--- Log opened Sat Feb 05 00:00:50 2022 00:34 -!- phill [uid429774@id-429774.ilkley.irccloud.com] has quit [Quit: Connection closed for inactivity] 00:42 -!- webmeister [~webmeiste@user/webmeister] has joined #hplusroadmap 01:36 -!- darsie [~darsie@84-113-55-200.cable.dynamic.surfer.at] has joined #hplusroadmap 01:42 < muurkha> maaku: what makes it a "natural commerce point" other than low Δv? 01:43 < darsie> delta-v in rocketry? 01:46 < muurkha> yeah. we were talking about the discovery of 2020 XL5, a Trojan (probably a carbonaceous chondrite) at L4 01:47 < muurkha> so I'm trying to figure out what the advantage would be of mining asteroids at L4 instead of in the asteroid belt 01:47 < darsie> Sun-Earth L4? 01:48 < darsie> mhm 01:49 < darsie> Could be used as shielding material for a colony. 01:50 < darsie> Hmm, has a significant inclinaiton and eccentricity. 01:51 < darsie> Might get kicked around by Venus. 01:51 < muurkha> L4 is a relatively shallow gravity well but it should be good for a few millennia 01:52 < muurkha> just saying there's a lot more shielding material for a colony in the main belt 01:53 < darsie> Yeah. Earth, being a planet, has cleared it's orbit, by definition. 01:53 < darsie> But hey, Jupiter has lots of trojans and is still a planet :). 01:54 < muurkha> yup! 01:56 < darsie> Due to 2020 XL5's high orbital inclination, a rendezvous mission to the asteroid from low Earth orbit (LEO) would require a minimum total delta-v of 10.3 km/s (6.4 mi/s)—too high to be considered an ideal target for a low-energy trajectory. https://en.wikipedia.org/wiki/2020_XL5#Exploration 01:57 < darsie> There are cheaper asteroids. 01:57 < darsie> You can sort by dv on http://www.asterank.com/ . 01:57 < muurkha> interesting. Jay_Dugger, is that what you were thinking of? 01:57 < muurkha> neat! 01:58 < muurkha> 10.3 km/s is pretty high 02:05 < darsie> I sorted by accessibility and looked for value, came up with Ryugu. 02:05 < darsie> 1989 ML 02:05 < darsie> Nereus 02:09 < muurkha> Ryugu: 1 km diameter, C-type, 10⁻⁶ gees. it's sure accessible but what's your definition of value? 02:10 < darsie> I have no definition for asteroid value. 02:10 < muurkha> what were you looking for? 02:10 < darsie> asterank has 'accessibility' and 'value'. 02:10 < darsie> I sorted by accessibility and looked for value. 02:11 < darsie> Value seems to correlate with size/mass there. 02:11 -!- Llamamoe [~Llamamoe@178235178060.dynamic-4-waw-k-1-2-0.vectranet.pl] has quit [Quit: Leaving.] 02:12 < darsie> You can build stuff with matter. 02:12 < darsie> Thats valuable in space 02:12 < darsie> Space manufacturing. 02:13 < darsie> some precious metals may be worth bringing to Earth. 02:13 < darsie> Oxygen and carbon etc. are needed for life. 02:13 < muurkha> do C-type asteroids have precious metals? 02:14 < darsie> idk 02:14 < muurkha> they do have oxygen and carbon! 02:14 < darsie> There are probably some in all asteroids. 02:16 < muurkha> maybe so! 02:17 < muurkha> 1989 ML is 0.6 km, 4660 Nereus is 0.33 km 02:20 < muurkha> 4660 Nereus is enstatite, I don't think we have any idea what 1989 ML is 02:22 < muurkha> maybe I'm too biased by my experiences here on Earth but isn't there an M-type NEO with a low Δv? 02:23 < darsie> idk. But you can extrat metals from oxides. 02:24 < muurkha> if they're there, yeah 02:24 < muurkha> but you can't extract platinum or nickel from enstatite, just magnesium and silicon 02:24 < darsie> silicon is only a semiconductor. 02:25 < muurkha> alternatively most of the main belt is under 10 km/s 02:26 < muurkha> maybe I'm being too blasé about the punishing exponential implicit in the Tsiolkovsky equation? 02:27 < muurkha> earth-crossers have lots more solar power density available at perihelion than any MBA but I feel like you can compensate just by assembling bigger panels 02:34 < darsie> Bennu, Didymos, 2011 UW158, 2002 AL31, Anteros, 2001 AE2, 2002 AT4, 1991 BN, 2001 SK162, 2001 CC21, 1992 TC, 2001 SG10, 2002 DO3, 2001 YE1, 2002 EC, 2000 CE59, 1995 BC2 02:34 < darsie> Those are the remaining ones with a stated value of the first 4000 most accessible ones. 02:36 < darsie> We're going to impact the moon of Didymos. 02:36 < muurkha> Don't tell me its moon is called Epididymus. 02:37 < darsie> I think low MOID allows for low delta-v if you use Earth gravity assists. 