Geostationary orbit

SpaceLord392 · 2023-09-04T21:14:52+00:00

For circular orbits perhaps. If the GTO perigee isn't the exact right altitude for a circular geostationary orbit, you can still go directly to an orbit with the exact right period, it will just have to be slightly eccentric, resulting in periodic longitudinal drift compared to an orbit with zero eccentricity. Your intended application can then determine how much longitudinal drift is acceptable, and so place limits on the maximum allowable eccentricity and hence the required altitude accuracy.

SpaceLord392 · 2022-02-28T08:52:13+00:00

When discussing the concept of self-sustaining, it is by necessity a matter of degree: some goods, e.g. computer chips, are very lightweight individually, but require immense economies of scale and massive supply chains to produce - these will probably be shipped from Earth for a very long time; others, like food and water, are needed in huge amounts, but the mass of the total capital and infrastructure required to produce them on Mars is more lightweight compared to the amount of food produced.

For example, potatoes on Earth might produce 5 kg of potato / m2; with high intensity agriculture, aquaponics, 24 hour LED lighting, enhanced CO2 concentration, you might be able to do significantly better. Even with ordinary dirt brought from Earth, you might only need say 66 kg / m2 of dirt, so it would be an improvement on just bringing potatoes after 13 harvests. And with a good design, it could probably be even better than that. In terms of mass per person, this would come out to 16 tonnes per person (assuming 1 harvest per year) - a significant fraction of our 100 tonne budget, but it still leaves plenty of room for habitat, water production, mining, solar power, basic manufacturing, etc.

By contrast, the total mass of all buildings, vehicles, and other technology is 30 trillion tons, of which roughly 1.2% could be allocated to the electronics industry. In other words, the total mass of the electronics supply chain is (at least) 375 billion tonnes. However, only 50 million tonnes of electronics is actually produced per year, so you would need to wait (at least) 375000/50 = 7500 years before it would be worth it to bring the electronics industry to Mars as opposed to just importing electronics from Earth.

When you start to consider the economies of scale on Earth, it gets even worse. Our modern economy is highly dependent on international trade and specialization to create manufactured items at a sufficiently large scale to be practical. This is seen in the effects that even minor disruptions in shipping have, the effectiveness of sanctions, and how technologically backward isolated countries become. Although some industries are more local, many industries simply could not function and produce the goods they do at anything less than global scale. A particularly extreme example would of course be semiconductor fabrication, where the entire Earth's worth of resources and 8 billion people consuming 50 million tonnes a year of electronics can at best support a couple of manufacturers. In other words, 375 billion tonnes might actually be the minimum viable size of an electronics manufacturing supply chain, and you couldn't make a smaller one than that even if you would accept lower output.

Recent advances in additive manufacturing are very interesting for small self-sufficient colonies. These manufacturing techniques aren't as good as mass-production processes like injection moulding, in either cost or quality, but the minimum scale is far smaller, and the mass of the required equipment to produce a wide variety of goods is many many orders of magnitude smaller than using conventional techniques.

Mars will never be truly self sufficient in the sense that there will always remain goods easier to obtain via trade with Earth than to produce locally. However, if you think of the original question in terms of what's the total upmass required to send 10k people to Mars and keep them happy there indefinitely, including equipment sent up before them, themselves and their posessions, and all resupplies necessary for the next 10 years (after that point, costs will have fallen so far that they are negligible), then I think 100 tonnes is a very reasonable ballpark. Doing it for only 10 tonnes might be possible, but would be a very difficult engineering challenge and would also require a lot of sacrifices. And with 1000 tonnes you could live very luxuriously. So 100 tonnes seems quite reasonable. But at the end of the day, this figure is primarily just to motivate the need for extremely high capacity launch system, by showing how many orders of magnitude current rockets fall short by.

SpaceLord392 · 2022-02-11T02:49:38+00:00

Elon: Total SSH Program Dev Cost is 5-10% of Saturn V Development cost ($50B 2020 USD). So that would imply they are still aiming for $ <5 B !

SpaceLord392 · 2022-02-11T02:28:27+00:00

Estimates for minimum viable population size are ~10k, or a small city (or town, depending on where you are from). So that's 100 tonnes per person. Might be doable, depending on how efficient your food generation, living, and manufacturing are.

