The Spy Satellite So Stealthy that the Senate Couldn't Kill It: "When first launched from the space shuttle Atlantis on March 1, 1990, it was believed to be the first advanced KH-11 spacecraft (the first of which would be launched in 1992). Within weeks, both U.S. and Soviet sources reported it had malfunctioned and would make a "fiery reentry . . . in the next 30 days."

Both assessments were wrong. The payload was a stealth imaging satellite code-named MISTY, which had been developed under the supervision of the DS&T's development and engineering office."

(Via The National Security Archive.)