02/1967 - Apollo 1 fire
01/1986 - Challenger disaster (19 yrs later)
02/2003 - Columbia disaster (17 yrs later)
It's been 23 years since Columbia, and there seems to be a 20-ish year rhythm to NASA disasters where the organization learns lessons, becomes more careful... and then standards potentially slip.
02/1967 - Apollo 1 fire
01/1986 - Challenger disaster (19 yrs later)
02/2003 - Columbia disaster (17 yrs later)
It's been 23 years since Columbia, and there seems to be a 20-ish year rhythm to NASA disasters where the organization learns lessons, becomes more careful... and then standards potentially slip.