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This weekend was a good one for writing; Kathleen and company were able to avoid major kid disasters or blowups, so I ended up with both Saturday and Sunday clear. I was in a Jason Wood mood on Saturday and wrote nearly 5,000 words in the first new Morgantown story since I finished Digital Knight back in early 2003; title is "Shadow of Fear". On Sunday, I went over 15,000 words on Threshold, the sequel to Boundary. Effectively I think this is over 20,000, as there's quite a few additions I expect from Eric.

Threshold is probably going to be the hardest of the three Boundary-universe books to write; we're developing the political, social, and personal universe equally in Threshold, and it's COMPLICATED. I was able to sort of fake out all of the stuff in Boundary, even though Eric seriously modified things; I can't pull that off on some of these, though. Eric will have to write those sections and, for once, I'll have to edit/smooth out his stuff to make it fit with mine. There's also a LOT of new science-related stuff I'm having to do -- people on Baen's Bar are seeing some of that, with me asking questions about nuclear reactors and superconductors and orbital calculations -- which isn't easy, even though I can (as an SF writer) decide to occasionally handwave away practical difficulties. Once Threshold is done, I'll have a good enough grasp of the entire universe to just write the next one, at least as a rough first draft. But Threshold itself is going to "be a pure bitch", as Maddie would say.

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From:

shana.livejournal.com

More Morgantown! So you're maybe a third to half-way through the story. So the nemesis has been introduced?

I predict that Jason will shoot whatever the monster is. (Whether it will do him any good is another question, of course.) :-)

From:

Actually, this one is more like "Mirror Image", in my estimation, than "Gone in a Flash", so I'm probably more like 1/4 through.

From:

shana.livejournal.com

The only problem with it being longer is that it will take you longer to write.

But it will give me more story to savor!

From:

True, true.

Hey, where's your review of Boundary? I always love reading your reviews...

From:

shana.livejournal.com

Unfortunately, my back has been giving me trouble. The position in which it is comfortable to use the laptop is uncomfortable for heavy typing.

After trying to start it, I decided I needed to reread it again. So it will be another couple of days.

From:

Well, that's okay. As long as it goes up. I got a quite excellently slagging 2-star beating this morning -- well, actually, it was ERIC who got the beating; it was as though I had nothing to contribute to the book.

BTW, you never did review Diamonds!

From:

shana.livejournal.com

Review posted.

I thought I had reviewed Diamonds...

Well, it will have to wait for another day. I'm not going to spend much time on the computer today unless you send PBEM updates. I've got too much else to do.

From:

kengr

Hmmm... I'll have to make a note to design a monster where shooting it is *worse* than not shooting it.

From:

Been done. Terry Brooks Jachyra got stronger on pain and suffering. Even its own.

From:

james-nicoll.livejournal.com

If you are talking interplantary stuff, www.jaqar.com has a swingby calculator that I have found rather handy.

From:

... interplanetary -- I want basically trips from Mars to Ceres, and Ceres to Jupiter and/or Saturn. (then, ideally, some idea of transits within those sub-systems, but I could probably handwavey and BOTE those)

Also, how would one use a planet like Jupiter to slow down, rather than speed up, and how much of a reduction in velocity could you get? Say you were going faster than your target and had to slow up quick?

From: (Anonymous)

I've been discussing similar moves with Travis Taylor and he suggests using aerobraking. Check '2010' for a fictional example, 'Mars Odyssey' for a real one.

-- Alex S.

From:

Hmm. That'd depend on the geometry of the craft rather heavily. And its makeup. You wouldn't even TRY that with Nike, for instance, or at least I'd be surprised if someone could come up with a safe way to try that with such a vessel. you'd want something pretty compact, tough, and probably aerodynamic, yes?

From:

kengr

Both the slow down and speed up gravity assists tend to involve craft that are *not* yet in orbit around the body, but in a solar orbit.

The difference is whether you pass "ahead" or "behind" the planet as it orbits. It basically tries to "pull you along". Which produces a velocity change on the order of the differencer in velocities.

The *details* are the killer.

And it's not good for a *quick* velocity change.

