Falcon Heavy + Sunbird: evaluated

Starfire and I assume Sunbird promise high-alpha thrusts, such that they could push their own engines into orbit and beyond. Their problems are twofold: they use expensive helium-3; and their thrust isn't all that high, in the teens of newton. The Merlin series, which the Falcon rockets use, each runs 845 kN at sea level. Falcon 9 therefore must use several rockets - nine Merlins. The Falcon Heavy uses two sets of Falcon 9s and a bigger one in the middle. The US military sometimes uses the latter and buys the discardation of the boosters for extra thrust.

SpaceX has earmarked Falcon Heavy for retirement once the Starship is ready. And when they can do one Starship a week, the whole Falcon series is done. But what if...?

Today I pondered firing the FH triple blast except to swap out the colossal core rocket. Instead we are lifting the fusion rocket. The Falcons on either side can possibly use methalox or even hydrolox for less boost and soot. These rockets can be retrieved as per usual. Fusion rocket doesn't need as much thrust after those detach - we'll put a button on this.

If hydrolox, I call in the Germans. Their RLV-C5 as boosters are rated 1972 kN. Although not as mighty as the 2700 kN Raptor-3; RLV-C5 uses ten apiece. Both my boosters would, then, glide to pickup allowing more efficiency.

We are here buying horizontality over verticality. These should be safer and cheaper to assemble on the ground. Buys some international goodwill also. As a direct small-load mission, we here RETVRN to Gajeri's 2010 thesis to Saturn or whith'rever other 5+ AU destination.

So: let's run this by Copilot. Even at LEO, the fusion rocket still has to blow out extra fuel and must take many days to get to escape-vel. Layla Mohsen, sorry to pick on her but she's tagged her name to the mission rather than to the engine, assumes a space infrastructure fit to assemble interplanetary manned craft in that LEO. I don't know that we have that. Will we have that in 2030? Will any of the proposed stations want to do that?

If our mission is for a light cargo, and if we're assuming orbital infrastructure: a better investment be to hoist that Tamil Tether. The orbital station maintains tether, at most (which scales better than being a direct shipyard). Tether catches our fusion mission and drags it higher. Fusion lights the fuse.

Starfire

Princeton haven't abandoned Sam Cohen's direct-fusion project. All they did was rename it: Starfire. They got new hire Layla Mohsen to deliver the youtube, covering much of what Marco Gajeri's old Turin thesis did (pdf).

The design is for D+³He, output ⁴He and a proton - ionic plasmata. A little secondary happens, where D+D passes a neutron making H+T, or just fuses into He-3... and a neutron. The former tritium can fuse too and give off more neutrons. These secondary reactions are well-studied and deemed nonproblematic for this design (the tritium is exiting the back door in time).

The earlier mission-architecture was for Saturn [UPDATE 1:11 PM for which I have mine own ideas]. Princeton are now promoting a Martian landing and takeoff. I'm going to LARP Zack Moussaoui and not care about any of that. Let's just order them to dock with Deimos or otherwise stick in high Mars orbit.

This design, they say, doesn't have to turn off. If they snap the exhaust-pipe shut, and replace the radiators with a Brayton cycle, they have a modest fusion electrical generator. And yeah, they're getting helium in that exhaust they've bottled; tritium too but this won't be in position to be fusing anymore. Maybe they burn the hydrogens in oxygen (oxygen is common in any planet's regolith).

Tritium extracted will beta-decay halflife 12.3y. This means electrons. I hear they are low-energy, so low-energy magnets can keep them at bay. Also, the byproduct is He-3 which is half our fuel. That helium is what you'll want to save, for the trip back home.

That assumes they haven't already guzzled all this propellant/fuel to get here. Along with 70% helium of whatever isotope, they want 30% xenon. The xenon must be imported, or added to the manifest; and so must additional helium, because the helium waste isn't nearly the amount they need. Good news is that in high orbit, the video itself assumes supply with nonfragile cargo from all manner of Earth low-speed (Hohmann) runs. This includes canisters of liquid volatiles, solar cells, extra radiators, solid foods. At Mars in perfect daylight, you can also use 43% of the Sun's radiation. You don't even need a fusion reactor.

