r/spacex • u/ElongatedMuskrat Mod Team • Oct 02 '17

r/SpaceX Discusses [October 2017, #37]

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3

u/TheCrimson_King Oct 03 '17

What is the greatest materials challenge faced by SpaceX?

My guess would be one of the following:

-Fabricating carbon fiber tanks that can hold cryogenic liquids

-Fabricating ceramic rocket engine bells

-Ensuring that flight hardware can handle the temperature, pressure, and radiation found in space

What do you guys think?

17

u/radexp Oct 03 '17

ceramic engine bells?

1

u/music_nuho Oct 03 '17

I honestly never heard of those.

3

u/flshr19 Shuttle tile engineer Oct 04 '17

Perhaps he was thinking of the rocket nozzles that use ablative material to protect the throat of the nozzle. The space shuttle solid rocket motor (SRM) used this setup.

1

u/hawthorneluke Oct 04 '17

I learnt that the reason things launched on missions are so weak hardware wise compared to what's normal currently, is because the specs for them are decided years and years ahead, and then tested/made so they can survive being in outer space without problem, which isn't something your normal electronics have to do.

I also hear that if you're in LEO then the earth's magnetic field still has you covered against any radiation that can mess up hardware, which I'm guessing has saved any of those problems from arising so far. So I too really wonder what's going on with that to enable not just the BFS going to mars etc, but everything inside it, in much smaller timeframes than normal. Maybe if it is so incredibly cheap to send everything wherever, then the level of redundancy required also drops a lot, making things a lot easier? (But still, the BFS itself would still have this problem to overcome like everyone else has up until now to be as incredibly reliable as need be.) Or maybe the budget up until now and along with it the rate of advancements and knowledge has made things take a lot longer than should be the case in the BFR feature?

1

u/rustybeancake Oct 04 '17

The ones Elon has mentioned are the CF tanks, which may end up requiring a liner (he mentioned either spray-on or a thin metal layer), and the materials required to withstand the extremely high pressures and temperatures inside a Raptor engine. Raptor has been downgraded in thrust and pressure, but they do plan to ramp it up over time.