APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
,http://www.planetary.org/blogs/emily-lakdawalla/2015/09281219-nasas-mars-announcement.html wrote:
NASA's Mars Announcement: Present-day transient flows of briny water on steep slopes
Posted by Emily Lakdawalla, The Planetary Society, 2015/09/28 19:26 UTC
<<...While I think the science is very cool, our new understanding that there may be extant liquid water appearing transiently all over Mars is actually not entirely good news for the future of Mars exploration. The reason why not is summed up in an article by Lee Billings for Scientific American: "Searching for Life in Martian Water Will Be Very, Very Tricky." The problem is one of planetary protection. We build all our spacecraft on a world that is just disgusting with life. Microbes bred on Earth can survive in every imaginable environment. We do our best to sterilize everything, but our best is not good enough; any spacecraft that departs Earth for Mars will necessarily carry stowaway microbes. How terrible would it be if we discovered microbes living on Mars, and then couldn't be sure that we didn't bring them to Mars from Earth?
NASA recognizes that the potential for contamination is a problem, so there is a Planetary Protection Office that is specifically charged with overseeing how missions avoid contaminating Mars with Earth biota. There are two main approaches. One approach is to sterilize the heck out of anything that will actually be touching Mars. That's why Curiosity's wheels were specially wrapped throughout its final assembly, and why it was such a scandal that the drill bits were handled after sterilization. The other approach is to avoid landing in any location where you might encounter -- or accidentally create, should you crash -- a present-day habitable environment where Earth microbes could thrive. For instance, current rules prohibit NASA from targeting a mission containing a hot radioisotope thermoelectric generator (such as Mars 2020) anywhere near a place where a failed landing might place that generator close enough to subsurface ice that the heat of the decaying plutonium could melt it.
But all bets are off once you send humans to Mars. There is absolutely no way to make a human clean of microbes. We are filthy with microbes, thousands and thousands of different species. We continuously shed them through every pore, every orifice, with every exhalation, and from every surface. True, almost all of our microscopic friends would fail to thrive in the radiation-baked, intensely cold and arid Martian environment. But life is incredibly tenacious. Sooner or later, humans will get to Mars; even if they die in the attempt, some of their microbial passengers will survive even the worst crash. Once we've put humans on the surface, alive or dead, it becomes much, much harder to identify native Martian life.
This is one of many reasons I'm glad that The Planetary Society is advocating an orbit-first approach to human exploration. If we keep our filthy meatbag bodies in space and tele-operate sterile robots on the surface, we'll avoid irreversible contamination of Mars -- and obfuscation of the answer to the question of whether we're alone in the solar system -- for a little while longer. Maybe just long enough for robots to taste Martian water or discover Martian life.>>
geckzilla wrote:
They say cleanliness is next to godliness but perhaps a more enlightened approach is to accept those microbes as part of our identity rather than considering them as filth sullying our otherwise pure bodies.
http://biology.about.com/cs/bacteriology/a/aa032504a.htm wrote:
<<The decision as to whether bacteria are friend or foe becomes more difficult when both the positive and negative aspects of the relationship between humans and bacteria are considered. Let's discuss three types of symbiotic relationships: commensalism, mutualism, and parasitism.
When all of the facts are considered, bacteria are more helpful than harmful. Humans have exploited bacteria for a wide variety of uses, such as: making cheese and butter, decomposing waste in sewage plants, and developing antibiotics. Bacteria have been able to survive without us, but we could never live without them.>>
- In a mutualistic relationship: both the bacteria and the host benefit. For example, there are several kinds of bacteria which live inside the mouth, nose, throat, and intestines of humans and animals. These bacteria receive a place to live and feed while keeping other harmful microbes from taking up residence.
Commensalism: is a relationship that is beneficial to the bacteria which live off of the host, but does not help or harm the host. Most of the bacteria that reside within the bodies of humans are commensalistic.
A parasitic relationship is one in which the bacteria benefit while the host is harmed. Pathogenic parasites, which cause disease, do so by resisting the host's defenses and growing at the expense of the host. These bacteria produce poisonous substances called endotoxins and exotoxins which are responsible for the symptoms that occur with an illness.
http://www.astrobio.net/topic/origins/origin-and-evolution-of-life/forget-selfish-gene-evolution-life-driven-selfish-ribosome/ wrote:
Forget the selfish gene — the evolution of life is driven by the selfish ribosome
Astrobiology Magazine, Jan 9, 2015
<<Since the discovery of how DNA encodes genetic information, most research on the evolution of life has focused on genes. According to the “selfish gene” theory, cells and organisms exist simply as packages to protect and transmit genes. New research challenges this idea, proposing instead that if anything is “selfish” it must be the ribosome. That up-ends everything we think we know about the evolution of life and, in fact, the function of ribosomes themselves.
