Engineering and testing errors by Northrop Grumman are to blame for the loss of a secret U.S. spy satellite, a new report says. Investigators apparently have found that a payload adapter modified by the aerospace and defense firm failed to deploy during the Zuma mission in January. The satellite never reached orbit after failing to separate from the SpaceX Falcon 9 rocket it was attached to. The Wall Street Journal cited unnamed sources in its report. The satellite was estimated to have cost $3.5 billion. — CNET