The phrase "whipping a dead horse" means to attempt to revive a moot point or issue. "Whipping a pile of horse bones" means to keep making futile and pointless attempts to revive interest in something that no one has cared about for so long its rotted away into a skeleton of its former self.

The safeguarding of Earth and other worlds from biological cross-contamination (i.e. billionaires with too much time on their hands).

Also known as “planetary protection.” Planetary protection / quarantine “reflects both the unknown nature of the space environment and the desire of the scientific community to preserve the pristine nature of celestial bodies until they can be studied in detail.”

There are two types of interplanetary contamination. Forward contamination is the transfer of viable organisms from Earth to another celestial body. Back contamination is the transfer of extraterrestrial organisms, if such exist, back to the Earth's biosphere.