totm nov 2023 SpaceX Discussion Thread

[Deddly]

Yes, it works both ways. 

[NFUN]

so you're calling us out for making this a fanclub by being annoyed at a comment even you don't think is productive 

 

meanwhile mikegarrison is very skeptical and good discussions are had with him

[JoeSchmuckatelli]

Deep breath time. 

 

One 

Two

Three

... 

[tater]

1 hour ago, JoeSchmuckatelli said:

Yeah, it does not matter now - as we are desperate to develop capacity to get off the planet - but someday we will want to bring stuff back, and I want to know how effective SS would be as a descent vehicle. 

Gotcha. What needs to be brought back that has substantial mass, though? I want to say that Musk said during one of those talks that SS could return with the crew compartment plus ~20t of cargo. Presumably including the crew

If you wanted to bring back 100t of cargo, say rare Earths from an asteroid—bring up some TPS and chutes, encapsulate cargo, deorbit it.

 

[JoeSchmuckatelli]

4 minutes ago, tater said:

Gotcha. What needs to be brought back that has substantial mass, though? I want to say that Musk said during one of those talks that SS could return with the crew compartment plus ~20t of cargo. Presumably including the crew

If you wanted to bring back 100t of cargo, say rare Earths from an asteroid—bring up some TPS and chutes, encapsulate cargo, deorbit it.

 

Well - you appear to have missed my question* (that started all this speculation) - but then inferred it and answered as well! 

... 

 

 

*

How much can SS bring back with it and still land?
 

    (presuming they figure out how to take it up and back down successfully).
 

     
 

    We often talk about the payload to LEO or beyond... but that's usually a limit based on lift capability.  I've not seen here much discussion about descent capacity.
 

    i.e. lets say EM and SX succeed beyond all rational hope and within 10 years we have a hundred SS's flying regularly and costs are waaaaay down.  Intrepid AsMining GmbH Ltd Partners and Associates Incorporated LLC decides to buy their own SS and configures it for asteroid mining and retrieval.  They find a likely candidate asteroid, shred it and centrifuge out the good stuff... how much goodstuff could they reasonably bring back in a single load?
 

 

 

Added - linking with my phone makes the site look weird (should have been just a link not a reprint and link

[tater]

I'm personally fine with any comments. There are repeated comments on both sides of all the various vehicle/company/program debates that are dead horses, or unproductive... meh, so what. It's something to talk about.

The SS will never leave Earth SOI comment is pretty much requires SS to fail to ever reach LEO, fail reuse, then fail propellant transfer for it to be an accurate prediction. All are possible. I think reaching orbit is certain at this point (might take iteration). Reuse is a long pole, highest chance of failure. I think refilling needs to happen for humanity to ever do anything at all interesting in space, it's not easy, but I think the probability of figuring it out is high.

Reuse is the tough one. We'll see soon enough.

 

3 minutes ago, JoeSchmuckatelli said:

How much can SS bring back with it and still land?

Yeah, certainly a valid question, but I think that along with P2P cargo, it's out there in the future, it's not really a current use case. They're designing this to take cargo to Mars, not Earth. Return relatively empty. At hte point where the up mass justifies down mass, they could make a variant designed for that use case, right? The SS form factor might not be ideal, or maybe it can be altered, I dunno.

[Deddly]

1 hour ago, NFUN said:

so you're calling us out for making this a fanclub by being annoyed at a comment even you don't think is productive 

I did not call anyone out, and I did not point at any specific comment. If you think I am annoyed at anyone, you are mistaken. This isn't the place to discuss that though, but feel free to take it up in a PM with me if there's anything you want clarified or if you disagree.

[betweenthelines1]

   i.e. lets say EM and SX succeed beyond all rational hope and within 10 years we have a hundred SS's flying regularly and costs are waaaaay down.  Intrepid AsMining GmbH Ltd Partners and Associates Incorporated LLC decides to buy their own SS and configures it for asteroid mining and retrieval.  They find a likely candidate asteroid, shred it and centrifuge out the good stuff... how much goodstuff could they reasonably bring back in a single load?
 

