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

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

#371

Post by ben_w » Fri, Aug 07, 2020, 6:46 AM UTC

nickik wrote: post #369

ben_w wrote: post #368

Earlier quoted context omitted.

Please, millions. The roads are already there, electric cars are quiet, road trains are even more efficient. I am no fan of American city design, having half encircled Davis CA on foot, having found the suddenly-terminating sidewalks in Salt Lake City, and having walked the really boring route from San Jose railway station to the hotel in the top left corner of the Apple Maps icon. (NYC is surprisingly pedestrian fri…

In Europe we are already trying to make more space for pedestrians specially around the city center. The value of the land above ground is incredible. Freeing up those spaces from cars makes sense and is incredibly nice.

I know, check my profile ;)

But:

1. Musk doesn’t live in Europe, he set up TBC while stuck in a traffic jam in Los Angeles.

2. Solid car trains moving at full speed (whatever that is for the road, 20 kph for residential or much higher than the current rules for highways) use less land area than any other traffic, so some lanes can become bicycle only or whatever.

3. They can “perfectly” obey traffic lights and give way to pedestrians

4. Raised walkways are cheaper than tunnels

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

#372

Post by simonh » Fri, Aug 07, 2020, 10:08 AM 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.

Air breathing engines don't work well with the flight profile of vertical launch systems. Sabre wont develop near enough thrust to get a Super Heavy + Starship stack off the ground.

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

#373

Post by anticensor » Fri, Aug 07, 2020, 11:51 AM UTC

fastball wrote: post #352

DannyB2 wrote: post #305

Earlier quoted context omitted.

Lettuce not forget Raptor runs on Oxygen and Methane. Both of which might be produced on Mars.

I mean we know for a fact that there is already (in small amounts) methane and plenty of CO2 on Mars. Obviously if we find lots of H2O this all becomes even easier as we can just combine the abundant CO2 with the H2O to get loads of CH4 and O2.

You mean, by unburning the fuel?

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

#374

Post by fastball » Fri, Aug 07, 2020, 11:55 AM UTC

anticensor wrote: post #373

fastball wrote: post #352

Earlier quoted context omitted.

I mean we know for a fact that there is already (in small amounts) methane and plenty of CO2 on Mars. Obviously if we find lots of H2O this all becomes even easier as we can just combine the abundant CO2 with the H2O to get loads of CH4 and O2.

You mean, by unburning the fuel?

Yep, effectively! That is what is great about these fuels (H2 and CH4) vs something like RP-1. First you get hydrogen by electrolyzing water. Then you can go H2 + CO2 → CH4 via the Sabatier process[1].

[1] https://en.wikipedia.org/wiki/Sabatier_reaction

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

#375

Post by pfdietz » Fri, Aug 07, 2020, 12:24 PM UTC

menybuvico wrote: post #341

pfdietz wrote: post #288

Earlier quoted context omitted.

Europeans were kept out of Africa by disease.

I always heard it was a logistic issue more than anything else? Getting from Europe to the Americas and then back in a sailing vessel is easier than getting to Africa's East coast and back.

Which explains why Africa was colonized so much more successfully than (checks notes) ... Australia?

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

#376

Post by anticensor » Fri, Aug 07, 2020, 1:53 PM UTC

doomlaser wrote: post #41

lmm wrote: post #38

Earlier quoted context omitted.

Parachutes are a lot fiddlier and less reliable than the layperson assumes, so the baseline for how complex a system like this can be is worse than you'd think.

In my mind, the multiple complex reorientations while falling at terminal velocity — with no plan B — just seems particularly harrowing..

Plan B is one more orbit and try again...

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

#377

Post by mosselman » Fri, Aug 07, 2020, 2:00 PM UTC

I was just looking at the stream and what struck me is that people were donating to the channel... Why would you ever do this? $20, etc even.

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

#378

Post by UnFleshedOne » Fri, Aug 07, 2020, 3:17 PM UTC

hnrq wrote: post #201

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.

I hate this argument. There is no foreseeable disaster that would make Earth less habitable than any other solar system body. Even if every nuke we have was detonated, it would still be orders of magnitude easier to survive on what remains of Earth than to live in Mars. I'm not saying there are no existential risks at all, but being on other planets would not make us any more likely to survive to them than to simply…

But only if you already developed technology needed to survive on mars and have an industrial base not touched by those nukes.

Having a self-sustaining outpost somewhere other than earth is valuable not only for its own sake, but also due to the developed technology and industry and infrastructure implied by its existence.

If tomorrow you suddenly need a huge fleet of fully reusable ships for some reason, the right time to start working on them was 20 years ago, or as soon as basic science and technology level allow.

There are also political risks (we are all too close to each other).

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

#379

Post by UnFleshedOne » Fri, Aug 07, 2020, 3:19 PM UTC

sangnoir wrote: post #266

nitrogen wrote: post #234

Earlier quoted context omitted.

Every comment of this nature overlooks the challenge of politics and territory. Any significant social experiment is basically impossible on Earth because every space and person is claimed property by an existing state. Mars would also offer cultural redundancy. Also, sometimes people choose to do things brcause they are hard.

> Every comment of this nature overlooks the challenge of politics and territory If I were a betting person, I'm not sure I'd go all-in on a CEO-Emperor-King of Mars over existing nation-states on Terra

Is that a bet on a basically functional society, or a bet on which place is better to live in for individual?

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

#380

Post by UnFleshedOne » Fri, Aug 07, 2020, 3:21 PM UTC

Koshkin wrote: post #356

stallmanite wrote: post #330

Earlier quoted context omitted.

And after a collision like the one that created the moon? How habitable during a gamma ray burst?

... and wha' if Earth jus' 'splodes one day... ( takes another sip )

That's a bit too much, but we still have a few month left in 2020...