on the crew cabin after the Challenger disaster so that the orbiter could be easily identified while in orbit. From its last refit to its destruction, Columbia bore markings identical to those of its operational sister orbiters–the NASA "meatball" insignia on the left-wing and the American flag afore the orbiter's name on the right-wing. SILTS pod Another unique external feature, termed the "SILTS" pod (Shuttle Infrared Leeside Temperature Sensing), was located on the top of Columbia's vertical stabilizer, and was installed after STS-9 to acquire infrared and other thermal data. Though the pod's equipment was removed after initial tests, NASA decided to leave it in place, mainly to save costs, along with the agency's plans to use it for future experiments. The vertical stabilizer was later modified to incorporate the drag chute first used on Endeavour in 1992. OEX/MADS "black box" One unique feature that permanently stayed on Columbia from STS-1 to STS-107 was the OEX (Orbiter Experiments) box or MADS (Modular Auxiliary Data System) recorder. On March 19, 2003, this "black box" was found slightly damaged but fully intact by the U.S. Forest Service in San Augustine County in Texas after weeks of search and recovery efforts after the Space Shuttle Columbia disaster. The OEX/MADS was not designed to survive a catastrophic loss like an airplane black box. Other upgradesColumbia was originally fitted with Lockheed-built ejection seats identical to those found on the SR-71 Blackbird. These were active for the four orbital test flights, but deactivated after STS-4, and removed entirely after STS-9. Columbia was the only spaceworthy orbiter not delivered with head-up displays for the Commander and Pilot, although these were incorporated after STS-9. Like its sister ships, Columbia was eventually retrofitted with the new MEDS "glass cockpit" display and lightweight seats. Planned future Had Columbia not been destroyed, it would have been fitted with the external airlock/docking adapter for STS-118, an International Space Station assembly mission, originally planned for November 2003. Columbia was scheduled for this mission due to Discovery being out of service for its Orbital Major Modification, and because the ISS assembly schedule could not be adhered to with only Endeavour and Atlantis.Columbia's career would have started to wind down after STS-118. It was to service the Hubble Space Telescope two more times between 2004 and 2005. Following the Columbia accident, NASA flew the STS-125 mission using Atlantis, combining the planned fourth and fifth servicing