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

Starship Update [video]

youtube.com

Post reply on HN
Print view View original

321–330 of 348 posts

Re: Starship Update [video]

#321

Post by sangnoir »

fastball wrote: post #306
sangnoir wrote: post #208

Earlier quoted context omitted.

> Because if an asteroid destroys earth, your volcano base ain't gonna save life as we know it If an asteroid destroys earth, your Mars base won't save life as we know it either. There's a lot of handwaving in this thread on the technologies required to bridge the gap between Starship existing and self-sustaining life on Mars. Paradoxically, self-sustaining space manufacture/Mars colony will obviate the need for freq…

How is that paradoxical? Bootstrapping a self-sustaining colony on Mars will require getting a massive amount of payload to the red planet. Once bootstrapped, yes that will no longer be required. Nobody is arguing that Starship is sufficient, just that it is necessary.

> Nobody is arguing that Starship is sufficient, just that it is necessary.

No, it's the yet-to-be-invented tech that is necessary. Your unstated prior is that this non-existent tech will in turn require heavy-lift capacity, and there is no evidence for that. Maybe we can bootstrap space manufacturing off 2 Arianne 5 launches, or 50 starship launches, nobody knows because it's all make-believe atm.

What Starship is good for, is frequent supply runs to a dependant Mars base, with today's technology - but that's nor what people are saying because that's not sexy.

Re: Starship Update [video]

#322

Post by elihu »

lamontcg wrote: post #318
elihu wrote: post #197

Earlier quoted context omitted.

Economic incentives include government-funded basic science, mining, tourism, real-estate speculation (i.e. claim a bunch of land while it's cheap), entertainment (sports and movies/TV shows), the ability to do things in a presumably lax regulatory environment that might not be allowed on Earth, and long-term care for those who have disabilities that would require a wheelchair in full gravity but not on Mars, and the…

A lot of that assumes an already functioning economy on Mars. We're not going to be sending anyone other than the richest people up to Mars in their old age. And for stuff like food and hydroponics you could have that on the Moon which is the natural waystation to the Asteroids. The Asteroids are going to be where all the mining is. Entertainment also assumes an already existing economy. Space tourism is the only thi…

The ability to make methane on Mars is pretty huge, though. If you're mining the asteroid belt and need to refuel your ships, it's a lot easier to ferry fuel from Mars to the belt than haul it all the way from Earth. And methane/oxygen production is likely to be one of the first things we get going on Mars because we'll want our rockets to be able to make return trips back to Earth and we really don't want to haul the extra fuel and oxygen we need all that way.

Most of the economic incentives I suggest don't really start paying off until you have at least some decent infrastructure and a population of semi-permanent residents, though. It might not happen in our lifetimes, but you never know. Once the technology exists, it's just a matter of whether someone has deep enough pockets to make human settlement of Mars a reality. Once someone has a foothold, it gets easier for others to expand on that.

Re: Starship Update [video]

#323

Post by avmich »

panick21_ wrote: post #292
johnyzee wrote: post #249

Earlier quoted context omitted.

Seriously, it's only a matter of time before Elon Musk announces the space elevator.

Space elevator on earth doesn't really make much sense. On Mars maybe, it will happen on Mars way before it happens on earth.

Space elevators conflict with satellites, so not really advisable.

Re: Starship Update [video]

#324

Post by lamontcg »

elihu wrote: post #322
lamontcg wrote: post #318

Earlier quoted context omitted.

A lot of that assumes an already functioning economy on Mars. We're not going to be sending anyone other than the richest people up to Mars in their old age. And for stuff like food and hydroponics you could have that on the Moon which is the natural waystation to the Asteroids. The Asteroids are going to be where all the mining is. Entertainment also assumes an already existing economy. Space tourism is the only thi…

The ability to make methane on Mars is pretty huge, though. If you're mining the asteroid belt and need to refuel your ships, it's a lot easier to ferry fuel from Mars to the belt than haul it all the way from Earth. And methane/oxygen production is likely to be one of the first things we get going on Mars because we'll want our rockets to be able to make return trips back to Earth and we really don't want to haul th…

Again though lifting methane off of Earth is expensive, but ships from the Asteroid belt will naturally be coming back to Earth, so refueling around the Earth or Moon doesn't go out of the way. Mars is a detour, and you have to sink the costs to sustain the colony which offsets the smaller gravity well.

Re: Starship Update [video]

#325

Post by Andrew_nenakhov »

elihu wrote: post #232
Isinlor wrote: post #230

Earlier quoted context omitted.

Elon thinking is that on long distance flight you increase moved cargo per vehicle per unit of time. He was saying that flying to the other end of the world will be 20x faster vs. airplane. So if you move 20x more cargo per unit of time, then cost of cargo per vehicle + static infrastructure are proportionally lower. But we need to take into account that number of cycles of a rocket engine may not be as good as jet e…

...also, shipping high-value time-sensitive things across the planet in a few hours or less may be a viable business model.

