Commander Kevin Kregel, Pilot Dom Gorie, and Mission Specialists Janice Voss, Janet Kavandi, Gerhard Thiele and Mamoru Mohri blasted off 14 minutes into the available 2 hour plus launch window at 11:44 a.m. Central time after a near flawless countdown, and arrived on orbit 8 ½ minutes later. The slight delay in launching Endeavour was due to the launch team needing a few minutes to resolve some minor technical issues before proceeding with the final portion of the countdown.
The STS-99 crew's first tasks were to set up Endeavour for dual shift, round-the-clock operations using a trio of radar systems mounted in the cargo bay for the most comprehensive three-dimensional map of the Earth ever attempted.
Once Endeavour's payload bay doors are opened, the Red Team of Kregel, Kavandi and Thiele will begin to activate the Shuttle radar instruments, and will prepare for the deployment of a 200-foot long boom over the left wing of the orbiter on which two of the radar systems are housed. That boom deploy will begin about 5 ½ hours into the mission.
Kregel, Kavandi and Thiele will conduct a series of jet thruster firings once the boom is deployed to test its ability to flex properly and will set up recorders on board on which the radar data will be stored for downlink to mission scientists on the ground.
Meantime, the Blue Team of Gorie, Voss and Mohri will begin an abbreviated six hour sleep period at 3:44 p.m. They'll be awakened at 9:44 p.m., soon after the radar boom has been checked out, to begin radar mapping operations late tonight.
Endeavour is orbiting the Earth in an orbit inclined 57 degrees to either side of the Equator for the radar mapping of around 80 per cent of the Earth's surface. Endeavour is orbiting the planet every 90 minutes at an altitude of about 127 nautical miles.