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.
Actually at the equator in summer it gets up to about 70 degrees. Not bad at all, you just need oxygen.
This is an interesting nonpolitical conversation and I hope no one gets angry due to a difference of opinion.
My question is how?
To meet the daily needs of man on a planet without food,water and heat or the means to generate heat, how do we survive and at what cost.Certainly we can transport the necessities but that would be uneconomical which was my point to start.If this is not a viable thing, is it really a wise use of resources to achieve it for it`s own sake.
So we drop comets every 100,000 years or so .... works for me.
Not at all! You're still thinking "in the box". You can divert a comet's path with a relatively miniscule amount of thrust, as long as you do it far enough away. A change of a fraction of a degree out in the Oort cloud would completely alter the path of a comet, and be relatively simple to do in terms of energy expenditure (you could do it with a conventional chemical engine, or even using the comet's own volatiles as reaction mass, if you wanted to get fancy). Calculating the exact change needed is the tricky part, and it's not THAT tricky.
In terms of melting the Martian polar ice caps, that's even simpler. Seed them with a genetically engineered plant that can thrive in the cold sparse atmosphere, but which (here's the key) is dark. You don't need to make that many, because they'll spread on their own (think ivy or kudzu). You lower the albedo of the poles, they retain more of the energy they receive from the sun, and they begin to melt. Soon, the amount of CO2 in the atmosphere is large enough to get a greenhouse effect going, and the process accellerates.
I'm not saying it would be a cake-walk, or quick, but it's certainly not a prospect that can legitimately be dismissed out of hand. Check out The Mars Society for a group of folks who have thought this stuff out a lot more than I have.
BTTT
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.
It's just a matter of time. Probably not in our lifetimes but eventually Mars will be terra-formed with an atmoshpere much like Earth's.
It gets so cold there because the atmosphere is so thin. We have just the opposite issue on Venus, which has a massive atmosphere and a resulting hot atmosphere. Venus is the closest planet to earth and almost the exact same size.
If we're talking about past life on a nearby planet, it's more likely that it existed on Venus. Unfortunately, it is so hot there we would never be able to do any research.
Transhumanist, thank you for pointing out those FACTS.
I also will point out that energy is an engineering problem and not an insurmountable one, especially when dealing with the environments we are talking about. The solar system has an almost limitless supply of energy in several forms.
As you pointed out comets contain volatiles for fuel production and also the gas giants. Solar power is available in three forms, the light itself, the solar wind, and heat. H3 is available on our moon for fusion power and who knows how many other planets or moons.
Carlr if the problem is of a religious predisposition I should inform you that I am both a Christian and my father is a Minister. I have found no wording in the Revelation that would preclude human life from exiting this rock. I in fact think it is in keeping with God's original and first message to us "Be fruitful and multiply".
If in fact your argument is not along the religious impute, than I sincerely apologize and ask you to explain yourself more fully.
Thank you.
Nuke Mars For its own good!
Now that the soviets are gone, we have all of these nuclear weapons lying around. Many are still attached to rockets capable of escape velocity. I propose that 90% of these be launched to detonate on the Martian icecap. There is a lot of water frozen on mars, and the energy of a colossal nuclear explosion will suspend a haze of water vapor and dust into the martian atmosphere. This will create a greenhouse effect, warming the planet, melting more ice, and causing more atmospheric haze. As the Martian atmosphere becomes warmer and wetter, several more rockets with varied photosynthetic bacteria should be sent to Mars as well. Natural selection and mutation (no doubt fueled by residual radiaoactivity) should allow these robust critters to adapt and begin putting out an oxygen atmosphere. I am a little concerned about available carbon but I understand the Mars does have some areas of carbon dioxide ice, which could be freed up for use by the remaining 10% of the nuclear missiles.
I see this program as akin to planting a seed from which will grow a wondrous fruit-bearing tree. In a few hundred years out descendants will thank us for beating our swords into plowshares and planting the seeds of a beautiful new world for them.
To meet the daily needs of man on a planet without food,water and heat or the means to generate heat, how do we survive and at what cost. Certainly we can transport the necessities but that would be uneconomical which was my point to start.
The key is to not just bring those things to the planet, but bring the means of creating them (or bring them in such quantities as to make the cost economical).
Several folks in this thread, including me, have spoken about the possibility of altering the Martian atmosphere (it's something called "terraforming"); especially in terms of melting the polar caps, it's pretty much a self-growing process once you kick it off initially. But that's a centuries-long prospect.
Even though the energy from the sun reaching the Martian surface is less than that reaching Earth, it's not impossible that solar power would prove effecatious. As a matter of fact, developing solar power for use on Mars would be something immediately useable on Earth. There's also the possibility of using nuclear power in a Martian colony to generate heat and electricity.
Food's a non-issue when you're talking about a long-term presence. They grow vegetables on the ISS right now; it wouldn't take much to imagine Martian settlers having their own greenhouses (it's easy to trap heat; just go into any greenhouse in January), fish ponds, and rabbit pens (rabbits, btw, have the best protein-yield to food consumed ratio; they'd be an ideal source of meat for a space station or Lunar/Martian colony).
