As we enter a new era of civil, commercial, and public-private partnership planetary exploration, attention has turned to planetary protection. The guidelines for this, laid down in the 50’s and 60’s to ensure that the scientific search for life in our solar system isn’t compromised by forward contamination from Earth and extended in the 70’s to protect the Earth from backward contamination from other planets, are now seen by many as being outdated.
Backward contamination, discussed by the great Carl Sagan himself in Cosmic Connection (1973) and Cosmos (1980), tends to get all the tabloid coverage and yet is generally considered to be the lesser concern. Aerospace engineer Robert Zubrin, a controversial critic of planetary protection, points to the 1,000 pounds of Martian meteorite that strike Earth every year as apparent evidence that if there were microbial life on Mars, which has yet to be confirmed, then it is already here.
Forward contamination, on the other hand, is, with the possible exception of tardigrades on the moon, less sensational and yet the threat it poses to research into the existence of extraterrestrial life is seemingly incontrovertible. What is questioned, by outgoing NASA Administrator Jim Bridenstine among others, is whether the concerns of this small subset of the scientific community warrant the additional costs and restriction they place on space exploration and research.
So controversial has planetary protection become that some have called for the term itself, which U.S. State Department lawyer Gabriel Swiney says “sounds like an absolute,” to be replaced by the more nuanced term “harmful contamination.” Others, such as planetary scientists Len Fisk and Meenakshi Wadhwa, while welcoming review, warn against discarding a technical term which is understood and has been forwarded for international agreement.