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Starship is still not understood

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Re: Starship is still not understood

#301

Post by rbanffy »

panick21_ wrote: post #113
spacemark wrote: post #51

Earlier quoted context omitted.

As someone who has worked on NASA contracts pretty much my whole career, you're quite right. 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. The author's claim that the potential benefits of Starship are not understood by NASA is cringeworthy naive. Everyone…

> 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 better path.

Also, Congress would be very upset with a bunch of failed launches, but that’s also how iterative development works.

Re: Starship is still not understood

#302

Post by gremloni »

vanattab wrote: post #123
gremloni wrote: post #98

Earlier quoted context omitted.

Based on what, your gut feel? 12 launches per hour does not seem insane at all.

In 2020 there was 114 orbital launches supporting all space missions around the world. That's 0.013 launches per hour. 12 launches per hour to support a single mission does not seem at least a little insane? I love SpaceX and am hopeful for their Mars plans but we are scientists and engineers let's think with our brains and not our hearts.

Think about what you’re saying, does 12 launches per hour sound all that crazy? Maybe having 1000s of planes up in the air at the same time would have sounded similarly crazy to someone on the 50s

Re: Starship is still not understood

#303

Post by nine_k »

marktangotango wrote: post #152
nine_k wrote: post #124

Earlier quoted context omitted.

Transcontinental railroads provided routes between already populated areas, with viable trade between them. Solar system beyond Earth is more like a desert, possibly rich with resources, but nearly no resource is precious enough to be worth carrying by a starship. The incentives for space expansion past LEO and GEO will not be economical.

That doesn't really hold up though. California has a lot desert and was sparsely settled until the gold rush for example. Also, in situ resource utilization is an area where technology and innovation are certain to provide advantage. https://en.wikipedia.org/wiki/In_situ_resource_utilization

California has a nice climate, lots of free air, some freshwater, several easily navigable havens for bulk transport. The barrier of settling there near the shore is pretty low, even if you don't trade much and just self-sustain.

A more proper comparison would be Klondike. Inhospitable, barren Arctic land, rather hard to self-sustain, really easy to die. It was only interesting because of the rich gold deposits.

Compared to that, Moon is like 100x the hardships of Klondike, but without the gold, and a ship back to Earth is so expensive that any cargo costs more than gold by weight. Or, at least, so it is now.

There are no immediate economic incentives to settle on the Moon or Mars or even further away. But there are non-economic incentives, much like those which produced the Mayflower.

Re: Starship is still not understood

#304

Post by nine_k »

wildermuthn wrote: post #257
marktangotango wrote: post #248

Earlier quoted context omitted.

Gobi desert doesn't have 1/3 earth gravity.

What are the economic benefits of low gravity? If so, would the moon be more economically valuable than Mars? I’m genuinely curious about the economics of doing more in space than putting up satellites.

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).

Re: Starship is still not understood

#305

Post by giantrobot »

TeMPOraL wrote: post #282
giantrobot wrote: post #281

Earlier quoted context omitted.

> With launch costs Starship offers even under pessimistic estimates, even non-space companies will be able to afford to just send stuff to space to see what breaks, and then iterate until it works. That "10% work" becomes orders of magnitude cheaper. That is a ridiculous position to take. If you have a drill on Earth that burns out you might pop a circuit breaker and have to deal with some acrid smoke for a second o…

> Sending random crap to space without understanding the environment or failure modes would be extremely foolish. Well, of course I'm exaggerating, but the point is: with low enough costs, you can afford to iterate on designs you previously had to do perfectly up front. Learning from failures becomes cheaper than having to predict every possible failure mode up front.

> Learning from failures becomes cheaper than having to predict every possible failure mode up front.

But this assertion is wrong. There's a minimum price of failure in space. To have just a bare minimum of safety you must understand at least some failure modes of things you're sending into space. That requires testing and qualification. It doesn't matter if our hypothetical drill costs $10 or $100, to even think of launching it in the first place requires thousands of dollars in qualification for the environment. At that point the difference in launch cost is negligible to the point of unimportant.

