Astra’s Rocket 3.1 blasts off from the company’s launch complex in Alaska. (Astra Photo) Back in the 1990s, cellular telecom pioneer Craig McCaw bought into a vision of ubiquitous wireless service via a constellation of satellites, with an assist from Microsoft co-founder Bill Gates. Almost a quarter-century later, McCaw’s Teledesic venture is long-dead, but the dream lives on — thanks to the impending merger of McCaw’s Holicity “blank check” company and Astra, one of the rising stars of the satellite launch industry. The deal — which takes advantage of the trend toward using special purpose acquisition companies, or SPACs, to take startups public — values Astra at a double-unicorn level of $2.1 billion, and would unlock up to $500 million in cash proceeds.