Yelp Day at SLOPE
The facility is now only open to guided tours... they post on their web site well in advance and you can call to be a part of a larger group if you don't catch the Yelp train to NASA.
We were not the first tour of the day...l so we got the bum's rush at times... they do have a gift shop still open... BUT... the larger exhibit / museum space is closed... it has been moved to the Great Lakes Science Center.
Soooo... if you are looking to let your kids crawl and explore head to the Science Center... if you are looking to get a great geek's view of one of the departments and talk to staff take the guided tour as early in the day as you can.