Posted on 12/13/2004 2:40:12 PM PST by tricky_k_1972
Evidence is mounting that the time-weathered red planet was once a warm and water-rich world. And a Mars awash with water gives rise to that globe possibly being fit for habitation in its past – and perhaps a distant dwelling for life today.
As sensor-laden orbiters circle the planet, NASA’s twin Mars rovers -- Spirit and Opportunity -- have been tooling about and carrying out exhaustive ground studies for nearly a year.
The Opportunity robot at Meridiani Planum, for instance, has found telltale signs that water came and went repeatedly within that stretch of Martian real estate. While that intermittent water at Meridiani Planum is thought to be highly acidic and salty, its ability to sustain life for some period of time cannot be ruled out.
What scientists now see is a Mars different in its first billion years of geologic history than once thought – and conceivably an extraterrestrial address for home-grown life.
Rainfall: From years to decades
Mars is one complex and perplexing world.
That was strikingly evident at the Second Conference on Early Mars: Geologic, Hydrologic, and Climate Evolution and the Implications for Life, held Oct. 11-15 in Jackson Hole, Wyoming. Nearly 140 terrestrial and planetary scientists took part in that seminal meeting hosted by the Lunar and Planetary Institute (LPI), NASA, and NASA’s Mars Program Office.
"One of the most significant new findings reported at the meeting was that it appears Mars underwent many of its most important changes much earlier in its history than previously thought," said Steve Clifford, an LPI planetary scientist. That includes core formation, the development of the crustal dichotomy, a rapid decline in geothermal heat flow, and the loss of a planetary magnetic field.
"Surprisingly, all of these events appear to have occurred within the planet’s first 50 million to 100 million years of existence," Clifford explained. A related discovery is the potential role played by large impacts during this same period, he said, a topographic record of which is preserved in the ancient cratered highlands and has now also been detected beneath the planet’s northern plains.
Clifford said simulations indicate that the very largest of these impacts may have blown away a significant fraction of the early Martian atmosphere. Impacts that produced craters greater than some 60 miles (100 kilometers) in diameter might have affected the climate on a regional and global scale, creating transient environmental conditions capable of sustaining continuous rainfall lasting from years to decades, he said.
Water-rich world
"There now appears to be overwhelming evidence that early Mars was water-rich – and may have possessed standing bodies of water and ice that ranged from large seas to a primordial ocean, perhaps covering a third of the planet," Clifford said.
Supporting evidence ranges from orbital observations of extensive layered terrains within, and possible paleoshorelines surrounding, the northern plains to on-the-spot investigations of the mineralogy and sedimentary record recently discovered by the Opportunity rover in Meridiani Planum.
"The implications of these findings are just beginning to be absorbed by the Mars community, yet they have already substantially revised our understanding of the planet’s early evolution. They are sure to be a continued focus of attention as the intensity and scope of Mars exploration increases over the next decade," Clifford observed.
Now mix in recent findings about the origin and range of life here on our own planet.
"Life is incredible and the envelope for what we know about where life can live -- data from planet Earth -- is ever expanding and is far beyond what we might have hypothesized," suggested Lynn Rothschild, a scientist in the Ecosystem Science and Technology Branch of NASA’s Ames Research Center, Moffett Field, California.
"There is a difference in perspective between planetary folks and biologists regarding where life might thrive. Organisms don't look for a global average. As a microbe, just give me 100 microliters of liquid water and I am happy. In any case, I certainly don't need an ocean! So think microenvironment," Rothschild advised.
Water and energy for microorganisms
Given the wealth of Mars Exploration Rover (MER) data, the likelihood that life could have existed on Mars -- or still does -- is viewed as more probable according to Carrine Blank, Assistant Professor of Molecular Geobiology in the Department of Earth & Planetary Sciences at Washington University, St. Louis, Missouri.
