tag:blogger.com,1999:blog-9094742788006644220.post5540887620170295663..comments2020-11-09T07_43_07.776-08_00Comments on Mike Brown's Planets: Whale bones on EuropaUnknownnoreply@blogger.comBlogger13125tag:blogger.com,1999:blog-9094742788006644220.post-20081384953746783882018-01-30T17_54_16.349-08_002018-01-30T17_54_16.349-08_00To change the subject for a moment professor. I am...To change the subject for a moment professor. I am an 81 year old retired gentleman who has just finished your book about the down-grading of Pluto. In it you talked about how moons are named and I believe you said all known moons were named. But one isn&#39;t and I&#39;d like to know why. That moon is the one that circles the planet Earth. The Earth has a name as do the other 7 planets. But our poor Moon does not and it is one of the biggest moons in the solar system . . perhaps the biggest. but we just call it Moon. That would be like naming your dog &quot;dog&quot; or your aardvark &quot;aardvark.&quot; How would you like to just be called &quot;MAN?&quot; How about coming up with an acceptable name for moon. If for no other reason than to make an old man happy before he dies. P. S. I really liked your book. bigbillbissonnette@gmail.comAnonymoushttps://www.blogger.com/profile/05629469837260101309noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-56023259337928039462016-04-28T15_41_54.399-07_002016-04-28T15_41_54.399-07_00Perhaps the chaos terrain was caused by a meteor s...Perhaps the chaos terrain was caused by a meteor strike...++Jameshttps://www.blogger.com/profile/09720776897189309266noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-80966350621655413832015-11-15T16_18_36.507-08_002015-11-15T16_18_36.507-08_00Dear Mr. Walker: Your comments are quite well tho...Dear Mr. Walker:<br /><br />Your comments are quite well thought-out, however it would seem that either tidal forces from a primary world and/or radioactive element decay like that which is found on Earth would be the most likely scenario that leads to life. Most life-forms as Earthling scientists are aware of, survive in warm to hot temperatures including those found around ocean bed smokestacks or geothermal hot springs such as those in Yellowstone National Park. Living cells may freeze through or burst from extreme cold, but some simple, primitive or even complex living creatures (that have evolved to live in such harsh conditions) may tolerate or even thrive under extremely cold environments. Perhaps exo-creatures have evolved with an anti-freeze that prevents cell damage; nobody knows, hence the need for caution. <br /><br />Just because a world is far from the Sun or other obvious heat source, does not mean a world is frigid through and through. Io for instance may have active lava and/or magma (flows) from aforementioned forces. <br /><br />It seems more likely that life would form and thrive in warm or hot environments such as in hot springs or thermo-volcanoes, not ones involving the extreme opposite. But in either case, the moral issue is what do we do if exo-life is discovered? G. Smithnoreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-23880080639611052562015-11-08T19_27_37.135-08_002015-11-08T19_27_37.135-08_00G Smith - just to say that the Huyguens probe didn...G Smith - just to say that the Huyguens probe didn&#39;t need special cleaning from Earth life because Titan is so very cold. -179 degrees C. Usually accepted that the lowest temperature Earth life can reproduce at is above -20 degrees C. There are some who think it may be possible below that but nobody would say it is possible at -179 degrees C. In addition - water there is in the form of ice and the liquid is ethane / methane.<br /><br />Now there is an idea that Titan has a subsurface ocean, and - just possibly might involve cryovolcanism. If that was possible, then that could change things. I think it is still a matter for debate<br /><br />http://onlinelibrary.wiley.com/doi/10.1002/jgre.20062/abstract<br /><br />If you had cryovolcanism, you could potentially have habitats for Earth life also.<br /><br />Anyway whatever the situation for Titan - for Europa then there is a major risk of contaminating it with Earth life. Any lander would have to be thoroughly sterilized. The radiation from Jupiter may not be enough - if there was liquid water below the surface with contact with the surface, and the contamination from the surface gets to it quickly enough - there are many microbes that can withstand very high levels of radiation. Radiodurans can withstand 5,000 grays for instance. https://en.wikipedia.org/wiki/Deinococcus_radiodurans<br /><br />And just a few meters below the surface of Europa then most of the radiation from Jupiter would be shielded already.