They have two options for cargo and for crew. The crew might use the onboard rocket to crank it the rest of the way out our well. That would be a high-thrust option which I expect to slash I_sp. They promise 5-10 N/MW powered by 1-10 MW. This may sound like weak newtons, and I warn that many typoes clutter this presentation. This may not be one of them; for 2 MW Sunbird's 2xDFD aims 10 N (up to 101) and here Gajeri had projected 8 N. Gajeri's thrust-to-weight α (you know, the N/N stuff you don't see in I_sp) ran 0.75.

Cargo... might not use this engine at all. That can take a whole year which sounds, basically, chemical.

Specific-impulse blows past any of those dangerous fission NΘP we've seen. One chart has exhaust velocity up to 25000 km/s - which is silly, and should be ignored. Gajeri - aiming to Saturn on a fairly lowthrust vector - expected 9.6ks. Matthew Chu Cheong follows Gajeri in using Rognlien's UEDGE: more like 88 km/s calculating 8.6-9.2ks, about half a Sunbird let alone θ-pinch. That exhaust can rise to 300 km/s. Mohsen also boasts α>1 (prosaically, 0.5-2) which - technically - can get you offa Earth (if we had cheap He-3). The lower I_sp bounds - they claim - deliver in 67 days to Mars which compares well with the fission Shockwave Exhaust (afterburner). Sunbird might not be fit for orbital test in 2027, note.

For Mars, contrast Saturn, needs assemble the whole ship in orbit. Princeton want three "SLS-class" launches. One of these launches would store the Starfire engine which is only 2m diameter; the others take up whatever cargo is to be delivered, including the propellants. I suspect they can get more launches off of Starships for cheaper. On assembly I see no radioactives on board; but fast exhaust, neutrons, and some tritiums will happen in the exhaust. Not much of a worry in the upper thermosphere which we're sideswiping (toward lower atmo, pretty sure cosmic rays would swamp this) but a worry for all those LEO sats. I'd let them do it maybe 700 km. Absent skyhooks Copilot is saying 3.5-3.7 km/s for delta-V to intercept Mars on Hohmann.

For Mars-system-injection, fun part is that Copilot recommends an elliptic orbit for additional 1.3-1.6 km/s (this may depend on adjusting inclination to equatorial). Thence I can transfer-burn to Deimos 150-250 m/s, that's meters lads. (As noted here, some mission-archies prefer Phobos, but we don't.) 5.3 km/s total would have mass-ratio, by Tsiolkovsky (or Moore, for Brits) and lowball 8000s: 1.07. 7% of my rogget would be propellant. That's like an epstein drive. (And as noted, Earth would be sending supplies, for the trip home.)

Princeton are presently testing the power-source mode. They'd be building the models 2028-35 which I assume includes testing at 700 km (Starship should be online 'round then). Production happens 2035-8 (Princeton's plan includes a large share of the mission, which itself makes Assumptions, on what we'll be able to do in orbit) and then they go to Mars in '40. If we assume Sunbird is on the level, 2028-35 seems like about when they'd be building models as well.

What was edited, and not edited

Earlier I wanted to get out-there a few more examples of diachronic Hebrew. Here's the payload: Juha Pakkala. Orthodox corruption, not language shift.

This comes under two headings. One is where the Greeks and/or the Samaritans took a problem text and edited the Hebrew, which Hebrew is now better preserved in MT. The other is the reverse.

There exists rather a lot of the former, famously, particularly in what we Occidentals call "the LXX" - this is the Greek Torah. Take the several places after the Exodus where all Israel is to come and see what Raiders has insisted we must never see. We are unsurprised to find in Exodus 23:17 (Covenant Code, 20:22-23:19) ἐναντίον Κυρίου τοῦ Θεοῦ σου, which mucks with Exodus' grammar here. The Samaritans were clumsier: to summon all Israel to the Ark of YHWH, presumably shut tight and safe. The Ark is supposed to host, exactly, the Covenant Code which would neither, then, have existed nor been commanded outright. (Gotcha!) Pakkala brings further post-Code 24:10-11, where indeed the assembly sees at (which means... "at") Israel's elohîm, which the Greeks change to "the place of Israel's God". And, yanno... ish/gabur again.

The Jews have been more reluctant to change the rasm. For Exodus' parallel Deuteronomy 16:16 see the face (pny) of YHWH they revocalise "appear before" this "face", the "face" then being dismissible as a fossil grammatical term. Smells like Qere u-Kethib to me, but in the Masorah; one might also consider "bosheth"'s vowels appearing in "Ashtoreth" (sic).

