Historically, the U.S.’s big launchers fly seldom enough that their costs are dominated by annual upkeep of facilities and staff, not by the actual cost of each launch. The expensive part is maintaining the launch capability, not actually conducting launches. Henry Spencer Read Quote
Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it’s hard to make it pay off – Moon bases are expensive, and just buying more rockets to launch fuel from Earth is relatively cheap. Henry Spencer Read Quote
Liquid oxygen is one of the cheapest manufactured substances on Earth. In large quantities, it costs pennies per kilogram – cheaper than milk or beer. Henry Spencer Read Quote
Rocket engines generally are simpler than jet engines, not more complicated. Henry Spencer Read Quote
