The Mars Science Lab project that sent the Curiosity rover to Mars cost about $2.5 billion in eight years.
In the same eight year period, an estimated $584 billion was lost in US tax revenue due to the religious tax exemptions.
Imagine the Possibilities
I think in reality, if the money from religions were taxed it would more likely be spent on wars rather than space exploration or other important thing like medicine and sustainable food sources energy and water supply!
I would actually like to know more about policies on taxing groups. It is strange to think a group that is non-religious yet has a positive motive would still be taxed... Yes, imagine the possibilities of all that bank.