine that you’re floating around outside of the habitat in any old location. You look at the mirrors. What do you see?’
‘I dunno.’
‘Mostly you just see black because the mirrors are just reflecting space. Maybe you might see a few reflected stars, depending on the quality of the mirrors. Now imagine that you’re floating around somewhere on a straight line directly between the habitat and the sun behind your back. Now guess what you see. You see the entire area of the mirrors brilliantly lit up. Lit up with light reflected from the interior, and bounced back preferentially in the direction of the sun, straight toward you.’
His face screwed up into a thoughtful frown. ‘I guess it would be a kind of aqua-marine light. Mostly green light reflected off of land area, but also some blue from lakes and from atmospheric scattering. Brilliant white scattering from clouds. The light would be quite bright.
‘Now the further back from the habitat you get, the smaller the apparent size of the mirrors that you’d see all lit up. But you’d always see the entire area of the mirrors lit up, as long as you were on a straight line between the habitat and the sun. And the mirrors would present a good deal more area to your view than the habitat itself. I bet you could see it all the way back to Earth!
‘Someone should do some observing with this in mind. It would be interesting to find out whether or not we live inside of an alien Dyson Sphere.’
‘Oh come on, now,’ I scoffed. ‘We can’t be living inside of a Dyson Sphere!’
‘Well, it would all depend on what percentage of the total amount of sunlight was being used, now, wouldn’t it? You know, Dyson never meant a continuous, hollow sphere. Simple physics tells you such a structure would collapse from the sun’s gravity. He only meant a swarm of solar energy collectors and’ orbital habitats. The very thing we’re talking about here! We probably should have coined the phrase ‘Dyson Swarm’ instead.
‘Now, is there an alien Dyson Swarm around our system collecting all or even half of the sun’s radiated energy? Obviously no, a fact any Cro-Magnon could have ascertained with naked-eye observation. What about a swarm using one percent of the sun’s energy; one well-scattered across the entire outer solar system? Such a discovery would probably have had to wait on the invention of the telescope. Now what about one tenth of a percent? Detection then would probably have required the more-modern equipment, like the world-class narrow-field optics we just finished putting on this big baby,’ Danny said, hooking a thumb toward the dome down the hall. ‘And that’s assuming anyone would even be bothering to look in the right way. As far as I know, nobody is.’
‘A tenth-of-a-percent Dyson Sphere doesn’t sound like very much of a Dyson Sphere to me,’ I opined.
‘Maybe not as Dyson Spheres go, but as civilizations go it could be mind-bogglingly huge, at least in comparison to our planetary civilization.’ Danny suddenly hopped up to stand on his chair so he could reach across his desk to get his calculator. ‘Dyson pointed out in his Dyson Sphere paper that the Earth only intercepts one six hundred millionth of the total energy the sun gives off”
‘Oh, put that thing away. We’re only sliding decimals here.’
Danny stopped pecking in numbers, and tossed the calculator aside. ‘OK. So a civilization that only uses one tenth of one percent of the sun’s energy could still have six hundred thousand times the surface area of our planet. Just think about a civilization which outstrips ours by five orders of magnitude. Now chew on that!’
* * *
That morning after I got home (all optical astronomers are on the nightshift), I immediately proceeded to the bedroom because I’d intended to go out again before settling down to a good day’s sleep, and wanted to get in a quick shave first. My ginger-and-white cat, G. Bruno, was lying on my bed. He sat up as I entered.
‘Marrrow,’ he pleaded.
‘I’ve told you before, we don’t have any marrow in the house,’ I explained. ‘And besides, what the heck do you think you are, a lion on the African savannah gnawing on zebra bones? Get real.’
I live alone, if you can’t tell.
I began to shave. Bruno was still petitioning for marrow. Or perhaps discussing the famous reporter Edward R. Murrow; it was hard to tell over the sound of the razor. I turned to look at him, but my retort died before it started.
Bruno’s eyes were shining back at me like brilliant, amber headlights.
