( Reuters)-The fourth commercial flight of Jeff Bezos' space tourism venture Blue Origin, offering short suborbital joyrides to well-heeled thrill-seekers and celebrity guests, was due for liftoff on Tuesday from the company's launch site in rural west Texas. Blue Origin's New Shepard spacecraft was slated for launch at 8: 30 a.m. CDT( 1330 GMT) with six would-be citizen astronauts strapped into the crew cabin atop the fully autonomous launch vehicle, standing nearly six stories tall, outside Va