#what problem is this thing solving?

[dead-generations]

Another misconception, which I should roll into a wider "why the moon is harder than mars" essay, is that low gravity makes space travel easier. Low gravity actually makes landing on a body, and traveling to it, more energy intensive and more challenging - especially because lower gravity typically means less dense atmosphere or no atmosphere. Let me explain

High gravity is obviously a challenge for space travel, especially launching from a body with high gravity. I dont think this needs explaining - heavy thing hard go up, more gravity mean more heavy. but theres a bit of a bell curve here. Too low (moon) and it becomes quite challenging. Too high (a 'super earth') and it again becomes quite challenging.

This isn't a nice even curve though, the "ceiling" is relatively low as far as gravity for stellar bodies goes, and the lowest gravity possible is merely challenging while gravity above earth's rapidly becomes "impossible".

Specifically, to get to a stellar body you need to "intercept" it, which basically means getting to it and spending enough energy to be sharing an orbit with it/orbiting it. A low gravity stellar body has a weaker and smaller gravity well, which means you cannot simply rely on being 'captured' by the body when you arrive. You will need to expend energy to get there, and then you will need to expend almost as much energy when you arrive just to be captured by it!

Low gravity generally means its harder to land or orbit, and high gravity means its harder to launch. And high enough gravity also makes landing challenging as well, as the continual force upon the vehicle is high enough that small errors in the final landing sequence can become rapidly catastrophic. A little caveat here is that sufficiently low gravities enable SSTO vehicles, though they may not enter into the realm of "better than a two stage vehicle".

So there's a sweet spot here, clearly, but funnily enough the earth isn't in it. Our gravity is frustratingly high for takeoff and just a bit high for landing. In fact if it was just a bit higher, maybe 10%, a lot of things would become impossible, like reusable rockets. Mars is much closer to that sweet spot!

But the presence and density of atmosphere is another factor for space travel similar to gravity. It mainly effects landing/orbiting, similar to gravity. Atmosphere too dense/high, and lower orbits become problematic as they "drag" on the atmosphere. Worse, when landing/deorbiting, one cannot avoid aerobraking, and more challenging one cannot help but generate a lot of heat via atmospheric friction. Heat which requires fragile/expensive/high-mass shielding which is unproductive mass for 90% of the use of your vehicle. Heat which can blind instruments and communications equipment. And heat which is of course exceptionally good at destroying spacecraft and killing astronauts.

But too low is a more common problem which also makes landing quite challenging. You have less or, worse, (and commonly) no atmosphere on which to aerobrake. which means you are screaming towards the surface at an accelerating rate from whatever energy you spent getting to that stellar body. which means you need to expend energy, specifically fuel, to decelerate, or go splat. which means more propellant. You also cannot use control surfaces for navigation/control, you have to expend propellant for even minor adjustments, which means you need still more more propellant. which is a big no-no for the rocket equation - you will have less useful mass as a portion of your overall mass. which basically means less cool stuff and more boring stuff.

It seems youd have another sweet spot situation, and that perhaps earth has just the right amount of atmosphere. Crucially, however, atmospheric density greatly modifies the effects of high or low gravity, especially low gravity.

If you have no atmosphere or a very low density atmosphere on a very low gravity stellar body, you are looking at huge energy expenditures. You need to travel towards the body and then spend almost exactly as much energy when you arrive just to land on it. Probably in practice even more than you spent getting there because of maneuvering. Which means less useful mass and even more opportunities for errors to become quite severe, and a very real possibility of running out of propellant as you deorbit, meaning you will helplessly and lazily drift down uncontrolled into a splat which, even under lunar gravity, is likely to be sufficiently destructive. Or it just lands sideways which prevents functional operation (see: like three separate moon landing failures in the last couple years)

Energy expenditures in spaceflight are basically the biggest determinator for how difficult a mission is. It constrains your design space, it constrains how long a mission takes, and it constrains how much useful stuff you bring along (people, instrumentation, rovers, etc). Actually, it would be more accurate to say that energy expenditure is difficulty.

