 Rocket Lab USA Inc has confirmed its initial public offer IPO in a blank cheque deal that will value it at US4.1bn and raise cash to challenge Elon Musks SpaceX Falcon 9 spacecraft. With 18 missions under its Orions Belt over the past four years, the small rocket launch company announced overnight that it plans to list in New York via a merger with a special purpose acquisition company SPAC called Vector Acquisition Corp NASDAQ:VACQ. 