[imjasonmiller]

In a press conference an hour or so ago, I think Elon mentioned that, if he had to pick one core that would experience “rapid unscheduled dissassembly”, it would have been the center one. I think he mentioned it was due to the boosters having the expensive titanium grid fins and also being reusable for future flights.

Regardless, it was absolutely wonderful to watch! I think the Youtube stream had 2,500,000 viewers at one point. I can’t wait for more footage of the launch the coming days.

[jacquesm]

Back when we did Shuttle launches on ww.com 10K or so was the maximum number of viewers we ever saw. It's absolutely incredible how far video delivery over the web has come since STS-87.

Keep in mind that we got kicked off the backbone because we were using too much bandwidth and 'the internet wasn't made for video' (which is why we moved to Canada to begin with).

[jlmorton]

The unspoken point in Musk's comment is that SpaceX doesn't actually care if they get these particular rockets back. They want to prove reusability, of course, but no matter the outcome they never plan to re-fly these cores. They will focus on the not-yet-flown Block 5 cores, and standardize on that going forward.

In this flight, the side boosters and center core were Blocks 3 and 4. So SpaceX definitely wants to recover the boosters, to perfect reusability, but they never intend to re-fly any of these boosters, so better to get back the one with the expensive and reusable titanium grid fins.

[kens]

> Block 5 cores

Why are rocket versions specified with the word "Block"? The Saturn launchers did the same thing, but it seems like a strange word to use.

[joezydeco]

It's a term carried over from the military/aerospace field.

https://www.f35.com/about/life-cycle/software

[perl4ever]

I boggle a little at what I read there, such as "With Block 3i, 89 percent of code required for full warfighting capability is flying". That's 89%? Not 88% or 90%?

[joezydeco]

You can be sure the specs for something like the F35 run into the hundreds of thousands of pages. Tagging exactly 89% of the features as making that milestone is probably the easiest part of the work.

[Eridrus]

Didn't they say these boosters had already flown before?

I'm also a bit surprised the grid find are so pricey, they seem pretty small? Not that I really know how much titanium costs to buy and machine.

[quasse]

They measure 4 by 5 feet, so we can estimate they are probably made from a solid chunk of titanium that was at least 20 cubic feet or almost 5,000 pounds. That would be nearly $150,000 in raw material and probably another 5x that in processing (guesstimating cost per cubic inch of titanium removal).

Either that or they were specially made castings, which are similarly expensive in low volume, if not more.

[larkeith]

Wouldn't you be able to recover most of the removed titanium, amortizing the majority of that guesstimated materials cost? Processing likely remains expensive, however.

[solarkraft]

I'd think so. They also 3D print a lot, but metal powder does seem expensive.

[cjsawyer]

Printed metal has huge issues with heat, and they just switched from aluminum gridfins to titanium because of the heat. I seriously doubt that they’re usung additive techniques here.

[stmfreak]

You are also dealing with low volume fabrication which means setup and tooling costs don't amortize across many components. I wouldn't be surprised if they cost $1M each.

[cryptoz]

The side boosters were flown before, and returned to Earth today for the second time. But they won't fly again.

[4minute]

They aren't reusing any more of the Falcons 9s we have seen. They are switching over to Block 5 of the rocket. They wanted to keep the fins, because I think those were Block 5 fins on them.