Most of the E-mail had come from NASA's Ames Biological Research Center in California, and the messages were routine requests for data confirmation. Many of the experiments were monitored from the ground, and scientists sometimes questioned the data they received. He scrolled down the messages, grimacing at yet another request for astronaut urine and feces samples. He kept scrolling, and paused at a new message.

This one was different. It did not come from Ames, but from a private-sector payload operations center. Private industry paid a number of experiments aboard the station, and he often received E-mail from scientists outside NASA. This message was from SeaScience in La Jolla, California. To, Dr. William Haning, ISS BioscienceSender, Helen Koenig, Principal InvestigatorRe, Experiment CCU#23 Archaeon Cell CultureMessage, Our most recent downlinked data indicates rapid and unexpected increase in cell culture mass.Please confirm with your onboard micro mass measurement device.

Another jiggle-the-handle request, he thought wearily. Many of the orbital experiments were controlled by commands from scientists on the ground. Data was recorded within the various lab racks, using video or automatic sampling devices, and the results downlinked directly to researchers on earth. With all the sophisticated equipment aboard ISS, there were bound to be glitches. That's the real reason humans were needed up here -- to troubleshoot the temperamental electronics.

He called up the file for CCU#23 on the payloads computer and reviewed the protocol. The cells in the culture were Archaeons, bacterialike marine organisms collected from deep-sea thermal vents.

They were harmless to humans.

He floated across the lab to the cell culture unit and slipped his stockinged feet into the holding stirrups to maintain his position. The unit was a box-shaped device with its own fluidhandling and delivery system to continuously perfuse two dozen cell cultures and tissue specimens. Most of the experiments were completely self-contained and without need of human intervention.