Additionally, and without going into too much detail on it, low density or no atmosphere means you also have to worry about kicking up particulates which will stay in the "air" for a very long time, and which are likely to be sharp or abrasive because of a lack of smoothing erosion by wind. This is a bigger issue than you might think.

Conversely, high density atmospheres, for all their faults, mean you can have reentry vehicles which require no propulsion, no active energy expenditure and thus no fuel, to safely deorbit and land. This is exactly what happens all the time. it is how capsules work, let the atmosphere bleed away your energy and use it for any maneuvering and then use parachutes for final descent, and a large body of water to ensure a soft landing. (this is why we call it spashdown). The space shuttle did something similar, except that it accomplished its final approach via controlled glide.

Here's the real trick though: if you have a sufficiently dense atmosphere on a lower gravity stellar body, you actually ameliorate almost all the downsides from the low gravity. You can use aerocapture instead of gravity capture to intercept a body, you can use control surfaces to manuever against the atmosphere, you can de orbit using aerobraking, and you can use aerobraking to perform most of the the work of landing. If the atmospheric density is low enough but not too low, you can even seriously reduce your need for heat shielding (and thus increase your useful mass) by simply making many many orbits while gently aerobraking, slowly bleeding away energy without generating significant heat via friction because the atmosphere just isn't very dense.

Unfortunately these circumstances will necessitate some propulsive landing on final descent. Parachutes are used on earth for that final bit of deceleration, but on a stellar body with lower atmospheric density, like mars, they simply are not fit for purpose. You have to put a lot of engineering into getting them to be just barely kinda good enough and still quite risky. It is better to just do propulsive landing in that sense, and the fuel expenditure will not be too great. You would need an atmosphere comparably dense to earths for a spaceplane like the shuttle to be a viable alternative method of landing.

There is however a problem with propulsive landing, which is that the payload of your lander is going to be significantly high above the surface. the engines and fuel tanks all need to be down the bottom and it has to land butt first, unlike a spaceplane. This is a design challenge, especially for deploying autonomous surface rovers.

You might well have guessed what I am getting at: in many ways mars is optimized for spaceflight. The moon presents significant challenges inherent to it, and the earth is at the upper end of comfortable/tolerable for spaceflight. If we had a much denser atmosphere or might higher gravity or both, spaceflight would be prohibitively challenging. Mars might even make SSTOs practical, though I am skeptical of that. The other thing I am getting at is that going to the moon is extremely challenging, and the thing that really makes it easier in any way over going to mars is that it is closer. Which matters of course, but it is not an inherent difficulty.

The last, petty point I am trying to make is that the space shuttle couldn't go to mars and it definitely super duper could not possibly be used to go to the moon.

[sesamestreep]

it’s wild to me that like every modern adaptation of Sherlock Holmes (and by modern I mean “made recently” not “set in modern times”) is like Hell Bent on coming up with a Reason™️ that Watson stays with Holmes and trots around with him on adventures all the time despite the inconvenience and the danger and all, and so it’s like “oh, Watson’s a gambling addict, he loves uncertainty and mystery” or “oh, Watson’s an adrenaline junkie, he gets off on being constantly in danger from criminals” or even like “Watson’s atoning for sins of the past of BEING IN THE WAR by solving crimes with Holmes now” or WHATEVER. And it’s like, girl, maybe he’s just in love! Did you think of that?? Maybe he’s got a crush and it’s making him do stupid things. Maybe he’s just got bad taste and his type is guys who don’t know how to refold newspapers properly but can identify different types of cigar ash by sight, smell, and taste. And wrote a monograph on the subject. Maybe he’s down bad is all. I mean, Keep is simple, stupid!!!