But here's a thought. Given Jupiter's magnetic field, you might be able to deploy a mag-sail and use *that* for braking. That would avoid the problems with aerobraking, and help with radiation shielding.

From:

The magbraking I thought of, and would be very interesting, but I can't find anything like sufficient detail on the magnetic field of the planets to determine whether it's actually practical to do, or whether you'll get no noticeable slowdown from the magnetic field until you're already IN the planet's atmosphere.

From:

kengr

Given that magsails are normally proposed to use the trapped filed in the solar wind, I think Jupiter's field is strong enough. :-)

Besides, you aim for a close pass, not straight at the planet!

From:

james-nicoll.livejournal.com

The forces that apply to magsails are minute, though. This means lots of time and space. I don't think you can halt a space ship at Jupiter this way (Annoying, I know I was in a thread about this but I cannot find it).

From:

james-nicoll.livejournal.com

Of course, you could exploit Jupiter's field in a different way: hang a conductive cable off Metis, then trade Metis' potential energy for power. You should be able to get 100,000+ terrawatt-years out of Metis before it deorbits and you could then apply the power to incoming space vessels, directly or otherwise.

From:

Now that's fun. But it would seem perhaps somewhat difficult to pull off as a sort of improvised method unless one had thousands of miles of conductive cable just hanging around in the closet.

From:

I rather thought not. Deploying a large magsail or equivalent while cutting through Jupiter's field would have SOME effect, but unless I can find a way to calculate it accurately I'm going to have to assume "not really very much".

From:

james-nicoll.livejournal.com

Aside from aerobraking (1), you can do a passive flyby, which can change your velocity thanks to the fact that your path by a given planet will be symetric with respect to the planet but not the star it orbits: the ship gains or looses energy wrt the star by a certain amount but the planet looses or gains in the same amount, opposite sign, so everything balances. You can also do an Oberth Maneuver, which I am very fond of.

Assume a rocket is falling from infinity past a massive object. The fuel in the tanks had a significant potential energy wrt to the object and if you do a burn at periapsis (closest approach), you can exploit this as follows:

delta vee (final) = [(Vesc+Vimpulse)^2 - (Vesc)^2]^1/2

Vesc is the escape velocity at periapsis, Vimpulse the change in velocity due to a rocket burn and delta vee (final) the delta vee you actually get.

This, in contradition to at least 40 years of SF, makes "gravity wells" a valuable resource, although not to the people in them. It's like Liars Poker, everyone else's gravity is useful.

Say the Oh God Don't Let Us Smash into Io and Explode into a Million Superheated Fragments is falling past Jupiter at 50 km/s. Jupiter has a high escape velocity (~60 km/s at the cloud tops) and the crew passes close enough to J that the Vesc is 55 km/s. If they do a 15 km/s burn at periapsis, their final delta vee would be about 50 km/s, bringing them to a dead halt wrt to Jupiter.

Of course, having neglected to take into account the fact that they probably wanted to be in orbit around Jupiter, not hanging very briefly in its sky, the OGDLSiIaEiaMSF then plummets out of space and into the upper atmosphere, where a combination of air pressure and rentry heat destroys the ship. Their math was solid, though.

1: Or Robert Forward's attempt to find a force stronger than gravity to couple to passing bodies, which involved a long bungee cord and a harpoon.

From:

Aside from aerobraking (1), you can do a passive flyby, which can change your velocity thanks to the fact that your path by a given planet will be symetric with respect to the planet but not the star it orbits: the ship gains or looses energy wrt the star by a certain amount but the planet looses or gains in the same amount, opposite sign, so everything balances.

Hmm. How much delta-V could you get out of that? I'm thinking of Fast Ship chasing Slower Ship, needing to match up with Slower Ship, and not having some other way of slowing down much. Either aerobraking or using the flyby are pretty much its main options here. No rocket fuel available to dump in an Oberth.

Say the Oh God Don't Let Us Smash into Io and Explode into a Million Superheated Fragments is falling past Jupiter at 50 km/s.[...] their final delta vee would be about 50 km/s, bringing them to a dead halt wrt to Jupiter.

