WASHINGTON — NASA announced July 9 two new directives regarding planetary protection for missions to the moon and Mars that implement recommendations of an independent review board last year.

The directives reflect “how NASA has evolved on its thinking as it relates to forward and backward harmful biological contamination on the surface of the moon and, of course, on Mars,” Bridenstine said.

The first of what are formally known as NASA Interim Directives revises planetary protection classification of the moon.

The second directive addresses future human missions to Mars, a planet with much greater planetary protection requirements.

The Mars directive doesn’t change the planetary protection requirements for missions to that planet, but instead calls for studies for how to do so.

Among its recommendations was reclassifying much of the moon from Category 2 to Category 1, as well as for NASA to develop planetary protection guidelines for future Mars missions.

The NASA directives apply to the agency’s own missions as well as those in which the agency participates in some way, such as joint missions with other agencies or commercial missions where NASA is a customer.