Although astronomers and astrobiologists discussed planetary protection as early as 1956, they didn't really mobilize until 1958. In the spring of that momentous year, the National Academy of Sciences created the Space Science Board to study the scientific aspects of the human exploration of space.
By June, the academy, based on the board's recommendations, shared its concerns about contamination with the International Congress of Scientific Unions (ICSU), hoping to make the issue a global concern. What did the ICSU do? Form a committee on Contamination by Extraterrestrial Exploration (CETEX) to evaluate whether human exploration of the moon, Venus and Mars could lead to contamination. The CETEX folks reasoned that terrestrial microorganisms would have little hope of surviving on the moon, but that they might be able to eke out an existence on Mars or Venus. As a result, CETEX recommended that humans send only sterilized space vehicles, including orbiters that could have accidental impacts, to those planets.
By the fall of 1958, the ICSU decided it was time to form yet another planetary protection committee. This one, known as the Committee on Space Research, or COSPAR, eventually came to oversee the biological aspects of interplanetary exploration, including spacecraft sterilization and planetary quarantine. COSPAR replaced CETEX. Got that?
At the same time, NASA was being born in the United States. In 1959, Abe Silverstein, NASA's director of Space Flight Programs, made the U.S. space agency's first formal statements about planetary protection:
The National Aeronautics and Space Administration has been considering the problem of sterilization of payloads that might impact a celestial body. ... As a result of the deliberations, it has been established as a NASA policy that payloads which might impact a celestial body must be sterilized before launching.
That same year, planetary protection responsibilities bounced around within NASA like an orphaned child. They were delegated first to the Office of Life Sciences and then to the Office of Space Science and Applications. In 1963, within that office's Biosciences Programs, the Planetary Quarantine Program began and eventually oversaw several Apollo mission activities, such as shielding moon rocks from terrestrial contamination and protecting Earth from lunar wee beasties, if they existed.
In 1976, the Planetary Quarantine Program became the Office of Planetary Protection, and the PQ Officer became the Planetary Protection Officer (PPO). Today, the PPO is still a major player when it comes to shaping NASA missions. He or she consults with internal and external advisory committees and then provides guidance on, well, just about everything, from how a spacecraft must be assembled to how samples from other celestial bodies are collected, stored and returned to Earth.
As you can imagine, the mission teams don't always love the PPO because his or her recommendations make their jobs harder. But then again, who cares? The PPO has a very profound -- and a profoundly difficult -- task, which is to protect life in the galaxy at all costs.