Of course the eerie radiance was just light from the bulbs around the mirror I was shaving in front of shining into Bruno’s eyes and then being preferentially focused back in my direction.
It was still spooky-looking, even when you understood the scientific explanation. No wonder Dark-Age Europeans nearly made Bruno’s kind extinct. Coming across a cat in the middle of the night while holding up a torch either behind your head or in front of it created perfect conditions for eye shine, igniting fears of satanic possession of familiars.
And of course the experience had me thinking back to my earlier conversation with Danny Treece.
The odd thing was that after showing so much enthusiasm for his new idea, Danny settled back down again, got his evening cup of coffee, and then calmly went back to his NEO observations, showing no apparent interest in following the idea any further. His mind was like that: astonishingly nimble, fleet but fleeting, madly dancing from one high-powered concept to another but never staying one place long enough to accomplish much.
As I continued my shave, I found myself actually contemplating the idea of doing the kind of observations he’d proposed since he had now seemingly abandoned the proposal. It suddenly occurred to me that, unlike the proposal to look at Europa or the Jovian Trojans, the kind of observations Danny had proposed were not time-critical. One wouldn’t have to wait the better part of a year for the precise line-up of Sun, Earth, and target, to attempt an observation on one critical night only which may or may not even have decent seeing conditions. If alien O’Neill’s were skulking about out there, they could be anywhere along the plane of the ecliptic, so any particular time was as good a time to look for them as any other. One only had to point the telescope in a direction precisely opposite to that of the sun. Each night, you’d be looking at a slightly different spot, as the Earth orbited. You could survey the entire ecliptic in this manner in a year’s time.
I briefly wondered if one could indeed take if for granted that alien space habitats would necessarily orbit in the plane of the ecliptic. But I finally decided that yes, one could. The aliens would have to mine small bodies for raw materials; for growth if for no other purpose. It would be more economical for them to orbit in the same plane as most of the available raw matter in the system.
Now please know that I didn’t seriously entertain much notion of finding ET living in Island Three in the outer solar system. But still, it occurred to me that one might instead find something else of interest using such a unique observational program; perhaps some ubiquitous, but presently-unknown aspect of the outer system. Rings of fine dust or ice, maybe. I couldn’t think of anyone else having ever made such observations. Something worthwhile might show up, even if Danny did have to look elsewhere for his alien friends.
* * *
That night when I returned to my office, I set about coordinating the night’s observations with the computer network which controlled the scopes. I saw that I had two observations scheduled for the night: one which was one degree above the ecliptic, and one which was two degrees below. There was some slack in the schedule. No reason why I couldn’t sneak in a quick observation while in the midst of slewing the telescope between the two positions, which would happen close to midnight anyway.
* * *
The next morning I returned home, and headed straight for the bedroom. Bruno was at his usual station: on my bed.
‘Do you know what the problem with you is? You’re a cat!’ I said, hoping I’d put the right intonation on ‘cat’ to make it clear I considered that sufficient insult all by itself. Bruno decided not to dignify my comment by responding to it.
I began firing up my home computer. My last task after completing a night’s observations was sending the digital processing and enhancement job off to the observatory computer. If it was a particularly gripping observation, such that I couldn’t be made to wait until after a day’s sleep, it was my habit to log onto the observatory server through the web first thing getting home. I’d found the length of my car trip home was just about the length of time it took for the results to be ready.
I brought the sun-opposition observation I’d snuck in between the other two up to my screen first.
I was looking at four tiny grey dots, soft with grainy pixilation, on a black background. They were all along a straight line. Now that all by itself wasn’t what made the arrangement seem artificial. Most everything in the solar system orbited in the same general plane with only a few degrees of relative inclination. If you looked at three or more solar system bodies at once, they could certainly appear perfectly lined up, at least to the sloppy limits of the human eye. But it was those first three dots that had the hairs rising on the back of my neck. The spacing was closer there. And the spacing seemed so damned regular! It was difficult to shrug off the feeling one was looking at an artificial arrangement.
