That's a very engineering way to approach the problem. The issue it runs into is that the question "should we go to mars" isn't a settled matter that leads into

That's a very engineering way to approach the problem. The issue it runs into is that the question "should we go to mars" isn't a settled matter that leads into the question of "how do we go to mars". The first question is as flexible as the second. Getting to mars means that the question "can you have babies on mars" now becomes highly emotionally charged, which means the answer to "should you have babies on mars" becomes obvious. Without any pressure, the former question will always be answered by asking the latter.