Of course, having neglected to take into account the fact that they probably wanted to be in orbit around Jupiter, not hanging very briefly in its sky, the OGDLSiIaEiaMSF then plummets out of space and into the upper atmosphere, where a combination of air pressure and rentry heat destroys the ship. Their math was solid, though.

I always love your examples, James. Though you left out the part where you say something like, "... plummets out of space and into the upper atmosphere, something I have always found much more amusing to watch than to do; the one time I did this, it caused several scars..."

1: Or Robert Forward's attempt to find a force stronger than gravity to couple to passing bodies, which involved a long bungee cord and a harpoon.

To what Forward story are you referring? Or were you just being snarky about Forward because it sounded amusing (which it did)?

From:

james-nicoll.livejournal.com

It's from SATURN RUKH, where the ship steals small amounts of momentum from a number of moons using a temporary physical connection along the lines of a harpoon and long cable.

The part I have a problem with is the impromtu connection at the surface of the moon. Otherwise, for low delta vees, the numbers aren't too bad:

Say the Queeqeg comes barreling by the TransSaturnian Station IMMOVABLE OBJECT at 10 km/s. A small ring on a cable is fired out to match veolcities with the ship's tow hook. Assuming that the ship can't take more than 10 gees, it will take about 100 seconds to stop the ship wrt to TST IO and about 500 km.

Depending on the design, you may have to deal with about half a megawatt of heat per kg of ship.

From:

Hi, James. Going over some of your old (and useful) messages, I was revisiting this one, and had some other questions/thoughts. You can just reply via email if you don't feel like posting.

Aside from aerobraking (1), you can do a passive flyby, which can change your velocity thanks to the fact that your path by a given planet will be symetric with respect to the planet but not the star it orbits: the ship gains or looses energy wrt the star by a certain amount but the planet looses or gains in the same amount, opposite sign, so everything balances.

How much delta-vee can you get out of that? I mean, if I want to either speed up or slow down as I approach Jupiter, can I do a passive flyby to get me to do so by 1 km/s, 10, 50? And is there a limit to how fast I can be flying to begin with (i.e., if I'm booking along at 10,000kps, do I still get the little nudge?)

You can also do an Oberth Maneuver, which I am very fond of.

Assume a rocket is falling from infinity past a massive object. The fuel in the tanks had a significant potential energy wrt to the object and if you do a burn at periapsis (closest approach), you can exploit this as follows:

delta vee (final) = [(Vesc+Vimpulse)^2 - (Vesc)^2]^1/2

Vesc is the escape velocity at periapsis, Vimpulse the change in velocity due to a rocket burn and delta vee (final) the delta vee you actually get.

You use the equation below in this amusing demonstration:

Say the Oh God Don't Let Us Smash into Io and Explode into a Million Superheated Fragments is falling past Jupiter at 50 km/s. Jupiter has a high escape velocity (~60 km/s at the cloud tops) and the crew passes close enough to J that the Vesc is 55 km/s. If they do a 15 km/s burn at periapsis, their final delta vee would be about 50 km/s, bringing them to a dead halt wrt to Jupiter.

Of course, having neglected to take into account the fact that they probably wanted to be in orbit around Jupiter, not hanging very briefly in its sky, the OGDLSiIaEiaMSF then plummets out of space and into the upper atmosphere, where a combination of air pressure and rentry heat destroys the ship. Their math was solid, though.

Rereading this raised two other questions for me:

1) Is the equation the same for trying to SPEED UP as you approach Jupiter or wherever, and if so where are you doing the burn to ensure maximum increase rather than slowdown?

2) Your figures above give the OGDLUSiIaEiaMSF a speed to begin with of considerably less than escape velocity. If they didn't do a burn at all, would they have ended up plummeting anyway? It would seem to me that at the very least they'd be stuck in an orbit around Jupiter rather than continuing on to some happier locale. If not, how slow would they have to be going as they passed Jupiter in order to end up flambe instead of escaping?

From:

... that's a Windows program, isn't it? Or not?

(deleted comment)

From:

Well, at this point Jason hopes NO more werewolves.

