Starship is still not understood • Hacker News Board

Re: Starship is still not understood

#281

Post by giantrobot » Thu, Oct 28, 2021, 7:15 PM UTC

TeMPOraL wrote: post #260

qayxc wrote: post #95

Earlier quoted context omitted.

The author is a physicist, not an engineer and shows in all of his articles. Physicists are trained to check whether a concept passes the constraints of the current theoretical models. If it does, the rest is just an engineering problem - i.e. take the theoretical upper limits of mechanics and material science and extrapolate from there. No concern for the pesky 10% that take up 90% of the development time and make o…

> No concern for the pesky 10% that take up 90% of the development time and make or break a product. You're missing the author's main point and the whole reason Starship is a big deal. With current launch costs, all that equipment has to be designed, reviewed and tested up front to guarantee, as much as humanly possible, that it'll work in space the first time, because there's no money to try again. With launch costs…

> 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 or two. You wave it away and it will dissipate into the five and a half quadrillion metric tons of atmosphere. If some parts fly off they'll fall to the ground pretty quickly. If you drop the drill it will fall to the ground.

If you've got a drill on a spacecraft that burns out popping a circuit breaker or some acrid smoke is a thousand times more dangerous. Just spalling of some parts can send debris flying around the craft to cause short circuits or damage life support equipment. If you let the drill go because it hurt you it doesn't fall to the ground but instead float there being dangerous or bouncing off equipment that won't like a drill bouncing off of it.

Lot's of stuff works fine on Earth, even down in mines or other places, because we've got a relatively thick atmosphere with favorable temperature and gravity. Lubricants don't literally boil off equipment if they're left in the sun for a few minutes. We also don't have to deal with temperature variations of hundreds of degrees between shade and full sunlight.

Sending random crap to space without understanding the environment or failure modes would be extremely foolish.

Re: Starship is still not understood

#282

Post by TeMPOraL » Thu, Oct 28, 2021, 7:18 PM UTC

giantrobot wrote: post #281

TeMPOraL wrote: post #260

Earlier quoted context omitted.

> No concern for the pesky 10% that take up 90% of the development time and make or break a product. You're missing the author's main point and the whole reason Starship is a big deal. With current launch costs, all that equipment has to be designed, reviewed and tested up front to guarantee, as much as humanly possible, that it'll work in space the first time, because there's no money to try again. With launch costs…

> 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.

Re: Starship is still not understood

#283

Post by giantrobot » Thu, Oct 28, 2021, 7:22 PM UTC

TeMPOraL wrote: post #274

giantrobot wrote: post #273

Earlier quoted context omitted.

> If you drop the launch costs by 100x, this means being able to launch 100x JWSTs for the same price As the GP pointed out the launch cost of the JWST is a small fraction of the program's overall cost. Launching a hundred JWSTs would mean building a hundred JWSTs and doing so is not cheap. Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's…

> Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's an expensive process that doesn't really benefit from economies of scale. My point is that all those processes are expensive because the final result has to work the first time, because launches are expensive and infrequent. Drop launch costs enough, you don't need so much reliability, so…

You can't just make space equipment less reliable because launching it is cheaper. Equipment failures will kill people and ruin missions. Things that might work fine on Earth's surface will not work the same way in space. Even seemingly mundane failures can damage important components.

Re: Starship is still not understood

#284

Post by JulianMorrison » Thu, Oct 28, 2021, 7:27 PM UTC

humanwhosits wrote: post #272

ncallaway wrote: post #151

Earlier quoted context omitted.

> But what's new in Starship? The planned recovery mechanism (the aerodynamic fall, with a very late righting maneuver and landing) is still quite new. They've successfully tested it once (which is great!), but the Starship concept really hinges on that being an extremely high reliability maneuver. I would argue that, until SpaceX can demonstrate that landing maneuver is high reliability, that the Starship concept is…

They can take the mass penalty of performing a large re-entry burn to reduce heat-load and land falcon9-style. It would mean _much_ less mass to orbit, but the cost savings of reusing the vehicles would still be there.

Except that one of the Starship's big new things is refuelling in orbit.

Re: Starship is still not understood

#285

Post by cryptonector » Thu, Oct 28, 2021, 7:30 PM UTC

Lambdanaut wrote: post #146

yk wrote: post #88

The entire space reporting has the problem that simultaneously there is an established genre of fanboy fawning about space x, which is kinda unconnected to space x actually starting to disrupt space. Right now, it looks like one could save a few billions if Artemis is not green lit a decade ago. However, private launches were still rare at that time, so in absence of a, likely expensive, time machine that's just not…

> star ship does not have a planned launch to orbit yet Starship has a planned launch to orbit in literally a month pending regulatory approval. * source: https://mobile.twitter.com/elonmusk/status/14515814656454942...

* A month, yes, in Elon time.

It's almost certainly going to be longer based just on past performance (though that performance is nothing short of astounding). They need at minimum to:

  - get the chopstick carriage moving
    and out of the way for launch
  - get the water deluge system in place
  - tank up enough water, LOX, and Methane
  - build more of a blast barrier for the GSE
  - maybe add a flame diverter
  - test-fire BN4 on the launch stand,
    testing all engines or enough that they
    can be certain of the robustness of the
    ignition sequence
  - re-assemble the stack and load it with
    liquid nitrogen to test structural
    integrity under load

etc.

