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SpaceX's giant Starship Mars rocket nails critical 10th test flight

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Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#281

Post by jjk166 »

ballenf wrote: post #53
stetrain wrote: post #21

Earlier quoted context omitted.

Yes, although it was stated before the flight that they were intentionally flying with some heat tiles removed and with a more aggressive profile to test some outer limits.

They even removed some near fuel tanks. In the past the missing tiles were in less critical areas. I'm surprised they didn't take less risks just to avoid a narrative of failure.

Unless they took extra risks to hedge against the string of failures continuing. "Yes we blew up three times in a row, but this time we meant to do that, so it's a success" sounds an awful lot better than "We did everything we possibly could to prevent it from blowing up this time but it still did"

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#282

Post by GMoromisato »

btilly wrote: post #267
WalterBright wrote: post #257

Earlier quoted context omitted.

> I still think Shuttle could have worked, if it had been cheaper to evolve it. I doubt it. It's a gigantic kludge that isn't fixable. For example, the requirement that it land like an airplane meant it needed wings, landing gear, and a full set of flight control surfaces. None of that is useful apart from the landing, and yet it is necessary to push it all into space and re-enter it. I once emailed Homer Hickam abou…

The shuttle is the only rocket system that put part of the rocket above the payload. Were it not for that fatal design flaw, both fatal flights would have been survivable. The first because the explosion would have done less damage. The second because there would have been nothing above the shuttle from which something could have fallen.

I think @WalterBright is probably right and that the Shuttle design was too compromised to be fixable.

Stacking the orbiter on top of the external tank is a non-starter, IMHO. Obviously you'd have to add engines at the bottom, but now your cost goes up unless you plan on recovering the external tank (and how do you do that?).

And now you need another fuel tank for the orbiter, right? Do you extend the orbiter so it can fit an internal fuel tank? Or do you remove the engines and move them to a separate disposable stage?

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#283

Post by m4rtink »

GMoromisato wrote: post #256
coolspot wrote: post #255

Earlier quoted context omitted.

Common folk assume that the space is super-cold, so it must be good for hot servers.

I don't know about common folk, but I've heard about radiators, which can be as large as you want if you can get mass to orbit cheaply.

Sure, but also much less efficient per unit of mass than regular cooling using the atmosphere or hydrosphere here on Earth.

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#284

Post by jjk166 »

ashishuthama wrote: post #268
patall wrote: post #227

Earlier quoted context omitted.

> SpaceX could start lobbing things in his direction within maybe 30 days? If Earth and Mars are on opposite ends of the sun, nobody is going anywhere within 30 days. I do not see how anything will change from the one transfer window per ~2 years for the foreseeable future

'lobbing things' i.e launching things, OP didnt mean it would reach there in 30 days.

You couldn't start launching things in 30 days, you need to wait for a launch window, which happens every ~2 years. The transit times are on top of that.

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#285

Post by DoesntMatter22 »

ndr wrote: post #61
ballenf wrote: post #53

Earlier quoted context omitted.

They even removed some near fuel tanks. In the past the missing tiles were in less critical areas. I'm surprised they didn't take less risks just to avoid a narrative of failure.

Why would they need to care about narrative at this point? It's privately own, might as well learn as much as possible with each dollar spent.

I'm certain they don't care about the narrative because ultimately even though yesterday was a big success some places had headlines that really downplayed it

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#286

Post by jjk166 »

FireBeyond wrote: post #195
mchusma wrote: post #174

Love it, great job SpaceX! I watched the Martian again the other day and I marveled about how much has changed. With Starship progress, almost none of the plot really makes sense (bespoke vehicles and payloads etc). The first mars expeditions will probably be stocked with a thousand tons of gear, enough to easily last a guy 5 years. And if some dude were stranded on Mars, SpaceX could start lobbing things in his dire…

> The first mars expeditions will probably be stocked with a thousand tons of gear, enough to easily last a guy 5 years. > The Martian is a vision for a 2035 mission from 2011. We seem likely to beat that! What, exactly, is that guy doing for those five years? We don't know how to terraform Mars, and it's questionable what having someone on the surface will add to the knowledge we have of surface composition. And the…

> What, exactly, is that guy doing for those five years?

Waiting to be rescued. We're not talking about sending one guy to mars for funsies, we're talking about one person left after an emergency. In the book he gets off mars by going to the launcher staged for the next mission, which again is a case of prepositioning extra hardware before sending someone to the planet.

