|
|
| (One intermediate revision by one other user not shown) |
| Line 1: |
Line 1: |
| [[File:Viking Oven.jpg|thumb|right|300px|<center>A Viking lander being prepared for [[dry heat sterilization]] - this remains the "Gold standard" <ref>[http://solarsystem.nasa.gov/docs/PPCCTECHREPORT3.pdf Assessment of Planetary Protection and Contamination Control Technologies for Future Planetary Science Missions], Jet Propulsion Laboratory, January 24, 2011<br>''3.1.1 Microbial Reduction Methodologies:'' {{bq|"This protocol was defined in concert with Viking, the first mission to face the most stringent planetary protection requirements; its implementation remains the gold standard today."}}</ref> of present day Planetary protection.</center>]]
| | During the Neolithic Revolution, humans started consuming large amounts of dairy products, beans, cereals, alcohol and salt. Mediterranean diets are typically high in olive oil consumption as well as cereals,dairy products(primarily yoghurt and cheese)legumes,vegetables and fish. The diet revolves on the concept that modern humans adapted to the diet of our Paleolithic ancestors and that our genes have barely changed since the introduction of agriculture. Prepare to leave your unhealthy habits behind in exchange of a better lifestyle, best trim healthy whole body, and days active. Heat a medium size pan with 1 tablespoons of tallow over medium heat Now put ready cut small pieces of carrot in to the pan fry it for 3 minutes and remove them from pan. <br><br>We drive ourselves harder in the community of others. - Mix arugula, spinach, bacon bits, blackberries, egg bits, walnuts, cinnamon and nutmeg. - Nuts are cholesterol free and eating one ounce per day reduces the risk of heart disease and type 2 diabetes. These benefits could expand the health claims now permitted to be identified by the FDA. The traditional symbol for the forces of yin and yang, are two fish swimming head to tail. <br><br>And what's my Paleo Diet weight loss result so far. What the Paleo guides you thru is referred to as a back-to-basics mentality. Those that follow this program can expect a lot of red meat as well as fatty food. One thing that you will want to do is keep track of your weight to see if you are on the right rack to a healthier life. Varied cooking used in dessert, shakes, and drinks and baking. <br><br>The Isabel De Los Rios diet is focused mainly on what kinds of foods you are taking into your body and less on the time that you need to spend in the gym. This diet basically consumed lots of fruits and veggies and also lots of protein rich food. You can find such products with as little as 4 grams of carbs in an 16 ounce meal serving. Advocates who have adhered to the paleo diet can attest to the range of paleo foods there is to choose from -- many are already on your list of routinely consumed foods. Lunches also feature salads and add a meat source as well. <br><br>Nuts(non processed) - Nuts are cholesterol free and eating one ounce per day reduces the risk of heart disease and type 2 diabetes. In order to satisfy vegetable segment of your diet, there are numerous vegetables to select from. Thanks to her hard work, Kristin is now just a couple of pounds away from her pre-baby weight. Protein satisfies your appetite more than any other macronutrient, it increases metabolism, and it will contribute to weight loss. Are you looking for more information regarding Paleo Diet Grocery List. <br><br>Those cave men and women led very different lives than we do today. Desserts are put together from fruits like bananas and berries. "Base your diet on garden vegetables, especially greens, lean meats, nuts and seeds, little starch, and no sugar. A versatile plant also used as a cow's alternative. At least it should be supplemented for those of us that don't live outside year round, and don't eat liver again and again.<br><br>If you enjoyed this write-up and you would such as to get additional information relating to [http://gritsandgroceries.info/sitemap/ paleo pizza recipe] kindly see our own internet site. |
| {{Merge from|Interplanetary contamination|discuss=Talk:Interplanetary contamination#Merger proposal III|date=July 2013}}
| |
| | |
| '''Planetary protection''' is a guiding principle in the design of an [[interplanetary mission]], aiming to prevent biological contamination of both the target [[celestial body]] and the [[Earth (planet)|Earth]]. Planetary protection reflects both the unknown nature of the space environment and the desire of the scientific community to preserve the pristine nature of celestial bodies until they can be studied in detail.<ref name='Rummel 1989'>{{cite journal | title = Planetary protection policy overview and application to future missions | journal = Advances in Space Research | year = 1989 | first = John D. Rummel | volume = 9 | issue = 6 | pages = 181–184 | url = http://www.sciencedirect.com/science/article/pii/0273117789902275 | accessdate = 2012-09-11|bibcode = 1989AdSpR...9..181T |doi = 10.1016/0273-1177(89)90161-0 }}</ref><ref name="Wired-20131002">{{cite web |last=Portree |first=David S.F. |title=Spraying Bugs on Mars (1964) |url=
| |
| http://www.wired.com/wiredscience/2013/10/spraying-bugs-on-mars-1964 |date=2 October 2013 |work=[[Wired (magazine)]] |accessdate=3 October 2013 }}</ref>
| |
| | |
| There are two types of [[interplanetary contamination]]. '''Forward contamination''' is the transfer of [[Natural selection#Types of selection|viable]] [[organisms]] from Earth to another celestial body. A major goal of planetary protection is to preserve the planetary record of natural processes by preventing introduction of Earth originated life.<!-- needn't be microbial though to date that is the main concern, the Russian tardigrades experiment was an example of non microbial concern --> '''Back contamination''' is the transfer of [[Extraterrestrial life|extraterrestrial]] organisms back to the [[Earth]]'s [[biosphere]], if such exist.
| |
| | |
| ==COSPAR recommendations and categories==
| |
| | |
| The [[COSPAR|Committee on Space Research]] (COSPAR) meets every two years, in a gathering of 2000 to 3000 scientists,<ref>[https://cosparhq.cnes.fr/events/scientific-assemblies COSPAR scientific assemblies]</ref> and one of its tasks is to develop recommendations for avoiding interplanetary contamination. Its legal basis is Article IX of the Outer Space Treaty <ref name=marscontaminationOST>[http://www.nap.edu/openbook.php?record_id=11381&page=13 Preventing the Forward Contamination of Mars ( 2006 ) - Page 13]</ref> (see [[#History|history below for details]]).
| |
| | |
| Its recommendations depend on the type of space mission and the celestial body explored.<ref name="COSPAR PLANETARY PROTECTION POLICY">[http://science.nasa.gov/media/medialibrary/2012/05/04/COSPAR_Planetary_Protection_Policy_v3-24-11.pdf COSPAR PLANETARY PROTECTION POLICY] (20 October 2002; As Amended to 24 March 2011)</ref> COSPAR categorizes the missions into 5 groups:
| |
| *''Category I:'' Any mission to locations not of direct interest for chemical evolution or the origin of life. such as the [[Sun]], or [[Mercury (planet)|Mercury]]
| |
| *''Category II:'' Any mission to locations of significant interest for chemical evolution and the origin of life, but only a remote chance that spacecraft borne contamination could compromise investigations. Examples include the [[Moon]], [[Venus]], and [[comet]]s.