02:37 < darsie> no 02:37 < darsie> Dimorphos 02:38 < darsie> Initial nickname was Didymoon. 02:38 < muurkha> clearly a missed opportunity 02:40 < muurkha> probably a waste of valuable high-altitude organics but if you squish chondrite material into a hollow cylinder you have a hybrid rocket motor 02:43 < darsie> Ryugu was only discovered in 1999. We'll find more. 02:44 < muurkha> yes, but they'll all be tiny 02:44 < darsie> How big do you want them? Is the Moon big enough? 02:44 < muurkha> the moon has sentimental value 02:45 < darsie> so? 02:45 < muurkha> you think the NIMBYs are bad now, just wait until you propose recycling Luna 02:46 < muurkha> Pallas is a nice size 02:50 < muurkha> hundreds of zettagrams 02:52 < darsie> I have no issue with a Moon colony with the water in polar craters or building stuff from its matter or bringing some to LEO with a slingshot, mass driver or space elevator for shielding a space station. 02:52 < muurkha> oh, sure 02:52 < darsie> Some idiot would probably mess up the Apollo landing sites. 02:53 < muurkha> but I feel like sending organics and putting your constructors in a gravity well are bad ways to start 02:53 < darsie> I proposed a single wire loop around the Moon's equator with two or three solar power plants for continous power during the two week night. 02:54 < muurkha> yeah, that's another drawback of Luna 02:55 < muurkha> not an unsolvable problem but an expensive oe 02:55 < muurkha> *one 02:56 < darsie> Settlements can patch in the loop in series and draw power with some voltage drop. 02:57 < muurkha> sure 02:58 < darsie> High voltage drops to minimize conduction losses. 02:58 < darsie> to keep the diameter/mass of the wire low. 02:59 < muurkha> sure 02:59 < muurkha> and on Luna air's low Paschen voltage is irrelevant 02:59 < muurkha> but think about, say, Psyche 03:00 < muurkha> 2 teragrams of stainless steel 03:00 < darsie> Use aluminium. 03:00 < darsie> There's ##space , btw. 03:00 < muurkha> why, if you have Psyche? 03:01 < muurkha> presumably contaminated with all kinds of delicious siderophiles 03:01 < darsie> ah, I meant for the loop on the Moon. 03:01 < muurkha> oh, yeah, that's clearly the right choice 03:01 < darsie> Magnesium can be an ion thruster propellant. 03:01 < muurkha> so can I, darsie, so can I 03:01 < muurkha> magnesium is not a particularly good ion thruster propellant though 03:02 < darsie> There has been some research. 03:02 < darsie> And prototypes, IIRC. 03:07 < muurkha> I'd never thought about "using half the wire" as being a potential advantage of current-loop power transmission before 03:09 < muurkha> you are of course correct about that, unless Luna's deep regolith is conductive enough to use as a return path 03:09 < muurkha> we take Terra's water for granted at times 03:27 < maaku> muurkha: L4/L5 has a consistent Δv and flight-time profile for cislunar space. So you can launch to there from Earth/Moon or back at any time without waiting 03:28 < maaku> and L4/L5 are energetically accessible from all of near-earth heliocentric orbits 03:29 < maaku> the asteroid belt is far away. any mining done in this century will be at NEO objects 03:29 < maaku> (or, more likely, the moon) 03:31 < maaku> so L4/L5 are likely to act as depot locations for refined materials, which can be shipped back to cislunar space on low energy trajectories on demand 03:34 < muurkha> maaku: the asteroid belt is only 10 km/s away; why do you think no mining will happen there this century? 03:35 < darsie> Because 10 km/s is twice as much as 5 km/s. 03:35 < maaku> darsie: 4 times as much 03:35 < maaku> and also, travel time is significantly longer 03:35 < maaku> and those energetically favorable transfer periods are further apart 03:36 < muurkha> even LEO is 7.9 km/s 03:36 < muurkha> why 4 times as much? 03:36 < darsie> Launch mass wise, I guess. 03:36 < maaku> rocket equation 03:37 < maaku> a NEO might have a transfer with Earth a couple times a year. 03:37 < muurkha> hmm, isn't that exponential rather than quadratic? 