From:

shana.livejournal.com

And he's got the werewolf in the little red circle with the line through it posted at his gate, too. :)

From: (Anonymous)

I stopped by to see if you mentioned whether _Boundary_ was a stand-alone or part of a set, and was pleased to see your discussion here. I read _Boundary_ some months ago as a Baen pre-publication draft, and loved it -- and of course, I bought the hardback soon as it hit the stand (Baen has us figured on that count), but I could see all sorts of loose ends that said: "Sequel, maybe." So I'm glad to see that you're on the way to the press with this pile of paper... Thanks for making the effort -- or is it that you can't escape the story, haunting you day and night, and like that?

I've been a professional archaeologist for the last thirty years or so (you know, "just yesterday, in 1975...") and I was impressed as hell how you caught the flavor of some part of what I do -- paleontology is somewhat different in some ways (way more sloppy, of course). Almost-archaeological events preserved at the KT boundary -- that's been an argument over several beers a few times.

Passing remark -- sure, your crew was a little heavy-handed in their treatment of your off-earth sites, but given the context of really good locational information on penetration of a room, I doubt anyone other than the professionally reactionary would raise hell about it. The situation is a lot closer to underwater archaeology, especially the sort that explores sunken ships. Not that I can hold my breath that long...

From:

Thanks much! I love discussing my work (who doesn't like talking about themselves? Well, okay, people without a need for personal image reinforcement.)

We always knew there was a possibility of sequels. When Jim seemed reluctant to offer me another solo novel right away, Eric asked how he felt about Boundary sequels, to which Jim responded with a two-book contract. This works for me.

As I mention in one of my other posts, the sequels are going to be... hard to write. But worth it. And if they remain popular enough to justify it, I can foresee quite a series coming out of this. One with some unique features.

RE the image of the profession: both Eric and my wife are paleontology buffs, and I've done some work in a quarry, trying to find fragile crystals in rocks; the combination enabled me to get across some of the atmosphere. Glad you felt it worked well.

From: (Anonymous)

You understand that at base there's a significant difference between archaeology and paleontology. Paleontology is focused on bringing back the specimen. Archaeology, however, wants more than artifacts (the equivalent of a specimen), although it doesn't get presented that way in pop fiction. Context is most important -- equivalent of paleoenvironmental research -- and for historical archaeologists like me, structures are the important thing. Depositions (the thin layers of earth that build up during the use of a building) record culture change through time, and artifacts are mostly for dating. Only very rarely do artifacts attract major attention on their own.

Since I was going to be an astronomer back in the day, I have naturally thought about doing archaeology in vacuum and in zero-g environments. Very interesting problems, which of course lead to very interesting solutions. Most critical thing is record-keeping on the ground -- rather, in a grav field -- but record-keeping is about location, and in zero-g location is and has been a variable since the site was abandoned. I have considered the idea that there would be a branch of archaeology called "paleotrajectory studies," for example, but the circumstances under which object movement is informative are limited. Too much chaotic rebound, too much friction from dust and trash in a room. Still...

Your discussion of the probabilities as argued by Dr. Glendale was great -- that unless there were artifacts or conditions that allowed no other explanation, a terrestrial origin for whatever "problem" we stumble over has to be the first assumption. I once proposed a what-if when the beer had softened the minds of the group enough: What if we found a concrete buiding floor, angle iron traces, fiber-optic and electrical cables sticking out of the floor, and so on, in a context that showed it was associated with an Indian village dating to about 1200 AD? What would be our first explanation of this? Talk about uncomfortable choices...

From:

Well, certainly they're different. Though context is deadly important in parts of paleontology (and is, in fact, one of the key points of Helen's find; the context in which the fossils are found is significant indeed)

I'm not sure that there are real "zero-G" locations, at least not commonly. Yes, very low gravity locations -- Phobos' gravity isn't noticeable by human musculature -- but the gravity is more than enough to make things settle down and stay put in very short time, even on a human scale, let alone archaeological. Even in a smaller rock, the thing is probably spinning enough to hold things down. So the only environment I can think of where real "zero g" conditions would hold as you describe would be a site on the OUTSIDE of an asteroid small enough that things could easily get detached and fly off away from the initial location.

