Comment by KennyBlanken

Fucking up the re-entry burn or thruster actuation during the burn for re-entry = loss of vehicle/crew

Improper control surface actuation during re-entry = loss of vehicle/crew

Also, rocket engines that are powered by the combustion of their fuel and oxidizer (the exhaust gasses of which drive the main pumps) have a very specific startup sequence. For example, if any of the combustion chambers have a mix of oxygen and hydrogen too close to stochiometric when the igniters fire, you get an explosion, not a burn. Not too dissimilar from what happens in car engines when you get detonation (which is very different from knocking. Detonation melts holes in stuff.)

Startup initially is open-loop with no feedback or adjustment based on sensors and then at some point the computer switches over to closed loop control. It starts with hydrogen first. The sparklers? Those aren't for igniting the engine, that's done by igniters inside the combustion chamber(s). The sparklers are to ignite all the hydrogen that is pushed out the nozzle initially so there's a very fuel-rich environment in the engine and it doesn't go kaboom.

If things go wrong - such as a valve not opening as fast as it should, or not being opened the right amount at the right time - the engine goes kaboom. This happened to a bunch of engines during development and testing.

But Artemis has basically the same engines, so...shrug