Dissenting views on Mars sample return back contamination risks

The official NASA and ESA view and the view of the Planetary Protection Office is that samples returned from Mars present a biohazard concern, but that this risk can be adequately contained with use of a Mars Sample Receiving Facility and sample containment.

Robert Zubrin argues that the back contamination risk has no validity. Note however that he shouldn't be regarded as a supporter of the NASA and ESA plans for a sample return, as he also feels that a Mars sample return has little value at present. He considers that humans would return better, more useful samples at a later date.

The ICAMSR argue that it is not possible to contain the samples adequately at our present stage of knowledge of Mars and with present day technology. With Levin's approach, sample return is done after a series of biohazard testing experiments have been completed in situ on Mars, and in orbit.

These represent two extremes in the international public debate that will be required in the future, in case of a Mars sample return to Earth, see Mars Sample Return Legal Issues and International Public Debate

This article presents their views, along with critical material in separate sections.

Robert Zubrin's view that back contamination risk has no scientific validity
Robert Zubrin, president of the Mars society, presented this view in a published article and in interview. This is a transcript of an interview with him on March 30, 2001. First he refers to research that shows that the interior of a meteorite from Mars can remain below 40C throughout its journey to Earth, and so is not sterilized, and then continues.

See also the Back contamination section of Human Mars Exploration: The Time Is Now Journal of Cosmology, 2010, Vol 12, 3549-3557. JournalofCosmology.com, October-November, 2010

NOTE - HE WROTE A COMPLETE PAPER ON THIS TOPIC BUT I HAVEN'T BEEN ABLE TO OBTAIN IT. SO THIS IS NOT A COMPLETE STATEMENT OF HIS VIEWS His paper: "Contamination From Mars: No Threat", The Planetary Report July/Aug. 2000, P.4–5

His current view however is that no MSR is needed at all before human colonization, see

NRC conclusions on relevance of martian meteorites to back contamination risks
This is considered in the NRC report. They observe that a sample return is returned directly from Mars over a short time period, with no impact shock and protected in a capsule. They observe that though meteorites from Mars reach Earth every year, they are ejected from Mars only rarely in the larger impacts (large impacts are needed to achieve escape velocity).

Taking into account theoretical models, and measurements of aging of meteorites through cosmic radiation, they conclude that when there is a large impact on Mars, most of the debris takes a time period of between hundreds of thousands and millions of years to reach Earth, and during that time period much of any dormant life is sterilized by cosmic radiation. A small fraction, 0.01% is expected to reach Earth in less than a century, and some of the material is only lightly shocked. So transfer of life from Mars to Earth does seem possible but likely to happen rarely, and more common in the early solar system.

They considered reports of micro-organisms with radiation resistance adaptations that have been suggested as possible candidates for micro-organisms that have come from Mars originally, and conclude:

Robert Zubrin's view that there is no need for a MSR before human colonization of Mars
Another advocate of vigorous study on the surface in place of a MSR at the current stage of exploration of Mars is Robert Zubrin, president of the Mars Society. He sees value in scientific study of Mars before a human colonization, but is of the opinion that the same objectives are better met using a vigorous program of robotic exploration.

He suggests an initial exploration stage with many rovers on the same model as Curiosity. As additional motivation for his approach, he suggests that humans post colonization of Mars can do far better sample return missions than a robotic mission can do now.: To assist editors in verification of paraphrase of Zubrin's views from: A curious future for Mars exploration

Then, writing an article himself in Space News in Dec. 3, 2012, he says as additional motivation for his approach, that humans post colonization of Mars can do far better sample return missions than a robotic mission can do now: from: Mars the Hard Way Space News, Dec. 3, 2012

Dissenting views of the ICAMSR on back contamination risks of a MSR
The International Committee Against Mars Sample Return (ICAMSR) is an advocacy group of scientists campaigning against plans for a fast MSR direct to Earth.

They take the stance that a sample return to the Earth surface should not be carried out at this stage, and that the samples need to be certified as "biosphere safe" in space or in-situ before they are transferred to the Earth’s surface. They cite as their main inspiration, Carl Sagan, who advocated considerable caution before samples are returned to Earth.

The ICAMSR are especially concerned, as was Carl Sagan, that a significant component of risk in biohazard release is the risk of human error, which has happened several times during the Apollo era attempts at containing the lunar samples. In particular they cite the example of an incident during the recovery of the Apollo 11 astronauts at sea. The hatch of the module was opened by divers, while the module was still in the sea, permitting lunar dust and any airborne micro-organisms to exit the module and enter the sea, in breach of the previously established planetary protection protocol for this landing.

Study In Situ followed by Return to the ISS or Earth orbital laboratory first
Gilbert Levin is motivated by concerns for back contamination of Mars, following the inspiration of Carl Sagan. For this reason, he recommends a 10 step sequence for returning Martian samples to Earth

His suggestion starts with a series of tests for micro-organisms in situ on Mars, including tests for biohazard potential to whatever extent is possible on Mars. They are then returned to the ISS.

Once in the ISS they need to be examined in secure biohazard facilities by volunteer scientists who are willing to give up their lives in the remote chance that a hazard is found that is of danger to life on Earth.

Finally, if they pass all the tests, they can be returned to secure biohazard labs on Earth for further testing (similarly to the ESF / NRC proposals). Once the samples are returned to Earth he recommends that laboratories should be provided for researchers all in the same location, rather than to send the samples to researchers in other locations for testing.

Issues with the use of quarantine periods in space to contain any biohazard
A 1997 study by the National Research Council found some issues with the use of humans in quarantine which would need to be addressed with any proposal that involves human quarantine, such as Levin's. First, the study raised the issue that it would be hard to know for sure if any detected anomaly was the result of contamination. How, they say, could sufficient certainty be achieved to justify destroying the returning spacecraft and its crew?

In the case of NASA's Lunar quarantine at the time of Apollo 11, one of the guiding principles permitted breach of quarantine in the case of danger to human life:

Indeed in practise containment was breached for a lesser reason than preservation of life; it was breached in order to prevent seasickness of the Apollo 11 astronauts during the sea landing. As Carl Sagan wrote about this incident:

So the issue here is whether it is politically or humanly feasible to have a policy that puts preservation of quarantine at a higher priority than preservation of the life of individual astronauts. If not, then it is unclear how much extra protection quarantine provides.

Another issue raised with this approach is that infection might not be the only biohazard to contain, since a returning organism could cause long term changes in our environment that does not turn up during a quarantine period with humans. There is also the issue of the latency period, that the astronauts may not show any signs of infection until after return from Earth.

The NRC study concluded that as a result of these issues, the human quarantine approach does not give guarantee of containment of any issues found.

Jeffrey Kargel in "Mars - A Warmer, Wetter Planet" considers an alternative possibility to death of the astronauts when he discusses the possibility of an indefinite quarantine in the case that an issue is found during the quarantine period. He has doubts about the workability of an indefinite quarantine on the Moon, and feels that a quarantine on a space station can't remain isolated indefinitely due to its low orbit and need to resupply, and suggests that "the most effective and practical lifetime quarantine would be on Mars".

ICAMSR Charter - certified safe in situ or in space first
The ICAMSR have as their main goal, that samples are certified safe in situ or in space first before they are returned to Earth.