VASIMR update

As long as we are looking in on orbital manoeuvres for low-mass craft, and/or entheppy drives: let's check in on VASIMR. Especially if we are getting space actuators.

The main practical uses thus-far have been high-isp high-efficiency trips. That's the outer system. Like far out: Eris, for one. This blog was considering gradual spin-up of space stations before humans set foot in them; heaven knows we all have time before they get there. Teased was also a human Martian visit in 39 days, which demands 200 MW[e] (if they want that cargo, I'd add: several roggets). I don't think such missions rate high on the priority-lists, given that what I'd linked came out 2011.

The company testing VASIMR is Ad Astra. Looking around the news, reporters are aware of Ad Astra's existence to itself and to the space community at large. Because the power they need is high, they need nukes. If we go back to 2024 they had a deal with SpaceNukes. At higher voltages in megawatt realms, Ebrahimi will surely follow. I think at that point, a thruster-customer may as well use fusion. Although, if either's customers stick to stationkeeping Venus in the hectawatt range, they might all get by with solar.

From Ad Astra I smell the scent of Howe. Company going quiet 2025-6.

VASIMR is clearly not a bad tech. I suspect it might have been a premature tech.

Leviathan evaluation

Some people earlier this decade assembled to propose Leviathan to NASA: Venus Aerobot for Low-altitude and Surface Explorations. Surprised they didn't call it the "valasé"; "vaflasé" might have sounded too Welsh. 22 pages, 50+ appendices.

They've figured that the tech mostly already existed 2021-5, excepting the one-way Starship for chassis. The stats on th'ship matter, so they've had to leave those parameters blank. SpaceX has had a working model of the one-way since late last July (with heat shield!), so Leviathan might want to run one more pass through the text.

The aerobot alone is 30 tonnes. They want also 17 tonnes of methane and a 20 t drop-tank. With the other material, all rounds up to 75 t. For propulsion purposes, Leviathan adds the standard Starship fuel tank, all six Raptor 3 Vacs, and all the other equipment once in orbit. Google AI estimates 120-160 tonnes here. I've told it to use the high end because Venus needs heat shields.

The Levvies expect refueling in LEO. Google thinks 400 t should do it; if so, that means four additional Starship there-and-backs. SpaceX hasn't yet offered that service. As long as we are dreaming of nice-to-have space infrastructure: someone else can compete here. The delta-V to get into a Venus Hohmann is the expensive part of the trip, because Venus can aerobrake. Starship, remember, comes with excellent heat-shield.

Over our sister planet the aerobot floats between "-2 km and 4 km". The -2, I think, means they can dip over the plains and not just over Alpha / Beta Regiones. Dunno about Maxwell, which rises, what, 10 km; nor even "continent" Aphrodite. So they're swimming through not just hot high-pressure CO₂ but supercritical.

As to how it floats, they've picked Project Loon's architecture with an internal titanium-foil "bladder". Methane is the lifting gas.

They need 6-7 kWe power, so are requesting a 10 kWe reactor. For that they're begging NASA - and not, say, SpaceNukes. Mostly because this has been a focus of NASA research over the five years the Leviathan project wrote the paper. If they won't let explorers raise a reactor into LEO, I'd hook a wind farm to the lee side of Maxwell, to charge any surface missions thence. And charge the Leviathan... to use it. Heh heh heh.

Two other essential pieces of tech: a lander, also NASA which in this case it may have to be; and Ingenium's refrigerator.

Unlike LEO or our moon, or asteroids, or even maybe Deimos: we cannot expect this planet to return treasures for investors. This project is for exploration. So they want a grant: NIAC-1. They justify it by comparison with the Martian rovers and Ingenuity-soon-Skyfall. Nerds tune in to watch this stuff, they say.

It should be permitted to say that Charlie Kirk sucked

This blog has never argued for the assassination of Charles Kirk, and certainly not for celebrating the "Kirkversary". The culprit - and Tyler Robinson's trial is I think pointing to the correct culprit - deserves justice. Those online pundits muddying the waters deserve... banning (Beale is right about one thing, that "free speech" is unworkable; I'd ban him too). I will further remind that I left the Catholic Church over their preference for Gaza over Kirk.

This is where readers can smell a "but" incoming. I don't want to say "but". So, I'll say - "that said":

I didn't ever think much of the man. I thought TPUSA was malign from the start, like Campus Crusade back in the day. I pegged Kirk as a Quaker Nationalist, which half-baked ideology (which it is - both) I disapprove. If you pressed 2009ish Yarvin on it, he'd disapprove too. Mencius Moldbug would dig him out and hang him, with ... Locke, to paraphrase; Cromwell on the rope next-over.

