Main Engine Cut Off

The first of what are formally known as NASA Interim Directives revises planetary protection classification of the moon. Mission to the moon had been in Category 2, which required missions to document any biological materials on board but set no cleanliness standards on them. That classification was driven by concerns spacecraft could contaminate water ice at the lunar poles.

Under the new directive, most of the moon will be placed in Category 1, which imposes no requirements on missions. The exceptions will be the polar regions — north of 86 degrees north latitude and south of 79 degrees south latitude — which will remain in Category 2. Regions around Apollo landing “and other historic sites” will also be in Category 2, primarily to protect biological materials left behind by the crewed Apollo landings.