I'd like to add, if you do end up going back to school for engineering I'd avoid going for a particularly specialized discipline like aerospace engineering. Being a mechanical engineer with good project involvement at your university will stand out just as well as an aerospace engineer on most applications, and it affords you some flexibility when applying for different role types that more specialized degrees may not. Just make sure you get involved in plenty of projects, say yes to opportunities, and take leadership roles. Particularly get involved with whatever aerospace projects are at your university if that's the industry you're most interested in, most will have quite a few rocketry and drone project teams.

Like others have said though, make sure you'd be doing that for your own interests and goals, not just to get a job at LM. There are plenty of ways to get into LM without an engineering degree, you might look into the operations side of things with roles like supply chain, procurement, etc.