A dispute between Motorola Inc and its Iridium Inc unit could delay the satellite company’s $186m initial public offering, BusinessWeek reckons. It says the companies are arguing over when Iridium will be up and running, with Motorola saying in financial documents that there is a delay in the launch of the satellite service because of problems with McDonnell Douglas Corp’s rocket to launch the birds. A Delta II rocket blew up on January 17, leading to an investigation, but Iridium claims there is no excuse for the delay because Motorola had missed four scheduled launch dates before the explosion.