Sixth Endeavor flight. The Space Radar Laboratory-1 (SPL-1) payload in the cargo bay gave scientists detailed information on human-induced environmental changes from the natural forms of global change. The Measurement of Air Pollution from satellite (NAPS) was also in the cargo bay. It measured carbon monoxide in the troposphere and lower atmosphere. Landed at Kennedy Space Center, FL. on April 20, 1994. Mission Duration: 269 hours 49 minutes 30 seconds.