<br /><br />This would have to be considered if anyone does a lander on Europa. And they&#39;ve already decided that the Sagan probability approach originally used for Mars is not appropriate for Europa. Because it is so hard to figure out the probabilities. <br /><br />I think myself that we simply shouldn&#39;t attempt a landing on Europa until we have examined it close up with orbiters and understand its surface properties very well. I.e. not send a lander on the next Europa orbiter mission. If we ever do it though, this seems useful and interesting research.Robert Walkerhttps://www.blogger.com/profile/09620101579236252814noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-58104550971708491112015-11-05T12_38_30.741-08_002015-11-05T12_38_30.741-08_00A very interesting read, Mike. I&#39;ve nothing to...A very interesting read, Mike. I&#39;ve nothing to add, but I feel that a comment from a Margarita is called for...Margaritahttps://www.blogger.com/profile/11264310483674735400noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-69945793136458233322015-10-31T15_30_47.034-07_002015-10-31T15_30_47.034-07_00In rebuttal to Reggie&#39;s comment on October 30,...In rebuttal to Reggie&#39;s comment on October 30, 2015:<br /><br />&quot;I believe that it&#39;s been Standard Operating Procedure to make sure that all outbound probes are sterile, precisely to prevent contaminating any planet (or moon) with Earth&#39;s biota. So I would expect that the Titan probe did not contaminate Titan&#39;s biosphere, if any.&quot;<br /><br />Although I understand that certain decontamination protocols are taken, but there will never be a 100% guarantee that any object, including people from Earth will be free of infectious disease pathogens or other forms of contamination such as chemicals. <br /><br />Mankind can not decontaminate hospitals with 100% effectiveness, let alone with 100% effectiveness every time; it only takes one &quot;germ&quot; or other contaminant to damage or destroy an ecosystem that is ill-prepared for such foreign &quot;assault.&quot; When Europeans came to the new world, the Indians were mostly wiped-out by germs brought over to the new world, not by war or starvation when the buffalo herds were culled. <br /><br />Another issue that could arise is a condition found on Earth where invasive species dominate and/or take-over an ecosystem, thereby unleashing an environmental catastrophe. <br /><br />It seems that preservation of exo-ecosystems is a low priority for the astronomy community, so maybe the time is right to form exo-world environmental lobbies and other exo-world environmental activist groups so exo-biologists, astronomers, (mining) companies and other groups will meet with resistance. <br /><br />All Hallows&#39; Eve is not the only scary thing going on.<br />G. Smithnoreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-72104678676211277992015-10-30T14_29_37.075-07_002015-10-30T14_29_37.075-07_00The &quot;chaos terrains&quot; of &quot;Margaritav...The &quot;chaos terrains&quot; of &quot;Margaritaville&quot; ... &quot;it&#39;s nobody&#39;s fault.&quot;neuferhttps://www.blogger.com/profile/00329447464267559943noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-36049643348012727662015-10-30T13_36_58.337-07_002015-10-30T13_36_58.337-07_001: How far from Jupiter is a &quot;safe&quot; dist...1: How far from Jupiter is a &quot;safe&quot; distance for a human being?<br />2: Given their respective orbits, how much time does Mars spend further away from Jupiter than Earth?<br />https://www.blogger.com/switch-profile.dohttps://www.blogger.com/profile/16326724179985027977noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-35249677616726948532015-10-30T13_27_27.075-07_002015-10-30T13_27_27.075-07_00I believe that it&#39;s been Standard Operating Pr...I believe that it&#39;s been Standard Operating Procedure to make sure that all outbound probes are sterile, precisely to prevent contaminating any planet (or moon) with Earth&#39;s biota. So I would expect that the Titan probe did not contaminate Titan&#39;s biosphere, if any.<br /><br />But in a roundabout way, this brings up an interesting question I&#39;ve wondered about. The Europa Rover will need some human piloting, just as the Mars Rovers do. Semi-autonomous rovers can only do so much; and if Europa&#39;s surface is as rough as is suggested some human input may be necessary. But from where?<br /><br />I&#39;ve been wondering if Jupiter might be explored from Mars. It&#39;s closer, so there&#39;s less time-lag in communications and the radio signals would be stronger. It&#39;s also far enough, that there&#39;d be no radiation problems; Jupiter&#39;s magnetic field and the particles it contains would kill any humans who got close enough.