The MER results indicate that there were both large bodies of liquid water on Mars and there were fluids carrying redox (oxidizing and reducing) gradients through the near surface which resulted in precipitation of the blueberries, Blank told SPACE.com. "Life not only requires liquid water, but it also needs a source of metabolic energy," she added, "and redox gradients are great sources of energy for microorganisms.
Blank said in her mind the really big question is just how long was this liquid water and energy present on the surface of Mars. Be it brief or extended, so goes drawing the life line in the sands of Mars.
"If it was for just a brief time in the geologic history of Mars, then perhaps the potential for life is low," Blank said. "If, on the other hand, it was for an extended period of time, then the potential for life at the surface becomes much higher."
What is needed now, Blank noted, is more information about how widespread sedimentary deposits are on Mars, and then identify age constraints on the presence of liquid water at the surface.
Planet swapping microbes
The idea that the seeds of life hobnob between far-flung celestial localities is known as panspermia.
Could Mars be a domain for both microbes flung off Earth due to asteroid and comet impacts, as well as a planet where a "second genesis" might have also occurred? Furthermore, if this was the case, could external life and made-on-Mars biology co-exist?
"Absolutely," advised Blank, adding yet another scenario: That life originated on Mars and was transferred to the Earth, and then went extinct on Mars.
"At present, there is no geologic evidence that the origin of life occurred on the Earth. So one hypothesis is that the origin could have occurred elsewhere, like Mars, and then transferred to the Earth," Blank suggested. Alternatively, life could have originated on the Earth -- but left no evidence since we don't have any rocks for the first billion years of Earth history -- and then transferred to Mars, she said.
"If life was transferred between the planets, then Martian life, past and present, should have similar characteristics to early Earth life," Blank said. "On the other hand, if there was a second genesis, then life on Mars should be very different than life on Earth, and may in fact be quite difficult to detect or even recognize as life…particularly if it has gone extinct!"
Deepest branches on the tree of life
Meanwhile back on Earth, Blank said that more research is needed to understand whether interplanetary transfer of life could have been possible. In particular, additional work on hyperthermophiles -- microbes that live at very high temperatures and that form the deepest branches on the tree of life -- is required, as they were the early inhabitants of the Earth and therefore were the ones most likely to have been transferred around the solar system by impacts, she said.
"We know very little about the origin of life on the Earth…how it happened, what kind of environment it might have happened in, and how long it look to go from the origin to the last common ancestor of life as we know it - a very complex organism very much like modern life," Blank said.
Casting her eye back on Mars, Blank also said an unknown is whether conditions on early Mars were similar to what they were like on the early Earth when the origin of life likely happened.
"If they were similar, then perhaps a ‘second genesis’ could have been possible on Mars. Even if conditions were different on Mars, there could still have been a second genesis only with a very different result than what happened on the Earth," Blank stated. "If these different life forms were spread throughout the solar system, then they might have co-existed if they could learn to depend upon each other. If, on the other hand, they were in direct competition for resources, then you might expect that one would ‘win’ and survive, and the other go extinct," she advised.
War of the worlds?
Jack Farmer, an astrobiologist at Arizona State University in Tempe, also contends that the chance for life having existed on Mars is definitely in the cards. He is a Mars Exploration Rover science team member.
"We now have what I consider to be definitive evidence for standing bodies of water on Mars and this has opened up a serious and focused discussion of habitable environments on Mars early in the planet's history. This discovery marks a first step in implementing a strategy for Mars exopaleontology," Farmer told SPACE.com.
Farmer said the idea that Mars could have played host to Earth-launched microbes, as well as being a planet where a second genesis might have also taken place "are both contenders for an origin of Martian life and deserve serious consideration."
"I also think the idea of a ‘War of the Worlds’ on Mars between life forms that originated there and those that arrived from Earth is a serious possibility," Farmer said. And that prospect, he continued, raises some key questions: Who would win? Is there the possibility for a competitive co-existence between life forms that originated on a different basis?
"The good news is [that] these alternative hypotheses appear to be testable in the context of future missions. But this discussion also points, again, to the importance of planetary protection and the potential for back-contamination arising from a Martian sample return," Farmer concluded.