 

IntrepidAsMining Gmbh probably won't use a SS to return mined asteroid materials.   The volume you need to make this economical is huge.  common materials like iron will be formed into a return craft that will reenter, and then hauled off to the smelter/refinery to complete processing.  SS would be used for personnel and more valuable items 

[Beccab]

news on the spacex crane from our spacex reddit insider:
"Tracks, cab, engines and bearing frame have arrived.

Boom sections, lift drives and cabling not sure."

Meanwhile, the LR11350 has been lowered for either changes or dismounting

Edited September 30, 2021 by Beccab

[cubinator]

1 hour ago, tater said:

Yeah, certainly a valid question, but I think that along with P2P cargo, it's out there in the future, it's not really a current use case. They're designing this to take cargo to Mars, not Earth. Return relatively empty. At hte point where the up mass justifies down mass, they could make a variant designed for that use case, right? The SS form factor might not be ideal, or maybe it can be altered, I dunno.

The thing is, though, it's supposed to land on Mars basically the same way it lands on Earth, with all the "up" cargo going "down" at Mars anyway. So I think they want to have the capability to land at least as much as is needed to sustain a crew there.

[tater]

10 minutes ago, cubinator said:

The thing is, though, it's supposed to land on Mars basically the same way it lands on Earth, with all the "up" cargo going "down" at Mars anyway. So I think they want to have the capability to land at least as much as is needed to sustain a crew there.

True, though the aerodynamics are substantially different. Not sure if they still have room for large cargo pods under the skirt.

 

[Beccab]

3 minutes ago, tater said:

Not sure if they still have room for large cargo pods under the skirt.

They either will be used for landing legs or be available

[magnemoe]

1 hour ago, tater said:

Gotcha. What needs to be brought back that has substantial mass, though? I want to say that Musk said during one of those talks that SS could return with the crew compartment plus ~20t of cargo. Presumably including the crew

If you wanted to bring back 100t of cargo, say rare Earths from an asteroid—bring up some TPS and chutes, encapsulate cargo, deorbit it.

Or take 1000 ton cover it it regolit or other cheap stuff say 3d printed steel around rocks, have it impact some dessert or shallow lake, dig it out. 
Here you probably want to do multiple drops and probably use some braking system but the point is that the payload land in an way you can easy pick it up. 

But this will be an very different time, go back 30 years and predict the impact of internet? Well I could download manuals for pc motherboards who made upgrading orders of magnitude easier in 1990, 
Predicted phones would replace all other music systems back then, but did not thought of the camera, 
I had an Nokia  Nokia Communicator  25 years ago, it was an smart phone with apps but still did not imagine how important smart phones would become. 
 

[RealKerbal3x]

Launch in early 2022 is looking more and more likely.

[JoeSchmuckatelli]

3 hours ago, tater said:

The SS form factor might not be ideal, or maybe it can be altered, I dunno

I actually like your suggestion about a dedicated cargo dump module.  Probably easier to develop that than add a whole new capacity to SS

[tater]

12 minutes ago, JoeSchmuckatelli said:

I actually like your suggestion about a dedicated cargo dump module.  Probably easier to develop that than add a whole new capacity to SS

First there would need to be a compelling reason for it I think. We can all argue about what SS can return to Earth, but it's not like SpaceX hasn't done all sorts of simulations of exactly that. We'll find out soon enough. If they get it working, and down mass has commercial value, I would expect to see it eventually on the Starship User Guide (P2P cargo is mentioned, but no mass). Dragon has a listed 3000kg return payload mass on their page.

 

[mikegarrison]

7 minutes ago, tater said:

We can all argue about what SS can return to Earth, but it's not like SpaceX hasn't done all sorts of simulations of exactly that.

I am sometimes amused by the almost touching faith that people have in "rocket scientists".

I am not at all assuming that SpaceX has "done all sorts of simulations of exactly that". That's really the whole point of "move fast and break things" -- to not spend time simulating everything in great detail when you could actually just build and test it.

[tater]

5 hours ago, mikegarrison said:

I am sometimes amused by the almost touching faith that people have in "rocket scientists".