03:37 < muurkha> Isp g₀ ln (m₀/m₁) 03:38 < maaku> and depends on staging and other things. quadratic is a reasonably accurate rule of thumb 03:38 < maaku> some random asteroid belt object is going to have transfer windows 2-10 years apart. that just doesn't work commercially 03:38 < darsie> I use v_e instead of Isp*g. 03:38 < muurkha> vₑ is totaly legit 03:39 < muurkha> oh, I see 03:40 < muurkha> it's not that m₀ (approximately, the fuel weight) increases as the square of Δv, it's that you have to square m₀/m₁ to double Δv? 03:40 < maaku> (the quadratic approximation is close because distance is better measured in kinetic energy, which scales quadratically) 03:40 < darsie> But you can get to a belt object in a single arc. For NEOs you launch at MOID and have to do two orbits for an encounter, maybe three for plane change. 03:40 < muurkha> I don't think the quadratic approximation is close at all or that distance is better measured in kinetic energy for rockets 03:40 < muurkha> but maybe you know something I don't 03:40 < maaku> if we had very low reaction mass engines (e.g. fusion) then it would be quadratic 03:41 < muurkha> oh, possibly 03:41 < maaku> in 21st century reality, it's worse 03:41 < darsie> Hmm, one orbit, then encounter at MOID. 03:41 < maaku> so >4x 03:42 < maaku> I didn't know there was anyone else here interested in asteroid mining, lol 03:43 < muurkha> well, not in the way you are :) 03:43 < darsie> I'm interested in self replicating machines that turn solar system bodies into space ships, habitats and a computronium type II civilization and colonize the galaxy. 03:43 < muurkha> why would you start by putting them on Luna then? 03:44 < darsie> computronum for uploaded minds and AI. 03:46 < muurkha> supposing vₑ ≈ 3km/s I think you need m₀ = 5.3 m₁ for Δv = 5 km/s and m₀ = 28 m₁ for Δv = 10 km/s 03:46 < muurkha> is that right? 03:48 < darsie> computes for me 03:48 < muurkha> those don't seem like absurd numbers, though 3% payload is clearly not as nice as 16% payload 03:49 < darsie> You can aerobrake at Earth from NEOs. 03:49 < darsie> If you want to bring stuff back. 03:50 < maaku> muurkha: when payload (and structure!) mass fractions are that low, you start doing everything you can to shave off weight to make it viable 03:51 < maaku> but ironically, that makes the whole setup unsustainable because you make the ship unable to survive repeat use or multiple failures 03:52 < muurkha> why is that unsustainable? spawning salmon, dandelion seeds, condoms, and bullet cartridges are also unable to survive repeat use or multiple failures 03:52 < maaku> Jeff Greason, who is a far better engineer than I, estimates that you can have airplane or container-ship level of reliability for reusable spacecraft with up to 4km/s delta-v 03:52 < darsie> With a wide cross section cone for aerobraking you may not need arcane heat shield. 03:53 < muurkha> darsie: oh? 03:53 < darsie> A piece of paper might deorbit without burning up. 03:54 < darsie> If you make a wide angle cone it would be aerodynamically stable. 03:54 < muurkha> hmm, but would it? 03:55 < darsie> Make one and drop it. 03:55 < muurkha> I'm not in orbit at the moment 03:55 < darsie> Ah, you mean not burn up. 03:55 < muurkha> when I think of a piece of paper in a 7.9 km/s wind I am somewhat doubtful about its survivability 03:56 < muurkha> but I suppose very thin air changes things 03:57 < darsie> You could make the cone of platinum sheet and put little boxes of other stuff inside it. 03:58 < muurkha> ♪ little boxes ♫ made of ticky-tacky ♪ 03:58 < darsie> Then slingshoot it to earth, with some little correction thrusters. 04:00 < darsie> You'd need a little factory at the mining site to do that. 04:01 < darsie> The thrusters could use O2 as propellant. 04:02 < darsie> Just pressure vessles with a valve and a nozzle. 04:03 < muurkha> could work 04:05 < muurkha> I guess the key to plasma-free aerobraking is to finish punching through Newton's penetration depth of atmosphere at such a high altitude that the heating is low enough power that you can radiate the heat away 04:06 < muurkha> say your platinum or nickel parachute can handle 1000°, then you can brake at 150 kW/m²? is that right? 04:08 < darsie> Paint it black :) 04:08 < darsie> https://www.youtube.com/watch?v=O4irXQhgMqg The Rolling Stones - Paint It, Black (Official Lyric Video) 04:08 < muurkha> ♪ I see a red bot ♫ and I want to 04:10 < muurkha> you can skip off the mesosphere like a stone by angling your parachute to provide lift 04:11 < darsie> We need to capture. 04:12 < muurkha> well, you're losing energy the whole time 04:12 < muurkha> if you aren't in a hurry you don't even need refractory materials. glass would work fine 04:12 < muurkha> or, yes, paper. if properly controlled! 