Review: Erinyes, by Scott McElhaney

I was really disappointed by this book, all the more so because the premise was so intriguing. A man wakes up from cryogenic freeze to discover that not only has his cancer been cured but that he’s untold thousands of years in the future and on a ship exploring another galaxy. The mystery of why they wanted him and a few other “popsicles” for this mission was enough to pull me forward through the story.

Alas, I found most of the other characters frustrating as their moods flipped around unpredictably, and the rest of the backstory around their mission and what’s happened on Earth was not very compelling. Then the story seemed to run out of steam and jump to the climax without much of any build-up, and when the mystery of why they wanted these 21st century popsicles for the mission, I was sadly disappointed. I won’t spoil it here, but I found myself saying, “Really? That’s the best they could do? Who the heck planned this mission?”

With better characters, better plotting, and a better explanation for why these guys were there, this could have been an awesome book. But it wasn’t. I hate to write bad reviews, but this one just didn’t work for me.

Review: Marsbound, by Joe Haldeman

I picked this one at random from a pile of samples and was totally sucked in. It’s a first person narrative of an eighteen year old girl who emigrates to Mars with her family in one of the first waves of colonists/explorers and then actually finds martians… sort of.

The science is pretty good, even for the martians (hence the “sort of”), and it was a lot of that minutiae that drew me in. No, it’s not page after page of technical exposition. Rather, it shows a lot of the “boring” day to day business of riding a space elevator up to an interplanetary ship, making the trip across the void, landing, and living in the harsh conditions of another planet. I suppose I liked it for many of the same reasons I enjoyed the daily details of Nathan Lowell’s Solar Clipper series, i.e. it made the fantastic life of space travel feel real without making it mundane. By the time we got to the “martians”, I was completely drawn into her personal world.

This book also comes close to one of my favorite kinds of conflict, where the bad guy isn’t really a bad guy, just that he is making decisions from his own values, and those decisions and actions end up conflicting with our hero’s goals. There are two bad guys in this. The first is a local administrator who is doing her best to protect the Mars outpost and humanity at large and who makes some bad calls in the process. The second is a distant group that is acting to protect itself at any cost with no apologies to those who get in the way.

In the end, heroes are heroic, bad guys are thwarted, and sacrifices are noble. It finishes with a semi-open happy ending, and I believe there are at least two sequels, so I may be looking at those soon.

DARPA’s 100-year Starship Program

I spent the weekend down in Houston for ApolloCon, and the most surprising panel I attended was on a DARPA program to lay down the research necessary to launch an interstellar ship a hundred years from now. To quote from their announcement last year:

In 1865, Jules Verne put forward a seemingly impossible notion in From Earth to the Moon: he wrote about building a giant space gun that would rocket men to the moon. Just over a century later, the impossible became reality when Neil Armstrong took that first step onto the moon’s surface in 1969.

A century can fundamentally change our understanding of our universe and reality. Man’s desire to explore space and achieve the seemingly impossible is at the center of the 100 Year Starship Study Symposium. The Defense Advanced Research Projects Agency (DARPA) and NASA Ames Research Center (serving as execution agent), are working together to convene thought leaders dealing with the practical and fantastic issues man needs to address to achieve interstellar flight one hundred years from now.

They’re not handing out research grants at the moment, but they hosted a symposium last fall to talk about issues from propulsion to philosophy, i.e. not just how to get there, but why we should go. This year, they kicked off the seed funding to create a private organization called the 100 Year Starship. They’re holding another symposium this September in Houston. Given that it’s just a few hours’ drive for me, I’m seriously thinking about it.

I mean, really, this is seriously cranking my geek.  Or… you know, something that sounds maybe a little less disturbing.

Exploring the Final Frontier on a Schedule

In the first two installments of this series, I looked at exploring a new star system and examining a planet from orbit. Depending on the level of detail you want, this could take a few days to a few years… for each planet. With 15,000 star systems to explore within 100 light years from Earth, how are we going to do this in a reasonable amount of time, even with our nifty FTL survey ships?

I think the best solution is to parallelize as much as possible. That is, throw more manpower at it, or in this case, more ship-power. Since it takes some number of orbits around a planet to map it with the desired detail, the best way to speed that up is to do multiple orbits at once by employing satellites rather than simply orbit in the ship.

Such satellites would not need independent launch systems. The ship could assume the desired orbit, lower the satellite out of a cargo bay, and gently move off towards the next desired orbit. That way, something that would have taken a few days could be done in one.

