User:Robertinventor/draft version of back contamination article as it was reverted mid edit by VQuakr

Back-contamination is the informal but widely employed name for the hypothetical introduction of microbial extraterrestrial organisms into Earth's biosphere. It is assumed that any such contact will be disruptive or at least have consequences over which human beings will have little control. The threat of back-contamination from the Moon was the main reason for quarantine procedures adopted for the Apollo program, up until the completion of Apollo 14. Astronauts and lunar samples were quarantined in the Lunar Receiving Laboratory.

The likelihood that a human being or any other animal could literally acquire an alien virus is effectively nil, as viruses are host specific. This does not mean that extraterrestrial microbes cannot act upon one pathogenically: spores might use an organism's body as hosts, while the ingestion of bacteria in any form could produce toxic chemicals. When human beings ingest contaminated food, for example, they are not acquiring a virus in the manner of the flu but the experience may still be lethal because of toxic compounds.

Further, the possibility exists that a microbe might aggressively metabolize some Earth resource were it introduced here, altering atmospheric conditions or the water cycle.

Back contamination from Mars
Since the Moon is now generally considered to be free from life, the most likely source of contamination is Mars. It would arise during a Mars sample return.

Since it is currently unknown whether or not life forms exist on Mars, the mission could potentially transfer viable organisms resulting in back contamination — the introduction of extraterrestrial organisms into Earth's biosphere. The mainstream scientific view as expressed by the NRC and ESF studies and the Office of Planetary Protection is that the risk of harmful back contamination is probably very low, but cannot be demonstrated to be zero. In the worst case scenario (thought to be very low probability) this could lead to environmental disruption and impact on countries outside the nation responsible for the mission. As a result, returned samples from Mars will be treated as potentially biohazardous until scientists can determine that they are safe.

The sample return mission will be designed to break the chain of contact between Mars and the exterior of the sample container, for instance, by sealing the returned container inside another larger container in the vacuum of space before return to Earth. In order to eliminate the risk of parachute failure, the current plan is to return the capsule to the Earth without the use of parachutes: the capsule will fall at terminal velocity and the impact will be cushioned by the capsule's thermal protection system. The sample container will be designed to withstand the force of the impact.

To receive the returned samples, NASA has proposed to build a biohazard containment facility - known as the Mars Sample Return Receiving facility (MSRRF).

The proposed sample return facility must be a biohazard level 4  laboratory. However, it must also contain unknown biohazards and the sizes of any putative Martian micro-organisms are unknown. In consideration of this, the ESF proposed additional requirements. Ideally it should contain particles of 0.01 µm, or larger, and release of a particle 0.05 µm or larger is unacceptable under any circumstances. Quotes from the ESF report to assist editors in verifying the paraphrase. See 3.Life as we know it and size limits, quotes are from 3.6 From new knowledge to new requirements European Science Foundation - Mars Sample Return backward contamination - Strategic advice and requirements

They then go on in view of the almost negligible chance of a GTA potential for large-scale effects on the Earth's biosphere, that

They recommend that in that case the requirements would need to be independently reviewed by a panel of experts to determine if it is the best that can be achieved at reasonable cost and if the risk is tolerable.

It also must double as a clean room to preserve the science value of the samples. A clean room is normally kept at a higher pressure than the external environmnent to keep contaminants out, and a biohazrad laboratory is kept at a lower pressure to keep the biohazards in. This introduces conflicting requirements and requires a novel architecture that will take some years from design to completion. Preliminary studies have warned that it may take as many as 7 to 10 years to get it operational and an additional two years is recommended for the staff to become accustomed to the facilities.

Legal requirements and need for public debate
The ESF report also considered the legal situation. In the event of a release of the contents of the MSR capsule during return to Earth then the state responsible has liability in respect to any damages caused under the Outer Space Treaty. This liability is unlimited in either amount or in time. The situation as regards liability is less clear if the release occurs after return to Earth.

Margaret Race has examined in detail the legal process of approval for a MSR. She found that under the National Environmental Policy Act (NEPA) (which did not exist in the Apollo era) a formal environment impact statement is likely to be required, and public hearings during which all the issues would be aired openly. This process is likely to take up to several years to complete.

During this process, she found, the full range of worst accident scenarios, impact, and project alternatives would be played out in the public arena. Other agencies such as the Environment Protection Agency, Occupational Health and Safety Administration, etc, may also get involved in the decision making process. The laws on quarantine will also need to be clarified as the regulations for the Apollo program were rescinded. In the Apollo era, NASA delayed announcement of its quarantine regulations until the day Apollo was launched, so bypassing the requirement for public debate - something that would be unlikely to be tolerated today.

It is also probable that the presidential directive NSC-25 will apply which requires a review of large scale alleged effects on the environment and is carried out subsequent to the other domestic reviews and through a long process, leads eventually to presidential approval of the launch.

Then apart from those domestic legal hurdles, there are numerous international regulations and treaties to be negotiated in the case of a Mars Sample Return, especially those relating to environmental protection and health, as well as domestic policies of other nations. She concluded that the public of necessity has a significant role to play in the development of the policies governing Mars Sample Return.

The ESF report has a shorter legal summary, and ends with a series of recommendations. On the need for public debate they say

Differing views on a MSR
Carl Sagan was first to raise back contamination concerns. In Cosmic Connection (1973) he writes:

This possibility has been confirmed in all the later studies, as the worst case scenario. It is considered low probability but can't be ruled out.

Later in Cosmos (1980) he wrote

The PPO and NASA and ESA view is that with present day technology, Martian samples can be safely returned to Earth provided the right precautions are taken.

There are dissenting views however.

The International Committee Against Mars Sample Return maintains that it is not possible to return samples to Earth safely at this stage. They urge more in situ studies on Mars first, and preliminary biohazard testing in space before the samples are returned to Earth.

At the other extreme, Robert Zubrin (Mars surface colonization advocate and director of the Mars Society) maintains that the risk of back contamination has no scientific validity.