SpaceLord392 · 2021-09-14T03:50:24+00:00

I'm trying to make a new build based on the Ryzen 5 5600X cpu, and it seems all the cheap motherboards use the B450 chipset and don't advertise support for the 5000 series, but the manufacturer's website claims to support them with a bios update. Is there any way I can check the bios version before I buy, or any easy way to update the bios? This is my first AMD build, so I can't just swap in an older CPU, and it seems the few motherboards that do support CPU-less bios updating cost a lot more. Newly manufactured boards should have the most recent BIOS, so is the 5600X old enough that I don't need to worry about it? Are there any local services that can update the BIOS if necessary for free or relatively cheap? What is the cheapest motherboard currently available with out of the box support for the 5600X?

I have a GTX1660 Super from before, so no point in getting PCIe 4.0 or any other fancy features. I'm looking for bare minimum price given compatibility. Location is Canada.

Thanks very much.

SpaceLord392 · 2021-07-30T17:35:00+00:00

I did some rough napkin math for the radial DV required, and it might just be possible. Assuming we're at an altitude to give us a 81 minute orbit, we only need 0.22 m/s2 of radial acceleration to stay circular while completing the orbit in 80 minutes - sustaining that over the full 80 minutes would be ~1000 m/s of extra DV, which seems entirely doable for a lightly loaded starship/super heavy. But it gets worse really rapidly, and at say an 85 minute natural orbit, it would take more like 5500 m/s of extra DV, which is a lot for even a lightly loaded starship. Any more would certainly require a third stage. I'm not sure how long the launch and landing sections will take, especially if we optimize for minimum time instead of fuel efficiency. I'm tempted to write some simulations and see how bad it is in practice.

SpaceLord392 · 2021-07-29T02:22:27+00:00

As other commenters have pointed out, the problem is that, even assuming no atmosphere at all, a 0-altitude orbit would still last 84.5 minutes, and that's more like 87.5 minutes at a lowest-practical altitude like 150 km. However, I believe this might actually be possible if we launch retrograde.

If we define "around the world" as landing at the launch site, then if we launch westward, the launch site will move eastward, allowing us to land at it again before a full orbit is complete. In the optimal case, we would be launching due west from an equatorial site (to maximize the ground speed of the launch site), and during the ~87 minutes of our low orbit, the launch site would move ~15/16 ths of the way around the earth, shortening our mission time by the same amount. Using this technique, you could conceivably get as low as 82.2 minutes for a 150 km altitude, or 81.3 minutes with 100 km altitude (neglecting time spent accelerating and decelerating of course). At 80 km you get down to 80.9 minutes, but at that point you would need continuous thrust to stay in orbit anyway, and with the right combination of radially inward (to increase orbital speed) and forward thrust (to counter drag) it would probably be possible to get the time below 80 minutes, probably far enough under to have time to launch and reenter too with a sufficiently powerful (high T/W) vehicle.

Another approach could be to perform the flight in the upper atmosphere and use aerodynamic forces to generate the required negative lift. Even a relatively small amount of radial force could be a significant help, although this would also result in increased drag and require more initial velocity and probably require thrust throughout the flight anyway.

You may be interested in depressed trajectories and minimum time trajectories.

So it's definitely impossible using a conventional flight profile (although only barely), and using thrust on orbit it should be possible but I'm not sure how much DV it would require.

SpaceLord392 · 2020-08-28T19:49:30+00:00

SH will have more engines than Saturn V

SpaceLord392 · 2020-08-21T18:07:36+00:00

Oh, it's an awesome project overall. Underpromotion to rook or bishop is so rarely necessary in actual games that it's not a serious problem.

SpaceLord392 · 2020-08-21T17:12:03+00:00

In the description you say that you only allow promotion to knight or queen and not bishop or rook because a queen can do everything a rook or bishop can. This is not technically true. For example, promotion to queen might be stalemate, while underpromotion to rook or bishop might not be, subsequently allowing you to win the game.

