[Purdue77]

There wasn't enough information in the article to make any judgments about why his mission was classified then and why it should be classified today. To answer your generic question, you need to review EO13526. There are a number of conditions applied to classifying information. One would be the perceived harm done to the country if the information was known. The second would be the category that the information would fall. See below for the current categories. Having said that, it may be possible that the information about his mission so many years ago under went an automatic declassification review and was deemed unclassified.

From EO 13526

Sec. 1.4. Classification Categories. Information shall not be considered for classification unless its unauthorized disclosure could reasonably be expected to cause identifiable or describable damage to the national security in accordance with section 1.2 of this order, and it pertains to one or more of the following:

(a) military plans, weapons systems, or operations;

(b) foreign government information;

(c) intelligence activities (including covert action), intelligence sources or methods, or cryptology;

(d) foreign relations or foreign activities of the United States, including confidential sources;

(e) scientific, technological, or economic matters relating to the national security;

(f) United States Government programs for safeguarding nuclear materials or facilities;

(g) vulnerabilities or capabilities of systems, installations, infrastructures, projects, plans, or protection services relating to the national security; or

(h) the development, production, or use of weapons of mass destruction.

[Rusty0604]

Thanks.

[Rusty0604]

Thanks.