Although even in MT rasm-mucking can happen. MT Exodus 23:17 sneakily swaps at from under the Deuteronomist's nose, for al. Exodus' people do not gaze "at" the Face but instead must, per the rasm, appear "before it", so al Him.

The Masoretes seem more free in other parts of the Tanakh. Like, Judges - especially if we expand it to 1 Samuel/Reigns which remains prekaige - knew of a temple at Shiloh. The MT has deleted this from its 1 Samuel 1:9-14. Booo

Pakkala brings "Lucian" to 2 Samuel/Reigns 15:8, that Absalom asked David to see YHWH in Hebron. This implies a Temple there in King David's own lifetime. Pakkala could well have brought 4Q51 too. Its overall "Absalom cycle" is considered subject to the kaige revision, Thackeray-Barthélemy "βγ"; 2 Sam 1-8 are considered not so adulterated. Yea even at the time of the revision, which may have been postTemple but wasn't Lucian's (postOrigen) work. So Lucian didn't translate the "βγ" part; he inherited a Jewish text that still had it well into Herodian times if not later. As to why to delete Hebron; arguably it was unnecessary. Waddn't Absalom the baddie?

Where dealing with baddies, the Jews seem to restrained themelves to mere qere on the kitab. 3 Reigns 16:32 is in γγ so later still than kaige. Here, in Greek, is Jewish alteration which had not been done back in βγ. Per MT, Ahab visits a temple of Baal. Again, Lucian is unlikely to have cared that a bad king is visiting the wrong god. Everyone knew which god it was. Jews - by then - didn't want so much as to utter this boshethic name. More exactly abominable: τῶν βδελυγμάτων is also in the Greek Daniel.

Fossil names in the diachronic context

Last week TheTorah posted a few interesting articles, in between bravely telling its mostly-secular-Jewish readers how sorry they were for not being liberal enough. Catnip for me is when they support an old-fashioned position like admitting Moses was a Semite after all. Thomas Schneider has posted this one.

"Phinehas" remains Egyptian. The p- prefix is a tell, before everything got all Aramaic. It would mean "the dark one", something like "Krishna"; in its Torah context the man may have been "Kushi". tꜣ-nḥsj would be the dark-person's land, which William Paul Coates stuck upon his kid because daddy was ign'int. (I don't find where Egypt used this construction.) Back to Torah: "Phinehas" would, I think, count as a fossil of a (foreign) name brought into Hebrew which origin the Torah's Ptolemaic-era transmitters and translators might no longer have remembered. Canaani in that ABH age of the Song of Miriam might not even have had its own (há-) prefix.

"Moses" rather represents that fossil "ABH" Hebrew. We've looked at a few examples, like Yoel Elitzur's elón preserved only in placenames. Schneider points at the yiph'al names like Isaac and mah ancestor Yakub.

Elitzur here brought ḌḤK as a basic Semitism. This is ṢḤQ for Genesis, which needs to explain the name יצחק; the root is also in Exodus (thus Ezekiel) and once in Judges. Alternative Hebrew is ŚḤQ from... Judges again, and Jeremiah and 1-2 Reigns/Samuel, and the Psalter and Proverbs. By the way Psalm 105, Jeremiah, and Amos(!) agree that Isaac's name is with S not Ṣ. The majority principle leads to ŚḤQ for the actual Hebrew. 'Tis a little harder to figure in Arabic because I cannot find it in Safaitic. Once it gets into the postNabati script it could just as easily be ḌḤK - or ṢḤK.

In yi'phal, Isaac meant "he scoffs". Schneider ponders an earlier stage where the tribal hero was the man who scoffs at his enemies. The man we know as Jacob/James is more problematic, but Schneider goes with old Amurru where it would mean "he protects" (*Yi'qab?). Either name can be made to imply that God is the ish/gabur who protects His people and laughs off their enemies. The Bible would represent a still-later phase at least for Isaac, as the Lord scoffs back: at... Sarah, who had scoffed at His angels (or avatars). Isaac is not "Tisaac" after all. By the way, as two fossils, bumbling through tribal formulae as they did, here are two more names which Elitzur cannot use to place the whole Torah into the Bronze Age as he'd like.

