I'm an indie game developer, software engineer, and friendly fella. Always trying to learn/grow and be a good person.
i am about to say some real nerd shit that you should probably disregard:
the question says you can take one object from the Smithsonian Museum in Washington DC. Space Shuttle Discovery is housed outside Washington DC at the Steven F. Udvar-Hazy Center in Chantilly, Virginia. ergo, if we're really rules-lawyering about this, you can't take the space shuttle.
I’d suggest taking a transportation team from the Smithsonian Museum in Washington DC to the Steven F. Udvar-Hazy Center in Chantilly, Virginia to get Discovery.
genuinely? nothing. the smithsonian is one of the few good things the federal government funds, and i would never actually want to own anything in their collection. it all belongs to the people. or in some cases some other countries and they really oughta give them that stuff back but hey at least its not the british museum.
but hypothetically, dispensing with morals? probably some piece of the Columbia command module from Apollo 11, which is currently on display in the Destination Moon exhibition in the main DC building. or maybe something from the Entertainment Nation exhibition in the National Museum of American History. Like maybe Scully's FBI ID from The X-Files.
Genuinely? Nothing, of course. For all the reasons above. 👍
Disingenuously? Probably not a space shuttle, that was just being silly (I hope). I do desire the Swamp from M* A* S* H, though.