Starship is still not understood • Hacker News Board

Re: Starship is still not understood

#321

Post by panick21_ » Fri, Oct 29, 2021, 7:43 AM UTC

zardo wrote: post #271

panick21_ wrote: post #133

Earlier quoted context omitted.

The current estimate is 2M or maybe 10M. If the first stage is reusable, having a cargo launcher second stage that is none, reusable can be done for 30M. First stage reuse is wall proven already. > Starship will be unable to leave Earth's gravity well. If its not reusable you can use it like any upper stage and it could launch anything anywhere you want. > And if they can't refuel in orbit (which as of now, has only…

> I really think this is overrated in how much of a technology risk this is. Specially if you have enough weight that you can invest in the solution. Refueling is a schedule risk, maybe the first design will fail to account for something and it will take a couple iterations to get it right. There is zero risk that the problem is unsolvable.

I would agree mostly. If you need to many iterations you might run out of money however.

In general I think refueling is a far smaller problem then the heat shield.

Re: Starship is still not understood

#322

Post by panick21_ » Fri, Oct 29, 2021, 7:44 AM UTC

ncmncm wrote: post #309

panick21_ wrote: post #117

Earlier quoted context omitted.

> Second, you need redundancy. No you don't. Just as there was no redundancy for Saturn V. As there is not for Falcon Heavy. There was no redundancy for Delta 4 Heavy. There is always a largest rocket. And if you do need redundancy, SLS is not how you would get there. If Starship doesn't work, then there will simply be no moon landing. Period. > Iirc, NASA is trying to shift SLS production to the private sector, to t…

Once it becomes Somebody Else's Problem, and not NASA's, then NASA can quietly abandon it. Since nobody else will want to pay for even a single launch, it may then die a final death.

> Once it becomes Somebody Else's Problem, and not NASA's, then NASA can quietly abandon it

No, what happens is that you create a seriously powerful group of private institutions that will go full force into lobbying congress to not kill the project. Even more so then now.

Re: Starship is still not understood

#323

Post by modeless » Fri, Oct 29, 2021, 7:50 AM UTC

ncmncm wrote: post #306

modeless wrote: post #197

Earlier quoted context omitted.

Nitpick: the booster does not achieve orbit. If it did it would need a heat shield like the upper stage. What's new in Starship? Rapid turnaround. Catching the returning rocket with the launch tower. A durable heat shield that needs zero refurbishment for back-to-back flights. The sheer number of engines on the first stage and the volume of engine production needed for that. Orbital refueling. The landing flip maneuv…

Rapid turnaround is not demonstrated. Nor is it even, in fact, planned , in any real sense. I.e., to be clear, there is no evidence that they have any idea how to achieve rapid turnaround of a Starship orbiter. (Superheavy is a different story.) All this turns on the design of the heat-shield tiles. Those we have seen are basically the same as on the shuttle. Each individual tile needs a great deal of personal attent…

I don't think that the heat shield is the same as the shuttle's. The tiles are tougher and attached in a different way, and the underlying steel structure can stand more heat than the shuttle's aluminum could.

Orbital refueling is required for HLS and depends on rapid turnaround so SpaceX and NASA must have some confidence that it can be achieved without a radical redesign.

Re: Starship is still not understood

#324

Post by panick21_ » Fri, Oct 29, 2021, 7:53 AM UTC

coldtea wrote: post #96

panick21_ wrote: post #68

Earlier quoted context omitted.

> and prints billions of money to fund the likes of Musk, Bezos, and so on That's not how monetary policy works but ok ... > also runs the other investments and public policy decisions So you don't like some things the government does and therefore anything the government does is bad and we can have no argument about what spending is good and what is bad?

> That's not how monetary policy works but ok ... Modern QE, for example, is not traditional monetary policy anyway, but ok. Nor is playing with such a huge percentage of the GDP, or facilitating lending to the already rich, to use to stock their fireplaces, VC bets, and in general, getting richer on a cheap supply of money... > So you don't like some things the government does and therefore anything the government d…

> Modern QE, for example, is not traditional monetary policy anyway, but ok.

