Perhaps the security is adequate if that is the best plan.
Security is not about making absolutely sure, it's about:
1. Lowering likelyhood: Making it reasonably hard to break, so that the bad guys will go somehere else.
2. Spend wisely: Not spending more to defend that the likelyhood of loss times (value lost + value bad guys gain) (in general terms)
a. Round up the likelyhood, the bad guys are better than you at getting ideas.
b. Destroy sensitive and remove generally valuable parts to reduce the bad guys value
c. The value lost is *not* the money spent on the lost property. Perhaps you wasted a small bit of effort making it? pehaps you can recreate new and better cheaper?
I think the value of the space-shuttle is mainly sentimental and image-loss on theft, so you should probably not spend more than a simple escort -- mainly to prevent traffic-problems.