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

SpaceX nails triple booster landing after satellite delivery

bbc.com

Post reply on HN
Print view View original

61–70 of 128 posts

Re: SpaceX nails triple booster landing after satellite delivery

#61

Post by wongarsu »

qmarchi wrote: post #24
bbojan wrote: post #16

Not only that, but apparently they recovered both fairings: https://www.google.com/url?sa=t&source=web&rct=j&url=https:/... So 5 out of 5...

It's an interesting issue with the fairings, and I'm interested to see what (or if) they're going to solve the issue with the saltwater contaminated fairings. Being a SpaceX launcher, as the article indicates, means they can accept higher risks, but in turn has a greater financial risk to the company. It's times like this where I'm glad SpaceX is a private company.

> in turn has a greater financial risk to the company

A financial risk you can count as R&D cost.

SpaceX has also positioned itself for some launches that would be acceptable to loose, like the deployment phase of starlink: loosing a few mass-produced satellites has to be much cheaper than loosing a big one-off satellite that takes months to rebuild.

Re: SpaceX nails triple booster landing after satellite delivery

#62

Post by wongarsu »

jessriedel wrote: post #51
taneq wrote: post #42

Earlier quoted context omitted.

I guess salt water isn't that much of an issue after all?

Yea, I wish we'd get a more detailed explanation of the accounting on this. For all I knew it was totally plausible that fairings would be destroyed by sea water, and it was also plausible there'd be no damage. The part that confuses me is why they would spend so much effort trying to catch them with Mr. Steven if they are in fact serviceable after a swim. Maybe the idea is that salt-water refurbishment-and-reuse sav…

The fairings are also quite big, so I imagine they get destroyed by waves very quickly if the sea isn't completely calm.

Re: SpaceX nails triple booster landing after satellite delivery

#63

Post by Ajedi32 »

azernik wrote: post #57
Ajedi32 wrote: post #49

Earlier quoted context omitted.

That's just speculation, I wouldn't cite it as an authoritative source.

The part that says they're able to reuse these ones is a tweet directly from Elon Musk; he also confirms they were recovered from in the water, not caught in the air.

That information was already covered by the news article linked in the root comment above.

The additional suggestion by a commenter in the Reddit thread that "they've saltwater hardened the fairings" is speculation.

Re: SpaceX nails triple booster landing after satellite delivery

#64

Post by bloopernova »

inflatableDodo wrote: post #20
agumonkey wrote: post #17

Earlier quoted context omitted.

you can, as long as SpaceX recovery truck has not reached your door

I'll swap the house numbers with next door. They'll never find it.

I know this is increasingly off-topic for hn, but the mental image of being woken up by loud booster noises, then seeing a huge booster sitting in your now-ruined garden is hilarious to me.

We certainly do live in the future.

Re: SpaceX nails triple booster landing after satellite delivery

#65

Post by Tuna-Fish »

inflatableDodo wrote: post #15
usermac wrote: post #5

I wonder what emergency procedure is in place in case the landing is off-course. Does it blow itself up?

As an addendum to that, if one accidentally lands in my back yard, can I keep it?

No, but if one crashes in the ocean, sinks, and SpaceX does not attempt to salvage it, it legally becomes a derelict and the property of whoever who goes lift it up.

Re: SpaceX nails triple booster landing after satellite delivery

#66

Post by bergoid »

narrator wrote: post #46

Can we finally stop having sci-fi films in which the whole outcome of the movie is solely determined on some heroic manual flying of a spaceship while simultaneously using manually aimed weapons like it's World War II?

The Apollo 13 astronauts would like to share a couple of anecdotes with you.

Re: SpaceX nails triple booster landing after satellite delivery

#69

Post by JshWright »

DennisP wrote: post #55
JshWright wrote: post #44

Earlier quoted context omitted.

Reusable is 8000kg to GTO, not LEO. LEO performance in fully reusable configurations is 30+ tons.

So assuming 32 tonnes it's $668/kg for the hardware (assuming full payloads). Probably also have to build in enough slack for occasional failed landings, but we don't know yet what the failure rate will be after the kinks are worked out.

You'd be hard pressed to fit 32 tons inside Falcon Heavy's fairing. It's far more likely to be volume constrained than mass constrained when flying to LEO.

Re: SpaceX nails triple booster landing after satellite delivery

#70

Post by CarVac »

theoh wrote: post #59
dom96 wrote: post #53

Earlier quoted context omitted.

Can anyone give a ELI5 (for developers) of how this technique works?

The control parameter space for the rocket is non-convex because, for one thing, it can't be throttled down close to zero thrust. You can think of the parameter space as having a hole in it. An optimal control algorithm might want to make very delicate low-thrust corrections, but that's not possible. This technique is based on "the idea of relaxing the nonconvex control constraints to a convex set in such a way that…

I read a paper on this—it's convex because any optimal trajectory will have the engines at full throttle whenever they're on, so they just fill up the parameter space, confident that illegal values will never be required.
Post reply on HN