04:13 < darsie> Can't make paper. 04:14 < darsie> Aluminium foil 04:14 < muurkha> carbonaceous chondrite paper made from polyethylene 04:14 < muurkha> asteroid tyvek 04:14 < darsie> Needs hydrogen. 04:14 < muurkha> C chondrites have plenty 04:14 < darsie> rly? 04:14 < muurkha> I don't know anything, I'm just quoting wikipedia 04:14 < darsie> NEOs? 04:15 < darsie> where? 04:15 < muurkha> but yes aluminum, iron, or glass is probably more practical 04:17 < fenn> 316 stainless 04:18 < muurkha> possibly 04:18 < fenn> carbon-carbon composite is pretty good at high temps 04:19 < fenn> why are we aerobraking again? 04:20 < muurkha> https://en.wikipedia.org/wiki/C-type_asteroid https://en.wikipedia.org/wiki/CI_chondrite 04:20 < muurkha> oh, we were just talking about how to deliver asteroid mining products to terrestrial buyers 04:21 < fenn> seems like a strict downgrade then 04:21 < muurkha> from what? 04:21 < fenn> not deorbiting them 04:22 < muurkha> not for the terrestrial buyers, but sure, plopping valuable mass into a gravity well devalues it 04:22 < muurkha> for most uses 04:22 < fenn> a "made in space" novelty industry will soon saturate the available market 04:23 < muurkha> thinking more about platinum and stainless steel 04:23 < fenn> platinum maybe, but the steel is worth more up there 04:23 < muurkha> not to the humans down here 04:23 < muurkha> I wonder if I'm misunderstanding the situation with the mesosphere parachute skipping thing. you'd think that if it were a viable strategy some space agency would have tried it instead of going through all the expensive and risky ablative heat shield stuff, so maybe there's a reason I'm not seeing that it doesn't work 04:24 < muurkha> can't, I mean 04:24 < fenn> reentry technology is a highly classified field 04:24 < muurkha> oh? 04:25 < fenn> most of that cold war stuff was about intercepting ICBMs in the reentry phase 04:25 < muurkha> ICBMs can't use approaches like that though, they need to reenter as fast as they can 04:26 < fenn> being able to change your trajectory by several km/s would change the whole missile-defense game considerably 04:26 < muurkha> not if it takes you an hour 04:27 < fenn> sure if it takes an hour too. bomb #1 hits its target successfully, bomb #2 and #3 that were scheduled to hit the same target now are re-targeted somewhere else for the next go-around 04:27 < darsie> A papercone was unstable and turned over. With 2.28 g payload (1 EUR cent) it wobbled a lot and almost turned over in a 3 m drop. With 7.54 g (1 EUR) it was stable. https://i.ibb.co/NN0ZBPV/IMG-6348.jpg 04:28 < darsie> Don't tell anyone. It's highly classified ;). 04:29 < darsie> Payload in center. 04:30 < fenn> why so obtuse? 04:30 < fenn> it's very wide and flat 04:30 < muurkha> I was born that way, fenn 04:30 < fenn> i wasn't born, i possessed this body 04:30 < muurkha> that's what they all say 04:31 < darsie> It's wide to have much drag. 04:31 < darsie> So we don't need arcane materials. 04:32 < darsie> But yeah, we could turn it around and use it like a parachute. 04:32 < muurkha> my analysis suggests we don't, but I wonder if I'm overlooking something 04:33 < muurkha> the plasma sheath is a big problem for communications and controllability 04:34 < fenn> i meant why not a pointy cone like an ICBM warhead 04:35 < muurkha> harder to control 04:35 < fenn> it would be more stable, have less heating per unit area than a flatter cone 04:35 < fenn> there's no control :) 04:35 < muurkha> not sure it has less heating per unit area 04:35 < muurkha> no control si bad 04:35 < fenn> if you wanted control you'd use a plasma magnet sail 04:35 < muurkha> *is 04:35 < muurkha> what, in the mesosphere? 04:35 < fenn> (helicon coupler on a long wire) 04:36 < darsie> My idea was to enter softly. 04:37 < fenn> http://www.nasa.gov/sites/default/files/files/Kirtley_2012_PhI_PlasmaAerocapture.pdf 04:37 < darsie> A pointy design would get very hot. 04:38 < muurkha> depends, not necessarily 04:38 < fenn> oh it was a simple dipole not a helicon 04:39 < darsie> Well, you'd have much more mass per cross section with a pointy design. 04:39 < darsie> So less aerobraking. 