I went through the SpaceX behavioral round as part of an onsite last month. Before I went in I only found vague "show mission passion" advice online. The reality was more structured than that.
First: yes, mission commitment comes up. The question was basically a version of "what would you do differently if you were working on software that directly affects whether a rocket launches successfully." They want to hear that you understand stakes, not just that you watched a launch video once.
But the rest of the behavioral round was more specific:
Ownership and decision-making under ambiguity. They asked me to walk through a time I had to make a call with incomplete information and no one above me available to escalate to. What did I do, how did I decide, what happened. Classic STAR but they pushed on what information I wish I'd had and whether I'd make the same call again.
Working in a resource-constrained environment. SpaceX is famously lean for a company its size. The question was framed as: describe a project where you had to ship something with less time or less support than you thought you'd have. I think they're screening for people who can move fast and don't need a lot of hand-holding.
Cross-functional conflict. One question was about disagreeing with a decision and how I handled it. They were interested in whether I escalated, how I communicated the disagreement, and whether I ultimately committed to the decision or continued to resist.
The behavioral was a single 45-minute round in my onsite. One interviewer. She took notes throughout but was also conversational. It didn't feel like a checkbox exercise. I got the sense they actually weighed it seriously.
My overall read: the values they actually screen for are ownership, urgency, and operating without a lot of structure. The mission passion piece is table stakes but it's not enough on its own.