Jan Joosten has brought a couple more examples. The Exodus employs a term for midnight. Joosten takes it literally: halfway-the-night; Westerners would think, "stroke of-". LBH in Psalm 119 and Job instead imply something more general, middle-of-the-night. This posed a problem for contemporary Exodus-inheritors who, reasonably, asked why The Knower Of All had played so loose with times at such an important event. Clearly Joosten has solved that little problem for us all: the Lord was telling Israel - in Egypt - exactly what time it was, and it's not His fault the language changed after the Exile.

A more touchy subject is the military use of psṭ. Aramaic owns its own psṭ which means "spread out", like classical (Najd?) Arabic basīṭ. But unlike, oh, CBH gly ("scour", I've argued, alongside Safa'-Arabic); here Joosten sees Hebrew going its own way, earlier. psṭ would have intended "raid" and such that Chronicler guff about "spread out after winning the war" would be an Aramaism, brought in after the invasions. Heck as far as I know, this sense might have entered Edomite and/or Nabaṭite as well.

Starshot's speed limit

Centauri Dreams exists to tout the Breakthrough Starshot, a mission to Alpha Centauri at 0.1-0.2C. Unfortunately this didn't get a dedicate team at the time, which was, what, the late 1990s such that we'd be getting data now. The fact of it taking 20 years tends to keep Congress (and any republocratic system) from greenlighting such a thing, like those Uranian missions we don't got (Voyager was politically-feasible only because it promised to relay data from Jupiter and Saturn en-route).

The one bit of tech that did get some work was the solar sail itself, having some local applications as it does. IKAROS went to Venus in 2010; ACS3 is in operation in NEO now. This blog has recommended solar-sails for 50ish AU targets, like Eris.

Suppose we could iterate that tech toward something faster. 0.75C (... like Passengers) means 5.66 years (Einstein & Copilot say 3.75y on-board). Senators - in particular - might be talked into that one, especially new Senators.

Engineering issues abound: for instance, light gets redshifted as the sail vanishes away, but we might fix that with a fleet of boosters, which expend their last enthalpic battery pulses punching out one last laser. Up to Jupiter, these expendable boosters can be "3U Plasma Magnets".

There's also dust. I expect that's more a worry at Oort and not interstellar (at present).

The real issue is a background photonic speed limit. We've discussed that here for cosmic rays and, uh. Something like it applies to Starshot too.

Assuming complete unobtainium and space-magic for everything short of warp, the sail is only getting to 0.75C. At that point diffuse scattering begins acting as drag. That's cutting it thin for our Senate.

Shuttle shenanigans, III

And here I was thinking that Sierra had forgotten about the Dream Chaser. Turns out, they've scaled it. If you have grams you've created in orbit, here's how to get them back. At "1.5 g" which I take to refer to accelerational pseudograv 14.7 m/s². (I'd hate for g to refer to grams here.)

In other spaceplane news, there's Dawn, filling in for the "New Shepard" - which (by contrast) Bezos has forgotten. That's testing Astral Materials' microgravity furnace, for four hours at a clip. So it won't need full orbit; it is doing some freefall before gently returning. Dream Chaser would be in orbit or near-enough, so can take longer before drag pulls it back to us. If Astral wanted it, the 'Chaser could test their furnace for that much longer.

I don't know if Dream Chaser ever intends to dock with one of those orbital stations we're getting next year. That would allow the furnace to be used for many days, with the return cargo being much larger. We might have ideas for shrinking that furnace, at that.

Alla'dhat's not nothing for unmanned cheap returns, but... doesn't Elon already have Starfall? That's a metric tonne in a a 2.5× 1.5× 0.5m container.

Maybe the issue here is that these grams being returned are just that fragile.

LANTR to Mars

The nonenthalp LANTR has been evaluated for Mars, against classic NERVA: Daria Nikitaeva and L. Dale Thomas. They studied both the more-or-less direct Conjunction Class and the Venereal fryby. We join the Mars Society to consider Conjunction only, until/unless we have first-aid stations at Venus.

Nikitaeva-Thomas calculated a LOX-assisted NERVA could cut propellant volume but - refer to the periodic-table - raises the mass (by 32.4% so - 132.4% the baseline). The mass buys 540% the thrust and 122% the impulse. Raising mass is a major problematic as long as we are delivering the LOX from Earth; but from our Moon, which may even get to use a electric-powered sling: that wouldn't be an issue. More at issue is this LOX mass takes from the "dry mass" of the rest of the mission.

When other planets be considered for humans, I suspect better options shall be at hand.