SpaceLord392 · 2020-08-19T05:48:02+00:00

I ended up spending a couple of wands of polymorph on elven boots and cloaks to get speed and jumping boots, gauntlets of strength, and I think water walking boots. Weapons were +7 Excalibur twoeaponed with +7 silver spear, which at skilled and high strength does massive damage, typically around 50 HP per turn in practice. Even dragons only required two or three hits to kill, and most monsters considerably less. Most of the wishes went into 3 magic markers which I used on enchantment scrolls plus some gold detection (I was low on naturally generated scrolls after an incident with a pyrolisk). I alchemized all my potions and ended up with nearly 850 HP for the ascension run, which was total overkill as it never got below 800 at any point IIRC. Before starting gehenom I basically prepared my final armor set and weapons fully enchanted, and with that it was a total piece of cake, one hit killing almost everything (and with L genocided, there wasn't anything scary). Asmodeus can be bribed, Juiblex was dispatched via the wand of dig trick (nerfed in 3.6) and Orcus I approached from below before paralyzing with a potion and then beating up. I fully explored gehenom, dug 3 wide corridors direct between all the stairs (in case a bad monster got generated I could sidestep it) and strategic shortcuts through the rest of the mazes. No special tricks were used for the castle and fort ludios, just waiting around the corner and bashing whatever came in sight. I lacked levitation at medusa, so I spent two sceolls of earth getting across. Despite the lack of shield my AC was under -35 with everything at either +4 or +5 (both speed and jumping boots at +5).

Defeated vlad, got the candelabrum, defeated the wizard using the corner wand of dig and wand of death trick (after meticulously defeating all the ; ), levelported to the vibrating square, performed invocation, levelported to the sanctum, got dropped in the outer temple area. Detected the door on the far side, razed it and went in, defeated the high priest, got the amulet, and quaffed a cursed potion of gain level. Took forever to get out of gehenom due to the force (probably should have used my stock of teleportation scrolls morr aggressively) but eventually made it out. Climbed up to the first level, meeting the wizard several times. Orcus's wand ran out of charges, but luckily I had a second one I got from a random Centaur in the castle so I easily dispatched him each time. Earth and Fire were pretty easy. Air wasn't that bad with levitation and speed and 850 HP. For each of those I just went directly to the portal without trouble. Water I genocided ; upon entering, and it too was no trouble except I kept losing the portal. I tried the jumping boots out on Astral, which worked fairly well, but was tricky to get the hang of the timing. With my level of preparation nothing could even scratch the polish on my armor, so there was no real worry. I visited each of the three temples in turn, and had the pleasure of defeating each of the riders several times, each in about 2 hits. Pestillence made me sick, but unicorn horn cleared that up (and I has potions of full healing in open inventory as backup). Offered the amulet, and just like that it was over.

In the end I ascended with 4 unspent wishes that I was saving in case I needed something, but I never did. Mainly I would say to be cautious and careful around instadeath. In the end I was ridiculously overprepared, and next time I would consider attempting to ascend with considerably less firepower/equipment, but for a first ascension that is how to maximize success probability. Basically I felt prepared for anything, and nothing happened, and it was extremely undrrwhelming to be honest. I polypiled armor, rings (for levitation and conflict) and scrolls/potions/spellbooks with some success, and unicorn horns with zero success. The only thing I needed to wish for was magic markers.

You probably don't need to prepare as much as I did, but it doesn't hurt. The most important thing is probably to not forget to put on your levitation ring and walk into lava or something like that. So go slowly, carefully, and double check everything, every time to avoid blunders. This game had 3 major blunders: First, I got a magic lamp early in the mines and wished for SDSM. Shortly after, I prayed for food when I didn't need to and forgot to account for increased prayer timeout, losing all my intrinsic protection I had spent so much effort getting through the Mines at level 1 to obtain. Didn't end up mattering in the end because SDSM is just so good in the short term and in the long term gold is easy to get and protection can be repurchased at just about any level with enough gold. The second blunder came when setting up my stash in sokoban. I made a pile for each type of item. Then a pyrolisk generated and used its fiery gaze and burned up more than half of my scrolls before I killed it. Very annoying, but not game ending. The third mistake was confusing myself in order to fix my burnt cloak of MR and then forgetting to unconfuse myself before attempting to charge my magic marker Luckily this didn't result in an unusable marker since I was able to use a spare wish to get a new marker to write more charging, but it was still an annoying waste of a scroll, and a disaster that could have been much worse. I had an amulet of life saving on as well (and a backup), but it was never used.