Nonsense, QE was done already 100 years ago and more.

> Nor is playing with such a huge percentage of the GDP

Not that new in history of money and bad measure anyway.

Your understanding of monetary policy is fundamentally flawed. Your idea that if the central bank just collapsed nominal spenidng to 'destroy' the 'bubble' is about the worst possible thing you could do. That is literally how we totally unnecessary had the Great Depression. Congratulation 'Bubble Burst'.

But I guess you have bought into some of the leftists conspiracy and nonsense propaganda about central banks so there is like not much to talk you out of it.

> phallic rockets.

Ask yourself who is actually obsessed with thinking about phallics.

Re: Starship is still not understood

#325

Post by yetihehe » Fri, Oct 29, 2021, 7:56 AM UTC

jonathankoren wrote: post #311

nine_k wrote: post #304

Earlier quoted context omitted.

1/6th of Earth gravity is even better. Short term: a wonderful tourist attraction. You can nearly fly. Long term: people with muscular / bone disabilities who cannot withstand Earth gravity. An interesting retiring home (for a narrow wealthy set, of course).

Who is going to pay to fly these sickly retirees to the moon, and then continuous supply them with resources that are literally free on Earth (ie air)? Medicare?

Moreover, if they struggle with earth gravity, how will they survive launch and landing?

Re: Starship is still not understood

#326

Post by elurg » Fri, Oct 29, 2021, 8:02 AM UTC

giantrobot wrote: post #247

ncallaway wrote: post #8

I’m kinda confused by the criticism of the industry and NASA not designing for Starship. The author argues that NASA doesn’t understand Tempe game changer that Starship is, but I don’t think that’s accurate. I think the risk to NASA of assuming the benefits of Starship before it’s proven are just too high. If NASA (or other industry players), assume Starship will deliver the benefits it promises, they to fundamentall…

The author trots out the "$10,000 a pound" launch cost which is really indicative of the overall quality of the article. For non-Space Wonks, the "$10,000/lb" to orbit number was the rough cost of launching some payload on the Space Shuttle to orbit. Costs for the Space Shuttle were basically NASA's entire manned spaceflight budget divided by the number of Shuttle launches performed in a year. It's not just a naive n…

The author mentions $10000/kg, not per pound. This number is reasonably accurate for recent launch within one order of magnitude.

Starlink launches were claimed to cost $35 million for 16 tons, this means SpaceX is still around $2000/kg even internally. This is the lowest cost of "real" missions with payload adapters and deployment mechanisms.

Atlas 551 is ~150M for max 18.8tons to orbit so best theoretical price is > $8000/kg.

Dividing the space shuttle program cost of $196B by 133 successful launches and a max payload of 23tons you get around $64000/kg.

Re: Starship is still not understood

#327

Post by pjc50 » Fri, Oct 29, 2021, 8:43 AM UTC

NikolaeVarius wrote: post #75

pjc50 wrote: post #56

Earlier quoted context omitted.

Would anyone like to estimate the CO2 emissions produced by that?

This hand wringing about CO2 Emissions by rockets is the weirdest ongoing trend I've seen. If you want to complain about environmental issues, at least complain about something interesting like how sound at the launch pad disrupts the breeding patterns of an animal or something. At least that can cause interesting discussion other than , BUT CO2 and WARMING.

It doesn't matter whether it's interesting or not, it only matters whether it's happening and who and what it's affecting.

Re: Starship is still not understood

#328

Post by elcritch » Fri, Oct 29, 2021, 9:00 AM UTC

TeMPOraL wrote: post #218

ncallaway wrote: post #141

Earlier quoted context omitted.

> I think the author is arguing for NASA to take a cautiously optimist stance on Starship, instead of assuming it won't work at all until it does. NASA has taken a cautiously optimistic stance on Starship. The assignment of the HLS to Starship and no other provider was an aggressively optimistic stance from NASA that surprised many of the space industry observers at the time of its announcement. The expectation (and…

The only way I can reconcile this is political constraints - perhaps they can't feasibly do what the GP proposes, but they could assign HLS to Starship and have some idea on how to capitalize from it "unexpectedly" exceeding expectations. But then, I know nothing about how NASA operates internally.