I made the menu selection which overlaid labels for known stars and solar system bodies. Hardly to my surprise, no labels appeared on my screen. Whatever these were, they weren’t stars, nor were they already-known bodies within the system.
It looked so damned artificial! Was it the power of suggestion from too much listening to Danny’s expansive speculations? Was I cracking up?
Even assuming Danny’s hypothesis was correct, in a search of this type one should realistically expect to have to search for many weeks, if not many months, before finding what one was looking for. This was my first observation! To have hit pay dirt on the very first try could only mean one thing: the outer system was positively lousy with orbiting colonies of non-human manufacture. Unless, of course, I was only cracking up.
* * *
That evening at work, I saw another opportunity to work in a quick sun-opposition observation among the other things I’d already scheduled. I also had Danny slip me Freeman Dyson’s E-mail address. While the telescope slewed and peered into the outer reaches, I composed an E-mail to Professor Dyson. I briefly outlined Danny’s points, and asked Dyson if his idea for finding space-adapted life-forms was equally applicable to alien space habitats.
* * *
The next morning I went home and to my bedroom. Bruno was in his usual spot.
‘You know what the problem is?’ I asked him. ‘You don’t pull your weight around here. You eat and then you sleep on the bed. Why do I need an animal for that? I think technically, the cat should be classified as a parasite. You don’t have any chores around here, and you certainly don’t contribute to finances. I happen to know they’re taking applications at Biggie Burger. The next time I come home, you’d better be wearing a funny little paper hat, or there’s going to be trouble.’
Bruno responded with a head-splitting yawn, and a trembling stretch. Then he settled back down on the bed again in a subtly-altered configuration.
Giving up on Bruno, I booted up the computer, and logged onto the observatory server.
This new picture had a string of eight smudgy dots on it. Six were tightly packed, two somewhat more widely-spaced.
The six simply couldn’t have been more evenly-spaced. It cried out with evidence of intelligent arrangement.
But wait. There was an asymmetry here. All of the dots were on a precisely straight line except for one of the two more widely-spaced. It was ever so slightly below the line of the ecliptic. It made me wonder if this dot was something different from the others; perhaps an asteroid or a distant star. But once again, the label overlay command failed to identify anything in the photo as a known object.
Otherwise, the odd man out certainly looked the same as the others. I began to get curious about its motion compared to the others. To get an orbital track, I’d need a second observation, plus a spectrograph in order to measure the Doppler shift. I began setting up both through the server for tonight, so I could get the numbers over to Danny before I left work tomorrow morning. But I was also anxious to get in more observations further along the arc of the ecliptic. That would mean bumping the KBO observations I’d already scheduled. Well, they could just go to hell.
* * *
When I got in to work that evening, one of the first things I did was check my E-mail. Sure enough, there was a reply from Professor Dyson:
Dear Keith,
You are a hundred percent right. The application of pit-lamping to
SETI was in my mind from the beginning. But my talk was given to the
engineers at JPL, and for the JPL audience it was better to leave
SETI out of the discussion. Their job is to search for life, not to
search for intelligent aliens.Yours sincerely,
Freeman Dyson.
Four hours into the night, and my spectrograph job on that displaced dot was completed. I went over to my browser to pull up the results. The lines were clean, and I was satisfied that Doppler shift numbers could be pulled. But as I looked at the absorption lines, I could clearly see the signatures of nitrogen, oxygen, and water vapor. If any astronomer had ever found such absorption lines in the atmosphere of a planet, he would have cried from the rooftops that he’d found a living, Earthlike world.
Rather than forwarding the entire spectrograph to Danny, I decided to extract the Doppler shift numbers myself, and just forward them instead.
I spent the rest of the night guiding the scope through its observations and mulling the possibility that at this moment in history there was an extraordinary truth which I alone, of all the humans on Earth, knew. Of course I had no intention of leaving the situation at that. But at this early point I wasn’t even comfortable sharing my findings with Danny. And I was going to make damn sure about my facts before going public with this. The field of SETI was filled with scientists going off half-cocked, and a press which made too much sensation out of too little data. Nothing would kill my career quicker than going to the scientific community with such an outrageous claim, and then later seeing some more-prosaic explanation for my data surface.
