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SpaceX nails triple booster landing after satellite delivery

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Re: SpaceX nails triple booster landing after satellite delivery

#91
post #55

Earlier quoted context omitted.

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.

That could bring satellite costs down a lot though - if launches are cheap and not weight limited a cheap steel frame satellite with heavy solar panels becomes feasible - all the old rules about building to optimise weight and not price go out the window.

I wouldn’t be surprised if spacex also enter the satellite building business after mass producing starlink.

Re: SpaceX nails triple booster landing after satellite delivery

#92
post #83

Earlier quoted context omitted.

What was amazing about it? Tell us the story.

Aside from the whole historical factors of the location itself (for instance: the humans sent to the moon were launched from that same launch pad), watching the launch from a video or live stream does not tell the entire story. To hear the roar of those 27 engines and feel it vibrating on your chest and the bleachers is an emotional experience. Then you can see the boosters coming back, and their entry burn and you c…

It's definitely the sound that most can't be reproduced at home. It really sounds like the air itself is being ripped apart. That's why I want to go back and see another launch. Also, the flame is SO BRIGHT, video doesn't do it justice. It's miles and miles away and it's almost like looking at a welding flare.

Re: SpaceX nails triple booster landing after satellite delivery

#93

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?

If you're talking about Star Wars, definitely not, because it's intentionally unrealistic.

Other sci-fi, maybe.

Re: SpaceX nails triple booster landing after satellite delivery

#94
post #47

Here's the video cued up to the booster landings: https://youtu.be/TXMGu2d8c8g?t=1643 with the main core landing a few minutes later. If it's not obvious, the main core landing was much harder this time around, because of how fast it was going due to the two boosters imparting a lot of extra speed on it before they separated. If you think about it, it'll have somewhere between 1x and 3x the velocity of a normal Falco…

It doesn't necessarily make it harder. There's a burn to slow the booster down for re-entry, and having the side boosters do a lot of the work means more fuel / delta-v can be saved to slow the core booster. The FH is apparently capable of 8,000kg in a reusable GTO launch ( https://en.wikipedia.org/wiki/Falcon_Heavy#Capabilities ), and this satellite was only 6,000kg. So it looks like there would be plenty of fuel av…

It's the same steps but it is harder, the center booster was going faster than any other core that has been recovered. The recovery itself was ~300 miles further out than any other recovery.

Swinging a bat at a 10mph ball is the same technology as swinging at a 90mph one. I don't think anyone would say that they were equally as easy.

Re: SpaceX nails triple booster landing after satellite delivery

#95
post #70
post #59

Earlier quoted context omitted.

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.

can you link to the paper please?

Re: SpaceX nails triple booster landing after satellite delivery

#96
I find this, and SpaceX, so inspiring. It's easy to feel that technology just moves itself forward. After all there are billions of people on Earth with people working on a countless array of different problems. And each day things seem to move forward, almost inexorably so. And so it's easy to feel that the value of the individual is really relatively low.

Yet imagine a world where Elon did not exist and thus SpaceX did not. Much of what he's done is stuff that we could have been working on decades ago. For some time we were. NASA as early as the 70s had already laid out plans for a Mars expedition including a tremendous space ship that would be assembled and fueled in orbit to take 5 man crew on a 600 day manned expedition to Mars, including landing of rovers similar to the moon.

Those plans got canned by Nixon, and space never really recovered. Not only did we not "inexorably advance" in space, we regressed. Today we're struggling to do a manned flyby of the Moon - when we went to having barely put a man in orbit in 1962, to putting a man on the moon in 1969. The point of this is that technology does not advance by itself, let alone inexorably so. I think it's extremely likely that had SpaceX not come to exist, it's entirely possible that we would still be effectively where we were at near the turn of the century.

Progress of our species, in spite of there being billions of us, is still dependent upon the individual. And SpaceX's plans have very much followed the old quote of Gandhi, "First they ignore you, then they laugh at you, then they fight you, then you win." But of course we've not yet won. As remarkable as this achievement is, it's but the starting line for where we need to be. And that line will not move forward unless we move it forward. But "we" does not mean waiting for somebody else to do so. As SpaceX and Musk have demonstrated, it's ultimately up to the individual to get up and move that line forward -- for the betterment of all.

Re: SpaceX nails triple booster landing after satellite delivery

#97

Earlier quoted context omitted.

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.

That could bring satellite costs down a lot though - if launches are cheap and not weight limited a cheap steel frame satellite with heavy solar panels becomes feasible - all the old rules about building to optimise weight and not price go out the window. I wouldn’t be surprised if spacex also enter the satellite building business after mass producing starlink.

What if SpaceX could combine cheap satellites with some form of reusable propellant-less or super high ISP propulsion? I'm thinking of solar sail or solar-ion drive tugs.

Re: SpaceX nails triple booster landing after satellite delivery

#98
post #81
post #78

Earlier quoted context omitted.

Same link but this one doesn't report your click to google: https://www.teslarati.com/spacex-falcon-heavy-fairing-recove...

I see multiple requests to ampproject on the official page, so Google is getting data regardless.

It does work for those using a content blocker or tracker-blacklisted DNS service.

Re: SpaceX nails triple booster landing after satellite delivery

#99

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?

Seems like it'd be tricky to do from a story telling perspective.

Totally removes all agency from protagonists. Every fight becomes a deus ex machina - "welp, our targetting subroutines continue to be superior to their maneuvering systems so they died. Hooray us?"

Or I guess more probably just a numbers game: "welp, our effective weapons range is larger than theirs, so that's that" with an MCRN exemption clause.

Re: SpaceX nails triple booster landing after satellite delivery

#100

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?

> 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?

Probably no, we can't stop having some of that. We can have her alternative, and, in fact, a lot of space combat in movies and TV is not resolved that way (both because it involves highly automated maneuver and targeting, and because, especially for combats that determine the outcome of the story, it is resolved by a social or technological advantage, often one provided by the quest making up the body of the plot, not by maneuvering or targeting (except to the extent that technical or social advantage impacts those abilities.)

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