| |
| *''Category III:'' Flyby and orbiter missions to locations of significant interest for chemical evolution and/or origin of life, and with a significant chance that contamination could compromise investigations e.g., [[Mars]], [[Europa (moon)|Europa]], [[Enceladus (moon)|Enceladus]]
| |
| *''Category IV:'' Lander or probe missions to the same locations as Category III.
| |
| :: '''Missions to Mars in category IV are subclassified further:'''<ref name="COSPAR PLANETARY PROTECTION POLICY"/>
| |
| :*''Category IVa.'' Landers that do not search for Martian life - uses the Viking lander pre-sterilization requirements, 300,000 spores per spacecraft and 300 spores per square meter.
| |
| :*''Category IVb.'' Landers that search for Martian life. Adds stringent extra requirements to prevent contamination of samples.
| |
| :*''Category IVc.'' Any component that accesses a Martian ''[[Planetary protection#Mars Special Regions|Special Region]]'' (see below) must be sterilized to at least to the Viking post-sterilization biological burden levels (30 spores total per spacecraft).
| |
| *''Category V:'' This is further divided into unrestricted and restricted sample return.
| |
| :* Unrestricted Category V: samples from locations judged by scientific opinion to have no indigenous lifeforms. No special requirements
| |
| :* Restricted Category V: (where scientific opinion is unsure) the requirements include: absolute prohibition of destructive impact upon return, containment of all returned hardware which directly contacted the target body, and containment of any unsterilized sample returned to Earth. <!-- the details of how this is achieved isn't part of the actual guidelines as such, not yet anyway, so better discussed in its own section below I think. -->
| |
| | |
| After receiving the mission category a certain level of ''biological burden'' is allowed for the mission. In general this is expressed as a 'probability of contamination', required to be less than one chance in 10,000<ref name=EuropaStudy/><ref name=ColmanSagan/> of forward contamination per mission, but in the case of Mars Category IV missions (above) the requirement has been translated into a count of ''[[Bacillus]]'' spores per surface area, as an easy to use assay method.<ref>[http://astrobio.net/news/print.php?sid=2338 ''Keeping it clean'']</ref>
| |
| | |
| For restricted Category V missions, sterilization of the returned samples would destroy much of their science value. For proposals to fulfill the containment requirements, see [[#Containment and quarantine]] below. Of course, Category V missions also have to fulfill the requirements of Category IV to protect the target body from forward contamination.
| |
| | |
| ===Mars Special Regions===
| |
| | |
| A ''Special Region'' is a region classified by COSPAR within which terrestrial organisms could readily propagate, or one thought to have an elevated potential for existence of Martian life forms. This is understood to apply to any region on Mars where liquid water occurs, or can occasionally occur, based on the current understanding of requirements for life.
| |
| | |
| If a hard landing risks biological contamination of a Special Region, then the whole lander system must be sterilized to COSPAR category IVc.
| |
| | |
| ==Target categories==
| |
| Some targets are easily categorized. Others are assigned provisional categories by COSPAR, pending future discoveries and research.
| |
| | |
| The 2009 COSPAR Workshop on Planetary Protection for Outer Planet Satellites and Small Solar System Bodies covered this in some detail. Most of these assessments are from that report, with some future refinements. This workshop also gave more precise definitions for some of the categories:<ref name=smallsolarsystembodies>[http://www.gwu.edu/~spi/COSPAR_OP_PP_Workshop_final_Aug2009.pdf COSPAR Workshop on Planetary Protection for Outer Planet Satellites and Small Solar System Bodies] European Space Policy Institute (ESPI), 15–17 April 2009</ref><ref>[http://science.nasa.gov/media/medialibrary/2011/06/29/Rummel_COSPAR_COPUOS_PPS_9May11_-_TAGGED.pdf COSPAR power point type presentation, gives good overview of the detailed category decisions]</ref>
| |
| | |
| ===Category I===
| |
| | |
| * Io, Sun, Mercury, Undifferentiated metamorphosed asteroids
| |
| | |
| ===Category II===
| |
| | |
| {{quotation|… where there is only a remote chance that contamination carried by a spacecraft could jeopardize future exploration”. In this case we define “remote chance” as “the absence of niches (places where terrestrial micro-organisms could proliferate) and/or a very low likelihood of transfer to those places.” <ref name=smallsolarsystembodies/>}}
| |
| | |
| * Callisto, Comets, Asteroids of category P, D and C, Venus,<ref>[http://www.nap.edu/openbook.php?record_id=11584 Assessment of Planetary Protection Requirements for Venus Missions -- Letter Report]</ref> KBOs (< 1/2 size of Pluto)
| |
| | |
| ===Provisional Category II===
| |
| * Ganymede, [[Titan (moon)|Titan]], Triton, the Pluto-Charon system, and other large KBOs (> 1/2 size of Pluto),<ref>[http://www.gwu.edu/~spi/COSPAR_OP_PP_Workshop_final_Aug2009.pdf COSPAR Final]</ref> Ceres,
| |
| | |
| Provisionally they assigned these objects to Category II. However, they state that more research is needed, because there is a remote possibility that the tidal interactions of Pluto and Charon could maintain some water reservoir below the surface. Similar considerations apply to the other larger KBOs
| |
| | |
| [[Triton (moon)|Triton]] they thought was insufficiently well understood at present to say it is definitely devoid of liquid water. The only close up observations to date are those of Voyager 2.
| |
| | |
| In a detailed discussion of Titan, scientists concluded that there was no danger of contamination of its surface, except short term adding of negligible amounts of organics, but Titan could have a below surface water reservoir that communicates with the surface, and if so this could be contaminated.
| |
| | |
| In the case of Ganymede, the question is, given that its surface shows pervasive signs of resurfacing, is there any communication with its subsurface ocean? They found no known mechanism by which this could happen, and Galileo found no evidence of [[cryovolcanism]].
| |
| | |
| Initially they assigned it as Priority B minus, meaning that precursor missions are needed to assess its category before any surface missions. However after further discussion they provisionally assigned it to Category II, so no precursor missions required, depending on future research.
| |
| | |
| If there is cryovolcanism on Ganymede or Titan, the undersurface reservoir is thought to be 50 – 150 km below the surface. They were unable to find a process that could transfer the surface melted water back down through 50 km of ice to the under surface sea.<ref>[http://www.gwu.edu/~spi/COSPAR_Titan_Report2010_final.pdf COSPAR Workshop on Planetary Protection for Titan and Ganymede]</ref> This is why they assigned both Ganymede and Titan a reasonably firm provisional Category II but pending results of future research.
| |
| | |
| They recommended more generally, that icy bodies that show signs of recent resurfacing need further discussion and might need to be assigned to a new category depending on future research.
