The satellite cell-service provider has big ambitions but little so far to show for its efforts. It will have to spend a lot of money before the business takes off.AST SpaceMobile (ASTS 0.95%) has an interesting business plan, which is basically designed to ensure that cellphone users can make calls from anywhere on the planet. How? By creating a space-based cellular broadband telecommunications network.The idea of no more dead zones is attractive, but it will take a lot of cash to get the company to a poin ...