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Comment by mabbo | Hacker News Reader

If you rewatch the live stream, at 31:45 or so the rocket starts hitting the atmosphere at 6500 km/h, or nearly 2 km/s. The grid fin, used to help steer through the atmosphere is burning, and then the video from that rocket cut out.

At that point I simply presumed it was over for it, yet somehow it still managed to land. They'll probably use it again. We live in a crazy, amazing world.

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> The grid fin, used to help steer through the atmosphere is burning

They're using ablative paint, so that's somewhat intended. It's needed because the current fins are made of aluminium, they intend to replace them with titanium ones in the future which will have improved reusability.

The future is here: http://twitter.com/elonmusk/status/878821062326198272

> Flying with larger & significantly upgraded hypersonic grid fins. Single piece cast & cut titanium. Can take reentry heat with no shielding.

There's a decent chance that they might not. They've been making more and more improvements to Falcon 9 in later blocks. In particular there's been an effort to improve reusability of the later designs. Currently SpaceX is having more and more used Falcon 9s piling up. Who knows for sure, but at the moment they have no shortage of reused rockets and it's preferable to them to start using the later designs.

If they're faced with a low probability landing scenario, such as the fastest re-entry velocity to date, and they need to "test" their control algorithms, which first stage would they choose? A near end-of-life used booster or a late block booster from which they would hope to get another several good launches? - assuming all others characteristics support the current launch parameters.

They're amazingly deliberate in how they mingle bleeding edge R&D and commercial activity. Something that fascinates me. And rockets.

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