This article is part of SPACE.com's weekly Mystery Monday series.
Who are we to question how the creator works?
I know I'm not qualified. Does the creation of life in any way he sees fit (not that I'm saying this is how he did it) have any affect whatsoever on our own salvation?
I don't see it.
My point is the reasons that life as we know it cannot practically exist on Mars today applies to the past as well.
The evidence that there was once liquid water on Mars is pretty conclusive at this point. The Martian environment was very different a billion years ago than it was today. It was not nearly as cold as it is today, because there was much more of an atmosphere to trap in the heat (the "greenhouse effect").
So, unfortunately, your point doesn't really apply, because conditions on Mars today are nothing like they were a billion years ago, when it is thought life might have arisen on Mars.
And, let us not forget, this talk of Martian life is pure speculation at this point. Just because the conditions on ancient Mars could have led to life doesn't mean it did arise. That's one reason we need to step up exploration of Mars; to settle those questions.
"Mankind" MUST "Go On,"----or we Perish.
Humankind MUST "Go On," or we "Involute," & Perish!!
Doc
The President's Commission on Moon, Mars and Beyond says that lack of private property rights will strangle any nascent space industry in the cradle. I would agree that the lack of private property rights is further guaranteed since the signing of the 196 UN Outer Space Treaty.
Worry about that, Mars will take care of itself.
(We should move both Mars and Venus to a point in earth's orbit where they could form a stable planet-and-moon system. Then we should develop at least Venus and sell real estate.)
There was a thread earlier that talked about moving planets.Use Mercury as a moon for Venus, and let me reiterate my claim to mineral rights to Mercury.
Do you think Apollo was a "waste"? Say goodbye to scratch-resistant lenses, freeze-dried food, athletic shoes, CAT scans, MRIs, cool suits, cordless power tools, transistors, and a host of other technologies, some of which are listed here.
In terms of energy for Earth, you might be more interested in the potential to be had on the Moon. Someone in this thread mentioned the possibility of Helium-3 mining, which is a terrific energy source. Also look to orbiting solar collectors, which beam electricity to Earth via microwaves. But that's not germane to the question of colonizing Mars.
Trying to find microbes on Mars really does`nt seem to have useful purpose.
You don't think knowing whether life on Earth is unique in the solar system (let alone the universe) is "useful"? Granted, it doesn't put food on anybody's table, but you yourself mentioned the profound theological implications. Isn't it better that such truths be proven, even if they have bad implications for your own religion? (And I'm not sure that would be the case...)
Many of the same scientists that are behind this say we will destroy life here within the next century.
Well if all life "here" (Earth) will be destroyed, all the more reason to get some (human) life in other places! (I'm being partially facetious; I don't subscribe to the idea that we'll destroy the Earth, but I think there's at least a slight chance that an asteroid or some other natural phenomenon might do the job for us, and that slight chance alone is reason enough to spread ourselves out.)
This is no where near a time needed to solve all the problems of trying to populate any solar body. For this reason I think a lot of this is pushed in academia for the purpose of diverting resources that could be better spent on our current protection, missile defense etc.
The problems are being solved without the government's intervention; it's a question of implementation. Given the way our government's budgeting process works, it's not like a dollar not spent on Mars will be spent on ABM systems; that is almost certainly not the motive for scientists to push Mars (or Moon) exploration. There are a bunch of good reasons to do so, which hopefully I've mentioned in this thread, not least of which is the fact that if we don't we condemn our species to die on this single, fragile, planet, if not tomorrow, then sometime in the far future. Either way, I don't want to see us leave this universe.
I have prior claim to the Asteroids. You all can fight it out for the planets.
Whoa. Tugging comets around and interfering with orbits is what caused the big crash in our solar system. Will we never learn?
See back of moon, and valle marinaris. Matching boo-boo's?