04:39 < darsie> So you need to get into denser atmosphere for enough drag. 04:40 < muurkha> you have 1/sin θ more mass per cross section with a pointy design 04:40 < muurkha> wait no 04:40 < muurkha> 1/cos θ 04:40 < darsie> Unless ... you make your foil thinner. 04:41 < muurkha> right 04:42 < darsie> What are we returning from hte asteroids? Precious metals? 04:42 < muurkha> the plasma thing is interesting, apparently you don't rely on existing ionization but make your own 04:43 < muurkha> siderophiles are the highest-unit-value thing 04:43 < muurkha> platinum, rhodium, etc. 04:43 < muurkha> but stainless steel may actually be the highest total value thing 04:44 < darsie> In space 04:44 < muurkha> also though 04:44 < darsie> We could aerocapture and then rapse Pe to orbit. 04:44 < darsie> raise* 04:44 < muurkha> computronium 04:44 < muurkha> raise Pe? Perú? 04:45 < darsie> Computronium is lightweight and requires high tech to make. 04:45 < darsie> periapsis 04:45 < muurkha> aha 04:45 < darsie> If we want steel in Earth orbit. 04:46 < darsie> I think theres cheaper steel on the ground. 04:46 < muurkha> no, Earth is a pain in the ass for stainless steel 04:46 < muurkha> it's so oxidizing that iron and even nickel and chromium don't occur native, you have to reduce them 04:46 < muurkha> and they often don't occur together 04:47 < darsie> How much is 1 kg SS? 50 EUR? 04:47 < muurkha> contrast Psyche: 2 teragrams, of which probably half is stainless steel 04:47 < muurkha> it varies a lot by grade 04:48 < darsie> Well, eventually it may be cheaper from space, but we're far from that. 04:48 < darsie> And you have to refine stuff, anyways. 04:48 < muurkha> depends on the use 04:49 < muurkha> Metals Depot wants US$75 for 1.8 kg of 316L stainless: https://www.metalsdepot.com/search?q=316 04:49 < muurkha> so €50/kg is about right 04:50 < fenn> scrap price is more indicative of the elements themselves rather than quality ontrol etc 04:50 < muurkha> what's the scrap price for stainless? 04:50 < fenn> dunno, everything's broken 04:51 < muurkha> what's mostly required to make computronium is freedom 04:51 < darsie> freedom of IP. 04:51 < fenn> aye 04:52 < muurkha> freedom of not getting your ass blown sky-high 04:52 < fenn> all the freedoms 04:54 < darsie> Mars is a free planet. 04:54 < muurkha> for the time being 04:54 < muurkha> time is running out 04:57 < muurkha> how do you suppose Perry's Black Ships affected the day-to-day life of the peasantry? 04:58 < darsie> 316L seems to be about 2000 USD/t on alibaba. 04:58 < muurkha> if that's a real price then Psyche is only about US$2 billion 04:58 < muurkha> not counting the PGMs 05:00 < darsie> China could copy computronium legally (if they can reverse engineer it). But not sell it abroad. 05:01 < muurkha> l'état, c'est moi 05:01 < darsie> I am the state. 05:01 * darsie understands a bit French. 05:03 < muurkha> China XIV? Or Computronium XIV? 05:08 < docl> psyche isn't 2 teragrams, it's 2 trillion long scale kilograms but tera- is trillion in short scale and that's kilograms not grams... zettagrams really 05:09 < muurkha> you're right, I'm an idiot 05:09 < muurkha> so more like 2e19 US$ 05:10 < muurkha> 23 Zg · 2000 US$/tonne 05:10 < muurkha> figure only 10 Zg is stainless 05:10 < muurkha> still the PGMs are almost surely worth more 05:31 < docl> I suspect demand elasticity is better for structural metals... increase the supply for both and PGM value will drop further vs iron 05:33 < muurkha> maybe, yeah 05:34 < muurkha> but these are very large numbers, so it's hard to guess 05:52 < darsie> muurkha: So you want to move Psyche to Earth? 05:55 < darsie> What would we do with an arbitrary amount of stainless magically appearing on Earth? 05:56 < darsie> Ships? Chemical reactors? Kitchen sinks? Turbines? 05:58 < docl> well it can't very well get cheaper than coal, since you can oxidize it to make electricity 05:59 < darsie> You'd burn stainless to make elctricity? 05:59 < docl> if it was cheap enough you could 05:59 < darsie> You'd get lots of iron and nickel oxide. 