What came first in the evolution of life? Until now, scientists have answered the question with three letters: DNA. But In a father-daughter collaboration published in Journal of Theoretical Biology, Dr. Meredith Root-Bernstein, Aarhus University, Denmark, and Dr. Robert Root-Bernstein, Michigan State University, USA, provide evidence that the question should rather be answered with the word: Ribosomes.
The ribosome is a large and complex molecule found in all living cells. It contains the machinery for translating the genetic information from DNA into the proteins that perform all the work of the cell and make up most of its structure. “Ribosomes are made of three protein-encrusted RNA strands that textbooks tell us are purely structural, but we show that ribosomal RNA once acted as the genes, mRNAs and tRNAs required to make its own components — and gave rise to these structures in modern cells”, says Dr. Meredith Root-Bernstein.
The father-daughter research collaboration started when Meredith was re-reading her father Robert Root-Bernstein’s 1989 book Discovering. “Halfway through the book, inspired by the discovery strategies my father discusses there, I looked up and asked “what does DNA want?” It may sound strange to anthropomorphize a large molecule. However, the selfish gene theory is commonly expressed in a scientific short-hand as “DNA wants to replicate itself”. But I wondered if this is really what DNA wants,” Dr. Meredith explains.
When organic chemists anthropomorphize molecules, they say that molecules “want to be in their lowest energy conformation”. This means that when they have energy molecules can move into different conformations, but they have a resting position that they come back to. The resting position of DNA is very tightly curled up. It is so hard to unravel that researchers do not fully understand how the various helper molecules uncurl and unzip it for replication and translation.
Thus, as Meredith realized, from the organic chemistry point of view, the answer to “what does DNA want” is: It wants to sit curled up in a knot. DNA does not want to replicate or translate. The conclusion that DNA was unlikely to be the dynamic mover of evolutionary processes led to the next question: So who does want to do replication and translation?
To Meredith and Robert Root-Bernstein the answer is clear: the ribosome. Its resting position is “ready to translate DNA into proteins.” And not only are ribosomes found in all cells of all organisms, they are almost identical in all living species.
Inspired by Discovering, Meredith turned the selfish gene idea around. What if ribosomes are “selfishly” trying to reproduce themselves? Did ribosomes recycle ribosomal RNA to interact with proteins–creating the mRNAs and tRNAs we know today– and invent DNA as securely stored assembly instructions? If this were the case, then the rRNA sequences should match the sequences of mRNAs, tRNAs, and DNA encoding ribosomal proteins. This new hypothesis was tested by Robert, comparing ribosomal RNA to databases of all the RNAs, DNA and proteins of the bacteria E. coli.>> More...
Beyond wrote:
Hmm... somehow "the ribosomes made me do it", just doesn't sound the same as "the devil made me do it". But then, perhaps the devil is in the details of the ribosomes?
http://www.slate.com/blogs/bad_astronomy/2015/09/24/ben_carson_anti_science.html wrote:
Ben Carson: Evolution Is Satanic and the Big Bang Is a Fairy Tale
By Phil Plait, Sept. 24 2015 9:30 AM
<<In 2012, in a speech at an event called “Celebration of Creation,” [Ben Carson] said that Darwin came up with evolutionary theory because the devil made him do it. I mean that literally. He said, “I personally believe that this theory that Darwin came up with was something that was encouraged by the adversary.” The Adversary is a nickname for the devil; it’s the actual translation of the word “Satan.” So there’s that.
He also dismissed the Big Bang, calling it a “fairy tale.” The irony of this is palpable. When recently called on this claim, he dug in, saying (about people who think the Big Bang is true), “Here’s the key, I then say to them look, ‘I’m not gonna criticize you, you have a lot more faith then I have.’ I couldn’t, I don’t have enough faith to believe that.”>>
saturno2 wrote:
I think that the virus were the first elemental life on Earth.
https://en.wikipedia.org/wiki/Virus wrote:
<<A virus is a small infectious agent that replicates only inside the living cells of other organisms.
Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.>>
http://tinyurl.com/pjoowwd wrote: It’s sci-fi, but the new movie ‘The Martian’ has a lot of real science in it
By Tina Hesman Saey, Washington Post, September 28
<<There’s one notable exception to the believability of “The Martian”: the storm that strands Watney. “The hurricane-force winds that tear things apart are exaggerated,” planetary scientist Ramses Ramirez of Cornell University says. That’s because the atmosphere is thin. Atmospheric pressure at Mars’s surface is only 0.6 percent of Earth’s. Winds could well reach hurricane speeds, but they would not push enough air mass to tear apart equipment and whip up sand and small rocks. A 150-mph wind on Mars is a breeze, Green says. “It’s not enough to straighten an American flag.”>>
https://en.wikipedia.org/wiki/Phoenix_%28spacecraft%29#Weather wrote:<<The Phoenix lander descended on Mars [68°N 234°E] on May 25, 2008. This represents a milestone in understanding Martian weather.Click to play embedded YouTube video.