Alternatively, if a particular system has more than one planet (or moon) in need of such mapping, a portion of the satellites could be deployed at one world, left to do their survey, while the ship goes to another world to deploy more of the satellites. In our solar system, this would be the equivalent of populating Earth’s orbit with observation satellites, popping over to Mars in mere moments using your nifty FTL drive to seed it with satellites. You might even dash out to Jupiter to set one around Europa. By the time you had set all that up, it would be time to swing back to Earth to collect your satellites and their data.

In fact, if one world in particular deserved a longer, high-resolution look, then one or more satellites could be left in place while the ship moves on to another star system entirely. It could then come back after a few months and collect a wealth of information. This would be useful if you saw signs of life or hints of artificial constructs on the ground and wanted to get that 1-meter resolution scan, or perhaps even zoom in further on the really interesting spots. I would not propose to attempt reading the New Rigel Times over someone’s shoulder, but you might discover that he did, in fact, have a shoulder to begin with.

How many satellites should the ship carry? All I have is a gut feeling for bringing about a dozen. It would be great to have hundreds, but when you start thinking about the big optical lenses, these satellites are bulky. A dozen should not take up an unreasonable amount of room, and it gives the survey crew enough to check out multiple planets at once as well as a few to leave behind without impairing the rest of the survey mission.

I would also want to carry along a number of communication satellites to be left in key locations. If my FTL communication system requires boosters or relays, it would make sense to leave them near interesting worlds, technology willing. And if the FTL communication is via courier ships, then these message queue satellites should be left at predictable locations, i.e. around promising stars near planets in the habitable zones. Hopefully, these could be of a reasonable size. It would be nice to leave one in every star system visited, but failing that, it would be nice to leave behind five or ten.

So how long will this take? I think with the extra satellites, a star system could get a decent exploration in about five days. For convenience, I’m going to assume an FTL speed of about one light year per day, and say that we can get from one system to the next in an average of five days. Yes, the distance varies from 10 light years for solitary stars to less than one for places like the Pleiades, but we’re into hand-waving territory here. This might take even longer when you considering the problems of efficient routing (i.e. the travelling salesman problem) and the inevitable backtracking to pick up any satellites we left behind, slowing us down just a little more. Then again, there’s nothing to stop me from waving my hands again and saying two light years per day. So let’s stick with five days travel between stars.

So, put those together, and you can explore a new star system every 10 days, and I think that’s pretty optimistic.

But how long will you explore? I’m going to use the U.S. Navy as a guide, and while ship deployment lengths vary, few are longer than six months at a time. Some of this is supplies. Some of it is wear and tear on the equipment (being as sea is kind of rough on things). But I think a lot of it is simply the limits of the human psyche. While visiting Alexandria, Hong Kong, or Rio de Janeiro can ease the stress, the real test would be those guys riding it out alone on the nuclear subs, and I believe their tours are no more than six months.

So is that six months of survey? Well, sure, as long as we’re only exploring the neighborhood right nearby, but as time goes by, we’ll be exploring further and further afield. Even at a light-year per day, we could spend three months getting out to those worlds in the 90-100ly range only to have to turn around and come back home.

So I’m going to assume that as the project progresses, we build up some forward bases. In fact, one of jobs of this survey would be to find good locations for those forward bases. Some of those more interesting worlds could be candidates for terraforming and eventual colonization. Building a meeting place for crews to get a little rest, repairs, and crew rotation would be a decent place to start with such an effort. Welcome to Deepspace-84.

So, I’ll assume that for the duration of the project, the survey area for a particular six month tour is roughly 30 days from a forward base. Furthermore, I’m going to give them two months of downtime back at that base. Ships will need maintenance, resupply, upgrades, and so on. Plus, it gives them some leeway in their schedule if they run a little behind.

After setting aside 60 days to get to and from the survey area, that leaves us with about 120 days to survey, and at ten days per star system, that’s only twelve new star systems. Add in the two months of downtime between survey missions, and that’s twelve new star systems per eight months. Since we’ll certainly be having more than one ship doing this, let’s average it out to only eighteen star systems per ship-year.

Now, how many stars were we talking about? Oh yeah, 15,000 stars within 100 light years. At the survey rate I’ve given, that’s about 830 ship-years worth of survey. If we want to do this in as little as twenty years, that means about 42 survey ships. Maybe even bump that up to fifty for some inevitable problems that we’ll run into along the way.

