Elon Musk's SpaceX postponed the highly anticipated launch of its upgraded Starship megarocket, calling off Thursday's test after multiple countdown stops-and-starts.

SpaceX's attempted Starship launch follows the company's release of its IPO prospectus, which set the stage for what's likely to be a record offering.

SpaceX is poised to launch its gargantuan Starship rocket on its twelfth major test flight on Thursday, part of a high-stakes mission as the Elon Musk-led company preps for the largest initial public offering in history.

The 12th test flight will feature the third generation of the mega-rocket that’s expected to help NASA return astronauts to the moon.