It seems much of the politics are external and come from congress pushing their various pork barrel projects.

Re: Starship is still not understood

#329

Post by Gravityloss » Fri, Oct 29, 2021, 9:16 AM UTC

moralestapia wrote: post #308

Gravityloss wrote: post #80

Earlier quoted context omitted.

100 tons of payload. Rockets are typically about 2% payload so 5000 tons fully fuelled. Fuel and oxidizer combine to H2O, OH, CO and CO2. So, not all the exhaust product is CO2. But some of the CO released is combined with atmospheric oxygen to CO2, so that increases the mass of CO2 besides direct propellant mass. We could as first guess say that it's about 5000 tons of CO2 per launch. So 1000 launches would be 5 mil…

Except it's not 10,000 launches, it's 170,000 (see other comments here). So that's 850M tons, about a 10% increase (on top of the 2nd most polluting country in the world), so yeah, not happening. I would personally rally against the govt. (and everything that allowed that to happen) if Elon gets a free pass on that.

Ok, I'm not that familiar with the plans with starship.

I think the premise of the article is wrong anyway.

I think no matter what the system is like, it still makes sense to optimize for mass in a reasonable way. That means, not sending dead weight to high delta vee. Leave big tanks or engines behind.

It's a bit like you don't transport your car with the airplane. It would be madness.

Exponentials are unintuitive. The total mass of all fuel in all stages is directly proportional to the mass that needs to be sent to the highest delta vee. So for example (to take a few shortcuts) if your moon ascent stage is 1% heavier, everything has to be 1% heavier, including the first stage of the launcher. So 1 kg in the ascent stage might not look like much but it grows the first stage at something like 1000 kg.

That's why I'm really skeptical of the architecture of landing atmospheric stages to the surface. They are just unnecessarily heavy. You have maybe quadrupled your total launch amount from the surface (haven't done an analysis).

Early Apollo planning had direct landing because docking in orbit had not been demonstrated. Gemini validated that. Orbital docking works fine and Apollo could continue with muchh more efficient architectures. Actually, docking has gotten a lot better, we did have Apollo, yes, and we have robotic tugs routinely flying to ISS.

Engines haven't made significant progress since the sixties, not enough to warrant really big architectural changes towards less mass efficiency.

If anything, the improved docking and automation that has already been demonstrated would swing the architectural plans for moon or Mars to have even more docking, berthing, refueling and staging!

Direct landing might only make sense with something like nuclear propulsion...

Re: Starship is still not understood

#330

Post by vimacs2 » Fri, Oct 29, 2021, 9:20 AM UTC

rbanffy wrote: post #301

panick21_ wrote: post #113

Earlier quoted context omitted.

> The author's claim that the potential benefits of Starship are not understood by NASA is cringeworthy naive. > Makes me wonder how old the author is. The author works for JPL. > Starship is still extremely unproven. If you look at the history of rockets, mayyyybe 1 in 5 that make it to an orbital launch debut (which is like 1 in 50 paper rockets) in turn make it to commercial rollout. How many of these had 10+ prot…

> Ares, SLS are basically just warmed up shuttle concepts Not really. They were started before SpaceX proved the idea of reusable boosters. They are a safe Plan-B, using engines and concepts that were already available. It’s a shame they decided to improve upon the existing hardware and took much longer than initially expected, but that’s what life with rockets used to be before SpaceX showed rapid iteration is a bet…

> It’s a shame they decided to improve upon the existing hardware and took much longer than initially expected, but that’s what life with rockets used to be before SpaceX showed rapid iteration is a better path.

Uhm, I think you're simultaneously doing a discredit to past rocket development and giving an easy pass to the mess that is SLS with this statement.

It's just shoddy project management and prioritizing collaboration with as many big donar aerospace companies as possible as opposed to what works. There is playing it safe and then there is just being complacent. The SLS is complacency personified.