Considering that the U.S. Navy has varied from 250-600 ocean-going ships over the last century, fifty ships does not seem an unreasonable number of ships to dedicate to such an effort. I’ve been imagining these ships as being fairly lightly crewed by naval standards, requiring probably only forty to one hundred crew each, but that’s still a few thousand crew.

But even 5000 is not that many people, especially considering the number of Earthbound explorers who would be dying for a chance at it. I know I would be eager to put in my resume. Even if I don’t get in on this one, I might still have a shot at the next phase of scoping out the 100,000 stars in the next 100 light years out from there.

Wouldn’t you want to spend a few years of your life on something like this?

Exploring the Final Frontier from Orbit

A couple of weeks back, we set forth in our sparkly new FTL survey ship to explore the 15,000 star systems within 100 light years of Earth. We hopped around a particular system to track down any planets it might have, and now we’re going to take a closer look at them. While it would be fun to zap down to the surface to get hands-on information, our mission really is survey. Let’s find the interesting places and let some other poor schmuck get fitted for a red shirt.

So what can we do from orbit?

In a lot of ways, this is a question for the CIA, or more accurately the National Reconnaissance Office (NRO), the agency in charge of the various US spy satellites. Most of us think of spy satellites as peeking in on missile complexes or uranium enrichment plants, but at a lower resolution, they are quite useful for map-making.

And that gets right to the heart of the matter: resolution vs. coverage area. The optical sensor in your orbital platform is of some fixed size. Maybe it’s ten centimeters or a full meter, but the key is that it’s a fixed number of pixels across, perhaps a hundred thousand. If your optical lenses project an image that represents a square kilometer on the ground, your resolution would be one hundred thousandth of a kilometer, i.e. a centimeter.

While centimeter resolution might thrill the NRO, it’s wasted on us for survey purposes, and the Earth would require at least 500 million of those snapshots. If we had that large of a sensor, we would be much better off taking snapshots of 100km by 100km and getting 1 meter resolution.

You can play around with this a little by taking pictures of things not directly beneath you but scanning east to west and patching them together, but doing it quickly (that is, at orbital speeds) could get quite complicated. I don’t know if our current spy satellites can manage that kind of east-west scanning, or if they simply have to pick their targets more carefully.

In addition to visible-light photography, we can take photographs at varying resolutions in the infrared and ultraviolet. Add in a RADAR transmitter, and we can do terrain height mapping as we fly over.

But how long does this take? Let’s assume a planet the size of the Earth. We do our observations from a polar orbit, taking 100km-wide swaths of photographs as we go. We’ll get lots of overlap near the poles, but we have to make enough passes to cover the entire equator in 100km chunks. At 40,000km around, that’s 400 passes. Orbit times depend on the mass of the planet and the height of the orbit, and on earth we see orbits range from 92 minutes (on the International Space Station) to 27 days (the moon).

But the Earth spins, and since that’s helpful, let’s hope our new planet does too. After 92 minutes, the equatorial land we pass over on the day-side is 2500km from the last picture we took. It would be nicer if it had only moved 100km, but we can work with that. If we choose our orbital altitude correctly, we can get our orbital period to line up so that we’re always hitting some multiple of 100km from the last pass, and with the right rhythm, we’ll keep hitting fresh bits of the equator. It’s one of those prime factor things, cycling over 400 swaths by 3’s (or 7’s, 11’s, 13’s, etc.) will keep hitting new swaths.

We may as well photograph things on the night side as well to capture any surprises like city lights, but we’ll mostly want the daylight side. So that’s 400 orbits of 90 minutes or more, which will take at least 25 days. It would take longer if we want higher resolution, or be done quicker if we settle for lower resolution. Notably, that centimeter resolution could take years, while backing off to 10m resolution could get the job done in a few days. Oh, and then there might be weather getting in your way.

See what I mean about the quandary of coverage vs. resolution? When flying over some of the overlapped areas away from the equator, you can squeeze in some zoomed shots of the more interesting bits, but your overall schedule is going to push your towards the lower resolution. With 15,000 star systems to get to, it’s going to be a hard argument to push for something greater than 10m resolution.

But what can we do to fit more into our schedule? I’ll be talking about that next week when I go after some of the logistics to make this survey project more feasible. Or maybe I’ll just see how mammoth it really is. Either way, I’m still wallowing in wish fulfillment, eager to don my Survey uniform.