Re: Starship is still not understood

#286

Post by TeMPOraL » Thu, Oct 28, 2021, 7:32 PM UTC

giantrobot wrote: post #283

TeMPOraL wrote: post #274

Earlier quoted context omitted.

> Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's an expensive process that doesn't really benefit from economies of scale. My point is that all those processes are expensive because the final result has to work the first time, because launches are expensive and infrequent. Drop launch costs enough, you don't need so much reliability, so…

You can't just make space equipment less reliable because launching it is cheaper. Equipment failures will kill people and ruin missions. Things that might work fine on Earth's surface will not work the same way in space. Even seemingly mundane failures can damage important components.

Most missions aren't manned. If your equipment is cheap enough, you can just send more and achieve reliability through numbers. If you don't have to optimize for mass so hard, you can achieve reliability through cheaper means - e.g. simplifying heat management by bolting on a larger radiator; simplifying radiation effects mitigation by having multiple CPUs running the same calculations and voting on results, and/or making thicker rad insulation. Etc.

Re: Starship is still not understood

#287

Post by giantrobot » Thu, Oct 28, 2021, 7:36 PM UTC

kitsunesoba wrote: post #270

giantrobot wrote: post #259

Earlier quoted context omitted.

Launch costs are not the end-all be-all of space exploration/exploitation. There are a large number of extremely difficult problems to solve beyond just throwing shit into space. 1. None of the current public Starship designs include payload doors. So none of these are in any way useful as launch vehicles for orbital payloads. Payload doors a huge structural weakness and requires a lot of engineering effort. None of…

> SpaceX is likely going to need to construct hundreds of Starships to maintain anywhere close to the promised cadence of launches. That's always been the plan. Even in the original 2016 presentation featuring the considerably larger Interplanetary Transport System that got scaled down to become what's now known as Starship and Superheavy, the plan was to churn them out en masse to make it possible to make the most o…

Producing a bunch of units is a small part of the system cost. Starships will need to be inspected and refurbished between flights (high personnel cost). Launch sites need infrastructure to support that launch cadence as well. That means clean room storage, fuel production/storage, housing, and adequate roads/rail/ports for surface transport. Launches also have regulatory requirements like clearing of airspace and potential downrange landing areas.

Their own deliveries of fuel and client payloads will be delayed from the airspace and downrange surface exclusion zones.

Once you've got vehicles in space you'll need 24/7 monitoring and management. Even if mission control teams are relatively small the only way you'll be able to safely manage a large number of missions will be with a large number of teams.

The personnel and infrastructure costs will put a cap on the number of Starship launches SpaceX will ever be able to manage. The costs of those will push up the costs beyond Musk's low-ball fantasy promises.

Re: Starship is still not understood

#288

Post by thereisnospork » Thu, Oct 28, 2021, 7:42 PM UTC

soco wrote: post #26

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…

In other words, NASA doesn't want to move fast and break things.

Considering the history of rocket development can be pretty fairly summarized as '[intelligently] breaking things' that seems a counter-productive design philosophy.

Re: Starship is still not understood

#289

Post by vanattab » Thu, Oct 28, 2021, 7:50 PM UTC

TeMPOraL wrote: post #274

giantrobot wrote: post #273

Earlier quoted context omitted.

> If you drop the launch costs by 100x, this means being able to launch 100x JWSTs for the same price As the GP pointed out the launch cost of the JWST is a small fraction of the program's overall cost. Launching a hundred JWSTs would mean building a hundred JWSTs and doing so is not cheap. Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's…

> Even with economies of scale producing various components for the hundred JWSTs those all need to be tested and verified. That's an expensive process that doesn't really benefit from economies of scale. My point is that all those processes are expensive because the final result has to work the first time, because launches are expensive and infrequent. Drop launch costs enough, you don't need so much reliability, so…

Launch costs are not the only (maybe not even the most) important factor for reliability. If your probe takes 9 years to reach it's destination and then fails to deploy it's not the launch costs that are the problem. Or if you want to land an unmanned cargo ship near your lunar or mars base reliability is defiantly a concern. Cheap launch costs are definitely in important step to colonizing the system we are simply pointing out it's one of many things we need before we can usefully launch millions of tons around the universe.

Re: Starship is still not understood

#290

Post by cryptonector » Thu, Oct 28, 2021, 8:02 PM UTC

humanwhosits wrote: post #266

The very second that Starship gets to orbit it'll be politically easy for NASA to make a sudden shift

It's not just a successful (sub-)orbital test. SpaceX needs to demonstrate re-use. That is essential.

The Angry Astronaut had a video about this where he argues that SpaceX should continue testing Starship to demonstrate reusability. But they can't now that they are committed to not using landing legs: first they need to test the chopsticks with a hopper and a load simulator, then they need to test the chopsticks with a booster and a Starship, and only then can they attempt a landing and re-use.