Wind speeds ranged from 11 to 58 km per hour. The usual average speed was 36 km per hour. These speeds seem high, but the atmosphere of Mars is very thin—less than 1% of the Earth's—and so did not exert much force on the spacecraft. The highest temperature measured during the mission was −19.6 °C, while the coldest was −97.7 °C.>>
Viruses might have devolved from very primitive (non-virus) forms of life.saturno2 wrote:Neufer
Thank you for your note.
On the same note of Wikipedia that you cite,
it says a hypothesis:
The cell nucleus Eucaryota evolved
from a large DNA virus.
https://en.wikipedia.org/wiki/Eukaryote wrote:
<<A eukaryote is any organism whose cells contain a nucleus and other organelles enclosed within membranes. Eukaryotes are more closely related to Archaea than Bacteria, at least in terms of nuclear DNA and genetic machinery, and one controversial idea is to place them with Archaea in the clade Neomura. However, in other respects, such as membrane composition, eukaryotes are similar to Bacteria. Three main explanations for this have been proposed:
The chronocyte hypothesis for the origin of the eukaryotic cell postulates that a primitive eukaryotic cell was formed by the endosymbiosis of both archaea and bacteria by a third type of cell, termed a chronocyte.>>
- 1) Eukaryotes resulted from the complete fusion of two or more cells, wherein the cytoplasm formed from a eubacterium, and the nucleus from
2) Eukaryotes developed from Archaea, and acquired their eubacterial characteristics from the proto-mitochondrion.
- a) an archaeon,
b) from a virus, or
c) from a pre-cell.
3) Eukaryotes and Archaea developed separately from a modified eubacterium.
Viruses are predators; one can't have a predator without a prey.saturno2 wrote:
I think that The virus would be a "quasi" form of life
Inorganic matter ----- Virus and prebiotics ---Organic matter
Evolution - - - - - - - - - - - - - - - - - - - - - - - - - -
That's why not many aliens come to our planet to visit.neufer wrote:http://www.planetary.org/blogs/emily-lakdawalla/2015/09281219-nasas-mars-announcement.html wrote:
NASA's Mars Announcement: Present-day transient flows of briny water on steep slopes
Posted by Emily Lakdawalla, The Planetary Society, 2015/09/28 19:26 UTC
<<... our filthy meatbag bodies...>>
Silicon Life, and other life forms.saturno2 wrote:There is the possibility of to find salt liquid
water on Mars.
It can to have elemental life on Mars.
But, you need to find another important
point for the life: the carbon element
Carbon element------------ life
Not element carbon ------ not life
It is far from certain. The measurements have anomalous characteristics, and there are multiple non-biological hypotheses.Sawngrighter wrote:With the seemingly continuously created methane seeping into Mars atmosphere it is certain there is life in Mars, if not on Mars.
Beyond wrote:That's why not many aliens come to our planet to visit.http://www.planetary.org/blogs/emily-lakdawalla/2015/09281219-nasas-mars-announcement.html wrote:
NASA's Mars Announcement: Present-day transient flows of briny water on steep slopes
Posted by Emily Lakdawalla, The Planetary Society, 2015/09/28 19:26 UTC
<<... our filthy meatbag bodies...>>
https://en.wikipedia.org/wiki/Tralfamadore wrote:
<<Tralfamadore is a planet in the Small Magellanic Cloud and the home of a civilization of machines, which dispatches Salo to a distant galaxy with a message for its inhabitants. The Tralfamadorians were originally developed by super-beings who built them to give meaning to their own lives. Unable to achieve this task, the precursor race used the Tralfamadorians instead to extinguish themselves.>>
If you wish to culture silicon based bacterium in a Petri dish, would that make you a Horta Culturist?Sawngrighter wrote:Silicon Life, and other life forms.saturno2 wrote:There is the possibility of to find salt liquid
water on Mars.
It can to have elemental life on Mars.
But, you need to find another important
point for the life: the carbon element
Carbon element------------ life
Not element carbon ------ not life
http://www.airspacemag.com/daily-planet ... 13/?no-ist
No Bones about it!BMAONE23 wrote:If you wish to culture silicon based bacterium in a Petri dish, would that make you a Horta Culturist?Sawngrighter wrote:Silicon Life, and other life forms.saturno2 wrote:There is the possibility of to find salt liquid
water on Mars.
It can to have elemental life on Mars.
But, you need to find another important
point for the life: the carbon element
Carbon element------------ life
Not element carbon ------ not life
http://www.airspacemag.com/daily-planet ... 13/?no-ist