06:00 < darsie> and chromium oxide 06:01 < docl> maybe just ship down the iron. iron oxides/silicates make up a big chunk of the crust already 06:03 < docl> .wik https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust 06:03 < saxo> Article not found: https://en.wikipedia.org/wiki/Https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust gave 404 | Searched en for 'https://en.wikipedia.org/wiki/Abundance of elements in Earth%27s crust' | https://en.wikipedia.org/wiki/No_result_found gave 404 | Searched en for 'No result found' 06:03 < docl> .wik Abundance_of_elements_in_Earth%27s_crust 06:03 < saxo> "The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%). / Estimates of elemental abundance are difficult because (a) the [...]" - https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust 06:03 < docl> it's the 4th most common after aluminum, roughly 5% of ths crust 06:04 < darsie> iron? 06:04 < docl> yeah 06:07 < docl> aerobraking at scale is a bit tricky if you want to avoid nox pollution... the compression creates plasma temps which atomizes the nitrogen species. fine in the ionosphere since there's UV to break it down constantly but if you brake down where the UV is mostly absent you have a potent greeenhouse gas. might be a way to use vast quantities of platinum, as a catalyst to break down the nox 06:24 < muurkha> stainless is kind of a pain to burn, but at those scales the more crucial resource would be the oxygen 06:25 < muurkha> docl: do you think our logic above about how to avoid plasma temperatures is sound? 06:27 < muurkha> Terra's atmosphere is only 5e18 kg of which only 1e18 kg is uncombined oxygen, which is probably about an order of magnitude too small to burn all of Psyche's metals 06:32 < docl> ah, I missed that you already discussed that -- yes, seems valid to me. slower braking high enough in the atmosphere with more radiative surface area seems like it would work 06:33 < docl> not sure you need atmospheric oxygen to extract power, could perhaps just use water (at lower efficiency, with hydrogen as a waste product) 06:34 < muurkha> hmm, maybe you're right 06:34 < muurkha> https://en.wikipedia.org/wiki/Atmospheric_entry says that usually most of the reentry energy is dissipated in viscous mixing after the reentry vehicle passes 06:35 < muurkha> only a minority is radiated as heat 06:35 < muurkha> not sure what that depends on 06:37 < muurkha> Fe₃O₄ has standard enthalpy of formation of -1121 kJ/mol, so -260 kJ per mol of oxygen. water's is -285 kJ/mol, so yes you could burn iron exothermically with water but for 90% less energy 06:40 < muurkha> (wüstite and hematite are worse) 06:52 < muurkha> reading further, it looks like the "feathered reentry" technique has been considered: 06:52 < muurkha> > In 2004, aircraft designer Burt Rutan demonstrated the feasibility of a shape-changing airfoil for reentry with the sub-orbital SpaceShipOne. The wings on this craft rotate upward into the feathered configuration that provides a shuttlecock effect. Thus SpaceShipOne achieves much more aerodynamic drag on reentry while not experiencing significant thermal loads. 06:52 < muurkha> > The configuration increases drag, as the craft is now less streamlined and results in more atmospheric gas particles hitting the spacecraft at higher altitudes than otherwise. The aircraft thus slows down more in higher atmospheric layers which is the key to efficient reentry. Secondly, the aircraft will automatically orient itself in this state to a high drag attitude. 06:52 < muurkha> > However, the velocity attained by SpaceShipOne prior to reentry is much lower than that of an orbital spacecraft, and engineers, including Rutan, recognize that a feathered reentry technique is not suitable for return from orbit. 06:56 < muurkha> NACA Technical Note 4276 07:29 -!- yashgaroth [~ffffffff@2601:5c4:c780:6aa0::f2f0] has joined #hplusroadmap 08:46 -!- spaceangel [~spaceange@ip-78-102-216-202.net.upcbroadband.cz] has quit [Remote host closed the connection] 10:14 -!- phill [uid429774@id-429774.ilkley.irccloud.com] has joined #hplusroadmap 11:45 <+gnusha> https://secure.diyhpl.us/cgit/diyhpluswiki/commit/?id=e6763e52 nmz787: >> http://diyhpl.us/diyhpluswiki/nanotech/ranch/ 11:55 < lsneff> nmz787: nanotech/ranch ? 11:56 < nmz787_> yeah, I bought 75 acres last summer with a 2000sq ft workshop, to house my ion/electron beam microscopes and (soon to come) cleanroom 12:41 < lsneff> What’s your plan? 12:44 < nmz787_> hours/days/weeks/months long workshops/internships... something like that 12:45 < nmz787_> also hike, garden, ride dirtbikes, maybe get some farm animals some day in the distant future... do nanofab stuff towards DNA synthesis/sequencing/transformation 12:45 < nmz787_> first pass at internet setup https://diyhpl.us/nature2nano_scienceranch/Internet_Access/ 12:54 < muurkha> nmz787_: hey, that's great! congratulations! 