SpaceX test flight of Starship SN-5 [video] • Hacker News Board

Re: SpaceX test flight of Starship SN-5 [video]

#311

Post by jvanderbot » Wed, Aug 05, 2020, 9:34 PM UTC

sandworm101 wrote: post #245

martythemaniak wrote: post #205

I really love the out-in-the-open development process. It doesn't cost SpaceX anything, yet they attract lots of internet media where people set up streams, discuss progress etc. The next year should be pretty exciting as they develop things further. Starship has a number of big innovations, which are: - the raptor engine. This was developed behind closed doors and is sort of finished. We won't see much of it, but it…

>> - in-orbit refueling. Starship is big and heavy and basically can't get anywhere unless it's re-fueled in orbit. This is one of those "let's see" things that SpaceX has talked about but never actually explained. Their current rocket tech offers no hint as to how this is might happen. They aren't running internal bladders in their tanks. So the physical act of moving fuel from one tank to another is an open questio…

Transfer tanks, not fuel. In-orbit servicing using robots, please. or just dock the tanks as vehicles.

Re: SpaceX test flight of Starship SN-5 [video]

#312

Post by nickik » Wed, Aug 05, 2020, 9:38 PM UTC

ben_w wrote: post #160

jacquesm wrote: post #149

Earlier quoted context omitted.

You write that as if it is a done deal. Mars' atmosphere is roughly .5% of that of Earth and almost exclusively CO2. Temperature ranges are well out of what they are on Earth. It is hard for technology to survive there, it is impossible for people to survive there until there has been an unbelievable investment in infrastructure. If you think there will be a million people colony on Mars in your lifetime than you are…

Although I’m also not expecting 1 million people on Mars in my lifetime, I think you’re assuming SpaceX never gets close to the Musk price goals. You might be right to do that — I’m no rocket scientist — but the target price would get a million people there for $200 billion, not your $5 quadrillion. Yes, I also expect the first few thousand to be in easily damaged domes. I also expect them to bring some of The Boring…

How are tunnels pointless in a future of self driving cars, the opposite is true, tunnels make even more sense when cars drive themselves.

Re: SpaceX test flight of Starship SN-5 [video]

#313

Post by Robotbeat » Wed, Aug 05, 2020, 9:45 PM UTC

pinewurst wrote: post #71

tjtrapp wrote: post #63

Earlier quoted context omitted.

We're hiring for Starship and Starlink software teams: https://grnh.se/080f65d02us It sounds like you're passionate about your work and that's an important quality. As gorgoiler points out, "Making a difference in the world is what counts." If you'd like to help, consider applying! :)

The application forms are pretty ridiculous with theIr insistence on school/graduation dates (some reqs) and SAT/ACT scores (all). As a very experienced engineer, I can’t accept being judged on (historical) trivia.

I would apply anyway. SpaceX judges more heavily on outside projects than academic credentials.

The US citizen (and/or permanent resident) thing is probably not negotiable, though, because SpaceX does a lot of Nat Sec stuff.

Re: SpaceX test flight of Starship SN-5 [video]

#314

Post by yazaddaruvala » Wed, Aug 05, 2020, 9:52 PM UTC

Ajedi32 wrote: post #268

mabbo wrote: post #249

Earlier quoted context omitted.

> Not sure why SpaceX haven't invested in it yet > an a air-hydrogen mix breathing-rocket hybrid design Tough to use a breathing rocket anywhere but Earth. And SpaceX's goal is to use this to land on the Moon, Mars, everywhere.

That's true for Starship (the second stage) but AFAIK Super Heavy (the first stage) will only ever be used on Earth. Seems like an air-breathing rocket engine could potentially be good for that use-case.

One benefit of Raptor is that its designed to be mass produced. Achieving cost efficiencies with scale.

Adding another engine means, one more production line each with less production volume (i.e. less efficiency of scale).

Re: SpaceX test flight of Starship SN-5 [video]

#315

Post by cosmotron » Wed, Aug 05, 2020, 10:00 PM UTC

0xffff2 wrote: post #306

h3rsko wrote: post #274

Earlier quoted context omitted.

My dream is to work for spaceX, but I'm NY. Do you his have remote teams or a NY office?

I find it completely baffling that it's your dream to work for SpaceX but you're unwilling to relocate? I'm stuck in the bay area (which I absolutely despise) because of my job, but I get to write flight software for spacecraft so I deal with it.

0xffff2, you yourself just said, "I'm stuck in because of ." It can't be that baffling to think that h3rsko is also stuck (e.g. because of a family).

Re: SpaceX test flight of Starship SN-5 [video]

#316

Post by sandworm101 » Wed, Aug 05, 2020, 11:09 PM UTC

Robotbeat wrote: post #262

sandworm101 wrote: post #245

Earlier quoted context omitted.