| |
| | |
| This approach has been applied, for instance, to missions to Ceres. The planetary protection Category is subject for review during the mission of the Ceres orbiter depending on the results found.<ref>Catharine Conley [http://www.lpi.usra.edu/sbag/meetings/jan2013/presentations/sbag8_presentations/MON_1530_ConleyDawn.pdf Planetary Protection for the Dawn Mission], NASA HQ, Jan 2013</ref>
| |
| | |
| ===Category III / IV===
| |
| | |
| {{quotation|“…where there is a significant chance that contamination carried by a spacecraft could jeopardize future exploration.” We define “significant chance” as “the presence of niches (places where terrestrial microorganisms could proliferate) and the likelihood of transfer to those places.” <ref name=smallsolarsystembodies/>}}
| |
| | |
| * Mars because of possible surface habitats
| |
| * Europa because of its subsurface ocean
| |
| * [[Enceladus (moon)|Enceladus]] because of evidence of water plumes.
| |
| | |
| ===Category V===
| |
| | |
| In the category V for sample return the conclusions so far are:
| |
| | |
| * Restricted Category V: Mars, Europa
| |
| * Unrestricted Category V: Venus, Moon
| |
| | |
| ===Other objects===
| |
| | |
| If there has been no activity for 3 billion years, it will not be possible to destroy the surface by terrestrial contamination, so can be treated as Category I. Otherwise, the category may need to be reassessed.
| |
| | |
| ==History==
| |
| | |
| The potential problem of lunar and planetary contamination was first raised at the International Astronautical Federation VIIth Congress in Rome in 1956.<ref>{{cite web | url=http://planetaryprotection.nasa.gov/history | author=NASA Office of Planetary Protection | accessdate= 2013-07-13 | title=Planetary Protection History}}</ref>
| |
| | |
| In 1958<ref>[http://www.nap.edu/openbook.php?record_id=11381&page=12 Preventing the Forward Contamination of Mars ( 2006 ) - Page 12 ]</ref> the U.S. National Academy of Sciences (NAS) passed a resolution stating, “The National Academy of Sciences of the United States of America urges that scientists plan lunar and planetary studies with great care and deep concern so that initial operations do not compromise and make impossible forever after critical scientific experiments.” This lead to creation of the ad hoc Committee on Contamination by Extraterrestrial Exploration (CETEX), which met for a year and recommended that interplanetary spacecraft be sterilized, and stated, “The need for sterilization is only temporary. Mars and possibly Venus need to remain uncontaminated only until study by manned ships becomes possible” In 1959 planetary protection was transferred to the newly formed Committee on Space Research (COSPAR). COSPAR in 1964 issued Resolution 26, which
| |
| | |
| {{quotation|affirms that the search for extraterrestrial life is an important objective of space research, that the planet of Mars may offer the only feasible opportunity to conduct this search during the foreseeable future, that contamination of this planet would make such a search far more difficult and possibly even prevent for all time an unequivocal result, that all practical steps should be taken to ensure that Mars be not biologically contaminated until such time as this search can have been satisfactorily carried out, and that cooperation in proper scheduling of experiments and use of adequate spacecraft sterilization techniques is required on the part of all deep space probe launching authorities to avoid such contamination.<ref>[http://www.nap.edu/openbook.php?record_id=11381&page=12 Preventing the Forward Contamination of Mars - p12] quotes from COSPAR 1964 Resolution 26</ref>}}
| |
| | |
| In 1967, most of the world's nations ratified the United Nations [[Outer Space Treaty]].
| |
| | |
| The legal basis for Planetary Protection lies in Article IX of this treaty:
| |
| | |
| {{quotation|"Article IX: ... States Parties to the Treaty shall pursue studies of outer space, including the Moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose...<ref>Full text of the Outer Space Treaty [http://www.unoosa.org/oosa/en/SpaceLaw/gares/html/gares_21_2222.html Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies]'' - See Article IX''</ref><ref name='CNES'>{{cite web | url = http://www.cnes.fr/web/CNES-en/5210-planetary-protection-treaties-and-recommendations.php | title = Planetary protection treaties and recommendations | accessdate = 2012-09-11 | author = Centre National d’Etudes Spatiales (CNES) | year = 2008}}</ref> }}
| |
| | |
| This treaty has been signed by almost all nations including the main space faring nations.
| |
| | |
| For forward contamination, the phrase to be interpreted is "harmful contamination", which could have varying meanings. However, an unofficial legal review concluded that Article IX must mean that “any contamination which would result in harm to a state’s experiments or programs is to be avoided”, and this is how it has come to be interpreted.<ref name=marscontaminationOST />
| |
| | |
| The 1979 [[Moon Treaty]] governing the activities of states on the Moon and other celestial bodies has more extended treatment of the subject of contamination, however it has not been ratified by any space faring nation to date:<ref name='CNES'/>
| |
| | |
| {{quotation|5.3. In carrying out activities under this Agreement, States Parties shall promptly inform the Secretary-General, as well as the public and the international scientific community, of any phenomena they discover in outer space, including the moon, which could endanger human life or health, as well as of any indication of organic life....<br><br>7.1. In exploring and using the moon, States Parties shall take measures to prevent the disruption of the existing balance of its environment, whether by introducing adverse changes in that environment, by its harmful contamination through the introduction of extra-environmental matter or otherwise. States Parties shall also take measures to avoid harmfully affecting the environment of the earth through the introduction of extraterrestrial matter or otherwise.}}
| |
| | |
| ==Current methodology, the Coleman-Sagan Equation==
| |
| | |
| The aim of the current regulations is to keep the number of micro-organisms low enough so that the probability of contamination of Mars (and other targets) is acceptable. It is not an objective to make the probability of contamination zero.
| |
| | |
| The aim is to keep the probability of contamination of 1 chance in 10,000 of contamination per mission flown.<ref name=EuropaStudy/> This figure is obtained typically by multiplying together the number of micro-organisms on the spacecraft, the probability of growth on the target body, and a series of bioload reduction factors.
| |
| | |
| In detail the method used is the Coleman-Sagan Equation.<ref>edited by Muriel Gargaud, Ricardo Amils, Henderson James Cleaves, Michel Viso, Daniele Pinti [http://books.google.co.uk/books?id=oEq1y9GIcr0C&pg=PA325&lpg=PA325&dq=Coleman+Sagan+equation Encyclopedia of Astrobiology, Volume 1] page 325</ref>
| |
| | |
| <math>P_c = N_0 R P_S P_t P_R P_g</math>.
| |
| | |
| where
| |
| : <math>N_0</math> = the number of micro-organisms on the spacecraft initially
| |
| : <math>R</math> = Reduction due to conditions on spacecraft before and after launch
| |
| : <math>P_S</math> = Probability that micro-organisms on the spacecraft reach the surface of the planet
| |
| : <math>P_t</math> = Probability that spacecraft will hit the planet - this is 1 for a lander
| |
| : <math>P_R</math> = Probability of micro-organism to be released in the environment when on the ground, usually set to 1 for crashlanding.
| |
| : <math>P_g</math> = Probability of growth. For targets with liquid water this is set to 1 for sake of the calculation.
