HOUSTON -- Friday marks 16 years since seven astronauts were killed in the space shuttle Columbia disaster.The crew launched on Jan. 16, 2003. Onboard were Rick D. Husband, Commander; William C. McCool, Pilot; Michael P. Anderson, Payload Commander; David M. Brown, Mission Specialist; Kalpana Chawla, Mission Specialist; Laurel Blair Salton Clark, Mission Specialist and Ilan Ramon, Payload Specialist.For 16 days, they worked on 80 experiments , conducting research in physical, life, and space sciences.They returned on Feb. 1, 2003. An investigation would later determine that tiles damaged during lift-off allowed super-heated atmospheric gasses to penetrate the shuttle's wing during re-entry, causing the ship to become unstable and quickly disintegrate. The crew was not told about any risk and didn't know something was wrong until very late in re-entry, according to ABC News The space shuttle broke apart during its return to Earth over Texas.This time of year marks multiple somber anniversaries for NASA. The Apollo 1 fire that killed three was on Jan. 27, 1967. On Jan. 28, 1986, the Challenger space shuttle broke apart shortly after takeoff, killing all seven onboard.