On skipping Phobos

A decade ago Hoppy Price, John Baker, and Firouz Naderi wrote "A Minimal Architecture for Human Journeys to Mars", doi 10.1089/space.2015.0018. On the assumption of SLS, four launches of those could get sufficient cargo to hop to inner (6000 km) moon Phobos. This would - they said - allow for the main prize some years later which is the Martian surface. Some have of-late proposed additionally supplying Phobos from the Belt; supplying Mars from the Belt, too. This blog doesn't endorse Martian surface missions exactly, preferring outer moon Deimos, but we can allow for supplying either moon from outside.

In 2021 Drake, Rucker, and Cianciolo henceforth DRC evaluated the earlier trio (pdf). Deimos - I think - has its own merits, which aren't Martian merits. Phobos on the other hand - they think - is still looking for purpose. Inasmuch as it's being sold as a waystation to Mars, DRC say it's a cuckshed.

DRC nod to Deimos as having similar issues as the inner moon. They don't really consider it however. Perhaps because indeed it is not really a Martian waypoint (I say an interplanetary waypoint).

The issues had in both, which are not shared with Mars, include gravity 3 mm/s² (twice that for Phobos), and yes that is in millimeters. Also they are entirely airless where Mars' atmo may be compressed for CO₂, nitrogen, and argon. On Mars water may, further, be drilled and now you have most of your requirements for feeding plants and housing us animals. More: on these moons regolith cannot be shaken off gloves as it can on Mars or our Moon. So you are going to have to send over two different kinds of life-support: one for whatever moon, and one for Mars' surface. Three if we count the craft getting everything over there (one assumes, a cycler).

The 2015 architecture was proposing just to land humans on that moon and then "teleöperate" robots on the Martian surface. In that case, life-support on Mars is to be built on Mars, by those bots. The 2021 DRC review denies the point of this. Just land everything on Mars all at once, they say. Maybe get into some lavatube tunnel, aerate the place and teleöperate thence.

It is further difficult to catch Phobos from the surface, and likely harder still to catch a tether dangling thence. Here Deimos has the advantage because it's almost in areosync (martistationary at that, it's equatorial).

Overall I must agree that Phobos is the also-ran in the Mars-or-Deimos competition. I still think Deimos deserves consideration as our first port-of-call however. Although here we'll have to be serious. We'll have to build a whole city from that rock.

Tales of Canterbury

Geoffrey Chaucer composed the Tales of Canterbury and it got copied - early. Barbara Bordalejo and Peter Robinson have a URL of that name.

These two believe that their predecessors had overcomplicated the manuscript tradition. Hengwrt and Ellesmere are good MSS, they agree. To these they'd add Christ Church 152 and Bodleian 686... to pretty-much ignore the others. Because they're all dependent on the four noted (or maybe on CC152's original, but CC152 itself is good-enough here).

The title "book of the tales of Canterbury" seems almost to roll off the tongue. Was it "Cantérbury" in Chaucer's time? A few centuries before him it was "Cantwareburh" or "Cair Ceint". I can't see the accent falling on the second syllable of the former... unless we allow for some lost Latinism. But in 13th-century Latin the Normans were using variations of "Dorobern" based off a tradition of Roman "Durovernum Cantiacorum". Chaucer was self-consciously English and no Norman. I think he'd rather say Cánterbury like we say; the "book of -" preface is tacked on, by scribes, because these Tales are poems which people declaimed from memory for sport.

As to the epigones: "Canterbury Tales" is a fair reduction in my opinion, but it remains a reduction. Also some Tales got memorised to the expense of others, which may explain how later editions might be wild compared to the originals. But - say Bordalejo and Robinson - we have good-enough originals. One might compare Homer, whose two main works seem deliberately-composed such that later copies don't deviate as far as, uh, sura 11 from sura 7.

That's a spicy meatball

Lucas Beveridge is talking about something he and Sam Piper did for Atomos Nuclear and Space. Suppose we only shipped one reactor to a HEO. That reactor hands over "enthalpy" energy to tungsten plates - one per mission. The plate then delivers those joules over time, in kilowatts. Here's how it was tested; here's what was tested.

At HEO - as in, GEO or higher - you can fuel up a lot of space tuggery. Take Tory Bruno's Blue Ring, which needs one tonne of xenon for four of payload. That reactor looks like it would in fact deliver the 5.5 kW needed to propel to Gateway's lunar NRHO. To get a mission rolling "for weeks or months", Beveridge prescribes Scandium-46 with its low 84-hour halflife. Maybe tugs; maybe Venus injection. Sc-46 is allowed to deorbit after three years.

