Huntsville police are investigating the shooting at the Space and Rocket Center on Thursday.
Officials suspected bullet fragments from the gun possibly came from a 308 caliber round.
Police also said the shots likely came from a moving vehicle on the I-565. Officials are interviewing witnesses from the shooting.
The Davidson Center is open to visitors while repairs are made. In the meantime, tape covers up one of the bullet holes.
Crews expected the damaged windows to be fixed by early next week. They plan to replace the entire pane rather than patch the hole.
"We've had our crews, they went up on lifts yesterday," said Tim Hall, Space and Rocket Center spokesperson. "Some of the windows have actually been taped up just a little bit but absolutely no concern or problems for any of our guests who were going through the door."
Teachers and school children attending Space Camp were inside the building when the shooting happened.
"We're just as perplexed and surprised as any of our visitors who were here yesterday when this incident occurred," Hall said.
No one was hurt, but it was a reminder that safety is paramount.
"We will look into anything we could do to enhance security for the children, and then for the guests who walk through our doors every day," said Hall.
As many as 2,000 guests were expected to visit the center on Friday alone.
Hall said no surveillance cameras captured evidence of the gunshots Thursday morning, but a follow-up meeting on Friday discussed what new security measures should be in place.
"We are evaluating and looking to see is there more that we could do to hopefully bring an even greater level of security for anybody who would come on our campus morning, noon or night," Hall said.
NASA's inspector general's office and federal authorities are now helping with the investigation on who fired those shots.
The Space and Rocket Center has also been in touch with the Smithsonian regarding repairs to the Saturn V rocket.