Exploring the Final Frontier

You’ve just been given the keys to your own FTL explorer ship… what do you do? This is a thought experiment that borders on wish fulfillment, but the kid in me thinks that’s the best kind. For all the flaws of the Star Trek prequel series Enterprise, it at least had some fun playing around with the “explore new worlds” part of the mission, and I really enjoyed those episodes.

So let’s play around with it some ourselves. Assume we’ve reached the level of space technology where we’ve set up a few permanent outposts throughout the solar system, and we’re able to build some reasonable spacecraft for scooting around the neighborhood. Then suddenly, FTL goes from a surprising theoretical possibility to an even more surprising engineering reality.

The NX-01 Enterprise rolls off the line, then the NX-02, and so on. They go off and take snapshots on Rigel-4 and draw lots to see who gets the next red shirt.

Meanwhile, you get a much more boring assignment on the exciting starship Survey-4. While those dashing captains check out the Top 40, you get to fill in the gaps, and there are some pretty big gaps. Within 100 light years, there are about 15,000 stars. Within 500 light years, there are almost two million. So if we’re going to be jetting around at warp 7, then there’s a lot of stuff between here and Rigel. (Approximately 850 light years, in fact.)

So where do you even start on an assignment like this? Let’s assume we got called in early on the project, so we can help lay out the scope of the mission. That is, what are we looking for? What do we need to find it? Where are we going to look? And just how long is this going to take?

We’re probably looking for life or at least places we could live, and from that we can narrow the scope a little bit, since not all stars are likely to support life as we know it. However, we’re probably also looking for useful resources, points of scientific interest, and staging points for further exploration. As such, we probably want to at least stop off at each star and give a quick look around.

What do we want from that quick look around? Personally, I’d want to know if there were any planets, and if so, how many? And if any of them seemed interesting, i.e. in the habitable zone, have big moons, or simply look pretty, I’d want an orbital survey on them.

Finding the inner planets will be easy enough by their reflected light. We found most of the ones in our solar system without even the aid of a telescope, simply because of the motion of planets against the background of otherwise static stars. The actual motion of the planets may not help us here, since waiting for Uranus or Neptune to move an appreciable fraction of their orbits can take a while.

However, the apparent motion of the planets will help us a lot. When an Earth-bound observer sees Saturn move against the stars, some of that motion is truly the motion of Saturn, but some of it is also the motion of Earth. As the Earth bounces back and forth from one side of the sun to the other, the viewing angle to Saturn swivels back and forth. In many cases, it appears as though it has reversed its orbital course, but it’s really just our own movement around the sun causing that motion. (This is what people mean when they say a planet is “in retrograde”, just that the relative motion of Earth and the planet makes it look like it’s going backwards.)

Well, in our nifty FTL survey ship, we should be able to bounce around in much less than the year Earth takes. The idea is to take a high resolution picture of the stellar system with our camera pointed towards a fixed location, like good old Sol, and when I say high-resolution, I’m thinking about stitching together a few thousand telescopic snapshots. Then move over a billion kilometers to the left, aim this camera array towards Sol, and take another picture. The position of the stars should stay more or less the same. Anything that appears, disappears, or moves from one picture to the next is probably local. (Or maybe some distant pulsar is just dicking with you.) If you do this from two or three directions, you should get a pretty good map of the inner planets.

It might not get you some of the outer planets. Neptune and Pluto were not originally discovered by telescope but by their gravitational interactions with Uranus. However, assuming better telescopes, no atmospheric interference, and better image processing than the eyes of early 20th century astronomers, we would probably find anything down to Pluto’s brightness. Whether or not we’d see something like Eris out in the Kuiper belt is more speculation than I’m willing to make right now.

So, what do we do with these planets once we’ve found them? As much as I’d love to send down some red shirts (and maybe even some people in them) to explore, an initial survey such as this should probably limit itself to space-based observations.

Telescopic observations can tell us a fair amount from a distance, but mostly that information can be used to rule out some planets from a more detailed survey. Spectrum absorption lines can tell us a lot about atmospheric makeup, and we can also measure the temperature to some degree. If it’s 200 degrees (or -200), then we’re probably not going to find life or suitable colony locations on it. I think we can also get a moderate idea of the atmospheric depth via telescope, since we knew of Mars’ minimal atmosphere years before we sent probes. (Though I confess, the science for extracting that info is beyond me.)

But if the atmosphere and temperature look appealing, it might be time for a much closer look. Just how much of a look can we actually take from space? I’ll take a stab at that next week.

Anything else you’d want from your initial system survey?