If you assume a team of 5 people with an intended stay of 6 months, 5 years of supplies is a factor of safety of 2. If you send enough supplies to keep the whole team alive till the next launch window, that would keep a single person alive for about 2 decades (ignoring potential storage lifetimes).

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#287

Post by GMoromisato »

jjk166 wrote: post #272
GMoromisato wrote: post #243

Earlier quoted context omitted.

I disagree. If Starship fails, the most likely reason will be technological. Either they can never get the heat shield to be reliable, or they can't get cost down below Falcon 9 (meaning, refurbishment costs are too high). And if it fails, who will spend billions on a new vehicle? Stoke Space: They are working on Nova, which is designed for 2nd-stage re-use, and they've got a novel architecture. But they are not well…

> Either they can never get the heat shield to be reliable, or they can't get cost down below Falcon 9 (meaning, refurbishment costs are too high). There are a lot of other potential technological problems (dozens of engines, stainless steel construction, the belly flop maneuver, etc). Ultimately if Starship would were to fail for technical reasons, it would only indicate the particulars of Starship's implementation…

Rocket Lab tried the alternative: low-cost, mass-produced expendable rockets, and Peter Beck famously ate his hat when they pivoted to reusable.

Partial reusability won't get the cost down to the ~$100/kg range. And it definitely won't do that and still loft ~100 tons to orbit.

Falcon 9 can get 15 tons to LEO for $45 million, and that's already the lowest price on the market. To hit $300/kg they would need to build a 2nd-stage, launch, recover (on a drone-ship) and refurbish for $4.5 million. That's just not going to happen.

There are only two companies that are actively building hardware for 2nd-stage reusability: Blue Origin (which doesn't even have a prototype yet) and Stoke (which has a max 3-ton payload). If Starship fails, we are not getting $300/kg orbital costs for 1-2 decades minimum.

I agree that Starship has lots of other potential technological blockers (although fewer each attempt--I never thought tower-catch would work the first time). But no other designs are even close to fulfilling the promise of low-cost orbital launch.

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#288

Post by GMoromisato »

jjk166 wrote: post #276
lordofgibbons wrote: post #193

Earlier quoted context omitted.

> After the Shuttle program ended in failure, work on reusable launch systems stopped for decades Did it really stop for decades? I think SpaceX and Blue Origin were both already working on re-usable launch systems around that time

SpaceX started with the business plan of low cost, mass producible single use launchers. Falcon 9 was not designed with any level of reusability in mind. There was a major redesign to add landing hardware, but the whole reason for Starship being a totally new design was the reusability that a Falcon "super-heavy" derivative could never achieve.

Good point! I don't think Falcon 9 is large enough for full reusability.

I don't think Stoke's first vehicle will be large enough either (beyond proving out the technology). They will eventually need to build a much larger one.

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#289

Post by jjk166 »

thesmart wrote: post #148
Aeolun wrote: post #79

And maybe more interesting. How much did it cost them to get this far vs the sls?

You can't really compare them because SLS was a jobs program intended to spread out contracts across many states by reusing suppliers from shuttle programs. Cheap? No. Wasteful? also no. Most of that money went back into those economies.

The money could have gone into those economies while also securing a productive accomplishment (or more productive accomplishments depending on your opinion of SLS). Factories could have been retooled and workers could have been retrained to produce things of greater value instead of deliberately keeping them obsolete. It's still wasteful even if not completely useless.

Re: SpaceX's giant Starship Mars rocket nails critical 10th test flight

#290

Post by GMoromisato »

m4rtink wrote: post #279
rozab wrote: post #271

Earlier quoted context omitted.

The thing is, there is no demand to get that much stuff into space. Falcon 9 has massively brought down the cost per orbit, and even with the whole world as a captive market, every university in every country putting up cubesats, they still don't have nearly enough payloads to make the economies of scale kick in. Hence Starlink. The majority of SpaceX payload mass has been Starlink, something nobody was even asking f…

Demand takes some time to ramp up, especially with quite expensive and complex stuff like Satellites. SpaceX is now even launching competing constellation comsats (project Kuiper), private manned space missions and there are quite a few manned space station projects under development that would be basically unthinkable without the cheaper lift Falcon 9 provides. As for "How much Starlink could we possibly need?" I th…

Agreed!

Even at $300/kg to LEO there are a ton of new applications that suddenly make sense. If we get to $10/kg we will literally colonize the solar system.

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