Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Starship Prototype Unveiled

space.com

Post reply on HN
Print view View original

311–320 of 342 posts

Re: Starship Prototype Unveiled

#311

Post by DennisP »

ben_w wrote: post #247
DennisP wrote: post #154

Earlier quoted context omitted.

Why not PV on the ground: because wire antenna is a lot cheaper. Why people don't have to trust us: because the technology isn't physically capable of maintaining even that low energy density at the target, without the reference signal from the ground. Why put the PV in space instead of on the ground: because there's 5.4X as much energy available and it's 24/7. There's real engineering behind this design, detailed in…

> Why people don't have to trust us: because the technology isn't physically capable of maintaining even that low energy density at the target, without the reference signal from the ground. From what I see that’s a design choice not a fundamental aspect of reality, but even if it isn’t: what stops a hostile actor creating their own guide signal, either to direct the power towards an vulnerable location, or to directe…

Sure, it's the physical design of the device. But that's a consequence of making something cheap from lots of small identical parts that self-assemble. You could make something that didn't require the reference signal, but it'd cost significantly more. And you could always allow inspections if people are really concerned.

Changing the beam target would require a repointing of the satellite in addition to the new guide signal. If you somehow do that militarily, it's still a pretty weak weapon; it'd slightly increase people's body temperature and they'd have to evacuate unless the guide transmitter could be found quickly. It probably wouldn't be hard since it's sending a signal that can be detected 36,000 miles away.

I'd like to see a real engineering cost estimate of transmitting power from one side of the planet to the other, by wires or any other method. I really doubt it can be done for four cents/kWh. And it would certainly introduce a possibility for hostiles to cause wide-scale power outages.

Re: Starship Prototype Unveiled

#312

Post by simonh »

drchewbacca wrote: post #308
bufferoverflow wrote: post #307

Earlier quoted context omitted.

> Soyouz is cheap. Only in relation to other single-use rockets. SpaceX has been eating russian's (and other countries') space business for years now, simply because they are cheaper.

I find it odd that Russia hasn't fought back and tried to do a reusable program of it's own. Putin talks big talk about wanting to develop high tech industries so why just give up on space? His nuclear cruise missile program is so lame by comparison.

Russia needs an oil price of at least $74/barrel to balance the budget, which means they've been in a lot of economic pain for the last 5 years. Roscosmos was seen as a cash cow, requiring minimal investment to make reliable $ income off their mature launch business. As a result they were starved of investment and are a pale shadow of their former selves.

Building a dynamic, innovative organisation capable of developing a re-usable architecture would be very expensive, and unless they can not just equal but handily beat SpaceX, there's just no money in it. Their current launch systems already meet their military needs, so there's no political support from that quarter either.

Re: Starship Prototype Unveiled

#313

Post by Symmetry »

twic wrote: post #265
iblaine wrote: post #169

Earlier quoted context omitted.

Musk thinks like a software engineer. Create simple, reusable, components that can scale efficiently. I’m taking some liberties in saying this, but the gist remains the same. Musk keeps it simple and focused.

Musk does not design the rockets.

He doesn't do most of the work but he's very involved. Here's an interview Mueller gave that describes some things Elon did with the Merlin engine, search for "face-shutoff."

https://zlsadesign.com/post/tom-mueller-interview-2017-05-02...

Re: Starship Prototype Unveiled

#314

Post by Symmetry »

davidivadavid wrote: post #123
drchewbacca wrote: post #89

I am so amazed by the genius of making it out of steel. It's just so completely counter intuitive but has accelerated their progress so much. If they told you the stats of the material, better strength at cryo tempertures meaning mass reduction, higher melting point meaning minimal heat shielding and great thermal conductivity it would be easy to imagine it was some new super composite. Then your head explodes when t…

How come no one thought of using steel before?

You're only heating your structure that much when you're landing an entire spacecraft. If you just have a capsule going down its usually easier to have an ablative heat shield.

Also, it's a lot easier to foresee the weight of a design than its cost so most space programs use it as a proxy for cost. So generally the space industry would optimize for minimizing weight and not even try to think about how the materials used would affect cost.

Re: Starship Prototype Unveiled

#315

Post by simonh »

wongarsu wrote: post #310
computerex wrote: post #302

Earlier quoted context omitted.

I disagree. Going to LEO vs going to the moon vs going to Mars each pose a unique set of challenges. Manned flights to the moon for instance is many times harder to achieve than putting someone in LEO. U.S, China and Russia have all achieved manned flights to LEO for decades whereas only the U.S was successfully able to put someone on the moon.

