Space

Science
41

I’ve been thinking recently on this topic and the explanation(s) that make the most sense to me are largely what the article addresses: space is really big. Like, really, really, really, big. No, even bigger! And related to that, traveling vast distances in space takes a long-ass time, the speed of light compared to the scale of the universe is surprisingly not quick and so far we can’t feasibly get humans anywhere near that speed and even signals take a long time to get somewhere and dissipate relatively quickly, especially if not narrowly targeted.

So basically, yeah it’s a numbers game and the universe still wins with the biggest numbers of all where it matters - size/distance.

42

Just gotta fold space like they do in Dune. Humans just need some spice.

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43

One of the things that has got me thinking about the enormous scale of the universe is this video. Specifically it is addressing the timeline of the universe, but it gets you thinking about dimensions so far beyond our human experience. I recommend a dark room, comfortable seat, maybe an enjoyable drink in hand and just kick back and absorb this.

https://www.youtube.com/watch?v=uD4izuDMUQA

44

UFO talk. I saw some talk about the “tic tac” a few days ago. As reported, it’s… implausible that it was a physical object.

Math time! I’m taking the numbers from the wiki page of the incident, as reported by Commander Fravor.

the object had now dropped from 28,000 feet to near sea level in less than a second

What can that tell us about how this thing moves?

28,000ft = 8,534m
8,534m/1 second / 343m/s = Mach 24.88

Right off the bat, we’re looking at something that can do ~Mach 25 in atmosphere. But that’s dramatically underselling it - the Space Shuttle would start reentry around that speed. We’re not taking acceleration into account.

Sighting similar objects on radar a few days prior, Officer Day on the Princeton “was startled by their slow speed of 100 knots”. So let’s assume the tic tac didn’t have any vertical velocity to start, and didn’t pancake into the ocean at Mach 25. We’ll see that 100 knots rounds down to nothing.

So our UFO needs to start with 0 velocity, accelerate downward for half a second, instantaneously reverse, and accelerate the same amount in the opposite direction for another half a second, dropping 8,534m in the process.

We can select the appropriate kinematic equation to get acceleration, given we know displacement, initial velocity, and time.

What do we get in the first half second?

Δx = v_initial * t + 1/2 * ​a * t^2
4,267m = 0 * .5 + 1/2 * a * .5^2

Solving for acceleration gives

a = 4,267 * 2 * 4 = 34,136m/s^2

Dividing that by 9.81 gives 3,479 gees. After half a second, it’s traveling 17km/s, Mach 99.

Given what we know about physics, doesn’t seem likely that anything could perform that kind of maneuver, especially in atmosphere.

45

Whoa, SETI@home is stopping.

46

Celebrity deaths thread maybe?

47

It’s not dead it’s just in a coma.

48

Catching up with some reading, and this entire article is just insane. But I mean that in a good way!

As in, within the existing paradigm of aerospace engineering, everything SpaceX and Elon Musk are doing with the starship project is insane.

And also, within the SpaceX paradigm of iterative design and production line thinking, everything in the old-style of rocket production is somehow even more insane.

49

Has anyone ever done it this way? The Russians? I thought space x did their first rocket a more traditional design process, and have been doing smaller iterations since.

That said, if I was right out of college in aerospace I would totally go down to Texas and try to work there. You get to build rockets and blow them up!

50

They haven’t, no. And you’re correct about their design process, too.

Odds are pretty good this is just Elon talking horseshit about manufacturing again. Remember when he said they’d be making 1000 Solar Roofs a week? Or 10K teslas a week? Or that they’d build 500k teslas last year and fell short by about 200K at best estimates?

51

Did you read the article? Of course there is always “Elon Time” and “Elon Numbers” but the overall process is what I’m talking about, not the absolute numbers or how long it will take. There’s no denying that despite Elon’s constant bullshit, the plan for a production line for spaceship parts to get the cost of each one down to a few million dollars each is amazing… and it’s hard to bet against SpaceX actually achieving their goals eventually, even if the goals are constantly being updated.

52

Well, yeah, it is! However, they’re hardly alone on that, or on developing unique processes, at least in the actual manufacturing space. ULA has their parts down to a similar price point, though they’re going for re-usable in the sense of recovering engines rather than the entire stage - their averaged price point per launch is higher because they actually factor in the loans and grants they’re given from the government, but their per-rocket cost is not that much more than the SpaceX reusable cost, about 20-30 million more depending on the payload faring, and lower than the SpaceX expendable cost for an equivalent Falcon Heavy.

Speaking of ULA, I meant to send you this on twitter a week or two ago, but it genuinely slipped my mind -

Destin from Smarter Every day went on a tour of the ULA factory, it was a very interesting watch. Sorry to have forgotten before. Not really related, but the conversation jogged my memory, and I know you like space stuff like this.

Of course! They’ve got shitloads of money and - the top of the C-suite aside - absolute truckloads of talent, I’d be more surprised if they didn’t hit their goals eventually. For just one, they’ve got Tom fucking Muller, the guy is legit one of the foremost rocketry engineers in the world today.

