Mission Specialist Valery Ivanovich Tokarev tries on an oxygen gas mask during Terminal Countdown Demonstration Test TCDT activities at Launch Pad 39B.

STS-96 Mission Specialist Valery Ivanovich Tokarev, with the Russian Space Agency, tries on an oxygen gas mask during Terminal Countdown Demonstration Test (TCDT) activities at Launch Pad 39B. The TCDT provides the crew with simulated countdown exercises, emergency egress training and opportunities to inspect the mission payloads in the orbiter's payload bay. Other crew members taking part in the TCDT are Commander Kent V. Rominger, Pilot Rick Douglas Husband, and Mission Specialists Tamara E. Jernigan (Ph.D.), Daniel Barry (M.D., Ph.D.), Ellen Ochoa (Ph.D.) and Julie Payette, with the Canadian Space Agency. Scheduled for liftoff on May 20 at 9:32 a.m., STS-96 is a logistics and resupply mission for the International Space Station, carrying such payloads as a Russian crane, the Strela; a U.S.-built crane; the Spacehab Oceaneering Space System Box (SHOSS), a logistics items carrier; and STARSHINE, a student-led experiment