>only the U.S was successfully able to put someone on the moon But is that because it's hard to put people on the moon or because only one country tried? (Sure, the USSR tried too, but they stopped trying before succeeding to put a large enough rocket into LEO). There is a very unique challenge in landing on the moon, and most moon landings still fail. But that can be perfected with unmanned landings, and Space X has…

As you say yourself, the USSR did try and failed. The N1 failed in all four launch attempts, including destroying the launch complex. They even orbited two prototypes of their lander design. I think that counts as trying.

Re: Starship Prototype Unveiled

#316

Post by caconym_ »

oska wrote: post #248
caconym_ wrote: post #195

Earlier quoted context omitted.

To me the SLS is like Brexit: obscenely wasteful and short-sighted, seemingly inevitable, but somehow I still don't believe it will ever leave the ground. The Artemis thing is like a joke for real, though. After the last 30 years of bullshit we've seen from the US government's manned space exploration efforts I think I'll be living in a SpaceX-manufactured igloo on Titan before Richard Shelby and his obstructionist,…

Just as a comment: I really hate seeing Brexit dragged into every conversation. We're talking about rockets here, which should be a million miles away from any discussion of Brexit.

The SLS is pure politics. You're welcome to ignore that, if you like, but that decision means you won't have a good understanding of why the rocket "exists", or why it's designed the way it is, or what the prospects are for its future.

Re: Starship Prototype Unveiled

#317

Post by caconym_ »

nickik wrote: post #298
oska wrote: post #248

Earlier quoted context omitted.

Just as a comment: I really hate seeing Brexit dragged into every conversation. We're talking about rockets here, which should be a million miles away from any discussion of Brexit.

Yes. Thank you. Brexit is the ultimate 'this proves my world view' and gets dragged into every conversation.

Please enlighten me: what's the world view I'm trying to prove by invoking Brexit?

Re: Starship Prototype Unveiled

#318

Post by hwillis »

paragraft wrote: post #144
35787 wrote: post #119

Earlier quoted context omitted.

Wow what an incredibly substantive comment. I remember pretty clearly he said that there would be a single seam weld. Maybe I’m remembering wrong. Or maybe they’ll seam weld multiple rolls into a really wide roll and the only weld required to turn the final roll into the shell is that final hotdog weld.

I think the idea's to go like a Pringles can, with a spiraling single seam.

maybe, but that's also pretty unlikely. For reference here's where musk talks about it: https://youtu.be/sOpMrVnjYeY?t=3156

No real indication he means a spiral.

There are a lot of problems with a spiral. Thin sheets of steel, even hot rolled, are very affected by the rolling process. There's also the weld line going up in a spiral. That will cause uneven heat diffusion and expansion, which is a recipe for disaster given that the skin will be cold enough to liquify helium on one side and boiling hot on the other. Then red hot during reentry. Straight lines don't have the same problems.

Re: Starship Prototype Unveiled

#319

Post by garmaine »

cbhl wrote: post #234
semi-extrinsic wrote: post #232

Earlier quoted context omitted.

> But raw performance on a single trip doesn't matter much if you can just deliver the same payload in two trips to orbit instead. Except that you're doubling the cost if you have to do two trips.

If you throw away the rocket, sure, you're doubling the cost if you have to do trips. If the rocket is reusable, then the vehicle cost gets amortized over the total number of trips, and the per-trip cost gets closer to just the cost of fuel (hopefully at least an order of magnitude less than a new vehicle+fuel on each flight).

Fuel and oxidizer is 2-3 orders of magnitude less than the cost of an expendable rocket.

Re: Starship Prototype Unveiled

#320

Post by bushin »

simonh wrote: post #312
drchewbacca wrote: post #308

Earlier quoted context omitted.

I find it odd that Russia hasn't fought back and tried to do a reusable program of it's own. Putin talks big talk about wanting to develop high tech industries so why just give up on space? His nuclear cruise missile program is so lame by comparison.

Russia needs an oil price of at least $74/barrel to balance the budget, which means they've been in a lot of economic pain for the last 5 years. Roscosmos was seen as a cash cow, requiring minimal investment to make reliable $ income off their mature launch business. As a result they were starved of investment and are a pale shadow of their former selves. Building a dynamic, innovative organisation capable of develop…

it's $42/barrel, the difference from the market price goes into their war chest
Post reply on HN