(dibs on the parka and hot chocolate concession)
So anyway, there was this martian spacecraft that landed in this farmers field. The farmer and his wife were very frightened as it landed about 40 yards from their back porch. Suddenly the door to the spacecraft slowly opened and 2 seemingly human like creatures walk out and up to the porch where the farmer and his wife were watching. The male martian raised his right hand in a sign of peace and then spoke and said, "We are from Mars and come in peace on a scientific mission." So after a few moments the farmer invited the two aliens into the house whereupon the martian and his female martian companion spoke and asked questions about the earth, entertainment, politics, oceans, continents,and every conceivable subjectmatter. Then the subject of reproduction came up and the martian asked how humans reproduce. So the farmer explaind the conjugal act. The martian said "Well, that is very similar to how it is done on mars." He then propositioned the farmer to allow him to experience the act with a human and let his female martian companion experience the act with him. Well the farmer got somewhat riled up at this proposition, saying " We don't act like that here on the earth." The martian explained it was for scientific endeavors and slowly convinced the farmer to consent. So the male martian and the farmers wife retired to the barn. She was somewhat confused when he disrobed and saw a tiny vestigeal member presented. She laughed and said "That certainly won't work." The martian said why. She said because, well, not want to hurt his feelings, said well, its too small. So the martian reached up to his right ear and twisted it. At that instant his pecker emerged about 9 inches and looked like a pencil. The farmers wife said, well, thats better, but it still won't work. The martian said "Why"? She said the diameter,...its, its too skinny. Whereupon the martian took his left hand and twisted his left ear. Suddenly the martins member looked like a hot house cucumber. She said, "That will work." Once the conjugation was completed, they returned to the house and there was a somewhat perturbed farmer washing the coffee cups. He said to his wife, "Well, how did it go?" She said "Great, really great." The farmer was fuming. She said to her husband, "How was it for you?" He said, "It was awful." The wife asked "Why?". The farmer replied curtly, "The bitch kept trying to rip off my ears."...............................Uh Oh...I thought it said "Wife Swapping on Mars"
ping
I have a belief as to the uniqueness of life hear on Earth.You`re correct this is a religious matter but setting that aside if we are not unique in the solar system or universe what does it really matter.Would proving that be justification for the expense of doing it.Our lives and outcome will not be changed just by knowing this.If hostilities are feared all I can say is I try not to worry to much about things that I have no control over.
There is a scientific agenda that has nothing to do with science and a lot to do with undermining the US.I do not wish to speak ill of the dead,but I remember Carl Sagan saying once that it was his dream for a new year(I don`t remember which one)that the defense budget be used to fund trying to land a man on Mars.
This was the scientist whose name was used to validate various ideas like a nuclear freeze and a nuclear winter.He had a leftist agenda and used "science"to vindicate it.
With that, this has been fun and as said before we all need to agree to disagree.Hope no feelings were hurt.Thanks.
(It's 1967; no bad on the typo.) That is indeed a significant hurdle to overcome. Or is it? just how difficult is it to withdraw from a treaty? I think it could be as simple as saying "we withdraw from the treaty". (China did sign in 1983, I note.)
On the plus side, Congress did pass the Space Tourism Bill, which is a HUGE step forward. Small steps...
Refreshing to hear scientists admit that they know very little about how life started and how long it took to get where we are today!
"Big crash"? Somebody's been reading too many books by Erik von Daniken and Zecharia Sitchen.
We won't withdraw from the 1967 Treaty. We should. There will be no private development of outer space. The State will not allow it until the State is firmly in charge in the new territory. We won't see it this century or next--it's nearly too late anyway. Seek enjoyment from the particle of land on earth the State allows the citizen to own.
But you'll note they are not anywhere near to claiming it's only 6,000 years old. 5.7 billion... 5.9 billion... that's a scientific debate. 6,000... that's a joke.
Once the government figures out it will make more in taxes from encouraging private space development than it will gain from maintaining a monopoly on space development, it'll happen faster than you can imagine.
And that's just started. Congress passed the Space Tourism act. I give it three years before we see a huge government commitment to privitization of space.
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