12:35 p.m. - The orbiter is rolling to the left in the first of several steep banking maneuvers. This series of rolls helps bleed off excess energy and slow the orbiter's speed. The atmospheric pressure is growing around Discovery and the orbiter's aerosurfaces are taking over control of the vehicle. 12:30 p.m. - Discovery is beginning to encounter the effects of the atmosphere, a point called "entry interface." Now flying at about 16,000 miles per hour, the orbiter is angled upward with wings level. The shuttle is set to touch down in just over 30 minutes.