The shuttle Endeavour docked with the station Wednesday night, and shares it with a Russian Progress resupply craft that arrived in February. The shuttle is slated to leave March 24. Europe's robotic cargo ship arrives April 3. Four days later Progress leaves, while a Russian Soyuz craft arrives April 10 for a crew swap. And next year, Japan is expected to add its automated resupply ship to the mix.

"That's quite a traffic flow. We're thinking about launching an air-traffic controller soon to keep it all straight," quips Mr. Shireman, the National Aeronautics and Space Administration's deputy program manager for the International Space Station.