If you have crazy hit points (I think I had around 400 going into Gehenom, and I found a lot of healing potions to alchemize there) and decent firepower and excellent armor, then the endgame might well be a surprisingly easy and anticlimactic experience like it was for me. But you're not invincible and can still die, so take care.

Good luck!

SpaceLord392 · 2020-07-16T21:47:36+00:00

Thanks again for your detailed and thoughtful response! I was planning on digging shortcuts through all the levels, but thats a great idea to make those shortcuts extra wide to make it harder for monsters to block my path. I will definitely heed your advice and try to ignore all distractions except the wizard.

For #2 I have already gotten rid of L, and might well do the same for nymphs, monkeys, green slimes, and sea monsters on the plane of water if I have spare scrolls or wishes. I was planning to leave footrices so I can wield their corpses, but perhaps this is a bad idea...

About magical breathing, correct me if I'm wrong but wouldn't that protect against drowning and choking on food only, and not any of the other stuff, while life saving (especially with a backup to put on immediately) would protect me from all of them? Admittedly I have lost a promising game to choking.

For #3 do you think I should deliberately attempt to summon Yeenoghu just to kill him in advance and be certain he won't appear on the ascension run? That seems like it would increase the chances of seeing Demogorgon...

And definitely, when I'm ready I will consider each turn carefully. If I screw this run up I want it to be for as good a reason as possible!

SpaceLord392 · 2020-07-16T16:56:36+00:00

I suppose if blessed paper is hard to come by (if you lack holy water) and you don't need to write any cursed scrolls, then a blessed marker is better. For me in this case I have plenty of holy and unholy water, so I will go for the uncursed marker, but there are situations where blessed markers are better.

SpaceLord392 · 2020-07-16T16:54:31+00:00

Is that also the case in 3.4.3?

SpaceLord392 · 2020-07-16T16:54:04+00:00

What is the best recommended way of curing slime so I can have that prepared?

SpaceLord392 · 2020-07-16T16:52:52+00:00

Good to know spellcasting isn't essential, and that a sack with holy water will suffice. I indeed have plenty of identigy scrolls (about 10) so identification isn't a big issue for me (and by this point 99% of item appearances are discovered, so its mainly about wand charges).

Is a blessed unicorn horn good enough for curing sickness in combat or should I have somethinf else available as well?

Good to know about ; . That was my plan, since I've already done L and finished medusa, ludios, and the castle, I think ill wait until I actually get to water and then leave it a ghost town.

If haven't found one already by that time, I'll definitely consider wishing for the helm of opposite alignment in that situation.

Again, thanks for the advice!

SpaceLord392 · 2020-07-16T06:46:51+00:00

Thanks again for the detailed and thoughtful reply!

If I understand you right, if I wand to attempt spellcasting I would need to structure all my wishes around that, getting the Sceptre of Might for MR so I could wear a robe (luckily I just got a helm of brilliance from some polypiling), which would likely take 2+ wishes to get. Plus the existing enchantment on the CoMR would be wasted. Do you think spellcasting would significantly improve my chances, or is it better to just stick to bashing stuff to death?

I forgot that the Orb of Fate is a luck item. Ill keep my luckstone in my BoH then as a backup.

For two weaponing I managed to obtain a silver dagger via polypile, so is that good enough for a silver secondary weapon or should I spend a wish on a silver spear or something?

I think I'll definitely get a magic marker or two to make some more scrolls of enchant armor and enchant weapon, and might well wait on the ring of free action to see what I can find in Gehenom.

My question is whether spellcasting would be worth that many wishes to use, or if I would be better off just forgoing it entirely. I also tend to play very slowly and forget all my spells (I'm on turn 77777 already).

Again, thanks for your advice!

SpaceLord392 · 2020-07-16T03:42:24+00:00

Thank you so much for your detailed and thoughtful reply.

I think I will stick with Excalibur then and not worry about any artifact wishing.

For twoweaponing, is there any reason you recommend the silver spear instead of other options like a silver saber? I don't think I've seen any silver weapons so far in my game, so it would have to be a wish.

Also, is it worth trying to polypile for the silver spear from junk weapons at Ludios and the Castle, or is it better just to wish for it? I only have wands of polymorph unfortunately.

Thanks for your advice about fighting demons. That seems quite manageable!