| |
| | |
| Then the requirement is <math>P_c < 10^{-4}</math>
| |
| | |
| The <math>10^{-4}</math> is a number chosen by Sagan et al., somewhat arbitrarily. Sagan and Coleman assumed that about 60 missions to the Mars surface would occur before the exobiology of Mars is thoroughly understood, 54 of those successful, and 30 flybys or orbiters, and the number was chosen to endure a probability to keep the planet free from contamination of at least 99.9% over the duration of the exploration period.<ref name=ColmanSagan>Carl Sagan and Sidney Coleman [http://books.google.co.uk/books?hl=en&lr=&id=pUQrAAAAYAAJ&oi=fnd&pg=PA470&dq=coleman+sagan+equation&ots=a75yzxe9rP&sig=wEcN3zkVJTKD3LSRxAT9LvwGaBQ#v=onepage&q&f=false Decontamination Standards for Martian Exploration Programs, Chapter 28] from Biology and the Exploration of Mars: Report of a Study edited by Colin Stephenson Pittendrigh, Wolf Vishniac, J. P. T. Pearman, National Academies, 1966 - Life on other planets</ref>
| |
| | |
| ===Problems with the Coleman Sagan equation for Europa===
| |
| | |
| The Coleman Sagan equation has been criticised because the individual parameters are often not known to better than a magnitude or so. For instance it is unknown whether the surface ice of Europa is thin or thick, and how do you allow for that uncertainty?
| |
| | |
| It's also been criticised because it makes assumptions about future exploration, in case of Europa it would only protect it with reasonable probability for the duration of the period of exploration. But maybe you want to protect Europa with higher probability, for all future time?<ref>Richard Greenberg, Richard J. Greenberg [http://books.google.co.uk/books?id=gwRAAQAAIAAJ&q=coleman+sagan+equation#search_anchor Unmasking Europa: the search for life on Jupiter's ocean moon] ISBN 0387479368</ref><ref>PAUL GILSTER [http://www.centauri-dreams.org/?p=17515 Europa: Thin Ice and Contamination]</ref>
| |
| | |
| Greenberg has suggested an alternative, to use the natural contamination standard - that our missions to Europa should not have a higher chance of contaminating it than the chance of contamination by meteorites from Earth.<ref>B. Randall Tufts, Richard Greenberg [http://www.americanscientist.org/issues/pub/infecting-other-worlds/2 Infecting Other World], American Scientist, July 2001</ref><ref>[http://books.google.co.uk/books?id=gmvfvs8BWccC&q=natural+contamination+standard#v=snippet&q=natural%20contamination%20standard&f=false Europa the Ocean Moon, Search for an Alien Biosphere, chapter 21.5.2 Standards and Risks]</ref>
| |
| | |
| {{quotation|As long as the probability of people infecting other planets with terrestrial microbes is substantially smaller than the probability that such contamination happens naturally, exploration activities would, in our view, be doing no harm. We call this concept the natural contamination standard.}}
| |
| | |
| Another approach for Europa is the use of binary decision trees which is favoured by the ''Committee on Planetary Protection Standards for Icy Bodies in the Outer Solar System'' under the auspices of the Space Studies Board.<ref name=EuropaStudy>[http://sites.nationalacademies.org/SSB/CurrentProjects/SSB_059273 Planetary Protection Standards for Icy Bodies in the Outer Solar System] - about the ''Committee on Planetary Protection Standards for Icy Bodies in the Outer Solar System''</ref> This goes through a series of seven steps, leading to a final decision on whether to go ahead with the mission or not.<ref>Committee on Planetary Protection Standards for Icy Bodies in the Outer Solar System; Space Studies Board; Division on Engineering and Physical Sciences; National Research Council [http://www.nap.edu/openbook.php?record_id=13401&page=13 Assessment of Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies ( 2012 ) / 2 Binary Decision Trees]</ref>
| |
| | |
| {{quotation|Recommendation: Approaches to achieving planetary protection should not rely on the multiplication of bioload estimates and probabilities to calculate the likelihood of contaminating solar system bodies with terrestrial organisms unless scientific data unequivocally define the values, statistical variation, and mutual independence of every factor used in the equation.
| |
| <br><br>
| |
| Recommendation: Approaches to achieving planetary protection for missions to icy solar system bodies should employ a series of binary decisions that consider one factor at a time to determine the appropriate level of planetary protection procedures to use.}}
| |
| | |
| ==Containment and quarantine==
| |
| | |
| <!-- Has to be included. I made this as POV neutral as possible by not stating any time periods or size requirements which caused so much debate and controversy on the Mars sample return mission section. I don't think this needs a POV-section template therefore, but if anyone thinks it does, do add and we can discuss.
| |
| | |
| I haven't mentioned the risk of environmental disruption at all here. IMHO it should be mentioned, perhaps similar language to the Mars sample return missio nsection, but prefer not to get involved in that debate right now, of whether and how to mention it, as it is not of central importance to this article, want to write something as totally non controversial as I can possibly manage here. -->
| |
| In the case of restricted Category V missions, Earth is protected through sample containment and quarantine of returned samples or astronauts. Missions would be designed so that no part of the capsule that encounters the Mars surface is exposed to the Earth environment.
| |
| | |
| One way to do that is to enclose the sample container within a larger outer container from Earth, in the vacuum of space. The integrity of any seals is essential and the system must also be monitored to check for the possibility of micro-meteorite damage during return to Earth. One solution there is to do final sample containment close to Earth before return to the surface {{Citation needed|date=July 2013}}. <!-- have citations for all this but need to look it up, thought I should put something in though right away as a place holder until I have the final content ready. -->
| |
| | |
| Sterilization is not appropriate for backward contamination protection. The science value of any returned samples is diminished if they are sterilized.
| |
| | |
| No restricted category V returns have been carried out in recent times.
| |
| | |
| During the Apollo program the sample returns were regulated through the [[Extra-Terrestrial Exposure Law]]. This was rescinded in 1991. So new legislation would need to be enacted. The Apollo era quarantine procedures are of interest as the only attempt to date of a return to Earth of a sample that, at the time, was thought to have a remote possibility of including extraterrestrial life.
| |
| | |
| Samples and astronauts were quarantined in the [[Lunar Receiving Laboratory]].<ref>Richard S. Johnston,John A. Mason, Bennie C. Wooley, Gary W. McCollum, Bernard J. Mieszkuc [http://lsda.jsc.nasa.gov/books/apollo/s5ch1.htm BIOMEDICAL RESULTS OF APOLLO, SECTION V, CHAPTER 1, THE LUNAR QUARANTINE PROGRAM]</ref> The methods used would be considered inadequate for containment by modern standards.<ref>Nancy Atkinson [http://www.universetoday.com/35229/how-to-handle-moon-rocks-and-lunar-bugs-a-personal-history-of-apollos-lunar-receiving-lab/ How to Handle Moon Rocks and Lunar Bugs: A Personal History of Apollo’s Lunar Receiving Lab], Universe Today, July 2009. See quote from: McLane who lead the group that designed and built the Lunar Receiving Facility: {{bq|"The best that I hear now is that the techniques of isolation we used wouldn’t be adequate for a sample coming back from Mars,so somebody else has a big job on their hands."}}</ref> Also the lunar receiving laboratory would be judged a failure by its own design criteria as the sample return didn't contain the lunar material, with two failure points during the Apollo 11 return mission, at the splashdown and at the facility itself.