[pinkfestivalpeanuttree]

this really is the yuri update.

she says something more like, "my name is eternal sugar cookie, the other half of the soul jam of happiness, your other half." in korean

shadowsugar mention

it sounds like eternal sugar's asking hollyberry to elope

eternal sugar cookie? more like. escapism sugar cookie

TOXIC YURI!!

fellas what's gayer: being gay or locking the literal other half of your soul in your precious jewelry box so that they may be "happy" and "safe" in your twisted fucked up escapism paradise prison

[artgletic]

case study of the self-identified god

[brokenphoenix99]

Out of All the Stars in the Sky, I Choose You to Light My Night

For @codex-week Day 3: Inspired by this stunning piece - Alt Prompt #3 - art BY JAMES FENNER

Cody and Rex finally get some downtime after a mission on a distant planet and enjoy the beauty and calmness of a rare Celestial event.

(Tried a painterly style for this one - it was so much fun!)

Also on AO3

Tiny art Tag list: @loverboy-havocboy @chaicilatte @elismor

[chiimeramanticore]

it's cool if I ramble about yes man unprompted right. ofc it is. i wanna talk about his capacity for violence bc I think it's one of the most interesting parts of his character

yes man is nice. obviously he's nice. but yes man is not a kind character. he helps you, sure, but that's mostly just because he likes you specifically (and even that's debatable depending on how you play). i feel like this is exemplified w his pre-combat lines– "a pulled trigger's a happy trigger!" and "woo! bang bang!" like, he's clearly having fun! he takes glee in killing people, but not because he's sadistic, but because he just doesn't realize the weight of taking a life- or if he does, it just doesn't matter to him.

he was programmed without a sense of morality or an understanding of mortality. to him, violence is second nature. to him, violence is no different from play. he's like a guard dog– he doesn't care who he's shooting or why, he's just excited to do the thing he's good at.

and on one hand, he is a fantastic guard dog. but on the other hand, six must watch how... efficiently he kills, and wonder if they'll ever wind up on the receiving end of it. he wouldn't do it as long as he likes six, of course, but... if yes man was given good enough reason to believe six deserved to die, would he even hesitate? would their history and relationship mean anything to him? or would six just be another target, forgotten about as quickly as a radroach you stepped on?

six can only hope they never need to find out.

[tea-cat-arts]

I simply think this fandom doesn't give Wei Wuxian enough credit for the various ways in which he saved Lan Wangji

[lesiasmadness]

Woops, hand slipped and I turned your mystery game into a teen drama

[themoderatespeaks]

"Israel's actions in Gaza are genocide and need to stop immediately."

"Hamas started this war. Return the damn hostages immediately."

....

Why is it so hard to say those two things at once?

[frobby]

i think a core component of the okumura twins relationship is that if you told them before the series what happens in the future, they would worry about each other before themselves

[nenoname]

honestly??? i still dont know what to do with the idea that there might be a bunch of clone fords out there???? it honestly makes me so unhinged??????

[clinicshamartia]

Why are they spending all this time, energy and money into making a new social media app when they can just bring back MySpace

[fisheito]

Whenever i colour skintones:

Morv and Dante: hello Kings you're lookin vivacious as usual. Have you been spending time in the sun lately, or more indoors? Well, we can adjust for that! Here's a range of colours that will make you distinctly You no matter what i choose. Love that!!

Everyone else: WHICH SHADE OF PALE ARE YOU

[castleclerics]

hot take the biggest reason that byler doubt still exists in this day and age is because people are viewing everything through a lens of mike being bi and not gay and doubting that they've written mike as fully gay directly contributes to them thinking byler may not be a possibility. (bc they think the writers are not capable of going all the way with anything in this show when it is literally the opposite, like why do u think he has to be bi or has to have been in love with el at one point??) but if i made a really long post explaining why and that mike's specific sexuality is actually extremely important for the context of his character ppl would get mad at me lol

[coquelicoq]

adsfkj i have dusted off the cql folder on my computer for the first time since 2021 and i just found a bunch of fic snippets so short i can't even tell what they were supposed to be about. except this one in which i apparently had the lan sect invent hash functions, all so that there could be a dramatic reveal that jiang cheng had never removed wei wuxian from the yunmeng jiang sect records??

