Wet and Mild: Caltech Researchers Take the Temperature of Mars’s Past
PASADENA, Calif.—Researchers at the California Institute of Technology (Caltech) have directly determined the surface temperature of early Mars for the first time, providing evidence that’s consistent with a warmer and wetter Martian past.
By analyzing carbonate minerals in a four-billion-year-old meteorite that originated near the surface of Mars, the scientists determined that the minerals formed at about 18 degrees Celsius (64 degrees Fahrenheit). “The thing that’s really cool is that 18 degrees is not particularly cold nor particularly hot,” says Woody Fischer, assistant professor of geobiology and coauthor of the paper, published online in the Proceedings of the National Academy of Sciences (PNAS) on October 3. “It’s kind of a remarkable result.”
Knowing the temperature of Mars is crucial to understanding the planet’s history—its past climate and whether it once had liquid water. The Mars rovers and orbiting spacecraft have found ancient deltas, rivers, lakebeds, and mineral deposits, suggesting that water did indeed flow. Because Mars now has an average temperature of -63 degrees Celsius, the existence of liquid water in the past means that the climate was much warmer then. But what’s been lacking is data that directly points to such a history. “There are all these ideas that have been developed about a warmer, wetter early Mars,” Fischer says. “But there’s precious little data that actually bears on it.” That is, until now.
The finding is just one data point—but it’s the first and only one to date. “It’s proof that early in the history of Mars, at least one place on the planet was capable of keeping an Earthlike climate for at least a few hours to a few days,” says John Eiler, the Robert P. Sharp Professor of Geology and professor of geochemistry, and a coauthor of the paper. The first author is Itay Halevy, a former postdoctoral scholar who’s now at the Weizmann Institute of Science in Israel.
To make their measurement, the researchers analyzed one of the oldest known rocks in the world: ALH84001, a Martian meteorite discovered in 1984 in the Allan Hills of Antarctica. The meteorite likely started out tens of meters below the Martian surface and was blown off when another meteorite struck the area, blasting the piece of Mars toward Earth. The potato-shaped rock made headlines in 1996 when scientists discovered tiny globules in it that looked like fossilized bacteria. But the claim that it was extraterrestrial life didn’t hold up upon closer scrutiny. The origin of the globules, which contain carbonate minerals, remained a mystery.
“It’s been devilishly difficult to work out the process that generated the carbonate minerals in the first place,” Eiler says. But there have been countless hypotheses, he adds, and they all depend on the temperature in which the carbonates formed. Some scientists say the minerals formed when carbonate-rich magma cooled and crystallized. Others have suggested that the carbonates grew from chemical reactions in hydrothermal processes. Another idea is that the carbonates precipitated out of saline solutions. The temperatures required for all these processes range from above 700 degrees Celsius in the first case to below freezing in the last. “All of these ideas have merit,” Eiler says.
Finding the temperature through independent means would therefore help narrow down just how the carbonate might have been formed. The researchers turned to clumped-isotope thermometry, a technique developed by Eiler and his colleagues that has been used for a variety of applications, including measuring the body temperatures of dinosaurs and determining Earth’s climate history.
In this case, the team measured concentrations of the rare isotopes oxygen-18 and carbon-13 contained in the carbonate samples. Carbonate is made out of carbon and oxygen, and as it forms, the two rare isotopes may bond to each other—clumping together, as Eiler calls it. The lower the temperature, the more the isotopes tend to clump. As a result, determining the amount of clumping allows for a direct measurement of temperature.
The temperature the researchers measured—18 ± 4 degrees Celsius—rules out many carbonate-formation hypotheses. “A lot of ideas that were out there are gone,” Eiler says. For one, the mild temperature means that the carbonate must have formed in liquid water. “You can’t grow carbonate minerals at 18 degrees other than from an aqueous solution,” he explains. The new data also suggests a scenario in which the minerals formed from water that filled the tiny cracks and pores inside rock just below the surface. As the water evaporated, the rock outgassed carbon dioxide, and the solutes in the water became more concentrated. The minerals then combined with dissolved carbonate ions to produce carbonate minerals, which were left behind as the water continued to evaporate.
Could this wet and warm environment have been a habitat for life? Most likely not, the researchers say. These conditions wouldn’t have existed long enough for life to grow or evolve—it would have taken only hours to days for the water to dry up. Still, these results are proof that an Earthlike environment once existed in at least one particular spot on Mars for a short time, the researchers say. What that implies for the global geology of Mars—whether this rock is representative of Martian history or is just an isolated artifact—is an open question.
The research described in the PNAS paper, “Carbonates in the Martian meteorite Allan Hills 84001 formed at 18 ± 4 °C in a near-surface aqueous environment,” was supported by a Texaco Postdoctoral Fellowship, NASA, and the National Science Foundation.
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Written by Marcus Woo
Interesting stuff. Very cool. Although I have to wonder what the orbit of Mars was like 4 billion years ago, and what the young sun was doing.
Interesting to see a temp for this famous meteorite. As for life on Mars, without an appreciable magnetosphere to protect delicate DNA/RNA/equivalent processes, I’m still thinking “no way” unless its microbial and well underground, out of the reach of our discovery capabilities.
Time to go to Europa.
good grief…..we can’t get the temp of the planet we’re on
“…was supported by a Texaco Postdoctoral Fellowship,…”
More filthy big-oil money given to climate change deniers…??
So a rock is “blast[ed . . .] off into space” from Mars (without any severe temperature changes) travels through space to Earth (without any severe temperature changes) and glides gently down to Earth (without any severe temperature changes). And we can gather the temperature of Mars to within ±4/291 from that. Science is a beautiful thing, ain’t it?