Building materials can be locally produced, too. Silicon (a big part of the Martian soil) is very versitile that way. Water? The chemistry is a little intricate, but finding hydrogen and oxygen isn't that hard on Mars, and all it takes is electricity to make water. See above on the solar/nuclear options. I wonder how wind power would do in a Martian dust-storm?
The point of all this is that there need not be a huge and steady stream of supplies from Earth to Mars. Any Martian colony would need to have the means to create its own needs from the materials available, as much as possible. It would take some doing, no doubt. And a hefty initial investment; make no mistake.
If this is not a viable thing, is it really a wise use of resources to achieve it for it`s own sake.
This is really a fair question, and I could respond with the purely economic arguments about spin-off technologies and the possibility of Martian resources being shipped back to Earth (which is really a better argument when you're talking about asteroid mining, but maybe that's a different thread). There's the nationalistic argument; it would certainly be a matter of national pride to beat the Chinese to a permanent Moon and Mars presence (I'm hoping this will happen, btw; I'd LOVE a new space race).
But ultimately, I think the biggest argument in favor of a permanent human presence on Mars is the simple human need to expand our horizons; to spread ourselves into new environments as they present themselves (the implications for the survival of our species come some planet-wide catastrophe should, I hope, be obvious).
The end result won't be anything like the vision of some NASA planner any more than the United States was in the vision of Isabelle of Spain when they sent Columbus on his mission of exploration. But without that initial boost, it's VERY hard for private enterprise to justify the risk and the expense. I tend to libertarianism myself, but the space program is one place I see definite benefit for government involvement, if only to give private enterprise the base it needs to grow.
The other point you make about a plant that can live in a cold,dark environment requires a plant that does not exist.If it is a water/carbon based life it will freeze and die.You would have to "create"new matter in the form of new genes that would allow a plant with characteristics opposite any that have ever populated the Earth.
No matter how you slice it,life on Earth can only be logically explained as the result of an intelligent design.
Just contemplate if you will all the factors that have to be in place for life to exist as we know it.
Not just exist but to do it in a practical,efficient manner.
"Excuse me, but the reason given by most scientists as to why Mars lost its atmosphere is because it lost its magnetic core because the core cooled off. This caused the loss of atmosphere. If this is true, then bringing in water and co2 is not going to help. Mars still does not have a molten core, iron to be exact, that it needs to have magnetism. Without it, we cannot hope to terra form it. This problem would have to be solved first or any atmosphere we bring in will be lost to space just as the original was."
-- Would a few thousand nukes do the job???
100 Nukes a year for 100 years???
My point is the reasons that life as we know it cannot practically exist on Mars today applies to the past as well.
I'm not really sure how you come to that conclusion. You could send a probe to a comet to alter its trajectory (assuming, as you and I both point out, that the difficult problem of calculating the change needed can be worked out) could probably be sent out for under a billion dollars (Rosetta, the ESA comet-probe, cost only US$344 million). And time is free; once you start the process, it doesn't cost any more if that process takes one year or ten. A billion dollars to bring 9 billion tons of water and 800 million tons of CO to help humans live on Mars? Sounds like a cost-benefit analysis winner to me.
(Unless you're of the opinion that any money spent on space exploration is a waste, in which case we're just going to have to end now and agree to disagree.)
No matter how you slice it,life on Earth can only be logically explained as the result of an intelligent design.
I disagree with you, naturally, but let's keep this discussion on the subject of Mars. I'm sure we'll have the opportunity to discuss evolution, ID, and Creationism in some other context.
I do not want this to seem as if you’re being ganged up upon here, but I personally have very strong emotions when it comes to this subject and that is a fault of mine.
I myself believe in intelligent design, but I do not limit my thinking to the Earth itself.
Technology has moved our species from one hardship to the next. We moved from small villages and tribes out to conquer a whole continent. We then developed new technologies that allowed us to conquer an entire world. We have now have developed still more technology that allows us to conquer the skies, a human presence in near space and our fingers in the farthest reaches of our solar system.
At any point in time we were physically safe and could have prospered quite well with no further development. So why do we continually reach for more? What specifically caused us to reach and grasp for that new horizon?
I believe the Creator put this in us, and he did it for a reason I cannot even begin to imagine.
At any point we could have stopped and still been his children worthy of his love.
I think we are coming to a turning point in human development and a rebirth of civilization as we know it. No longer will governments be able to oppress his children, how can they when we can just leave as the pilgrims did during the birth of our own country.
I think if you want the true promise of God's teachings we will find it out there in the rest of His Creation.
All these worlds he created for us. We are living in the Garden, our birth place. It is high time we left the cradle and inherit the promise and command of our Lord, Be Fruitful and Multiply.
Probably many viewing this are scratching their heads wondering "what the"
I do consider space exploration to be a waste if not done for military or for a practical, efficient energy source for life here on Earth.
Trying to find microbes on Mars really does`nt seem to have useful purpose.
Many of the same scientists that are behind this say we will destroy life here within the next century.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.
I am in no way accusing you or any one here of espousing these ideas.I'm just skeptical of the agendas of some pushing this.
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