12:56 < muurkha> can you do FIB milling? 13:01 -!- nmz787_mobl [~nmz787_mo@2600:100f:b121:b7e9:63d:2c60:78bb:67cb] has joined #hplusroadmap 13:01 < nmz787_mobl> Yes, BMP files so far, but the control software is buggy and i haven't quite figured out the safe zone 13:03 < nmz787_mobl> http://diyhpl.us/~nmz787/pdf/smi3200/pics.html 13:04 < nmz787_mobl> https://m.imgur.com/gallery/YQwPaMe 13:04 < nmz787_mobl> .title 13:04 < saxo> Yard Mushrooms and their spores under Focused Ion Beam microscope, with sectioning of some spores - Album on Imgur 13:05 < muurkha> what kind of materials are you equipped to deal with? 13:06 < muurkha> I mean, there's lots of possible processes you could do, and probably you aren't doing most of them yet, if you ever will 13:07 < muurkha> there's a lot of MEMS stuff that uses SiO₂ as a sacrificial scaffolding material, for example, and then removes it with an HF etch or something 13:08 < muurkha> I've been wanting to try some flexure stuff 13:09 < muurkha> do you have a list of things you want to get done? 13:16 < muurkha> the wasp on http://diyhpl.us/~nmz787/pdf/smi3200/pics.html is especially gorgeous 13:39 -!- nmz787_mobl [~nmz787_mo@2600:100f:b121:b7e9:63d:2c60:78bb:67cb] has quit [Ping timeout: 240 seconds] 13:43 -!- nmz787_mobl [~nmz787_mo@172.58.43.234] has joined #hplusroadmap 13:43 -!- nmz787_mobl [~nmz787_mo@172.58.43.234] has quit [Client Quit] 13:58 < nmz787_> muurkha: here's some patterning https://diyhpl.us/nature2nano_scienceranch/Internet_Access/ 13:58 < nmz787_> err 13:58 < nmz787_> https://twitter.com/norklemcdorkle/status/1144707912561860609 13:58 < nmz787_> .title 13:58 < saxo> No title found 13:58 < nmz787_> currently not really setup to deal with much in the way of materials processing, basic solvents really 14:00 < nmz787_> goal is to do nano/microfluidic MEMS like stuff but using CMOS compatible processes/materials (or as close to CMOS compatible as possible), so I can hope to integrate electronics into the fluidics very closely, for signal fidelity reasons from molecular sensing 14:01 < nmz787_> after cleanroom is setup, plan is to get ALD (atomic layer deposition) setup, along with DRIE (deep reactive ion etch) 14:02 < nmz787_> so I can do "deep" fluidics and possibly flexure-sort-of fluidic pump stuff, as well as etch out things like fluidic vias 14:02 < nmz787_> and ALD for electrode deposition, or possibly other work-function/surface-function modification/passivation 14:04 < nmz787_> this is sort of a "north star" work that I would like to recreate or approximate in some form https://gnusha.org/~nmz787/pdf/Fabrication_of_sub-20_nm_nanopore_arrays_in_membranes_with_embedded_metal_electrodes_at_wafer_scales.pdf 14:05 < nmz787_> and then bond that to an existing ADC with PGA chip, possibly one with a voltage sweep generator on it to (like for building bode plots) 14:05 < nmz787_> i.e. this https://www.analog.com/en/products/ad5933.html 14:05 < nmz787_> .title 14:05 < saxo> AD5933 Datasheet and Product Info | Analog Devices 14:06 < nmz787_> 1 MSPS, 12-Bit Impedance Converter, Network Analyzer 14:37 < lsneff> Any of you know of any 3d electronics projects? I’m pretty sure most PCBs could be significantly more compact if ICs were situated in 3D rather than 2D 14:48 < nmz787_> I think that's called "dead bug" 14:48 < nmz787_> or daughter card 14:49 < nmz787_> or https://blog.samtec.com/post/custom-connectors-for-stacking-pcbs/ 14:50 < nmz787_> but more honestly, I think the focus for most of that sort of thing is 3d die stacking 15:17 < lsneff> Probably 15:18 < lsneff> I’m trying to make the smallest mcu + uwb transceiver device I can, and PCBs aren’t great for this 15:18 < lsneff> A chunk of plastic or resin with the ICs routed in 3d would be much more compact 15:38 < fenn> missile guidance used to be done in "cordwood" style 15:39 < fenn> i think you'll still want to have some sort of overarching regularized layout strategy even in 3D, just to keep from going insane 15:44 < lsneff> Ideally, I’d just specify the connections and software would design it given many different constraints 15:45 < nmz787_> SAT solver 15:45 < nmz787_> https://github.com/nmz787/sat_solver_examples 15:45 < nmz787_> https://gist.github.com/nmz787/ae4a6121ce4aa42c2caed5b062b97c70 15:45 < nmz787_> .title 15:45 < saxo> An attempt at making a point-to-point route solver for 3D grids, using DIMACS SAT clauses with cryptominisat · GitHub 15:47 < lsneff> Ah, very interesting! 