| |
| | |
| However the [[Lunar Receiving Laboratory]] was built quickly with only two years from start to finish, a time period now considered inadequate. Lessons learnt from it can help with design of any Mars sample return receiving facility.<ref>[http://www.nap.edu/openbook.php?record_id=10138&page=60 The Quarantine and Certification of Martian Samples - Chapter 7: Lessons Learned from the Quarantine of Apollo Lunar Samples], Committee on Planetary and Lunar Exploration, Space Studies Board</ref>
| |
| | |
| Design criteria for a proposed Mars Sample Return Facility, and for the return mission, have been developed by the American National Research Council<ref name=nrc2009>
| |
| {{cite report |title=Assessment of Planetary Protection Requirements for Mars Sample Return Missions |publisher=National Research Council |year=2009 | url=http://www.nap.edu/openbook.php?record_id=12576}}</ref> and the European Space Foundation.<ref name=esf2012>[http://science.nasa.gov/media/medialibrary/2013/01/17/ESF_Mars_Sample_Return_backward_contamination_study.pdf European Science Foundation - Mars Sample Return backward contamination - strategic advice] July, 2012, ISBN 978-2-918428-67-1</ref> They concluded that it could be based on biohazard 4 containment but with more stringent requirements to contain unknown micro-organisms possibly as small as or smaller than the smallesst Earth micro-organisms known, the [[ultramicrobacteria]]. The ESF study also recommended that it should be designed to contain the smaller [[gene transfer agent]]s if possible, as these could potentially transfer DNA from martian micro-organisms to terreestrial micro-organisms if they have a shared evolutionary ancestry. It also needs to double as a clean room facility to protect the samples from terrestrial contamination that could confuse the sensitive life detection tests that would be used on the samples.
| |
| | |
| Before a sample return, new quarantine laws would be required. Environmental assessment would also be required, and various other domestic and international laws would need to be negotiated not present in the Apollo era.<ref name=race>M. S. Race [http://salegos-scar.montana.edu/docs/Planetary%20Protection/AdvSpaceResVol18(1-2).pdf Planetary Protection, Legal Ambiguity, and the Decision Making Process for Mars Sample Return] Adv. Space Res. vol 18 no 1/2 pp (1/2)345-(1/2)350 1996</ref>
| |
| | |
| ==Decontamination Procedures==
| |
| | |
| For all the spacecraft, the starting point is clean room assembly in class 100 [[cleanroom]]s. These are rooms with less than 100 particles of size 0.5 µm or larger per cubic foot. Engineers wear [[cleanroom suit]]s with only their eyes exposed. Components are sterilized individually before assembly, as far as possible, and they clean surfaces frequently with alcohol wipes during assembly.
| |
| | |
| For Category IVa missions, the aim is to reduce the bioburden to 300,000 bacterial spores on any surface from which the spores could get into the martian environment. Any heat tolerant components are heat sterilized to 114C. Sensitive electronics such as the core box of the rover including the computer, are sealed and vented through high-efficiency filters to keep any microbes inside.<ref>[http://marsrover.nasa.gov/technology/is_planetary_protection.html In-situ Exploration and Sample Return: Planetary Protection Technologies] JPL - Mars Exploration Rovers</ref><ref name=NASA>{{cite web | url = http://planetaryprotection.nasa.gov/methods | title = Office of Planetary Protection - Methods and Implementation | accessdate = 2012-09-11 | author = Office of Planetary Protection | date = August 28, 2012 | work = NASA}}</ref><ref>{{cite journal
| |
| | title = Temperature–time issues in bioburden control for planetary protection
| |
| | author = Benton C. Clark
| |
| | journal = Advances in Space Research
| |
| | year = 2004
| |
| | volume = 34
| |
| | issue = 11
| |
| | pages = 2314–2319
| |
| | doi = 10.1016/j.asr.2003.06.037
| |
| |bibcode = 2004AdSpR..34.2314C }}</ref>
| |
| | |
| For more sensitive missions such as Category IVc, a far higher level of sterilization is required. This needs to be similar to that of Viking, which was sterilized for a surface which, at the time, was thought to be potentially hospitable to life similar to special regions on Mars today.
| |
| | |
| In microbiology, it's usually impossible to prove that there are no micro-organisms left viable, since many micro-organisms are either not yet studied, or not cultivable. Instead, sterilization is done using a series of tenfold reductions of the numbers of micro-organisms present. After a sufficient number of ten-fold reductions, the chance that there any micro-organisms left will be extremely low.
| |
| | |
| The [[Viking program|Viking Mars landers]] were sterilized using dry heat sterilization. After preliminary cleaning to reduce the bioburden to similar levels to present day Category IVa spacecraft, the Viking spacecraft were heat treated for 30 hours at 125C (five hours at 125C was considered enough to reduce the population tenfold even for enclosed parts of the spacecraft, so this was enough for a million-fold reduction of the originally low population).<ref name=JPL2011/>
| |
| | |
| Modern materials however are often not designed to handle such temperatures, especially since modern spacecraft often use "commercial off the shelf" components. Problems encountered include nanoscale features only a few atoms thick, plastic packaging, and conductive epoxy attachment methods. Also many instrument sensors can't be exposed to high temperatures, and high temperatures can interfere with critical alignments of instruments.<ref name=JPL2011/>
| |
| | |
| As a result, new methods are needed to sterilize a modern spacecraft to the higher categories such as Category IVc for Mars, similar to Viking.<ref name=JPL2011/> Methods under evaluation, or already approved, include:
| |
| | |
| * Vapour phase [[hydrogen peroxide]] - effective, but can affect finishes, lubricants and materials that use aromatic rings and sulfur bonds. This has been established, reviewed, and A NASA/ESA specification for use of VHP has been approved by the Planetary Protection Officer, but it has not yet been formally published.<ref>Fei Chen, Terri Mckay2=, James Andy Spry, Anthony Colozza, Salvador Distefano, Robert Cataldo [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130010386_2013009876.pdf Planetary Protection Concerns During Pre-Launch Radioisotope Power System Final Integration Activities] - includes the draft specification of VHP sterilization and details of how it would be implemented, Proceedings of Nuclear and Emerging Technologies for Space 2013 Albuquerque, NM, February 25–28, 2013 Paper 6766</ref>
| |
| * [[Ethylene oxide]] - this is widely used in the medical industry, and can be used for materials not compatible with hydrogen peroxide. Is under consideration for missions such as ExoMars.
| |
| * [[Gamma radiation]] and [[electron beams]] have been suggested as a method of sterilization, as they are used extensively in the medical industry. They need to be tested for compatibility with spacecraft materials and hardware geometries, and is not yet ready for review.
| |
| | |
| Some other methods are of interest as they can sterilize the spacecraft after arrival on the planet.