Safety regulations are written in blood. The Apollo I disaster occurred in part because the behavior of nylon (Velcro and cargo netting)[0] in the crew cabin in a pure oxygen environment was not understood. A material that was perfectly safe in an Earth-like environment had a catastrophic failure mode in a pure oxygen at high pressure like during the "plugs out" test being conducted.

You can't just throw random crap into enclosed environments to tear them out in situ. That's how to write uncomfortable letters to next of kin. Real life isn't Kerbal Space Program. You don't respawn or reload a save game if your ship explodes.

[0] https://www.space.com/14379-apollo1-fire-space-capsule-safet...

Re: Starship is still not understood

#306

Post by ncmncm »

modeless wrote: post #197
JulianMorrison wrote: post #128

Earlier quoted context omitted.

If they were trying something genuinely new - like falling out of orbit and making a propulsive upright landing of a wingless booster - then some skepticism would be justified. But what's new in Starship?

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 attention before and after each use, including squirting in some goo that will boil off on the next flight. Many will need to be replaced, each flight.

So, turn-around time is weeks, minimum. More probably a month or two, or three.

It is conceivable that a future version of Starship will have a heat shield that needs less attention. Maybe a fabric shroud in place of tiles, over most of the hull, will turn out to be practical. If that happens, it might get possible to turn around a re-entered Starship faster. But that will require entirely new development not obviously begun.

I will be happy to be proved wrong.

Despite all of the above, even without quick turnaround or even re-usability, Starship is obviously overwhelmingly superior in every conceivable way to Artemis/Ares. NASA has the unenviable chore of trying to unload that turkey on some commercial contractor to get out from under the obligation to pour ever more treasure down its gaping maw, endlessly. If NASA succeeds in selling it at a penny on the dollar to Marietta, and leaving Marietta to try to find someone, anyone willing to pay for even a single hull, we can all breathe a sigh of relief.

Re: Starship is still not understood

#307

Post by jonathankoren »

dane-pgp wrote: post #269
jonathankoren wrote: post #240

Earlier quoted context omitted.

I think Shotwell keeps Elon away from SpaceX, and that's secret to SpaceX's success compared to Elon's other ventures.

Or maybe SpaceX is more successful because improvements in that industry are easier to achieve and the technology of the competition is relatively primitive. I mean, it's not exactly brain surgery.

> I mean, it’s not exactly brain surgery.

No. It’s rocket science. :)

Re: Starship is still not understood

#308

Post by moralestapia »

Gravityloss wrote: post #80
pjc50 wrote: post #56

Earlier quoted context omitted.

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

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.

Re: Starship is still not understood

#309

Post by ncmncm »

panick21_ wrote: post #117
tehbeard wrote: post #106

Earlier quoted context omitted.

Several problems with that. One, it's Congress' baby.. ain't noone taking it out behind the barn. Second, you need redundancy. If something is proven bad with falcon or starship design... You don't want another situation like we had with the shuttles where your paying for Soyuz seats for years on end while the problem is debugged and mitigated. Iirc, NASA is trying to shift SLS production to the private sector, to tr…

> 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.

Re: Starship is still not understood

#310

Post by atq2119 »

qayxc wrote: post #78
altcognito wrote: post #66

Earlier quoted context omitted.

Blue Origin said it would be 16, Musk has claimed it won't be more than 8. https://wccftech.com/musk-rejects-blue-origins-claim-of-16-s... It ends up being ~100,000 launches over 10 launch windows. Elon has talked about building 1000 starships (presumably you would need less boosters) https://www.tesmanian.com/blogs/tesmanian-blog/1000-starship... Anyway, it's absolutely the case that transferring a million tons of c…

Even 90,000 launches over 10 launch windows is 9,000 launches per window. Launch opportunities are about 30 days max per window (depending on the flight profile) so that'd be 300 launches per day or over 12 launches per hour . I'm not saying this is bonkers, but this is completely ridiculous and it doesn't matter whether it's 90,000 or 180,000 or even "just" 45,000 launches - it's completely impractical. Not to menti…

Genuine question: how important is the launch window when you start thinking about bulk transport to Mars? If you build thousands of starships, how much does it matter if some of them are slower to arrive?

It's not like flying to Mars is impossible outside the launch window. It takes longer and probably needs more fuel, but by how much?

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