Dissenting views on Mars sample return back contamination risks
|Editor's note: This article needs attention. This is based on part of the original Planetary protection for a Mars sample return - is it best separated out or included - or transcluded?|
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[edit | hide all | hide | edit source]
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.
If you want to get a sense of this. Close to two trillion kilograms of Martian material has been transferred to Earth over the past 3.5 billion years in which the surface of Earth could support life. And from at least a thousand different sites on the surface of Mars. And so the stuff about back contamination simply has no scientific validity whatsoever.Robert Zubrin
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 #Robert Zubrin's view that there is no need for a MSR before human colonization of Mars
NRC conclusions on relevance of martian meteorites to back contamination risks[edit | hide | edit source]
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:
"Despite suggestions to the contrary, it is simply not possible, on the basis of current knowledge, to determine whether viable martian life forms have already been delivered to Earth. Certainly in the modern era, there is no evidence for large-scale or other negative effects that are attributable to the frequent deliveries to Earth of essentially unaltered martian rocks. However, the possibility that such effects occurred in the distant past cannot be discounted. Thus, it is not appropriate to argue that the existence of martian meteorites on Earth negates the need to treat as potentially hazardous any samples returned from Mars via robotic spacecraft."
Robert Zubrin's view that there is no need for a MSR before human colonization of Mars[edit | hide | edit source]
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.: 
Dissenting views of the ICAMSR on back contamination risks of a MSR[edit | hide | edit source]
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[edit | hide | edit source]
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[edit | hide | edit source]
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:
2. The preservation of human life should take precedence over the maintenance of quarantine.
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:
"The one clear lesson that emerged from our experience in attempting to isolate Apollo-returned lunar samples is that mission controllers are unwilling to risk the certain discomfort of an astronaut – never mind his death – against the remote possibility of a global pandemic."
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.
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[edit | hide | edit source]
See also[edit | hide | edit source]
- Discussion of science value of a Mars sample return - relevant to decisions about whether or not to proceed with the mission
References[edit | hide | edit source]
- Robert Zubrin "Contamination From Mars: No Threat", The Planetary Report July/Aug. 2000, P.4–5
- transcription of a tele-conference interview with ROBERT ZUBRIN conducted on March 30, 2001 by the class members of STS497 I, "Space Colonization"; Instructor: Dr. Chris Churchill
- "5: The Potential for Large-Scale Effects"". Assessment of Planetary Protection Requirements for Mars Sample Return Missions (Report). National Research Council. 2009. p. 48.
Despite suggestions to the contrary, it is simply not possible, on the basis of current knowledge, to determine whether viable martian life forms have already been delivered to the Earth. Certainly in the modern era there is no evidence for large-scale or other negative effects that are attributable to the frequent deliveries to Earth of essentially unaltered martian rocks. However the possibility that such effects occurred in the distant past cannot be discounted. Thus it is not appropriate to argue that the existence of martian microbes on Earth negates the need to treat as potentially hazardous any samples returned from Mars via robotic spacecraft.
- Jeff Foust A curious future for Mars exploration thespacereview.com, Monday, August 13, 2012
- Robert Zubrin Mars the Hard Way Space News, Dec. 3, 2012
- To assist editors in verification of paraphrase of Zubrin's views
from: A curious future for Mars exploration
I believe the program has become overfocused on sample return,” Zubrin said. While he supported robotic exploration for Mars as a step towards human missions, he worried that trying to land on Mars, collect samples, place them into a rocket that launches them into Mars orbit for later retrieval and return to Earth may be too complex. “I think that extrapolating the robotic program to sample return is taking it beyond when it beneficially trades off against human exploration,” he said.
“I do not see how sample return, as such, is vital for human exploration, and I think that saying that it is actually creates an obstacle to human exploration,” Zubrin said. Zubrin instead supports an “aggressive” program of rover missions, based on the highly-successful MERs. “Here we have a very successful system, why don’t we churn these things out, start sending two of them every two years to Mars, different locations with different instruments, conducing different kinds of investigations, make them into a workhorse,” he said. Doing so, he said, could reduce the cost of each mission to $200–400 million, far less than the estimated $2.5 billion cost of Curiosity.
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
It is certainly possible to propose alternative robotic mission sets consisting of assortments of orbiters, rovers, aircraft, surface networks, etc., that might produce a greater science return than the Mars sample return mission, much sooner, especially in view of the fact that human explorers could return hundreds of times the amount of samples, selected far more wisely, from thousands of times the candidate rocks, than a sample return mission.
- International Committee Against Mars Sample Return.
- Barry E. DiGregorio The dilemma of Mars sample return August 2001 Vol. 31, No. 8, pp 18–27..
- Safe methods for MSR
- The Human Exploration of Space, By Committee on Human Exploration, National Research Council, 1997
- Richard S. Johnston John A. Mason Bennie C. Wooley, Ph.D.[*] Gary W. McCollum Bernard J. Mieszkuc BIOMEDICAL RESULTS OF APOLLO, SECTION V, CHAPTER 1, THE LUNAR QUARANTINE PROGRAM Lyndon B. Johnson Space Center
- Carl Sagan,The Cosmic Connection - an Extraterrestrial Perspective (1973) ISBN 0521783038
It is no use arguing that samples can be brought back safely to Earth, or to a base on the Moon, and thereby not be exposed to Earth. The lunar base will be shuttling passengers back and forth to Earth; so will a large Earth orbital station. The one clear lesson that emerged from our experience in attempting to isolate Apollo-returned lunar samples is that mission controllers are unwilling to risk the certain discomfort of an astronaut – never mind his death – against the remote possibility of a global pandemic. When Apollo 11, the first successful manned lunar lander, returned to Earth – it was a spaceworthy, but not a very seaworthy, vessel – the agreed-upon quarantine protocol was immediately breached. It was adjudged better to open the Apollo 11 hatch to the air of the Pacific Ocean and, for all we then knew, expose the Earth to lunar pathogens, than to risk three seasick astronauts. So little concern was paid to quarantine that the aircraft-carrier crane scheduled to lift the command module unopened out of the Pacific was discovered at the last moment to be unsafe. Exit from Apollo 11 was required in the open sea.
- For editor verification of the paraphrase
Using the return flight as an incubation period and the crew as guinea pigs (as has been suggested) is not a solution to back contamination on human missions. Would the whole mission be risked if an unanticipated contamination occurred? How would the cause of the infection be known with enough certainty to justify destroying the returning spacecraft before it entered Earth's atmosphere? The whole spacecraft, not only the astronauts, would be contaminated. In addition infection might not be the only risk. A returning organism could possibly cause some long-term changes in our environment, perhaps remaining undetected for a while. Although such an event may be judged to have a very low probability, a convincing case that prudence has been exercised will have to be made to the public. (Page 30)
- Mars - A Warmer, Wetter Planet. Springer. 2004. p. 440.
What if the astronauts should fall ill on the return journey? How would we quarantine them? On a space station? Space stations eventually return to Earth; until they crash, they must be resupplied. Quarantine at a moon base? That would be expensive and requires resupply. Would it be a lifetime quarantine? How could anybody deal with that? The most effective and practical lifetime quarantine would be on Mars, where the astronauts, by design, could raise families and build an infrastructure. The astronauts would venture forth from Earth much a Europeans and Polynesians of the last two milenia ventured across the seas, knowing that return was unlikely. Hopefully and most likely, fears of a Martian Andromeda Strain will not be realised.
- ICAMSR - Charter