15:47 < lsneff> I’ve messed around with sat solvers a bit 15:47 < lsneff> Tried to write one a few months ago, but got distracted 15:47 < nmz787_> that was an attempt at smart autorouting, I had done something with a SAT solver for auto netlist generation before and wanted to take it further but work ran out of money, and then I ran out of steam on my own 15:48 < lsneff> Yeah 15:49 < nmz787_> https://ada.liacs.nl/papers/BayEtAl16.pdf 15:50 < nmz787_> https://scholar.google.com/citations?user=28Ww4H0AAAAJ&hl=en&oi=sra 15:50 < nmz787_> .title 15:50 < saxo> Alexander Nadel - Google Scholar 15:50 < nmz787_> oops, you want to sort that by date 15:51 < nmz787_> https://scholar.google.com/citations?view_op=view_citation&hl=en&user=28Ww4H0AAAAJ&sortby=pubdate&citation_for_view=28Ww4H0AAAAJ:M3ejUd6NZC8C 15:51 < nmz787_> .title 15:51 < saxo> View article 15:51 < nmz787_> Routing under constraints 15:52 < nmz787_> http://diyhpl.us/~nmz787/pdf/SAT/ 15:52 < lsneff> Definitely seems like a solvable problem 15:52 < lsneff> The physical aspect of making a 3d object with embedded electronics seems difficult though 15:52 < lsneff> Would require some sort of 3d printing with highly conductive traces and pick and place at the same time 15:53 < nmz787_> they have that... let me search for it 15:55 < lsneff> Okay 15:58 < nmz787_> I believe it's this group at Georgia Tech: https://tentzeris.ece.gatech.edu/ectc18_tehrani.pdf 15:58 < nmz787_> https://tentzeris.ece.gatech.edu/ectc18_bahr.pdf 15:59 < lsneff> Oh interesting 15:59 < lsneff> Seems promising 16:02 < lsneff> So that’s like, stereolithography with silver conductive ink and pnp ? 16:08 < lsneff> It looks like it didn’t have components connected in 3D 18:05 < L29Ah> i'm pretty sure you'll figure out a compact 3d routing of your mcu + uwb transceiver device quicker than finding the tool to do it for you 18:05 -!- webmeister [~webmeiste@user/webmeister] has quit [Ping timeout: 250 seconds] 18:13 -!- darsie [~darsie@84-113-55-200.cable.dynamic.surfer.at] has quit [Ping timeout: 256 seconds] 18:19 -!- Malvolio [~Malvolio@user/malvolio] has quit [Quit: ORGANS IN MAINS] 18:20 < superkuh> I suppose if you are doing things in 3D with wires you may was well make it a spherical multi-arm helix antenna to optimize for bandwidth in a volume. But most "UWB" wideband stuff just gets away with a gradient/stepped PCB ground and super fat monopole. 18:21 -!- Malvolio [~Malvolio@user/malvolio] has joined #hplusroadmap 18:25 < superkuh> I played around with using ground defect (slots and other geometries) beneath microstrip to move signals between via defined substrate integrated waveguide cavities made from two 1.6mm stacked PCBs. 19:07 -!- Jay_Dugger [~jwd@47-185-250-228.dlls.tx.frontiernet.net] has quit [Ping timeout: 240 seconds] 19:21 -!- Jay_Dugger [~jwd@47-185-250-228.dlls.tx.frontiernet.net] has joined #hplusroadmap 19:41 < lsneff> I mean, sure I’d be able to figure out routing by hand faster than writing a tool to do it, but having a tool do placement and routing automatically would speed up people overall 19:48 -!- yashgaroth [~ffffffff@2601:5c4:c780:6aa0::f2f0] has quit [Quit: Leaving] 20:04 < lsneff> Well, at least routing should be automatic. Perhaps placement should be manual for now 20:28 < nmz787_> automated place and route is definitely a tough problem, but worthwhile to have solutions for (and could even be worth a lot of $$ if done right and with great performance) 20:31 < nmz787_> I saw presentations from that lab, I think maybe that year or the next, and I can't quite remember the specific details 20:40 < lsneff> I feel like there’s gotta be a better way than messy SLA for this 20:42 < lsneff> But I guess it’s really the only thing that can match the necessary accuracies 21:47 < lsneff> https://www.nano-di.com/ame-technology 21:47 < lsneff> Looks like at least one company did it 22:04 < lsneff> Yep, looks like this is through inkjet 3d printing 22:11 < lsneff> It’s hard to get one’s hands on inkjet printheads, but this doesn’t look impossible to build an open source version of --- Log closed Sun Feb 06 00:00:51 2022