There are 3.5 billion reasons to get to know AST SpaceMobile.Long-term investors shouldn't make decisions about buying or selling a stock based on a single event. Data from a quarterly earnings report, for example, should be monitored, reviewed, and added to an investor's mental database. But a quarterly report is just a single snapshot of the company's business.Yet in the case of AST SpaceMobile (ASTS -0.72%), there is one upcoming event to which investors looking for a growth opportunity should be paying ...