* * *
At the end of my shift, I returned to my home and my bedroom. Bruno was on my bed, having apparently considered lack of opposable thumbs sufficient justification for his continued lack of employment. It could easily be that he felt his exotic good-looks would always ensure his place in the household, and, as I scratched the top of his head, I wasn’t even sure I could argue the point.
He was curled up into a tight ball, legs invisible, nose tucked into his hips, tail neatly wrapped around his periphery. It never failed to amaze me how stingy cats were with their calories. Fall was in the air, and I’d yet to switch from central air conditioning over to central heating. The house was only slightly cool, but Bruno was dealing with it in the ancient way of all cats, by efficient minimization of surface area. I’d reflected before that when calculating the power dissipation of a cat, the mathematical simplification of considering the cat a sphere actually yielded fairly good results.
I strode to the computer and pulled up the first of the previous night’s observations.
My jaw dropped as I looked at an exposure with too many dots to easily count, all the way across the picture.
They were four rows high now. But each column was staggered up and down slightly from its neighbors. The dots were in a tight hexagonal packing configuration, like that of B-B’s pushed together on a table top.
I pulled up two other exposures. More of the same. Endlessly repeating columns of giant, artificial constructs marched past my scope. I must have begun my observations at the frontier of this array of objects in the outer system. I was sure these photos were more typical of what the bigger portion of the array looked like.
It didn’t make any sense. A single ring of objects orbiting the sun might be possible. But how could there be four even rows? You can’t have parallel orbits. The laws of celestial mechanics demand that all objects must orbit in a plane cutting through the center of mass of the body being orbited. These four rows couldn’t orbit in formation; each object would have had to crisscross each other twice per orbit. Then habitats would be periodically blocking each other from the sun.
I suddenly realized to my surprise that all doubt was now gone from my mind that these were orbital habitats I was looking at: the abodes of some unknown technological life gathering energy from our sun for their use and sustenance. Alien settlers right here in our own solar system.
The repeating pattern with four rows could only mean one thing. Though it couldn’t be seen in the exposures, these objects were interconnected with some physical framework. There was a limit to how far they could go with that. They couldn’t arc over, roofing over our sun, without the structure collapsing. But a structure only several hundreds of kilometers tall, that far from the sun? Sure, something like that could be built with members only somewhat stiffer than soda straws and still successfully keep the array of colonies evenly spaced.
It was the beginnings of Danny’s one-tenth-of-one-percent Dyson Sphere. And we lived inside of it.
That morning I lay in bed, Bruno plastered against my side. But I wasn’t getting any sleep, despite the heavy curtains screening out the mid-morning sun. My mind was too busy soaring amongst slowly rotating, orbiting habitats ringing the better part of our solar system.
In my mind’s eye I sailed past exotic-looking space colonies too many to count. Millions upon millions. As I coasted down one of the middle rows, the vast mirrors extending from each habitat would flash briefly with a dazzling aqua-marine hue as my point of view cut across the line between the habitat and the distant sun behind me.
I started speculating about the nature of the structure connecting each habitat to its neighbors. At first I started visualizing pressurized tunnels, allowing easy transportation from one habitat to another. Then I realized that was almost certainly wrong. High-speed transportation would prefer vacuum over air-drag, and vacuum would certainly be easy to arrange. The tunnels would be open frameworks then (vastly reducing material costs); with electromagnetic coils enabling rapid, efficient magnetic flight between habitats.
I tried to remember the technical details of a book Danny had made me read which talked a bit about magnetic flight through evacuated tunnels. It could be very energy-efficient, with a portion of the electrical energy surrendered from decelerating vehicles going into the acceleration of others. Not that these inhuman creatures had to worry much about energy-efficiency. Our sun blazed power for their constant benefit; they only had to build mirrors the size of states to harness it.