I am not at all assuming that SpaceX has "done all sorts of simulations of exactly that". That's really the whole point of "move fast and break things" -- to not spend time simulating everything in great detail when you could actually just build and test it.

Except they do simulate everything, they don't just slap a rocket together then try it, they slap it together in the computer, if it looks like it's worth finding out how good the model is in the real world, then they fly to validate it. This isn't fanboy talk, there have been presentations at conferences (not by Elon) where the engineers show off their CFD code, for example. There was that interview with the NASA guy who worked on COTS with them, he mentioned it as well I think (EDIT: probably not). It's not just that they are willing to try/break things. I mean, why would anyone trying to cut costs not first use lower cost simulation, then bend metal?

I have "faith" in exactly nothing. It simply makes sense. Center of pressure, mass, and thrust are all rockets 101 stuff they have to have down pretty well to be able to land. The sensitivity of the vehicle to payload mass and location has to be understood by them at some level. For all we know the only return mass to start will be the vehicle (plus landing props). Since they plan on a crew version (I'm not willing to be the ballast mass on that one until it's flown many thousands of times with zero failures) there must be some mass above the tanks that can land in their sims, because people/ECLSS/etc have nonzero mass.

Spoiler

The above I had bookmarked.

Didn't have time to watch the Dan Rasky again, but a quick skim to the bullet point slides shows no discussion of simulation, I was probably misremembering that. He was a TPS guy for Dragon COTS, so his examples seem to be about rapid prototyping at various scales—build small models, test and test again, build a full size, then test that, etc. Loads of testing—but not flight testing, lab testing. But crazy fast.

 

 

EDIt2: Yeah, just got to actually rewatch that (still skimming) he doesn't mention computer models, but loads of real life testing of things before building the actual vehicle. Still, it's pretty clear they are not just eyeballing stuff—as we have seen with parts delivered for the various SS iterations. Some very early looked rough, but every quickly the plumbing in particular looked very designed as it showed up on site.

Edited October 1, 2021 by tater

[zolotiyeruki]

As others have said, you don't need Starship as the re-entry vehicle for bulk materials.  Could you launch Starship with a bunch of inflatable re-entry vehicles?  I.e. a heatshield, parachutes, deorbit rocket motor, and inflatable enclosure to keep stuff from falling out?  Stack 'em 100 deep in starship, and you can deorbit a whole lotta stuff for cheapish.

[Minmus Taster]

3 hours ago, RealKerbal3x said:

Launch in early 2022 is looking more and more likely.

Hmm... I wonder who who did that XD

[JoeSchmuckatelli]

7 hours ago, RealKerbal3x said:

Launch in early 2022 is looking more and more likely.

Nothing like a little bureaucracy to slow down innovation.  (That said - I have a feeling / hope that the FAA's review will end up positive and we're only seeing a temporary delay.)

On the other hand; Bezos and others have both the money and the clout to really slow things down if they want to - so time will tell.

[CatastrophicFailure]

5 hours ago, mikegarrison said:

I am sometimes amused by the almost touching faith that people have in "rocket scientists".

I am not at all assuming that SpaceX has "done all sorts of simulations of exactly that". That's really the whole point of "move fast and break things" -- to not spend time simulating everything in great detail when you could actually just build and test it.

I still remember how floored I was by SN8's flight. The descent, using a control method never before used, especially at that scale, was absolutely rock solid. No oscillating, no wobbling, it was under complete control the entire way up and down, to the point of engine ignition. That kind of control can only come from extensive and exhaustive simulation. The ultimate failure was a hardware issue, of the sort of thing that's extremely difficult to properly simulate and only rears its head in actual testing. 

[GuessingEveryDay]

9 hours ago, JoeSchmuckatelli said:

On the other hand; Bezos...has the money and the clout to really slow things down if they want to - so time will tell.

To be honest, it feels more like Bob Smith is influencing Jeff to do stuff. He's not this evil usually (Looking at his track record), but he is being more aggressive.

[tater]

 

Thrust simulator removed, Raptors to pad for SN20.

[Beccab]

Coll extract from the last episode of the Inspiration 4 Netflix documentary which came out yesterday