Wei Wuxian sighed and slumped back on his heels. It wasn't that he was incapable of being patient, he just didn't want to. Here was an array that could tell a sect if a prospective initiate was currently on another sect's rolls, without actually giving any sect access to the records of another sect. How was it doing that? The applications for this technology were potentially enormous. Wei Wuxian couldn't wait to get his grubby little hands all over the design.

there's also a more extended passage from a different "wei wuxian finds out he's still a member of ymj" concept (feat. jin ling!) which includes the paragraph

"He can't join the Lan sect!" Jin Ling was exclaiming. "He's already in a sect, technically, and you can only be on the official roster for one sect at a time. I should know, my elders have only been hounding me about it since before I could even say the words 'conflict of interest.'"

but the rest of them are just single sentence one-offs like

'Hey‚' Wei Wuxian protests weakly. 'It’s not my fault. I’ve been dead for quite some time.'

and

After customer service‚ there isn’t much an unearthly shriek can do to phase a person.

and then there's this sentence fragment:

The leader of the Jiang Sect‚ who looks like a Sect Leader‚ is dressed like a Sect Leader‚ and‚ most importantly‚ is not stuck in a hole like an idiot‚ therefore behaving with the dignity of a Sect Leader‚

dying to know where i was going with this. and who was the narrator? whoever it is, they are definitely comparing someone unfavorably to jiang cheng. some idiot has fallen in a hole and jiang cheng comes along and the narrator is like now that's what i'm talking about. maybe the narrator is the idiot in question? maybe wei wuxian is the idiot. but then i don't know why i would have been leaning on the sect leader thing since wei wuxian is not a sect leader. 2021 was a long time ago apparently because i have no memory of this.

[asexualbookbird]

Okay, so, I didn't read a whole lot this month. Hear me out. I'm not mad about it. I got SO much crafting done across different mediums. Nothing to show for it, really, but I'm having so much fun being creative in a way I haven't felt in a very long time. I think I might actually be able to set up some type of tiny shop about it, too. Got my embroidery machine up and running in a way that allows me to create my own designs, and when I tell you the creative juices are flowing, boy howdy it's like a dam has broken. I also started pokemon Violet, and while that's slow going, I'm having a lot of fun with it. So, no I'm not mad at my reading habits this month.

In the Ravenous Dark by AM Strickland ⭐️⭐️⭐️ - Phew. Okay. This was. A very bumpy ride. The first half was a slog, honestly, and the writing and pacing is not great, but the last third or so reminded me a lot of Beyond the Ruby Veil which was also not outstanding, but it was fun. Fucked up, feral lesbians. Poly family friendship going on. The plot is so basic, the magic neat, the worldbuilding lacking. I would not read it again, but at the end I'm not entirely mad I did.

Dark Matter by Blake Crouch ⭐️ - I don't even know what to say. I didn't expect to be wowed, I went in expecting no more than a mediocre thriller. What I got was A Book Written By A Man™️. How many times can a guy fridge one wife? Infinitely, apparently! I was semi on board until he started fighting his other selves. That was dumb as shit.

The Art of Prophecy by Wesley Chu ⭐⭐⭐⭐ - *Gordon Ramsay voice* Finally, a good fucking book. This took me most of the month to read, but I'm not mad about it. It was nice to sit quietly with this book, and while it took it's time, I never felt bored with it. I can't really pinpoint what keeps it from five stars, and maybe my rating will change in the future, but I did really enjoy this. It has a wonderful cast, everyone felt very real and well rounded, it was bloody, but never felt gratuitously so. It was a good book and I very much want to continue the series.

Favorite of the month was most definitely Art of the Prophecy. Kind of unfair because Dark Matter was such a disaster, but Ravenous Dark had it's perks. Mainly being batshit crazy and ending in polyamory.

My friends, as always, have been incredibly kind to me. I could not have gotten through the last couple months without them. Would like to do a couple of buddy reads in the coming months. I really did like taking my time with a longer book, and I think I'm ready to tackle the final book in the Rook and Rose trilogy. My library also finally got a copy of The Bone Maker on audio and while I haven't listened to an audiobook since December, I'm excited to give that a listen. As always, be kind whenever possible.