The test used Manganese-56 which decays in 2.6 hours. This can deorbit rather sooner. Maybe use the Mn-56 for high-thrust tugs between HEOs and be done with it. Like if you just want to hit the Spaceline cable at the 80 Mm this blog has promised.

Naturally none of this is to run on Earth (the least radioactive Co-60 is legendary). The idea is that the reactor - which is way too high up for Earthlings to care - creates neutrons, which then irradiates the neutral cobalt or scandium. The hot stuff, in turn, rams gamma (and not more neutrons) into the metal plate, which then heats up. Or maybe just heats up some beryllium, which I'm seeing recommended for high-enthalpy rockets for Martian landers.

For longer missions, he's talking Cobalt-60 at its 5.27 year halflife. We might not want this in Earth orbit... ever. Beveridge is suggesting this for a Uranus orbiter, or series of orbiters. First it has to get there but we can probably do that with a Starship. And/or with a fusion-driven ship launching off Deimos.

The asteroid/Martian economy

Mark Thompson last April relayed a Swiss(?) study by EPFL on how to deliver materiel to Mars (to its well, anyway).

Serena Suriano, Shamil Biktimirov, Dmitry Pritykin, Anton Ivanov seem to be picking up where Zubrin left off; they're not stopping at Deimos (like I'd stop). Except, Zubrin wanted Martians to mine the 'stroids and these three Russians (and one Sicilian) are asking the Belters to do it themselves and sell to the Martians.

To read the article, they want to deliver the goods to a Low Mars Orbit 500 km. Phobos, for reference, is at 6000 km. Why not just send it all to Phobos? Gravity there is higher than Deimos' and this place should be able to dangle a tether to 500 km. Our authors are already aware of the doi-10.1089/space.2015.0018 mission architecture which targets, exactly, Phobos.

On the Earth side, all this assumes a depot at STL2. That's "ST", not "TL". Somehow they have to stationkeep that.

The 'stroids they want are metallic, like 332 Siri. Guess they want the tungsten... or Beryllium. That one sails out 2.7 AU where Mars is, what, 1.6 and Vesta 2.36.

But... isn't Mars literally littered with meteorites of all sorts? If it's volatiles you want, just drill for the ice. And if we're staying at Deimos (or Phobos), it's probably mafic such that there should be a few iron and siderophiles right there. Or anyway sicila fit for anhydrous glass fibre.

NASA's new tungsten mine

There is, today-announced, a vast tungsten reserve in Nevada. Tungsten as you know comes with other essential elements like boron and lithium. Some of the land however overlaps with 17 square miles of NASA. NASA say they need the land.

My suggestion is for NASA to earmark a tax on the land they've inherited. Materials from that part of the land go to NASA as first-choice customer, for NASA's own use.

Meanwhile I guess NASA should calibrate its satellites elsewhere; the Feds can scout around for other parts of its enormous Southwestern lands for anything likely. Southern Cali? Utah?

BAqDAyT 8/7 from Stephen "Vodka" Green.

What was wrong with the Sack of Troy?

One of those prefaces to The Odyssey is The Sack of Troy, summarised here. In antiquity, most agreed that Homer didn't write it. It tended to be attributed to fellow Milesian, Arctinus. Aristotle wasn't complaining about this one particularly when his Poetics lambasted the likes of Cypria for being Just A Bunch Of Stuff That Happened unlike Iliad, which promised a theme and, he thought, held to that theme, this-or-that chapter aside.

But even if Arctinus wasn't Homer (some today doubt Odyssey was Homer)... Hesiod wasn't Homer either. And what Proclus and others claim of The Sack of Troy is that it is in fact restricted to a single episode, after the Horse. So Aristotle shouldn't have minded... right?

Giampiero (or, Jean-Pierre) Scafoglio has an essay, "Two Ways of the Epic Genre in Late Antiquity" discussing the Homer / Aristotle reception in works such as Triphiodorus' epic about the "Capture". This epic, you can read today. And this, wikipedia is saying a lot of authors did read. Latinists of course are aware of Virgil in Aeneid Book II covering the same episode, but self-consciously a preface to the epic of Rome to come.

