Two different concepts here.
First, "...world governments owe the money to their own citizens, not to the Martians." Actually governments owe the money to whomever they borrowed it from.
Second, the money the government uses to pay off that government debt, must come from taxes on people and corporate "people." The government has no wealth of its own, nor does it create any. The most it can do is run the printing presses which is money, not wealth.