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53

Again, I can’t help but wonder if you’ve read the article. I’m not talking about Falcon 9 cost per launch. I’m talking about a fully reusable rocket, and the cost per rocket that could each be used many many time.

Not 20-30 million per launch. 5 million per entire reusable rocket.

To make it entirely clear how this is different from even how the Falcon 9 is built and priced, I’ll quote at length from the article. If you still want to compared flight costs of Falcon 9 rockets and anything else existing today, go ahead, but you’re going to have to do a lot more to convince me that the plan for Starship is Normal.

…

Let’s just step back for a moment to acknowledge how nuts this is. Starship is only the upper stage for SpaceX’s Super Heavy rocket, but it is arguably the most novel spacecraft ever built. No one has ever built a fully reusable rocket, and the second stage that goes into space is the hardest part. SpaceX remains a long way from making the interior of Starship habitable for humans on a journey to Mars. But even building a fully reusable vehicle that can lift 150 tons into low Earth orbit would be a marvel. That’s more throw capacity than the Apollo Program’s Saturn V rocket had.

And Musk wants to build one of these each week .

Compare that to NASA and its Space Launch System, the big rocket that the space agency has been developing for a decade and for which Boeing only recently completed a single core stage. This core stage is about 15 meters taller than Starship but lacks its complexity. NASA will, in fact, toss each SLS core stage into the ocean after a single use. And Boeing doesn’t have to make the engines, as the rocket uses 40-year-old space shuttle main engines. Despite this, and with nearly $2 billion in annual funding from NASA, Boeing’s stretch goal for building core stages is one to two per year… some time in the mid-2020s.

SpaceX’s stretch goal is to build one to two Starships a week, this year, and to pare back construction costs to as low as $5 million each.

“That’s fucking insane,” I said.

“Yeah, it’s insane,” Musk replied.

“I mean, it really is.”

“Yeah, it’s nuts.”

54

And I’m afraid, due to who they’re interviewing and his notoriously loose grasp on the truth, along with the fact that Mr Berger takes other self-aggrandizing claims from Musk seriously, such as his handing himself the title Chief Engineer because only he could do it, despite having no qualifications, no experience, no education on the topic, and a PR-friendly backstory for the title that’s objectively nonsense - I’m afraid you’re going to have to do more to convince me that this isn’t just someone(In this case, the reporter, I mean, not yourself) buying in bulk when they’re being sold some serious bullshit.

Sure, maybe they’ll do it. Maybe they won’t. I don’t know. But I do know I’m going to remain skeptical until doing-it-or-maybe-not becomes done. (Or didn’t.) I want them to. But I’m still remaining extremely skeptical.

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55

Sure. I get the skepticism. I just wanted to be clear you were being skeptical of the actual claims the article was making, not whatever numbers you came up with on your own.

And to be clear, my entire point is that this entire approach seems insane. And Eric Berger thinks it’s insane. And Musk also seems to think it’s insane. But it seems to be what they are actually aiming for!

56

Published numbers from SpaceX and ULA, but point taken. Though it’s a hell of a compliment, even if unintended, that the assumption is I’m smart enough to figure out even quasi-realistic costings for these things. Not my strength, I’m afraid.

Well, to be perfectly frank, from a manufacturing standpoint, it is insane. Not just insane, absurd. Fantasy-land stuff. You’ve reviewed more realistic fiction. And that’s not even counting the fact that it’s not just Manufacturing, it’s aerospace manufacturing, which has a whole set of requirements beyond regular manufacturing work - for example, you can’t just use regular old industry-grade steel, you’ve gotta use application-specific steel that you - not just someone else, you - have tested for the application.

Like, if you use industry grade stainless that’s up to the mechanical stress, but isn’t rated to strength under cryogenic conditions, pop goes the rocket. That shit takes time, and there’s no shortcuts - or at least, if you want your rocket to land in one piece, rather than a few thousand.

I just don’t see how they can achieve the manufacturing foundation, do the tests, get all their space-going ducks in a row, in remotely the timescale suggested.

57

Seems like they want to skip all the tedious lab testing of pieces and test the whole thing at once - it’s faster!!! and they get to see a lot of rockets blow up and hopefully get enough data from the explosions.

I’ve done some carpentry by just eyeballing it and changing the design as I went. Do they not use specific tooling or jigs? If I wanted to make a bunch of anything, even stools, it would take a long time to set up the process, and any design change would be a giant pain.

58

I meant I didn’t want you to be looking at published numbers about the cost of Falcon Heavy launches, but the stretch-goal numbers about Starship from this article. This article doesn’t mention anything about Falcon Heavy, and it was never what I was talking about.

Compared to this production line plan for Starship iteration, the way the Falcon Heavy was developed might be as old-paradigm as anything by ULA or Boeing (for the SLS).

I did see some headlines about SpaceX switching to a different form of stainless steel but I’m in no way knowledgeable enough to know why or how that would help.

59

The article specifically talks about tooling and jigs.

60

Sorry, read it a weak ago. What I was trying to get at is that they are optimizing how to manufacturer a rocket, but every time they change the design they will have to change their process.