It's a good news, horrible news kind of a day for investors in cellphone-to-satellite-to-cellphone company AST SpaceMobile (ASTS -20.79%), as shares of one of the world's more popular space stocks plunge 25.2% through noon ET on Friday.The good news is that AST just announced a plan to get hold of the cash it needs to finish building out its constellation of satellites, providing the world's cellphone users a means of calling anyone from anywhere via satellite. The bad news is that getting hold of this cash ...