The Unknowns claimed to have hacked a NASA website hosted at the Glenn Research Center on May 1, said Sally V. Harrington, a public affairs specialist with the center in Cleveland, Ohio, in an email statement.

"NASA security officials detected an intrusion into the site on April 20 and took it offline," she said. "The agency takes the issue of IT security very seriously and at no point was sensitive or controlled information compromised."

The Unknowns posted a of several weeks of hacking on Pastebin earlier this week, claiming to have also hit a subdomain belonging to the U.S. Air Force, the French Ministry of Defense and the European Space Agency, among others.

The group also claimed to have hacked the Bahrain Ministry of Defense, but the website actually belongs to the Ministry of Development in Brunei, a small nation on Borneo next to Malaysia.

The Unknowns released about 215MB of documents that it said came from the U.S. Air Force. The information varied from receipts for expense reports to documents related to emergency communications plans. Many documents were dated 2012, and some carried the label "unclassified." U.S Air Force officials did not have an immediate comment.