What kind of speeds would be attainable with such magnetic flight through vacuum? Supersonic, easily. Oh, that was being far too conservative; velocities of quite some kilometers per second should be possible. I began thinking now in terms of vast, multilane electromagnetic superhighways. Slower lanes for vehicles going to a close neighbor. Adjacent higher-speed lanes for others bound for habitats many millions of kilometers away.
Science fiction fans had been so impressed with Larry Niven’s Ringworld. But its construction had required a magical building material with an implausible strength-to-weight ratio. As far as I could tell, the structure I’d found did not go beyond currently-known material strengths. And if I was right that it was an arc rather than a continuous ring, it would have none of the instability problems of the Ringworld. But it could still represent a mega-structure with six hundred thousand times the surface area of the Earth; land area which, even if not continuous, was at least all within easy travel.
I lay there and tried to imagine a civilization with six hundred thousand times the land area of the Earth available to it. I couldn’t. A merely-human head just couldn’t wrap itself around such a concept. Our seemingly-vast global society was an ant-hill in comparison.
It made me uncomfortable to reflect that while the alien colonists were a complete and total unknown to us, they doubtless already knew everything about humanity. Unlike these more-sensible beings, we were indiscreetly beaming all of our baser flaws and foibles out into space in the radio spectrum. Where they were, they could pick up our TV shows only a few hours after transmission. This means they knew everything there was to know about us, from the size and shape of female breast our men preferred, to our WWF wrestler’s predilection for settling old scores with metal folding chairs. I could only hope they had the wisdom to perceive that neither was entirely real!
But that second aspect of it was disturbing. From Vietnam forward, all of our wars have been televised. What could they possibly think of us?
Suddenly the phone rang, and Bruno leapt from my side, Pavlovian conditioning letting him know this sound meant snuggle-time was over. I leapt to the phone.
A familiar, slightly piercing, high-pitched voice: ‘Keith, are you still awake?’
‘Danny. Christ, you’re still at the office this late into the morning?’
‘Well, when I saw where your numbers were headed, I got a little concerned, and didn’t want to leave until I’d cranked out the final tightenings.’
‘My numbers?’
‘The orbital plot you asked for on that outer system body.’
‘Oh, yeah.’
‘Yeah, once I got started crunching the numbers, I quickly saw why you were being so weird about it. First off, you can stop working on that ulcer. You are not fated to be the herald of doom to the human race. It’s not an intercepting trajectory.’
My confusion only grew worse. ‘What?’
‘It’s not going to hit the Earth. It’ll be a close call, mind you. At point of closest approach, it should come to within’ about half the distance of the moon. But it definitely won’t collide with the Earth.’
I sat in stunned silence.
‘Keith, are you there? Did you hear me correctly? It won’t collide. Won’t. Hello, are you still there?’
The phone slid from my hands. At that moment, there wasn’t the slightest doubt in my mind what the object would do at its point of closest approach: a braking thrust, and then a swing around into a high Earth orbit.
I guess it was unreasonable to expect close neighbors to not eventually come over for a visit. I just hope they’re friendly.
The End
The theory ascribed to Freeman Dyson in this story is indeed one of his more recent proposals, and the described talk given to JPL took place in the real world. I tend to view things from the High Frontier perspective, and when I first heard about this proposal, the points Danny Treece makes about pit-lamping’s applicability to O’Neill-type orbital habitats occurred to me. I didn’t know Prof. Dyson, but knew someone who did, and they relayed a short inquiry from me. The E-mail Dyson sends to Keith in my story is the E-mail he sent to me with scarcely any editing.
Those who are interested in the provocative suggestion that there might well be orbital habitats of alien manufacture right here in our own system should read The Reenchantment of the Solar System: A Proposed Search for Local ET’s, a paper by Dr. Gregory Lee Matloff which discusses this very possibility and suggests possible telescopic search strategies.
An ebook version of this story is available at Eyes, Shining Back from the Dark
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This content is a part of the Mike Combs Space Settlement collection and is provided as a courtesy of the Chicago Society for Space Studies and Mike Combs.