Space, Time and Aimless Wandering

Right now I’m just kind of swimming with ideas and I figure I need to get them down, if not in writing then in lovely ephemeral electrons. I just don’t know if any or all or none of these ideas is good or productive, but I’m just going to throw them out there.

The first idea has been floating around in a different form in my head for awhile. It just recently gelled into something different, possibly interesting and probably insane. I’d been looking at a thread on the Alternate History Forum about how the world might be different, “If the moon was a place like Earth…” The idea of building an alternate Apollo program to put men on a nearby world that was, in fact, at least marginally habitable, really tickled my imagination. The thread didn’t really go in a direction that I would have preferred and I wasn’t too interested in maintaining the huge herd of alien space bats needed to make such an Earth resemble our own degree. I’d have to either somehow figure that these two large worlds hadn’t fallen into a tidal face lock(which would have required a lot of those space bats to maintain) or somehow figure on some really alien world with a day more than a month long that some alternative Kennedy would engage in a race to the moon with some alternative Kruschev. My imagination quailed.

I’d just been reading The Dispossessed(affiliate link to Amazon 🙂 ) by Ursula Le Guin, which describes a world and its habitable moon. Its a good book and an interesting idea for a more leftish libertarian society than I’ve gotten used to seeing of late. Although she doesn’t make the society on Annares(the previously mentioned moon) into a utopia, I think she may be over estimating just how well such a society might work. But I digress. The important thing about her description of statist-capitalist Urras and its moon Annares(at least for this discussion) is that there is no sign that these two worlds are face-locked. The planet maps give no hint which hemisphere has the other world perpetually hanging in their sky and there is no hint in the text of exceedingly long days.

If these are true moons, they should definitely be face-locked. The tides between any reasonable Earthlike world and an Earthlike moon would be so great as to slow the relative rotation to a standstill within a few million years easily, definitely within the billion years plus required for life to evolve to any halfway interesting degree. Stephen Dole in Habitable Planets for Man(free link: here’s an Amazon link if you want to own the dead-tree version) gives a mass range for a habitable planet of between 0.40 and 2.35 Earth masses. The book may be a bit dated, being older than I am, but the range still makes sense. I’m convinced enough by Chris Wayan’s arguments to extend the range down to 0.3 Earth masses, although I think 0.25 Earth masses may be pushing it a bit. In any case, even at the extreme lower limit of mass for a habitable moon and extreme upper limit for the mainworld any moon within the mainworld’s Hill radius is certain to become mutually face-locked. Even in the really extreme lower limits for size the world is going to be 20-25 times as massive as our Moon.

So the crazy idea that I have that might avoid tidal locking(assuming its at all stable for large masses; a big ‘if’! ), is a horseshoe orbit. Not so much, “WI the Moon was a  Habitable World,” as, “What if Cruithne was a Habitable World!” Clearly, this needs some work with Gravity Simulator. In any case, even a giant Cruithne couldn’t be habitable even if its orbit proved to be stable. At perihelion it lies just outside the orbit of Mercury and at aphelion it’s orbit takes it out beyond Mars. The climate would be awful! I’d just like to see if a stable horseshoe orbit could be managed between two bodies of mass similarly as large as Earth’s. Should be a fun place to visit…

My other ideas are also related to space flight. One book I’ve been reading recently is Energy Crisis(another affiliate link for those want the book), by Ralph Nansen(link to one of his earlier books on orbital solar power available online. Yay!). The book is about how solar power satellites could be used to provide clean renewable power to the world in the kind of quantities needed by a modern society. Solsats are very interesting to me both in reality and fiction as I try to reconcile my Buck Rogers technophilia with a certain affection I have for living planets with intact ecosystems. But the guy worked on spaceships back at the tail-end of the Apollo golden age and the leading-edge of the Shuttle days. Some of the early ideas for the Space Shuttle really struck me as promising. Too bad we got stuck with the political compromise we did.

Two of the Shuttle concepts that struck me as interesting was one that carried LOX in its wings and LH2 in tanks above its wings. This was possible in part because hydrogen was only being used for the upper stage, not from the ground all the way to space. It used some kind of kerosene-burning LOX booster to get it up above the atmosphere where hydrogen comes into its own as a propellant. NASA has kind of gotten obsessed with hydrogen as a propellant, which is unfortunate. It’s not very dense, so to get a reasonable mass of propellant, you have to carry it in unreasonably massive tanks. As to its supposed environmental advantages, unless you have a clean source of electric power to support electrolytic separation of water, creating hydrogen fuel actually burns up more petroleum and produces more pollution than burning kerosene. So I’ve developed a temporary affection for kerolox first stages.