I enjoyed writing Glendale's dissection (and Eric tweaked it, as I recall) of those probabilities. Glendale himself refused to fade away, so he's getting a much bigger part in the sequels.

From: (Anonymous)

I was thinking in terms of a shipwreck for a zero-g site, actually. Drifting between the stars lightyears from anywhere... O'course, how you find such a thing is a question. Just spot it next to the standard spacelanes? I don't think so. Lagrange-point wrecks are more likely, I guess -- orbiting wrecks just won't last any significant length of time. But "excavation" of a shipwreck in zero-g requires developing some fascinating methods.

If I switch over to open ID, does the system want my email address as my identity URL? If so, does it cut it down to the short listings on other postings?

From:

True, a freefalling ship would be interesting -- but I would think the interior of the ship is something analogous to the interior of a pot in earthbound archaeology, rather than analogous to a whole site. You can be fairly well assured that there aren't different layers to unravel, just some interesting material preserved inside.

I don't know exactly what open ID does -- I show up on LJ as "seawasp" -- i.e., as my LJ identity. If you post as Anonymous, though, there are a lot of LJs that won't accept your comments; I didn't disable it, but many people do disable anonymous postings.

From: (Anonymous)

While I was printing the illustrations from pics.livejournal, I was looking at the cover of Boundary, wondering how the scene shown there was supposed to tie in with the scene as presented in the story. I realized, finally, that I could see the fingers of a Bemmius just at the right-hand side of the cover illustration -- which suggests to me that there should be several dead Deinonychus scattered over that way as well. Looks like you only got half the illustration onto the cover, and the part that made it on was not the part described in the story. Designer just couldn't pass up that irate Tyrannosaurus, I guess.

From:

While I was printing the illustrations from pics.livejournal, I was looking at the cover of Boundary, wondering how the scene shown there was supposed to tie in with the scene as presented in the story.

You are laboring under a very common misapprehension: that the cover is expected to show something in the book. In a few cases, it is. In most cases, the idea is to convey something of the SPIRIT of the book in an eyecatching fashion. In some cases, the idea is just to be eyecatching. The author has no -- repeat, NO -- say in the cover. If the author is fortunate, he or she will be allowed to suggest a scene, but there is no obligation on anyone's part to listen.

In this case, the cover is excellent at conveying part of the spirit. There were not, alas, any Bemmies ever painted. The only illustration yet done of Bemmie is the one printed in Boundary, touched up at Baen but mostly done by my wife Kathleen. What you're seeing on the righthand side are the claws of another raptor; you can see a small part of its snout a little ways above the claws.

I'm very happy with the cover, overall. It certainly comes closer to the actualities in the book than did the cover for Digital Knight, and it's a very well-done cover.

From: (Anonymous)

Back from two weeks in California...

I'm trying a limited ID to see what the results are.

Aha. It will accept no connection to my email address, only to various blogisms. Since I have no other existence online, it appears that anonymous is pretty much my only choice.

I'd be interested in volunteering as one of your readers if you want more opinionated pronouncements on archaeology. You know in the real world (no, wait, do I want to actually use that phrase? Ah, what the hell) world opinion would force the presence of an archaeologist on subsequent expeditions -- I'm surprised they let the big trip to Phobos go through, knowing it was an archaeological site, but with no archaeologist. Just paleontologists and linguists. Hrmph.

I've worked on an excavation where we had a suite of remote-sensing operations carried out. This included soil resistivity, ground-penetrating radar, magnetometry, and seismic tomography. Larry Conyers (U Denver)did the GPR and the cesium magnetometry, John Hildebrand (UC San Diego) worked with Conyers on the magnetometry and the ST. The results were typical of the state of the art these days, before the years of calibration, site to results, that are needed to make this stuff work at high resolution: a lot of blotches that we had to excavate to see what they were. I think this will be a critical part of any excavation eventually, after calibration, but right now it confuses some, at least, of the field people more than it helps.

From:

... since LJ has you listed as anonymous, would you care to email me and tell you who you are (if you did and I'm just blanking, I apologize)? (If you do, I can address the problem of having no archaologists in Boundary by putting in one named after you in Threshold.)

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