<br /><br />Which brings me to my question: How could I get a picture of Jupiter, as seen from one of the Mars Rovers? If I read my digital orrery (The Sky, v. 5) correctly, Jupiter should be close to Martian opposition; rising at sunset, and setting at sunrise. A photo of Jupiter, low on the horizon at Martian twilight, should be terrific.Reggiehttps://www.blogger.com/profile/17478546089651522517noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-56299810708797212062015-10-28T19_30_22.085-07_002015-10-28T19_30_22.085-07_00As it appears that the astronomers and especially ...As it appears that the astronomers and especially exobiologists are throwing the &quot;l&quot; word around again. It is suspected that Mars had an ocean(s) for 150 million years, but no evidence of life has been detected; no fossils, bones, shells or freeze-dried whales.<br /><br />Just because there may be liquid water, is little fodder for optimism. The Dead Sea is mostly devoid of life, if salt is what keeps the ocean liquid beneath the estimated 1-10 mile thick ice shell, then only microbes if that can survive such hyper salinity among the other extreme conditions. <br /><br />The Rosetta mission earlier this year demonstrated that a probe could fly through comet ejecta and analyze its composition, so we have the technology to fly through cryo-guysers without disturbing and possibly contaminating any world. <br /><br />Unfortunately, scientists will stop at nothing if the possibility of life is present. Joking aside, what if whales were discovered; would we launch a probe to penetrate the protective ice and hunt down this creature as in Herman Melville&#39;s novel Moby-Dick, place it in a box and ship it back to Earth where it would be dissected for billions of live TV/Internet viewers? If life exists elsewhere we should study it, but not disturb it, let alone kill it for our selfish desire to do whatever it takes to achieve our goals, no matter how immoral they may be.<br /><br />Mankind has such a poor record regarding the preservation of life on Earth and to trust people to do the right thing is like trusting a fox to guard a hen house. <br /><br />Remember the Huygens mission to Titan about 11 years ago and the thought that life may exist there? Did you think for once that by sending a probe to another world which may harbor life, that we could inadvertently contaminate it with Earth life such as microbes or viruses? If we contaminated another world, there would be noting to stop such an outbreak. <br /><br />After Titan revealed nothing, why such interest in Europa, after all there are several suspected worlds with cryo-vulcanism including Titan, Triton, Enceladus, Ganymede and Miranda? Maybe Ceres has an icy shell and a liquid ocean...so what?<br /><br />Until scientists understand how life forms, we seem to be grasping as straws, just hoping to find life elsewhere, oh how exciting that would be...or not.<br /><br />Live and let live. <br />G. Smithnoreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-15816365388406629702015-10-28T09_30_23.834-07_002015-10-28T09_30_23.834-07_00Good thing about whale bones and a wider range of ...Good thing about whale bones and a wider range of biominerals is that these would recognizably survive far longer from intense radiation on the surface than would organic biosignatures. Impact gardening would mix these minerals meters deep into the ice over tens of millions of years after surface emergence from the ocean. Yep, you better have a high-resolution multi-spectral imager on the lander. <br />In case you do land on a pile of fish or whale bones that have no residual organics after long irradiation. Welcome to the field of paleoastrobiology. John Cooperhttp://science.gsfc.nasa.gov/sed/bio/John.F.Coopernoreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-31544313568360532352015-10-28T06_06_11.734-07_002015-10-28T06_06_11.734-07_00A new post! Just recently I was evangelising the ...A new post!<br /><br />Just recently I was evangelising the virtues of reading this blog for learning more about Pluto and Eris, but a bit bummed out that it hadn&#39;t been updated for so long.<br /><br />What a wonderful update to (hopefully) retstart your blogging!Navneethhttps://www.blogger.com/profile/08605371412809015201noreply@blogger.comtag:blogger.com,1999:blog-9094742788006644220.post-19596728117080652612015-10-27T20_36_10.434-07_002015-10-27T20_36_10.434-07_00Thanks, Mike for this excellent post! I downloade...Thanks, Mike for this excellent post! I downloaded the paper and it is fascinating! Thank you so much for providing this report and the access to this paper.<br /><br />Shelia Cassidy, OCA and PalomarAnonymousnoreply@blogger.com