| |
| * [[Supercritical CO2]] snow (Mars) - is most effective against traces of organics rather than whole micro-organisms. Has the advantage though that it eliminates the organic traces - while other methods though they kill the micro-organisms, leave organic traces that can confuse life detection instruments. Is under study by JPL and ESA.
| |
| * Passive sterilization through [[UV radiation]] (Mars). Highly effective against many micro-organisms, but not all, as a Bacillus strain found in spacecraft assembly facilities is particularly resistant to UV radiation. Is also complicated by possible shadowing by dust and spacecraft hardware.
| |
| * Passive sterilization through particle fluxes (Europa). Plans for missions to Europa take credit for reductions due to this.
| |
| | |
| ===Bio-burden detection and assessment===
| |
| | |
| The spore count is used as an indirect measure of the number of micro-organisms present. Typically 99% of micro-organisms by species will be non spore forming and able to survive in dormant states{{Citation needed|date=July 2013}}, and so the actual number of viable dormant micro-organisms remaining on the sterilized spacecraft is expected to be many times the number of spore forming micro-organisms.
| |
| | |
| One new spore method approved is the "Rapid Spore Assay". This is based on commercial rapid assay systems, detects spores directly and not just viable micro-organisms. and gives results in just 5 hours instead of 72 hours.<ref name=JPL2011>[http://solarsystem.nasa.gov/docs/PPCCTECHREPORT3.pdf Assessment of Planetary Protection and Contamination Control Technologies for Future Planetary Science Missions] see Section 3.1.2 Bio-burden Detection and Assessment. January 24, JPL, 2011</ref>
| |
| | |
| Some studies that suggest that the spore count method has limitations as an assay method, since often surfaces with the lowest or even zero spore count have similar numbers of micro-organisms to surfaces with higher spore counts.<ref>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3147454/ Comparison of Innovative Molecular Approaches and Standard Spore Assays for Assessment of Surface Cleanliness]</ref>
| |
| | |
| Two new molecular methods have been approved<ref name=JPL2011/> for assessment of microbial contamination on
| |
| spacecraft surfaces.<ref name=NASA/><ref name=Debus>{{cite journal
| |
| | title = Estimation and assessment of Mars contamination
| |
| | author = A. Debus
| |
| | journal = Advances in Space Research
| |
| | year = 2004
| |
| | volume = 35
| |
| | issue = 9
| |
| | pages = 1648–1653
| |
| | doi = 10.1016/j.asr.2005.04.084
| |
| |bibcode = 2005AdSpR..35.1648D
| |
| | pmid=16175730}}</ref>
| |
| | |
| * Adenosine triphosphate (ATP) detection - this is a key element in cellular metabolism. This method is able to detect non cultivable organisms. It can also be triggered by non viable biological material so can give a "false positive".
| |
| | |
| * Limulus Amebocyte Lysate assay - detects Lipopolysaccharides (LPS). This is only present in Gram-negative bacteria. The standard assay analyses spores from microbes that are primarily [[Gram-positive bacteria|Gram-positive]], making it difficult to relate the two methods.
| |
| | |
| ==Impact prevention==
| |
| | |
| This particularly applies to orbital missions, Category III, as they are sterilized to a lower standard than missions to the surface. It is also relevant to landers, as an impact gives more opportunity for forward contamination, and impact could be on an unplanned target, such as a special region on Mars.
| |
| | |
| The requirement for an orbital mission is that it needs to remain in orbit for at least 20 years after arrival at Mars with probability of at least 99% and for 50 years with probability at least 95%. This requirement can be dropped if the mission is sterilized to Viking sterilization levels.<ref>[http://www.nap.edu/openbook.php?record_id=11381&page=27 Preventing the Forward Contamination of Mars ( 2006 )] Page 27 (footnote to page 26) of chapter 2 Policies and Practices in Planetary Protection</ref>
| |
| | |
| In the Viking era, the requirement was given as a single figure, that any orbital mission should have a probability of less than 0.003% probability of impact during the current exploratory phase of exploration of Mars.<ref>[http://www.nap.edu/openbook.php?record_id=11381&page=27 Preventing the Forward Contamination of Mars ( 2006 )] Page 22 of chapter 2 Policies and Practices in Planetary Protection</ref>
| |
| | |
| For both landers and orbiters the technique of trajectory biasing is used during approach to the target. The spacecraft trajectory is designed so that if communications are lost, it will miss the target.
| |
| | |
| ===Issues with Impact Prevention===
| |
| | |
| Despite these measures, there has been one notable failures of this element of the planetary protection policy, the [[Mars Climate Orbiter]] which was sterilized only to Category III, and crashed on Mars due to a mix-up of imperial and metric units. The office of planetary protection sheet about it states that it is likely that it burnt up in the atmosphere, but if it survived to the ground, then it could cause issues of forward contamination.<ref>[http://planetaryprotection.nasa.gov/missions-past/climateorbiter/ Mars Climate Orbiter] page at [http://planetaryprotection.nasa.gov/]</ref>
| |
| | |
| [[Mars Observer]] is another Category III mission with a potential planetary contamination issue. Communications were lost three days before its orbital insertion maneuver. It seems most likely it didn't succeed in entering into orbit around Mars, and simply continued past on a heliocentric orbit. If it did succeed in following its automatic programming, and attempted the manoeuvre, however, there is a chance it crashed on Mars.
| |
| | |
| Three of the landers also had hard landings on Mars, which is potentially more of an issue for planetary protection than the designed for soft landing. These are the [[Beagle 2]] the [[Mars Polar Lander]] and [[Deep Space 2]].
| |
| | |
| ==Controversies==
| |
| | |
| {{POV-section|Issues section|date=July 2013}}
| |
| | |
| ===Meteorite argument that there is no need for Planetary Protection===
| |
| | |
| Alberto G. Fairén and Dirk Schulze-Makuch published an article in Nature recommending that Planetary Protection measures need to be scaled down. They gave as their main reason for this, that exchange of meteorites between Earth and Mars means that any life on Earth that could survive on Mars has already got there and vice versa.<ref>Alberto G. Fairén & Dirk Schulze-Makuch [http://www.nature.com/ngeo/journal/v6/n7/full/ngeo1866.html The Over Protection of Mars] Nature Geoscience 6, 510–511 (2013) {{DOI|10.1038/ngeo1866}}</ref>
| |
| | |
| Zubrin used similar arguments in favour of his view that the back contamination risk has no scientific validity.<ref name=zubrin>Robert Zubrin "Contamination From Mars: No Threat", [http://www.planetary.org/explore/the-planetary-report/ The Planetary Report] July/Aug. 2000, P.4–5</ref><ref name=zubrin-interview>[http://astronomy.nmsu.edu/cwc/Teaching/SpaceCol/sts497i/Zubrin/transcript.txt 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</ref>
| |
| | |
| ===NRC's Examination of the Meteorites Argument===
| |
| | |
| The meteorite argument was examined by the NRC in the context of back contamination. It is thought that all the [[Martian meteorites]] originate in relatively few impacts every few million years on Mars. The impactors would be kilometers in diameter and the craters they form on Mars tens of kilometers in diameter. Models of impacts on Mars are consistent with these findings.<ref name=Eugster>O. Eugster, G. F. Herzog, K. Marti,
| |
| M. W. Caffee [http://www.lpi.usra.edu/books/MESSII/9004.pdf Irradiation Records, Cosmic-Ray Exposure Ages, and Transfer Times of Meteorites, see section 4.5 Martian Meteorites] LPI, 2006</ref><ref>L.E. NYQUIST1, D.D. BOGARD1, C.-Y. SHIH2, A. GRESHAKE3, D. STÖFFLER [http://seismo.berkeley.edu/~manga/nyquist.pdf AGES AND GEOLOGIC HISTORIES OF MARTIAN METEORITES] 2001</ref><ref>Tony Irving [http://www.imca.cc/mars/martian-meteorites.htm Martian Meteorites - has graphs of ejection ages] - site maintained by Tony Irving for up to date information on Martian meteorites</ref>
| |
| | |
| We receive a steady stream of meteorites from Mars, but they come from relatively few original impactors, and transfer was more likely in the early solar system. Also some life forms viable on both Mars and on Earth might be unable to survive transfer on a meteorite, and there is so far no direct evidence of any transfer of life from Mars to Earth in this way.
