Depleted uranium

The DU penetrator of a 30 mm round from the GAU-8 Avenger

01Hanson's 1998 paper listed nine developmental steps from dead matter to star-colonizing civilization; each step is a candidate filter.
02Finding microbial life on Mars, Hanson argues, would be the worst possible news — it suggests the filter lies ahead, not in abiogenesis.
03Hanson also developed 'futarchy,' a governance system where policy is decided by prediction markets rather than elected officials.

The US Army fired roughly 300 tons of depleted uranium rounds into Iraq and Kuwait, then left the radioactive debris in the sand. Birth defect rates in Basra spiked in the years that followed.