Key PointsSpace and artificial intelligence (AI) are two of the hottest growth opportunities in defense.SpaceX's broad footprint across both industries will earn it a lot of government business.A hefty valuation might ruin the fun. Meanwhile, Lockheed Martin isn't going anywhere.10 stocks we like better than Space Exploration Technologies › There's far more to warfare than guns and missiles. So, when thinking about defense stocks, it's important…