User:Robertinventor/Back contamination from Mars

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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.

The proposed NASA Mars Sample Return mission will not be approved by NASA until the National Environmental Policy Act (NEPA) process has been completed. The NEPA process would require a public review of all potential impacts that could result from MSR, including worst case back contamination scenarios. It is likely that a formal Environmental Impact Statement (EIS) would have to be prepared. The quarantine situation would also need to be clarified. There are also numerous international regulations and treaties to be negotiated in the case of a Mars Sample Return, especially those relating to environmental protection and health.

The ESF report ends with a series of recommendations. On the need for public debate they say

Several other papers and studies have come to the same conclusion.

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.