>> - in-orbit refueling. Starship is big and heavy and basically can't get anywhere unless it's re-fueled in orbit. This is one of those "let's see" things that SpaceX has talked about but never actually explained. Their current rocket tech offers no hint as to how this is might happen. They aren't running internal bladders in their tanks. So the physical act of moving fuel from one tank to another is an open questio…

It's not particularly hard. Just like with regular rocket upper stages that require multiple burns to complete the mission, you can use small ullage thrusters to settle the propellant and make sure liquid (instead of pressurant gas) is transferred from one tank to another. The physics is exactly the same as making sure the engine receives fuel. Just need the thrusters to be fired longer. SpaceX has done experiments w…

Yes but ullage thrusters would have to fire continuousky for the duration of the transfer. That is a significant burn time. If they are going to be draining the fuel using only the ullage thrust, it will take more than a slight nudge.

Re: SpaceX test flight of Starship SN-5 [video]

#317

Post by ncmncm » Wed, Aug 05, 2020, 11:19 PM UTC

TomMarius wrote: post #207

ncmncm wrote: post #154

Earlier quoted context omitted.

Anything said about libertarianism is necessarily hypothetical, because it has never happened. If it ever did, it would instantly dissolve into something certain to be very unpleasant for almost everyone.

It happened in the United States before the first world war, and continued for a few decades after that. Pretty long time to be called "immediately". While it was unpleasant from our current POV, it was way better than anything else at that time, and didn't end because it dissolved, but because the world wars needed funding.

I see that you are not up on the Sherman Antitrust Act. Go ahead, I'll wait.

The 1890s demonstrated what a Libertarian regime would dissolve into, instantly: Absolute rule by the biggest dog. It has happened myriad times in human history, from all kinds of pre-conditions. We were lucky, 130 years ago, that the armed forces still believed in voting. Not sure they still do...

Re: SpaceX test flight of Starship SN-5 [video]

#318

Post by bbojan » Wed, Aug 05, 2020, 11:26 PM UTC

h0l0cube wrote: post #180

sekai wrote: post #174

Earlier quoted context omitted.

Let's look at this way, humanity needs to become multiplanetary species to prevent extinction if some sort of cataclysm happens on Earth: nuclear war; Yellowstone erupts, etc. Compared to that, any other problem seems insignificant.

Life will go on in other parts of the universe, and all life, no matter where they locate themselves, will have some kind of existential threat. And it doesn't matter how many Dyson spheres are made, if humans aren't dedicated to improving the collective opportunity to live life without suffering, there's little real 'significance' to extending the project of humanity compared to any other life-form.

How do you know there is life in other parts of the universe?

Do you at least consider a possibility that life originated only once?

Re: SpaceX test flight of Starship SN-5 [video]

#319

Post by ncmncm » Wed, Aug 05, 2020, 11:30 PM UTC

Jach wrote: post #217

ncmncm wrote: post #158

Earlier quoted context omitted.

To get a sense of the difficulty, imagine sending a million people to the South Pole to set up a self-sustaining colony. That would be much more than 1000 times easier than establishing such a base on Mars.

Easier is a downside.

It would be smart to demonstrate ability to do thing A before attempting thing B that is 1000 times harder.

With any luck, things you learn actually doing A, and then A' that is 10 times harder, and then A'' that is 100 times harder, will all turn out to be useful, even necessary, in tackling B. Failure is always an option, but there is no point in choosing it at the outset.

Re: SpaceX test flight of Starship SN-5 [video]

#320

Post by greycol » Wed, Aug 05, 2020, 11:35 PM UTC

chrisjc wrote: post #233

mpweiher wrote: post #128

Earlier quoted context omitted.

> game changer Absolutely, and the quantitative analysis is just stunning. In 2018 all of humanity launched a total of 111 payloads into space (out of 114 attempts). At around 5t per launch, that would be 555 tons. Starship is supposed to have a payload to LEO of > 100 tons. So 5-6 launches would handle all of that, by weight. But SpaceX says their goal is to fly these up to 3 times a day. So let's assume they can do…

Perhaps a stupid and naive question, but is there even the demand to lift that much mass into orbit? I may just be lacking in imagination. Obviously most of that mass would have to leave orbit in order for it not to end up looking like an LA freeway in rush hour. edit: i guess propellant/fuel would be one of the heaviest and important payloads we would need to get up there.

With out current capabilities space only offers intangible services to earth (not to discount them as they are still profitable markets). With the step change in capacity we can start talking about getting equipment into space to bootstrap making it physically productive for earth.

We can start looking at the infrastructure that makes moon or asteroid mining for fuel possible. 'Cheap' fuel in space is the dream because it means asteroid 'mining' for materials that get returned to earth can be profitable (massively profitable to the point of dwarfing any investment currently made).

But the amazing side effect is suddenly we also have materials in space that like the fuel now costs orders of magnitude less than if we were sending it up. It'll becomes viable to build more infrastructure in space and so (perhaps ironically) there will be more demand to get materials from earth to space.