"The Russians have requested that we don't hit their space station this time as hard as Apollo hit Soyuz back in 1975," says TIME's veteran aerospace watcher Jerry Hannifin. But that may not be an easy task. As the two spacecraft hurtle toward theirscheduled 9 am docking over Central Asia tomorrow, pilot Hoot Gibson will have to contend with a much more difficult linking than in the Apollo-Soyuz maneuver. "The Apollo and Soyuz capsules approached each other straight on," notes Hannifin. "This time, Mir will be stationary while the shuttle comes from underneath. The inertia of two 100-ton objects traveling at 17,500 miles per hour leaves no room for error. This will definitely be the most exciting part of the mission. But Hoot Gibson is an excellent pilot, and should handle it well."