Triphiodorus clearly didn't think Arctinus got the job done or he'd not have bothered. I do not see where Triphiodorus chose to rewrite a "Wrath of Achilles" or "Tragedy of Hector" (there's talk he redid an Odyssey however). Our man may have been right, given that I cannot link to a full Arctinus. As of this decade the 2020s, it looks like the Sack was no longer even in the late-antique libraries (pdf)... which puts Proclus under suspicion as well.

What we can do, perhaps must do, is to compare Triphiodorus to his peers and middlemen.

Against Virgil, our man chooses Cassandra over the other prophet Laocoön. For the great tragedians, that's Aeschylus over Sophocles. As a narrative choice in a postAristotelian epic, Laocoön doesn't work here and he's also not in the two Homerics. Arctinus did note that the gods chose now to knock him out, but this episode serves mainly to get Aeneas out of the city before all the fun starts.

Triphiodorus and Virgil do seem to agree on Sinon. Also Triphiodorus agrees that Aeneas was at the sack so tacitly sides with Virgil against Arctinus here.

Ultimately, Triphiodorus feels like a writing-exercise. He seems to be showing that he can write a "Sack of Troy" as might meet Aristotle's rules, if not his approval - because personally I doubt that Aristotle liked writing-exercises, of which a lot of those elder-epics smell. Virgil on the other hand wants to bring us into the Trojan side as to see the full iniquity of the Greeks' crimes. Like Nolan this year, Virgil has a point.

Going back to Arctinus: if I was doing a writing-exercise in years B.C., I'd play up the glorious deeds of the Achaeans sacking this city. I'd tick the boxes of the Homeric heroes in Troy meeting their own ends and/or causing appropriate ends to other heroes. As to, why; because Miletus was precariously maintaining its autonomy against the Anatolian barbarians in Lycia, Caria and especially Lydia and, before that, Phrygia.

Yeah, Virgil probably wore it better.

BACKDATE 8/6

SDI's plasma-core rocket

In lieu of Cassenti's microfission-catalysis for fusion rocketry, for interplanetary missions Omira and Mourad suggest "plasma core". Interstellar is another matter (heh). So let's look at plasma-core. This is an idea from 1985 to power NERVA/NΘP.

The core is Uranium Hexafluoride, either U-235 or -233. In theory a Curium-247 hexafluoride also can be made. Anyway, UF₆ is a solid at reasonably-warm temps (<56.5°C). As a plasma the fluorine ions are likely more problematic but we're hoping to make a nuclear blast out of it so noöne cares.

In 1985 they were trying to contain a sphere of this plasma, swimming in a mutually-immiscible noble gas; and why not, in microgravity. They picked argon, probably-obviously. They measured 50km/s exhaust. We divide that latter by Earth 9.8 to make of that a ratio independent of SI or Freedom units, called Specific Impulse; 5.1 kiloseconds. (Although now it seems dependent on Earth being that frame-of-reference.)

They got it running for about two minutes. After that, they lost enough uranium that the critical-mass went subcritical. Also there won't be microgravity during the thrust phase. Before anyone could figure out how to make this practical for a space trip, after January 1986 the launch costs per kilogram hit the Challenger wall.

Spacenerd life is better now. But the middle-1980s flights of fancy have been forgotten... mostly.

Hence such fission pulse engines as in Howe two years ago, which promised 5ks specific-impulse which would have compared nicely with 1985. Or last year centrifugal NERVA... 1.8ks. They'd make it up in thrust though; so if they just wanted to push loads to Deimos or Venus rather than all the way to Jupiter, it might work.

Gerald Marsh seems unhappy with Howe and, more so, with that lumbering 1.8ks solution.

Marsh proposes to revive Ronnie Raygun's tech: with magnetic confinement, in a spheromak. Marsh seems an expert in magnets, working on them in 1996. Marsh must however conclude that one (not he) must also find a way to generate the plasma with the field configuration chosen, maintain thermal stability, and find a way to turn the rocket engine off; opining these are non-trivial engineering problems.

I counter that turning the rocket off is the least of this rocket's problems. What you do here is to calculate the cooloff of the rocket and let the spacecraft reduce its acceleration naturally. It all gets tested in the field like SpaceX tests its Starship. If you're asking after an abort sequence then whatever, just separate your craft from the engine and push the still-running engine to the side as it makes its own merry way to the outer AU fringe.

BACKDATE 8/5