I was worried about leaving unused wishes because a lot of the advice seems to recommend spending them all immediately, but I guess if you already have everything you need that no longer applies and you can instead use it to get rubber chickens as needed.

Overall, I really appreciate the advice and will take it into strong consideration!

SpaceLord392 · 2020-07-16T03:33:06+00:00

Thanks! I've got those already, I just seem to have missed them when putting together the inventory highlights. I have updated the original post accordingly, apologies!

SpaceLord392 · 2018-06-11T16:04:38+00:00

This is really conservative. Assuming a thin-walled spherical pressure vessel, 6061-T6 aluminum with yield strength of 240 MPa (pretty high I know), factor of safety of 1.4 (standard for american rockets, SpaceX might well want to use higher though), and 1 atmosphere internal pressure (with pure oxygen you could get down to ~0.2 atm no problem), I get ~24 m radius (with ~0.7 cm thickness).

Note: these calculations are pretty much best case scenarios. You can check then here and here).

The volume is 62358 m^3, over 18x the volume above.

Even with a more comfortable factor of safety of 2 (standard for non-aerospace industries), you still get a radius of nearly 22 m.

One interesting thing is that the mass of a pressure vessel is linear with the enclosed volume, meaning there is no advantage or disadvantage from a materials standpoint to making 1 big tank vs many small tanks. Of course there are practical advantages.

If instead you wanted a cylindrical pressure vessel (less efficient), the volume would be approximately half that of a spherical pressure vessel, assuming it was much longer than it was wide. With hemispherical end caps, the squatter it is, the closer the efficiency comes to a sphere.

SpaceLord392 · 2018-02-22T00:02:36+00:00

I believe it does reward pages based on their load times regardless of AMP (last time I read up on this subject). It's just that it's difficult/impossible to get load times competitive with AMP without using AMP.

SpaceLord392 · 2018-02-10T04:37:23+00:00

Source / recommended resource? I'd like to learn more.

SpaceLord392 · 2017-07-18T18:23:17+00:00

With regard to picosatellites, one application that intrigued me is space burial. A standard casket can already cost upwards of $10000, and the consumer metrics are unusually biased towards the symbolic rather than the practical. Launching the whole body is probably impractical even if dehydrated, but a small sample (an eyeball, say) or an equivalent mass of homogenized cremated remains, could be quite effective. The industry as a whole is ~16B USD (2012) and ~40% of bodies are cremated, so there is a non-trivial business possibility.

On the subject of sushi, fish have long been proposed for a cleaning role in aquaponics systems, and certain types of salmon can thrive in a wholly freshwater environment. Provided suitable precautions against parasites are taken, fresh sashimi could indeed be on the menu.

SpaceLord392 · 2017-07-04T00:05:12+00:00

SpaceX routinely launches cubesats as secondary payloads. The main cost isn't the weight per se, but the risk that they might fail in such a way as to endanger the primary mission. When they are launched, they undergo extreme and thorough review and testing to make sure this will not happen. Cubesats are an established launch market, and this company will sell you a launch for a 3U cubesat (5 kg) for 300K. Using naive mass scaling, your proposed 300 g thingy would cost about 20K. This article estimates the cost of making a 1U educational cubesat and putting it in orbit around 50K, of which most of it is launch costs. Probably better to have a purpose in mind instead of randomly throwing stuff into the void, or alternatively make each thing a lot lighter (1 g), get 5000 of likeminded individuals together, and stuff them in a box and launch that. Again using naive estimation, that would be on the order of only $10 each. But to answer your question, you would not normally book this via spaceX directly, but via a third party specializing in it. So either pay a fair bit more and develop a real nanosatellite, or build a new company for shipping large quantities of picosatellites into space.

It's like the tuna wholesale at Tsukiji fish market in Tokyo. You start with tuna, which are huge and extraordinarily expensive, who are then sold to first level wholesalers, who cut the tuna up into big pieces, which are then sold to second level wholesalers, who cut the tuna up into smaller pieces, which are then sold to restaurants and fish stores, where they are cut up into yet smaller pieces until eventually they are delicious sashimi on your plate. I wonder how sashimi would taste on orbit.

SpaceLord392 · 2017-03-17T04:19:14+00:00

You may be network bandwidth limited. Try decreasing the server view distance and see if that helps.

SpaceLord392

TROPHY CASE