The answer was provided by NASA in the form of 'Insurance Covers', as seen here, a number of which were given to every crew member and subsequently signed by every astronaut involved, as close to launch as possible. Its value would instantly be high, but would no doubt sky-rocket (no pun intended) should the astronauts never return; the deceased's surviving family then at least safe in the knowledge that in future they could cash-in their makeshift insurance policy if required.

During the Apollo space program, astronauts were apparently ineligible for traditional life insurance. So they and NASA came up with an innovative solution. Link (with photos of two additional covers). Via Reddit