1.   An experiment involving two crew members, Japanese heart surgeon Chiaki Mukai and payload commander Rick Hieb, was under way for much of the day Thursday.

2.   Dr. Janice Voss, on her fourth space mission, is the payload commander.

3.   Its most experienced member is Kathryn Thornton, the payload commander and a member of the spacewalk team that repaired the Hubble Space Telescope two years ago.

4.   The research team is led by payload commander Rick Linnehan.