As to Kirk in life, Richard Hanania has lately poasted a dossier of various stances he'd took, which, he Considers, Harmful - to the body politic. As is well known, you cannot cancel Herr Hoste. So they're trying to cancel Sohrab Ahmari, for agreeing with Hanania.

I cannot read all of Hanani-Hoste's paywalled article like Ahmari can. Here and there one can read the odd snippet. Like that Kirk supported Carlson past the point Carlson was worthy of this (which is how Carlson got to speak at the funeral, which funeral I virtually-attended instead of Communion With Gaza). Or like that Kirk supported "Stop the Steal". This blog did not support StS. I thought some states were stole, in fact, but not such as would have made the difference, and that Team Trump had lost the room by the end of the week.

Because I haven't (because: can't) read Hanania, I can't judge all he wrote. I can judge only what I can read, which here range from "true" to "honest arguments can be brought". There also exist Kirk's vaccine comments.

So whatever. Ahmari can say what he wants, and shouldn't apologise. As to "Captive Dreamer", Yarvin, whoever else: if you want us to treat Kirk as some icon like Steinem or King, then I'll start mocking Kirk like I've mocked those eminently mockable American Saints.

Some opinions on early Islam

Joel Hayward, who had joined the jund, in 2022 put his book Warrior Prophet through "Claritas" Press. For some reason Catholic-coded institutions seem to love supporting apostates. Anyway I haven't read it; it isn't apologetic like Esposito's, it seems more honest like the works of Juan Cole and Jonathan Rape-Rape Brown. In 2021 I'd poasted a roundup of modern consensus around the maghazi; maybe some of that is in Hayward's book.

From late 2023 as you know I'd moved more toward the preMuhammadan era of Near Eastern Araby. So I might not get to Hayward's work anytime soon. That much isn't a reflection of my views on Hayward, who for all I know has good reason for embracing the faith of the surat al-anfal and of its supposed author. He can try convincing me later.

For more evenhanded takes, rather than "Hellz ya he kilt 'em Khaibar JAHOODS!": Razib is recommending Kyle Orton who runs a 'stack of his own. Adomnán's hadith from Arculf, the Islamic understanding of religio... basic Ibn Warraq stuff from circa 2000 before the towering day.

Relevant to this blog might be the milieu of Late Antiquity. That would track more with IQSA 2015. I was writing Tidings of Flame around the time of Orton's poast.

PS. Happy New Year.

Passive shielding

This isn't really the magnet blog, so I'll relay Space Startup News who knows better. He's talking radiation-shields. To replace his overview, here is one from 2025.

What appears to have inspired our boy is Zenno. They announced a few weeks ago they'd loaded Supertorquer on "Starburst-1". The latter is Portal Space, which rideshares Transporter-18. Present plan: Falcon-9 next month. Portal are trying to shift sats between MEO and GEO, which engine they grandiosely term "Supernova".

Zenno's Supertorquer in this, confusingly termed a "flagship", is the actuator for this ship. It's a superconductor: a passive magnet at 3,500 A·m. Contrast, the usual passive shielding of lithium-hydrates which then add to the dry mass. SSN points out that superconductors are now a commodity, made more-or-less cheaply. (This is because of the work done in the fusion field. If those customers go away, as they well might, this application will keep superconductors in business.)

Although the Zenno magnet be passive it must be kept below 100 K or so. The mission is going to use power (by solar), if nothing else for the "TRL11" diagnostics also on board. It is in fact sun-sync so will be in daylight for a full year. Basic thermodynamics will heat up the chassis, and that heat is not going to be blowing propellant all the time. One assumes radiators will be brought.

Portal's aim is to use Earth's magnetic field for control authority. That's the "torque" part, to turn itself about. This leaves, for propellant, only shifting orbits. I imagine it also simplifies the design as the engine(s) shouldn't need gimbals (the solar and radiators get their own torque). In a future when sats might use the spicy-meatball for higher I_sp, any improvement on shifting cargo about is good.

Naturally the torque part works only over planets with dynamo. Such include the four big'uns, plus Mercury and Ganymede-why-not. We gotta start somewhere so, Earth it is.

This mission already-excellent hasn't even got to SSN's stake in it. Zenno want to test how well this magnet, which again is passive so always-on, keeps out the radiation. That can help scale to such human-rated habitats as can't bury themselves under regolith. Thinking here not so much of longterm space-stations outside Van Allen (Jensen imports regolith - and hydrates), as the shuttles to/from those stations or, perhaps, the stations-under-construction. Meanwhile all those LEO stations are likely going to stay lightweight (so micrograv) so will need the shields too. So much for those BVDs!

