Paying passengers have lined up to rocket to space to experience a few minutes of weightlessness. Now some are seeking a bigger thrill: spacewalking. The stage is set Thursday for the first private spacewalk when a tech billionaire and his crew will attempt the feat. To date, 263 astronauts representing a dozen countries have popped open the hatch. Experts say it’s inevitable that non-professionals will end up performing spacewalks and worry the wealthy could try to jump to the front of a spacewalking line with minimal training. For safety, the latest spacewalkers will always keep a foot or hand on the capsule.