“…Shukor is keeping the details of his plans fluid until he is actually on board ISS, a point with which Dr. Khaleel Mohammed, assistant professor of religion at San Diego State University, concurs. “In space,” Mohammed points out, “the ritual prayer might be offset for more of a prayer that is allowed when on jihad … for the lack of gravity and directional accuracy makes it legitimate to do as one sees fit. God does not take a person to task for that which is beyond his/her ability to work with.”

“Questions like these will continue as more and more religious astronauts travel into space. When is sunset in low Earth orbit if you’re experiencing a dozen sunrises and sunsets in every 24-hour period? When does Sabbath begin on the moon, where the sun sets once a month? When is the first sighting of the crescent moon if you’re on Mars? Religious councils of all faiths will have plenty to keep them busy for years.”

http://www.wired.com/2007/09/mecca-in-orbit/