[justin66]

> 1) Problem during launch. There's been one successful use of a launch escape system in rocketry history[1], and such a system has never been developed for a shuttle type craft.

I'm not sure if you're aware, but this is a feature of the latest version of SpaceX's capsules. I'm sure it would exist for their larger vehicles.

edit: although I'm just not sure what you'd do during an abort with all that fuel that larger vehicle holds...

[mikeash]

I'm not so sure. The Dragon 2 integrates a launch escape system by using the same engines that are also intended for propulsive landing (which is now probably off the table for good, but that was the idea). The BFR ship won't have near enough TWR when fully loaded for its landing engines to double as launch escape engines, and I see no evidence of any other engines.

The fact that the BFR ship serves as both second stage and capsule combined, whereas the Dragon 2 is just a capsule with a separate second stage to put it into orbit, makes the problem a lot harder. I bet that the system for the BFR will consist of "don't explode."

[justin66]

> which is now probably off the table for good, but that was the idea

Oh, that's interesting. What makes you say so?

[mikeash]

Apparently I'm remembering an official statement!

https://spaceflightnow.com/2017/07/19/propulsive-landings-ni...

The reason seems to be a combination of NASA not being interested in propulsive landing (and they're funding most of Dragon 2) and deciding to go all-out on BFR instead of refining Dragon 2 further.

[justin66]

Thanks for sharing, that is news to me! I need to review their inventory at some point when I have a few minutes...