| |
| | |
| The NRC concluded that though transfer is possible, the evidence from meteorite exchange does not eliminate the need for back contamination protection methods.<ref name=nrc2009_5p48>{{cite report |title=Assessment of Planetary Protection Requirements for Mars Sample Return Missions |publisher=National Research Council |year=2009 |chapter=5: The Potential for Large-Scale Effects" |page=48 |url=http://www.nap.edu/openbook.php?record_id=12576&page=48 |quote=''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.''}}</ref>
| |
| | |
| Impacts on Earth able to send micro-organisms to Mars are also infrequent. Impactors of 10 km across or larger can send debris to Mars through the Earth's atmosphere but these occur rarely, and were more common in the early solar system.{{Citation needed|date=July 2013}} <!-- can find citations for this --> <!-- also is a while since I researched into forward contamination, need to check out refs for this direction of this argument as the NRC citation above only covered back contamination -->
| |
| | |
| ===Argument that proposed restricted Category V containment measures may be insufficient===
| |
| | |
| The scientific consensus is that the potential for large-scale effects, either through pathogenesis or ecological disruption, is extremely small.<ref name=nrc2009>{{cite report |title=Assessment of Planetary Protection Requirements for Mars Sample Return Missions |publisher=National Research Council |year=2009 |url=http://www.nap.edu/openbook.php?record_id=12576&page=R1}}</ref><ref name=iMars>http://mepag.nasa.gov/reports/iMARS_FinalReport.pdf Preliminary Planning for an International Mars Sample Return Mission Report of the International Mars Architecture for the Return of Samples (iMARS) Working Group June 1, 2008</ref><ref name=esf2010_PP>[http://science.nasa.gov/media/medialibrary/2013/01/17/ESF_Mars_Sample_Return_backward_contamination_study.pdf European Science Foundation - Mars Sample Return backward contamination - Strategic advice and requirements] July, 2012, ISBN 978-2-918428-67-1 - see Back Planetary Protection section. (for more details of the document see [http://elib.dlr.de/78092/ abstract] )</ref><ref name=Lederberg>Joshua Lederberg [http://profiles.nlm.nih.gov/ps/access/BBGNMX.pdf Parasites Face a Perpetual Dilemma ] Volume 65, Number 2, 1999 / American Society for Microbiology News 77.</ref><ref name=NAS>http://planetaryprotection.nasa.gov/summary/msr Mars Sample Return: Issues and Recommendations. Task Group on Issues in Sample Return. National Academies Press, Washington, DC (1997).</ref> Nevertheless, returned samples from Mars will be treated as potentially biohazardous until scientists can determine that the returned samples are safe. The goal is to reduce the probability of release of a Mars particle to less than one in a million.<ref name=esf2010_PP />
| |
| | |
| The [[International Committee Against Mars Sample Return]]<ref name=icamsr>[http://www.icamsr.org/protection.html International Committee Against Mars Sample Return]</ref> agree with the assessment of low probability of large scale effects, but consider the proposed containment measures are not sufficient, given the possible severity of the worst case scenario. They come to this conclusion partly as a result of considerations of human error and the novelty of the mission proposal. Consequently, they advocate much more in situ research before undertaking MSR.<ref name=icamsr /><ref name=woese>Barry E. DiGregorio [http://pubs.acs.org/subscribe/archive/ci/31/i08/html/08digregorio.html The dilemma of Mars sample return] ''August 2001 Vol. 31, No. 8, pp 18–27.''</ref>
| |
| | |
| ==Proposal for extension of protection to non biological considerations==
| |
| | |
| A COSPAR workshop in 2010, looked issues to do with protecting areas from non biological contamination.<ref>Rummel, J., Race, M., and Horneck, G. eds. 2011. [http://cosparhq.cnes.fr/sites/default/files/ppp_workshop_report_ethical_considerations_princeton_final_v1a_7nov2012.pdf COSPAR Workshop on Ethical Considerations for Planetary Protection in Space Exploration] COSPAR, Paris, 51 pp.</ref><ref name=cosparethical>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698687/ Ethical Considerations for Planetary Protection in Space Exploration: A Workshop], Astrobiology. 2012 November; 12(11): 1017–1023.</ref> They recommended that COSPAR expand its remit to include such issues.
| |
| | |
| Recommendations of the workshop include
| |
| | |
| {{quotation|'''Recommendation 3''' COSPAR should add a separate and parallel policy to
| |
| provide guidance on requirements/best practices for protection of non-living/nonlife-related aspects of Outer Space and celestial bodies"}}
| |
| | |
| Ideas for doing this suggested since the workshop include protected special regions, or "Planetary Parks"<ref>[http://www.space.com/19302-planetary-parks-space-wilderness-protection.html 'Planetary Parks' Could Protect Space Wilderness] by Leonard David, SPACE.com’s Space Insider Columnist, January 17, 2013</ref> to keep regions of our solar system pristine for future scientific investigation, and also for ethical reasons.
| |
| | |
| ==Proposal to extend planetary protection beyond the initial period of exploration==
| |
| | |
| [[Christopher McKay]] has argued that until we have better understanding of Mars, our explorations should be biologically reversible.<ref name=RestorationEcology>Christopher P. McKay [http://esseacourses.strategies.org/EcosynthesisMcKay2008ReviewAAAS.pdf Planetary Ecosynthesis on Mars: Restoration Ecology and Environmental Ethics] NASA Ames Research Center</ref><ref>Christopher P. McKay [http://www.sciencemag.org/content/323/5915/718.summary Biologically Reversible Exploration] Science 6 February 2009:
| |
| Vol. 323 no. 5915 p. 718 {{DOI|10.1126/science.1167987}}</ref> For instance if all the micro-organisms introduced to Mars so far remain dormant within the spacecraft, they could in principle be removed in the future, leaving Mars completely free of contamination from modern Earth lifeforms.
