SpaceX founder Elon Musk recently presented his plan for human colonisation of Mars, and one of the most widely quoted comments has been:
If you want to be on the frontier, where things are super exciting even if it’s dangerous, that’s who we’re appealing to. I would not suggest sending children. Are you prepared to die? If that’s ok, you’re a candidate for going.
which brings to mind the closing lines of W.B. Yeats’ “An Irish Airman foresees his Death” (written during World War I, full poem here):
I balanced all, brought all to mind,
The years to come seemed waste of breath,
A waste of breath the years behind
In balance with this life, this death.