Second contact

In AD 1022ish, a tree surrendered its life to build a Scandinavian-themed home in Markland. Map Myths reports a possible Danish attempt to reëstablish contact. With the help of a couple of German pirates and the Portuguese.

As you may imagine this has run up against 1930s German nationalism and general we-wuzzery around Europe about "who discovered the Americas". (The answer is "the Navajo". Because screw you.)

Frankly all this is the wrong question for the last decades of the AD 1400s, on account of a few factors long mooted here on this blog. tl;dr everyone already knew about the "Markland" for at least a century. Few in the 1400s cared about cold worthless islands. The great powers - which did not then include Denmark nor England - cared about bypassing the Ottomans and getting to the Indies. Whatever these privateers were doing well north of all that, didn't figure. No northwest passage, no cities of gold in Labrador, nothing but cod.

I do however find this of interest for several other, if I may say better, reasons. Cod wasn't worthless in this Catholic age. And the fisher fleets were improving. Perhaps the Danes were starting to care about those "islands" again.

It may witness the fifteenth century in Greenland; when the old towns were abandoned. The island might not have been abandoned. These Danes coming toward the end of the century thought some "pirates" might have lingered there. If so: what was their prey? Basque fishermen? the Welsh and Cornish?

Evaluating the large temporary laboratory

ToughSF's actual link, for which we were planning those mammoth toroidal habitats, was to "Tackling a Mars Cycler Design Head-On" (pdf but badly encoded). Let's abstract it out.

These habitats aren't asteroidal mines. For the trio who wrote that paper, they're temporary housing - shuttles. That allows them to be designed smallest, first. The smallest torus they'll allow fits maybe high-fifties of people. There's a lot of room per person, because this is a 180 day mission until the cycler drops them off at Deimos. Once at Deimos they're Mars' problem; their emptied shuttle then cycles back to Earth where it's Earth's problem.

The trajectory this paper assumes is the classic Aldrin, maintained by solar-electric propulsion. They want to build it in LEO where the SEP paper proposed much higher: TLL1. I'd rather the far-side lunar base with assembly at TLL2... but that might be harder now.

This doesn't have to be a T/M cycler. It could be Hohmann, with less outgoing delta-V. But to Mars/Deimos that takes longer and then it would have to brake and stay there. It could also be a temporary lab in space but then, why not just use a Janhunen or an asteroid-colony to be worked indefinitely. So, we hohmann it out to Deimos or some isolated nearby rock, which we then dock and exploit.

The lab of 55 dudes isn't a colony. Whether it stay there or cycle back, its crew-and-cargo are not staying at Deimos or Atíra or wherever. This is a mission to say they were there. What they might be able to do is patch together some infrastructure for the next shuttle - which will host hundreds.

The design overall might be better for shifting into other orbits. As noted the outgoing Hohmann is less delta-V than the insertion into Aldrin. If the shuttle can take that, it can certainly take the deceleration to dock Deimos. Can you do that with a Janhunen or a big rolling bag of Bennu? I am pretty sure once you have an orbiting Janhunen, it's not going anywhere else.

How planets (can) lose (half) their crusts

On topic of lavaworlds, last April four people wrote "Coupled orbital and interior structure evolution of lava planets" and, on the 20th, posted it. But the pdf says 22nd. Dude! Whoa.

The claim is they ain't natural. Planets born to that heat should have all their material blasted out on formation. Where planetary systems are known to have stayed in-situ, like the Trappist-1 system, are no lava planets. The lava planets instead are around K2-141, K2-360, TOI-141, TOI-431, TOI-2431, HD 3167 and GJ/Gliese 367 all marked "b". (No 55 Cancri e?)

The thought is that they formed in systems where are much larger planets further out. These, as our planets have done to Mercury, pulled their orbits into eccentricity. As they skirt their stars, they raise tides - on the star and on themselves. Now another equilibrium can assert itself. These shattered worlds (like in Star Control 2) reform themselves this close to their stars, in a circular orbit which outer planets cannot much touch. Then they lock tidally. Inner side melts; outer side re-hardens.

The process happens over billions of years so is not done for, say, TOI-431 which isn't even 3Gy yet.

A hundred tonnes at a time

TransAstra proposes to shift 100 tonnes of rock from near-Earth space to Earth space (or Lunar).

ToughSF prefers this over sending humans over to the rocks. Longterm I agree. What's a Bennu orbit compared to a planetary orbit, or a Lagrangian or even the 13:10:8 Laplacian? People should live on natural ports-of-call.

And some of those rocks are eminently movable. 740 missions by such robots and they could disassemble all Bennu, or at least the parts colonists want; and bring its pieces to, oh, STL4 or to a soft landing on the Lunar equator. In the other direction Casey Handmer can yeet Lunar regolith and maybe even Lunar-assembled critical parts - somehow; and catch them at TLL2.