| |
| | |
| In the 2010 workshop one of the recommendations for future consideration was to extend the period for contamination prevention to the maximum viable lifetime of dormant micro-organisms introduced to the planet.
| |
| | |
| {{bq|"''''Recommendation 4.'''' COSPAR should consider that the appropriate protection of potential indigenous extraterrestrial life shall include avoiding the harmful contamination of any habitable environment—whether extant or foreseeable—within the maximum potential time of viability of any terrestrial organisms (including microbial spores) that may be introduced into that environment by human or robotic activity."<ref name=cosparethical/>}}
| |
| | |
| In the case of Europa, a similar idea has been suggested, that it is not enough to keep it free from contamination during our current exploration period. It might be that Europa is of sufficient scientific interest that we have a duty to keep it pristine for future generations to study as well. This was the majority view of the 2000 task force examining Europa, though there was a minority view of the same task force that such strong protection measures are not required.
| |
| | |
| {{quotation|"One consequence of this view is that Europa must be protected from contamination for an open-ended period, until it can be demonstrated that no ocean exists or that no organisms are present. Thus, we need to be concerned that over a time scale on the order of 10 million to 100 million years (an approximate age for the surface of Europa), any contaminating material is likely to be carried into the deep ice crust or into the underlying ocean."<ref>[http://www.nap.edu/openbook.php?record_id=9895&page=2 Preventing the forward contamination of Europa - Executive Summary page 2] National Academies Press</ref>}}
| |
| | |
| ==See also==
| |
| {{Portal|Spaceflight}}
| |
| * [[Astrobiology]]
| |
| * [[Cassie Conley]], current [[NASA]] Planetary Protection Officer
| |
| * [[Mars 2020 rover mission]]
| |
| * [[Panspermia]]
| |
| | |
| ==References==
| |
| {{Reflist|33em}}
| |
| | |
| ==General references==
| |
| {{Refbegin}}
| |
| *{{cite journal| author = [[Carl Sagan|Sagan, C.]], and S. Coleman| year = 1965| title = Spacecraft sterilization standards and contamination of Mars| journal = Journal of Astronautics and Aeronautics
| |
| | volume = 3| issue =5| pages = 22–27}}
| |
| *{{cite journal
| |
| | title = Evolution of the planetary protection policy: conflict of science and jurisprudence
| |
| | author = L. I. Tennen
| |
| | journal = Advances in Space Research
| |
| | year = 2006
| |
| | volume = 34
| |
| | issue = 11
| |
| | pages = 2354–2362
| |
| | doi = 10.1016/j.asr.2004.01.018
| |
| | bibcode=2004AdSpR..34.2354T
| |
| }}
| |
| *{{cite journal
| |
| | title = Planetary protection: lessons learned
| |
| | author =L. Perek
| |
| | journal = Advances in Space Research
| |
| | year = 2006
| |
| | volume = 34
| |
| | issue = 11
| |
| | pages = 2354–2362
| |
| | doi = 10.1016/j.asr.2003.02.066
| |
| | bibcode=2004AdSpR..34.2368P
| |
| }}
| |
| *{{cite journal
| |
| | title = COSPAR's planetary protection policy: A consolidated draft
| |
| | author = J. D. Rummel, P. D. Stabekis, D. L. Devincenzi, J. B. Barengoltz
| |
| | journal = Advances in Space Research
| |
| | year = 2002
| |
| | volume = 30
| |
| | issue = 6
| |
| | pages = 1567–1571
| |
| | doi = 10.1016/S0273-1177(02)00479-9
| |
| |bibcode = 2002AdSpR..30.1567R }}
| |
| *{{cite journal
| |
| | title = Refinement of planetary protection policy for Mars missions
| |
| | author = D. L. DeVincenzi, P. Stabekis and J. Barengoltz
| |
| | journal = Advances in Space Research
| |
| | year = 1996
| |
| | volume = 18
| |
| | issue = 1–2
| |
| | pages = 311–316
| |
| | doi = 10.1016/0273-1177(95)00821-U
| |
| | pmid = 11538978
| |
| |bibcode = 1996AdSpR..18..311D }}
| |
| *{{cite journal
| |
| | title = U.S. planetary protection program: Implementation highlights
| |
| | author = J. Barengoltz and P. D. Stabekis
| |
| | journal = Advances in Space Research
| |
| | year = 1983
| |
| | volume = 3
| |
| | issue = 8
| |
| | pages = 5–12
| |
| | doi = 10.1016/0273-1177(83)90166-7
| |
| |bibcode = 1983AdSpR...3....5B }}
| |
| *{{cite journal
| |
| | title = Viking heat sterilization—Progress and problems
| |
| | author = L. P. Daspit, J. A. Stern, [[Edgar Cortright|E. M. Cortright]]
| |
| | journal = Acta Astronautica
| |
| | year = 1975
| |
| | volume = 2
| |
| | issue = 7–8
| |
| | pages = 649–666
| |
| | doi = 10.1016/0094-5765(75)90007-7}}
| |
| {{refend}}
| |
| | |
| ==External links==
| |
| *[http://www.esa.int/esaCP/ESAUB676K3D_index_0.html No bugs please, this is a clean planet!] ([[ESA]] article)
| |
| *[http://cosparhq.cnes.fr/Scistr/PPPolicy(20-July-08).pdf COSPAR planetary protection policy, July 2008] ([[COSPAR]] article)
| |
| *[http://planetaryprotection.nasa.gov/ NASA Planetary Protection Website]
| |
| *[http://www.jpl.nasa.gov/news/news.cfm?release=2009-154 JPL Develops High-Speed Test to Improve Pathogen Decontamination] at [[JPL]].
| |
| *[http://tierra.rediris.es/Geoethics_Planetary_Protection/ Geoethics in Planetary and Space Exploration]
| |
| *[http://www.thespaceshow.com/detail.asp?q=1868 Catharine Conley: NASA & international planetary protection policy, methodology & applications], The Space Show, October 2012
| |
| *GYRE.org [http://www.gyre.org/news/explore/interplanetary-contamination Mars Robot may have destroyed evidence of life]
| |
| *St. Louis Post-Dispatch [http://www.highbeam.com/doc/1G1-125688298.html Scientists fear Interplanetary Contamination in new Mars missions]
| |
| *Wired Magazine [http://www.popsci.com/science/article/2009-10/water-bears-headed-martian-moon-someday Water Bears Are Headed for a Martian Moon]
| |
| | |
| {{Extraterrestrial life}}
| |
| {{Astrobiology}}
| |
| | |
| {{DEFAULTSORT:Planetary Protection}}
| |
| [[Category:Space Pollution]]
| |
| [[Category:Spaceflight]]
| |
| [[Category:Human spaceflight]]
| |
| [[Category:Space colonization]]
| |
| [[Category:Space colonization literature]]
| |
| [[Category:Astrobiology]]
| |
| [[Category:Extraterrestrial life]]
| |