There are other people working on it, actually:

https://destinus.ch/hyperplane/

Re: Starship Update [video]

#326

Post by byw »

iliketrains wrote: post #156
ewjt wrote: post #124

Earlier quoted context omitted.

I thought 100k HP was either too incredible or a typo. Then I looked it up: “You def don’t want electric pumps on a rocket engine! Raptor turbopumps alone need 100,000 horsepower per engine. That’s not a typo.” —Elon Musk x 32 engines. Amazing! For comparison, this is an internal combustion engine with 100k HP: https://www.zmescience.com/science/biggest-most-poweful-engi...

That is interesting, so could you replace the biggest and most powerful internal combustion engine in the world that weighs 2,300 tons by [whatever powers] turbopumps from a raptor engine and get the same power output? Where is the catch? Less fuel efficient? Less torque? Edit: What I meant to ask was: Can one use "whatever is powering the turbopumps and delivering the 100k HP" to power say a ship propeller, instead…

You could potentially use a turbine engine as a generator in a hydrocarbon-electric setup. It would in theory be lighter, simpler, and require less maintenance.

For now there's already a lot of momentum with ICE and they are very polished products. But I think the potential for turbine is there given the shift towards electrification.

Some hurdles include working with materials that can tolerate very high stress, and finding ways to improve efficiency from significant heat loss.

https://www.wikiwand.com/en/Microturbine

Re: Starship Update [video]

#327

Post by Andrew_nenakhov »

maccam94 wrote: post #281
Isinlor wrote: post #239

Earlier quoted context omitted.

Actually there is fuel in space - water and sunlight. You can split water into hydrogen and oxygen using electricity from sunlight. In long term, most likely both Hydrolox and Methalox will be in use.

I think the parent comment meant to say there is no propellant in space.

Solar sails can get you to anywhere in the Solar system. Not very fast, but essentially free. So a swarm of drone ships with solar sails can transport an almost infinite amount of propellant to your refueling bases from mining sites.

Re: Starship Update [video]

#328

Post by tim333 »

iliketrains wrote: post #156
ewjt wrote: post #124

Earlier quoted context omitted.

I thought 100k HP was either too incredible or a typo. Then I looked it up: “You def don’t want electric pumps on a rocket engine! Raptor turbopumps alone need 100,000 horsepower per engine. That’s not a typo.” —Elon Musk x 32 engines. Amazing! For comparison, this is an internal combustion engine with 100k HP: https://www.zmescience.com/science/biggest-most-poweful-engi...

That is interesting, so could you replace the biggest and most powerful internal combustion engine in the world that weighs 2,300 tons by [whatever powers] turbopumps from a raptor engine and get the same power output? Where is the catch? Less fuel efficient? Less torque? Edit: What I meant to ask was: Can one use "whatever is powering the turbopumps and delivering the 100k HP" to power say a ship propeller, instead…

Here's a guy with a 48,000 HP marine turbine for doing ships propellers. https://www.navyhistory.org/2016/12/commercial-use-of-marine...

And some other images https://www.google.co.uk/search?q=Rolls-Royce+MT+30&sxsrf=AP...

It's not as small and powerful as the SpaceX one but I guess it needs some extra bits. Also it runs off air rather than liquid oxygen which must reduce power a tad.

Re: Starship Update [video]

#329

Post by avmich »

gpm wrote: post #170
bagels wrote: post #168

Earlier quoted context omitted.

The turbopump on its own won't do anything. The turbopump takes the 100k hp, and uses that to compress fuel and liquid oxygen. It's powered by the engine. It doesn't produce power on its own.

IIRC it's powered by a relatively small in size pre-burner - and I think it's fair to assume that he was including that pre-burner in his comparison.

Also known as gas generator, and while it's small, in Raptor two of them consume all (or practically all?) of both fuel and oxidizer in tanks.

Re: Starship Update [video]

#330

Post by avmich »

hoseja wrote: post #198
iliketrains wrote: post #156

Earlier quoted context omitted.

That is interesting, so could you replace the biggest and most powerful internal combustion engine in the world that weighs 2,300 tons by [whatever powers] turbopumps from a raptor engine and get the same power output? Where is the catch? Less fuel efficient? Less torque? Edit: What I meant to ask was: Can one use "whatever is powering the turbopumps and delivering the 100k HP" to power say a ship propeller, instead…

The raptor burns highly purified methalox for a couple minutes at most. The ship engines have to work for weeks and years economically running on bunker fuel. From fundamental thermodynamics, the bigger an engine is the more efficient it is but you obviously need to compromise on that in a rocket.

Soyuz rocket takes 9 minutes to get to orbit. Raptors are multiple-use engines, their lifetimes could be hours of work, which is a lot for rocket engines. However it could be possible to increase lifetimes at least another order of magnitude - an NK-33 engine once run uninterrupted for 14 thousands seconds. Consumed a lot of kerosene.

RL-10 can avoid too big stresses, at least not heating to high temperatures, so this is another hint on possibly long working rocket engines...

Post reply on HN