LOOKING BACK

1993: in a serious setback for NASA, engineers lost contact with the Mars Observer spacecraft as it was about to reach the red planet on a $980 million mission.

2015: a trio of Americans, U.S. Air Force Staff Sgt. Spencer Stone, National Guardsman Alek Skarlatos and college student Anthony Sadler, and a British businessman,

Chris Norman, tackled and disarmed a Moroccan gunman on a high-speed train between Amsterdam and Paris.