Good free family event in Worcester, MA for those in this area. Last year, I brought my then 14 year old son, and we had a great day even though some of it was more grade school age.
They had WPI (Worcester PolyTech Institute in Worcester, MA) seniors showing off their projects and lots of cool stuff. My son walked out of there wanting to go to WPI he was so inspired by the cool projects they did which isn't all bad. There is lots more to do beyond just the Nasa Challenge.