Jeff Bezos achieved two technological milestones in barely 24 hours.<br />His Twitter debut quickly landed him in an online spat with another billionaire with space ambitions: Elon Musk, whose Space Exploration Technologies Corp. wants to bring back Falcon 9 rockets to upright touchdowns after hoisting commercial payloads to orbit.<br />"Not quite 'rarest,' " Musk replied via Twitter, citing SpaceX's completion of six suborbital flights by its experimental Grasshopper rocket three years ago.<br />Blue Origin's craft took off Monday from the company's west Texas launch site, reached an altitude of 329,839 feet , deployed a capsule and then landed vertically atop a pillar of flame from its engine.<br />Musk, 44, initially offered kudos to Blue Origin and Bezos in a tweet, writing , "Congrats to Jeff Bezos and the BO team for achieving" vertical takeoff and landing.
