You don't have to go into the crowds at the Air and Space Museum in DC because there is a Visitor center here right here on Goddard Space Flight Center. There is a real spacecraft on display where astronauts Buzz Aldrin and Jim Lowell. It's actually a replica but children can go inside and press 100 buttons! There is a computer stations, where children can design their own satellites and rocket systems. Sometimes during the summer time, there is puppet show. It's a free to the public and you may want to call in advance about the hours.