Cooling the halo

This morn we posted Orion's answer to the Halo: the spinning wheel is supported by a nonspinning magnetic shell. Like a lobster is boiled in its own shell.

You see, the older, simpler, thicker shell can offer something Elliot Orion Ruzicka hasn't considered: heat exchange. The outer shell gets outfacing radiators pointing in any direction. But... if there's a vacuum between the habitat and the outer shell, how's the habitat getting its heat to the outer shell?

Perhaps the separative medium is an efficiently-conductive gas. Like hydrogen. Superheated hydrogen between our oxygen-infused habitat and the outer shell, which spin we maintain by some turbine in the hub of the spokes. Oh the humanity.

Nah. The outer shell has to be a half shell, reflective on the outside. The radiators are then attached to the inner shell orthogonal to the direction of spin, or maybe tilted slightly outward.

As they say, amateurs study engineering; professionals study thermodynamics.

Breaking diameters

Been a hot minute since I last dropped in on the ToughSF X account. Ten days ago it linked to a cycler plan - to which I may or may not get. Right now I'd like to discuss its own source, Elliott Orion Ruzicka's submission to the IAF's 75th congress 2024. In his capacity as head of "Orbital Design" in New York.

That's a "Mr.", not a "Dr.". Shows how much credentials matter for awesome material-science papers.

Ruzicka notes that the Halo doesn't work, much less the Ringworld. Since they both spin, each puts pressure on her outer wall. Maximum pressure happens to correlate with radius (or diameter, or circumference): F / gr. Humans like g=9.8 m/s². I'm willing to negotiate for Venereal 8.7 - but now we have to consider the tensile strength of the outer hull, and how thick that might be. The outer shell can't be allowed to dip much less than 9.8.

Given alla'that, cometh our list of tensile materials before this contraption flies apart. As usual Kevlar is in here, maxing out 0.513 mega-meters... 513 km across. As a post-1980 paper we can also use Zylon 759 km. Nanotubes and graphene also make their appearances but I consider them unobtania. Six years ago our boy ToughSF related the T1100G. This was density 1790 and max force 7000 MPa. That last looks rounded: I get 400 km radius = 800 km diameter.

Janhunen's dumbbell and Jensen's smaller stuff were keeping it to decakilostructures, fit for high Earth orbit where space is at a premium and we don't want to bombard our green home. The max-out hectakilostructures were more than enough and, who cared about muh nanotubes. Ruzicka, mad lad, wants a MEGA structure. He floats up to 102,040 km held by 100 m of graphene; compare Earth equatorial 12,756 km... or Saturn 120,536 km. Maybe keep this monster at Venus Equilateral.

But even if we're not demanding this absurd artificial subSaturn, Ruzicka can still save on construction-material to keep it together. A 10,204 km subEarth might need that 100 m now; this would go down to 9.09 m.

Ruzicka's magic is in installing a torus within a torus. The outer ring keeps the micrometeors out and does not spin. Only the inner ring rotates for the artificial gravity. The inner and outer rings are thereby decoupled. They just need to keep from mutually crashing into each other, which can be gently nudged by magnets.

Ruzicka proposes to spin it up in the first place, by - you guessed it - magnets (but stronger). This will require the outer ring to spin in the opposite direction, at first; but this can be mitigated either by using rocket-engines or, better, building two at a time to spin in opposite directions, which would cancel each other's twists.

THERMO 9:50 AM: A hot minute indeed.

The book of Psalm 108-110

We have a few articles by Christians asserting that the early Church read the Psalter - which is our Psalter - as a unity, a single book. Lately: SD Ellison (which I haven't read) and James Hamilton Jr (pdf - have read). Maybe Jon Alan Ginn. Let us ponder unity as unification.

The Greek translation is pretty-much just the MT here except enumerated with some offsets. Qumran has some differences to be discussed (soon!). Our main topic is the Psalms triplet 108-110 in MT, 107-109 in Greek. If deliberate, the editor presented Psalm 109 as a royal work alongside 108 and 110.

Most agree the edition of this last fifth of the Psalter dates well after the exile, adopting Psalm 137 among others. The collection's motive would be that of Messianism: the people didn't necessarily have a king in those days, so - they wanted one. Note that this is the fifth where Qumran rates the collection as fluid-enough that variant orders can be ventured, secondary or not; Qumran does not venture this for Psalms 1-88.

I stress this does not mean all these Psalms were composed for that editorial purpose. Psalm 137 didn't expect any king but God. We are, for now, discussing the edition, which allows for angry strays like Psalm 137 to exist along more-hopeful work.

Psalm 109 would then be such an angry stray. It reads like a curse tablet. The man is going before the court with a satan at his right v. 6, an accuser human or otherwise. Instead the man requests YHWH at his right v. 31. Thematically it leads well into Psalm 110.