Cheaper syngas

Syngas is a mix of carbon-monoxide and hydrogen. I expect Martians can get the hydro' from ice; Venerians must scoop the acid clouds. I hadn't really checked how the chem would work, I'll probably ask Copilot. Where carbon and hydrogen can't be had, or they can't just loot an errant comet for its methanol, I've suggested breaking plastics. Waste Not Want Not.

Some planets by contrast are awash in methane. This study, mostly Chinese, proposes an alumina-based catalyst. This is just bauxite sent through the Bayer process (or, hell, pulverised soda cans) and should be cheap. A little pure nickel is added, like 0.8%, which at that concentration can't be expensive either.

Why the Samaritans didn't want our Joshua

Bible-believers as with Jeremiah and others contend, further, with two Joshuas - or, perhaps, four. For the JudaeoChristian community the main two are the MT (> Vulgate and near everyone else) and the Greek (> Old Latin). The Dead Sea is less helpful than you'd think - or hope: it has a MT (with a few variants) and "4Q Joshua a". The latter might be a retelling, like the Samaritans have their own "Joshua"; albeit, here, perhaps based on an earlier Joshua edition. This topic is colossally complex, but it seems not complicate.

Ernst Knauf, generally-respected at this blog, is respected enough on better fora to be allowed there a summary (pdf).

The story (of the story) begins with a Joshua 6 and 9-10. This, per Knauf page 359-60 #1-3, is what arrived in Achaemenid Jerusalem 500-450 BC with chapter 11 as supplement. Also arriving was the Holiness redaction of Leviticus, which got notorious enough that Ezekiel will read it. The Deuteronomic History from 1 Reigns/Samuel 9+ also by-then was extant. This is where Knauf #4 kicks in, assigning the bulk of Joshua 1-21 as the Greeks will know it.

Copilot is telling me that Holiness has infused Joshua chapters 3, 5, and 7 (also 24 but everyone agrees it's late). Knauf doesn't cite what Copilot is citing, nor say much of these earlier chapters at all; but they independently come to the same conclusion that these chapters be postexilic and [Holiness-]priestly. For Knauf, Joshua 1:6-21:45 was entwined with the prior five "Mosaic" books in a Hexateuch.

Recently one Erasmus Gass has posted "The Land Distribution in Joshua 13-19". This stands to fine-tune #4. Trickling through the Temple circles was a census of cities and, also, of Tribes. The Tribes numbered... seven (18:9). These were Judah, Ephraim, Benjamin, Zebulun, Issachar, Asher, Naphtali. Gass can understand the absences of outliers Simeon, Dan, Reuben (and Machir although nobody asked him). He cannot so understand Manasseh's absence. Gass posits that our Joshua 18:1-10a, then lacking MT v. 4 (as Greek lacks it), omitted Manasseh at the time of composition. Manasseh was Samaritan territory. The "document" had excommunicated this tribe.

Now as we all know, the Samaritans came to find all manner of ways to harmonise Numbers with Deuteronomy. So did the Greeks, even unto Joshua 5:6. Gass is arguing the same process for the Jews. This antiSamaritan document now in our Joshua 18 was accreted, with reference to ... Numbers and Deuteronomy. These were never the same book, as the Samaritans knew, so the accretions were done in different stages. First was another "Priestly" (sic) redaction, to enholify the Tribes. Gass thinks Joshua 18 here got repurposed, to introduce 15-17 also 19:1-48. This chunk was to follow Numbers 34:2-12. Gass argues for the same "ideolect" of Hebrew in these pericopae. Copilot, incidentally, is telling me that Numbers 34:2-12 if not quoting Holiness Code shares Holiness ideology. I expect that serving this ideology, Numbers 14:6-9,38 inject Joshua (and Caleb) to that episode of the Scouts.

Then Joshua 15-19 got reassembled, between 14:1-5 and 19:49f as "frame". From here out, I'll let to others. I'll just note that Gass doesn't see Ezekiel as influencing the assemblage or redaction of Joshua in any way.

Overall, I'll note that the Holiness Code was a Jerusalem project and that Joshua 18:1-10a may, indeed, have been structurally antiSamaritan. The Samaritans accepted Numbers 34 on their own terms, with a lot of redaction. They simply refused the Jewish Joshua; incidentally adding some small evidence toward the lateness of this project. Maybe the men of Gerizim could have accepted Joshua 6 and 9-11 (and 1 Samuel 1-8 la-de-da), but the first scroll proffered to them had the accursed chapter 18 therein. Knauf and Gass ponder if the Jews had attempted to soften Joshua for the north. The north chose instead to write their own "Joshua".

Meanwhile the Jews shrugged; they broke their own holy Joshua into its own book, offset from Torah. Thus Joshua 1:1-5 were born. And the stuff which connects Joshua to Judges and beyond, which the Jews were also assembling.