1.   Astronauts have problems moving around in the spacecraft because they are virtually weightless.

2.   Astronauts have special breathing apparatus.

3.   The astronauts had mind-blowing views of planet Earth.

4.   Astronauts do have their vision, hearing and blood pressure checked, much like commercial pilots.

5.   Astronauts have to ace psychological tests of self-sufficiency, patience and ability to tolerate isolation.

6.   Astronauts in simulators have practiced missteps and recoveries endlessly to give them as much experience as possible in sidestepping disaster.

7.   Astronauts will have to rely on the system when they dock space shuttles to the planned international space station.

8.   Astronauts still have repairs to do on the Mir space station.

9.   Because the interim control module also uses a different docking mechanism than Zvezda, astronauts would have to reconfigure the dock in the Zarya module now in orbit.

10.   After earlier long flights, astronauts often had trouble recovering.