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SpaceX lands rocket at sea second time after satellite launch

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Re: SpaceX lands rocket at sea second time after satellite launch

#151
post #9

A white ball of fire. And then there it is...resting! Beautiful!

Love how the autobalance on the cameras cut almost everything to black so you could not see the rocket at first, until it emerged from the darkness.

That was an unexpected and delicious bit of Hollywood drama. My first assumption with the flash followed by darkness is that it had impacted too hard and exploded or wrecked the camera. The autobalance stabilizing was a great big-reveal moment.

Re: SpaceX lands rocket at sea second time after satellite launch

#152
post #108

Here is the video http://www.space.com/32811-spacex-rocket-landing-jcsat-14-la... Hopefully we won't have the typical hacker news discussion about why the employees chant USA.

Yoo.Ess.Ae! Yoo.Ess.Ae! Yoo.Ess.Aeh! There. See. No harm, no foul. Anyways, as a non-American living in the US since 2001, I fail to see an issue with chanting USA, one way or another. It is an American company, with majority US employees, running this project (mainly) for an American entity (NASA), on US sovereign territory (or ocean?), using a significant chunk of US resources. So, it is their company and their cou…

Any proud chant is problematic only to the degree of pride it conveys for the wrong thing(s). Landing a space ship in 2016 surely warrants significant pride.

Whether the USA is worth praising for this particular success, I'm not as sure. But damn, congrats to everyone involved. You just landed a fucking space ship. Good job.

Re: SpaceX lands rocket at sea second time after satellite launch

#153

I remain confused about why SpaceX is getting so much fanfare and praise. What have they accomplished that NASA didn't already accomplish during the Apollo missions? I know SpaceX is doing it all more cost effectively, because we have better technology, but have they actually accomplished anything tangible that NASA didn't a generation ago?

Based on some talks the first lunar landings were way more adventurous and lucky than what SpaceX is doing. Making a snooker trick shot is nice, announcing it and doing it twice is another thing.

Re: SpaceX lands rocket at sea second time after satellite launch

#155

Earlier quoted context omitted.

Do customers get a discount for launching on a used rocket?

Assuming SpaceX gets to the point where they are re-flying stages a dozen or more times, I might expect to see a discount on a "new" rocket, as opposed to a "tried and true" rocket. Would you rather be on the first flight an aircraft makes after leaving the factory, or the tenth?

I would make the decision based on the data available at the time.

It could easily be the case that the initial launches have the lowest failure rate.

Re: SpaceX lands rocket at sea second time after satellite launch

#156
post #85

Doing it one time is a technological leap. Doing it twice in such a small window of time is a logistical/programmatic leap.

Were they different rockets? If so I don't see the logistical leap.

Different use cases. This was a GTO launch which means the first stage had way more energy and therefore way tighter margins than the last attempt. This attempt used three engines to land and had a more difficult landing trajectory.

Re: SpaceX lands rocket at sea second time after satellite launch

#157
post #33

Earlier quoted context omitted.

No, it's something else, a cultural quirk among Americans.

No it's not. The French, British and Italians for example all have extreme amounts of nationalistic pride and show it throughout their economies, the pride they hold regarding their history and culture. Scandinavia is very proud of its broadly tremendous standard of living and their well run welfare states, etc. - and Scandinavians are never shy about bragging about it online in my observation, you can hardly get awa…

We British would never dream of claiming our country was the best at everything - we might grudgingly admit that we get by all right considering - and my impression is that the rest of Europe is similar. Whereas Americans seem to get offended if you suggest there might be anything that another country was better than theirs at. Not to say it's necessarily good or bad but there is a real cultural difference there.

Re: SpaceX lands rocket at sea second time after satellite launch

#158
post #121

Earlier quoted context omitted.

I'm still surprised there's no active system on the barge to secure the rocket. Even now they seem to be able to stick the landing with some reliability, it's always nice to have belt and suspenders. I'm thinking a system with a pillar at each corner of the barge, pairs of cables between opposite pillars, and puller cables to open out the main cables into an iris-type aperture which can be rapidly closed on the rocke…

The center of mass of the rocket is _very_ low. According to Elon, the CRS-8 core was very stable (it needed even less stabilization than they thought it did). They may add some means to secure it if it needs to travel through rough seas on the way home, but if the conditions are calm enough to land, they're calm enough for the stage to be stable. Watch the CRS-8 landing and look at how much the barge is rolling whil…

The response crew comes and secures the legs on the barge immediately after landing. They bolt them down somehow, I think.

Re: SpaceX lands rocket at sea second time after satellite launch

#159
post #134
post #102

Earlier quoted context omitted.

> you just KNOW What a complete load of utter tripe. Its a bunch of people getting excited and happy and celebrating success. That's it. Are England supporters chanting after a soccer match aggro-patriotic douchebags? The SpaceX crowd aren't even celebrating a victory over anybody, it's purely about achievement. Good for them.

> Are England supporters chanting after a soccer match aggro-patriotic douchebags? Aggro-patriotic douchebaggery isn't exactly unheard of when it comes to football stadiums. For some it's a feature, for most others it's a very well known bug. Also, you seem to have completely missed his finer point: a nuanced distinction between those who start and those who just sing along because they are in the mood for making noi…

> you seem to have completely missed his finer point

That's because I don't think there is a finer point. If the only way a chant like that could happen is if it's started by aggro-patriotic douchebags, which specifically was the contention, then the chanting only exists as a result of aggro-patriotic douchebaggery. That's a slur that taints everyone involved in it, and I don't accept that at all.

Re: SpaceX lands rocket at sea second time after satellite launch

#160
post #112

Earlier quoted context omitted.

> because there's not much fuel left in the tank to hover They can't hover at all, since the throttle doesn't go low enough. They need to do the landing perfectly, on a single try.

Interesting. That's a change from the Grasshopper testing platform? If I recall correctly, it was able to hover.

I was all set to post something about how the Grasshopper used a different engine, but apparently both the Grasshopper and the F9 first stage use Merlin 1D engines.

Wikipedia says that these produce 700kN at sea level and can be throttled down to 70%, which means at minimum power one engine could hover about 50 tonnes.

I can't find out what Grasshopper massed. Does anyone know?

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