Another system Nansen described was the mighty RS-IC, basically a Saturn V first stage with wings and a nose tacked on. In principle. In practice it surely wouldn’t have been quite that simple. The shuttle that went with this extreme version of the Flyback-F1 seemed to be a Saturn V second stage with wings tacked on, though the analogy was probably weaker. The shuttle had external drop tanks for liquid hydrogen, the propellant masses would presumably have been different and it wasn’t literally built from an extra Saturn stage that Boeing had lying around, but it had five J-2s on the tail. So there you go. Presumably the shuttle, while carried on the back of the first stage would have air-started its engines since J-2s aren’t really built to run at sea level and those five F-1s on the RS-IC weren’t going to need any help kicking a mere shuttle into motion. Unless that shuttle with its five J-2s was damn heavy or carrying a heck of a lot of payload, I could see them dismounting the center engine on that RS-IC. The reusable SI-C would have been a lot more scaleable than our shuttle and would have been much closer to a truly reusable launch system. Eventually, I imagine they could have made modifications to the expendable F-1 engine to make it more reasonable to refurb, but even as it was they would have gotten three or four launches out of each set of engines. Also I doubt they would have been too much more expensive to refurbish than SSMEs if they could be returned to Earth intact. F-1s were pretty simple beasts and SSMEs were beastly complicated and running right at the ragged edge of what seventies technology could do. They were breakable…

One thing I looked into was a thought experiment to re-design the humungous Delta IV launch system as a kerosene LOX burner. Filling up that enormous tank volume with appropriately proportioned volumes of kerosene and LOX rather than LH2 and LOX resulted in a very heavy launch vehicle of 608,920 kg total first stage mass that needed four ex-Soviet RD-180 engines as used in the Atlas V to get it off the ground, but using a version of the Ares V Earth Departure Stage(massing about 227,093 kg) as its upper stage it could put over 40,000 kilograms into 450 km LEO. Not bad when even the silo-like Delta IV Heavy with three hydrogen burning cores strapped together can only put a little over half of that in a somewhat lower orbit. Actually that upper stage may be part of the reason, but hey my little thought-rocket(which I call the Delta-K, for kerosene) has enough puissance to put that big upper stage up there. Strapping three of those kerosene monstrosities together like that Delta IV Heavy and keeping the EDS upper stage gives you the mighty Delta-K Heavy massing a total of over 2 million kilograms plus payload(a little smaller than the propellant load of a Saturn V first stage, but still pretty big). That thing would be capable of lofting over 90 metric tons of payload to a 450 km orbit. I figure with more optimization of stages those results could be improved considerably.

Yeah, I’m getting into this whole rocketry thing. I still like my warp drive for getting between stars, but I think my fictional universe may be about to lose its reactionless engines, antigravity and artificial gravity. Those damn atomic rockets are just too damn sexy. There’s also something fun about working with something that’s a little closer to something we know we can do. I hope Alcubierre and such can eventually get us those wonderful warp drives, but we’re doing chemical rockets, we could do nuclear thermal rockets of some sort, even the wonderful and terrifying Orion drive should be doable if you’re not too particular about how you treat your planet.

So yeah, people will flit around between the stars in faster than light warp ships, but they may be burning oil to get off the planet in the first place. Or where the locals are finicky about the environment they can use bulky solar-power-electrolyzed hydrogen. For the Harkonnen-run corporate hellhole worlds, you may even go to orbit in style on a big Orion-drive shuttle leaving a trail of nuclear explosions in your wake. Some of the more advanced worlds might have strung strips of carbon nanotube up to orbit and have regular elevator service to space. Yeah, I’m liking this. Seriously cool and plausible enough for my standards of wishful thinking.

More in the alternate history front, I’m curious what kind of difference it would have made if the Apollo program had adopted GE’s Soyuz-like D-2 concept for its space capsule. Lighter and roomier than the our Apollo capsule because a lot of its space was contained in a mission module that didn’t have to be built to survive reentry into Earth’s atmosphere. For every kilogram that wasn’t needed to effect entry and landing that could be expended with the mission module, two kilograms could be saved from the vehicle’s weight. Heat shields are heavy, especially if your doing an aerocapture entry from near escape velocity. Those kilograms add up by the time you get to the bottom of the stack of rockets used to get a spaceship off the Earth and out to the Moon or Mars or elsewhere. Kilograms in a spaceship are expensive. How much cheaper could the Apollo program have been with an MM/CM/SM system that weighed less than the actual Apollo CM reentry vehicle? Could we have had an Apollo 18, 19 and 20 as originally planned? Maybe with a little left over to build a moon base as the seventies wore on?

Some alternate history threads I’ve gotten interested in with a space bent are That Wacky Redhead(five years of good Star Trek, president Humphrey, no, “Sock it to me,” the full run of moon landings to Apollo 20 and roughly doubled NASA budgets, at least through the seventies… all ’cause Lucille Ball was a bit nutty); Eyes Turned Skywards(Nixon doesn’t support Space Shuttle, Apollo hardware continues in use throughout the seventies and into the eighties, Skylab, Skylab II, Saturn IB replaced for orbital missions with new booster based on a single F-1 engine, evolutionary development of space technology, later Saturn Multicore, oh yeah!); a thread with a more active European Space Agency(much more subtle differences than some of the others, since even doubling the ESA budget doesn’t exactly blow NASA out of the water, but it does add some interesting variety compared to our space history.)

In general, I’m more interested in alternate history stories as a way of looking at ways that a future can unfold from a set of beginning conditions. Besides, if H. Beam Piper can steal from the history of the Sepoy Rebellion to make a future
, why can’t I steal from history
that didn’t actually happen?

This entry was posted in History, Planetary Stuff, Science Fiction, World Building and tagged , . Bookmark the permalink.

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