4 billion years ago Mars probably still had a molten core so there would have been a magnetosphere. It is when all that Iron solidifies that you have to worry.
I still cannot understand how we *know* that this particular rock is from Mars.
Four billion years old means that the carbonate formed during the same Hadean period on Mars that saw the continual bombardment of Earth by large comets and asteroids. It’s not too surprising that under these conditions Mars had a wet and warm surface; wet from cometary water and warm from the impact heating.
Stark carbonates are not particularly thermally stable. Strong heating drives off the CO2, leaving behind a metal oxide. So, just the fact that ALH84001 contains carbonates at all says that it could not have been heated very strongly.
The most common metal carbonates — calcium carbonate and sodium carbonate — are white. The ALH84001 carbonates look orange, which could mean they’re contaminated with iron oxide. Here’s a picture of ferrous carbonate, FeCO3, which is typically colorless but here contaminated with ferric iron giving it a brownish caste similar to the Mars carbonate. Notice that the Terran version is highly crystalline. The Mars version is a globule, probably amorphous or a microcrystalline agglomerate, which indicates a different depositional process.
More here about ALH84001, including why some scientists seem so certain it is from Mars:
http://www.lpi.usra.edu/lpi/meteorites/The_Meteorite.shtml
Exactly Stark, exactly….
I’m with Stark on this one. I honestly can’t imagine any method this rock could have gotten from Mars to Earth that would have left much evidence of anything.
Excuse me, but what are the chances of an occurrence as the one described in the above article could happen;
– A small piece of the planet Mars’ surface is flung off into space, It navigates its passage to the planet Earth where it successfully transcends the atmosphere without as much as one small “melt Mark”, etcetera, etcetera —-
No wonder there are scientists who believe the Earth’s main heat-source is a trace gas called Carbon Dioxide.
Stupid ancient Martians drove too many SUVs rising CO2 and now there is no life on Mars.
ALH84001 is not a rock but a fossilized fewmet of Archelous, the great Sky Dragon prone to migrating from Sol’s third to her fourth planet over many eons when those worlds were new.
What’s that you say, Show us the evidence? Well, if evidence is your concern, Archelous and AGW are one. “The dragons we slay lie within us,” as Saint George well knew.
http://www.universe-galaxies-stars.com/mars.html
“Martian surface temperatures vary from lows of approximately -140 ºC (-220 ºF) during the polar winters to highs of up to 20 ºC (70 ºF) in summers. ”
So why is it a big deal to declare that it might have been 64º at some time in the past,
when we have actually measured 70º temps in our lifetime ?
Is it daring scientific boldness or merely attention seeking, obviousness ?
Like making a press release that says “Rocks are hard”, “Water is wet” “Winter is cold” etc.
{quote} In this case, the team measured concentrations of the rare isotopes oxygen-18 and carbon-13 contained in the carbonate samples. Carbonate is made out of carbon and oxygen, and as it forms, the two rare isotopes may bond to each other—clumping together, as Eiler calls it. The lower the temperature, the more the isotopes tend to clump. As a result, determining the amount of clumping allows for a direct measurement of temperature. {/quote}
By any chance is this ‘clumping’ rate influenced by any other environmental conditions other then temp… such as Atmospheric Pressure or Composition? Or GRAVITY? And did the scientists include that in their figures? Do they KNOW what the Atmosphere of Mars was like back then? Because it sure sounds like they are using the Temp they think the rock formed at to determine what the environment was like. Seams like circular reasoning.
Given that the Earth formed slightly later than Mars and then got hit by a Mars sized planet and forming the Moon, the speed at which life appeared has always been a bit of a puzzle.
Some have postulated that the early Mars would have been farm more amiable for abiogenesis. Life could originate on Mars, then be transplanted to Earth following a shallow strike on Mars and subsequent meteorite transference to Earth.
I do not buy the magnetosphere or ‘delicate’ DNA/RNA.
Firstly, we have no idea if Mars had a molten magnetic core 4.5 billion years ago.
Secondly, Surveyor 3 landed on the moon on April 20, 1967, it was visited on Nov. 12, 1969, by Conrad on Apollo 12. Conrad removed some cabling and placed it in a sterile bag.
Back on Earth, when placed in nutrient broth, Streptococcus mitis grew. Three years on the moon, and still alive.
http://science.nasa.gov/science-news/science-at-nasa/1998/ast01sep98_1/.
Here is a bit of Mars as the origin of our solar systems abiogenesis.
http://www.bibliotecapleyades.net/ciencia/esp_ciencia_life09.htm
Anthony et al,
Does anyone have a reference for martian surface temperature over the last 30 years? or more?
I recall reading that mars had been warming coincidentally with the earth. It ought to be leveling off now or in a cooling phase. Any links out there?
So let me see… Assuming the rock is indeed from Mars, its initially formed about 4 billion years ago at about the same time the planet is formed and is believed to have come from some way underground. One would tend to think the whole planet would have started out quite hot as all the pieces crash together and coalesce to form the plant. And at some point would have cooled through 18C whether there was ever warmth or water there or not.
Using 18C as a formation temperature for structure in a 4 billion year old rock that has been though the process of blasting off mars, floating around at varying completely unknown distances from the sun for billions of years and burning up in our atmosphere …as a proxy for Mars’ temperature is “Science” at its absolute worst.
Re: “I still cannot understand how we *know* that this particular rock is from Mars.”
A 2005 article from The New Scientist helps answer this, although they don’t elaborate much.
“Birthplace of famous Mars meteorite pinpointed”
http://www.newscientist.com/article/dn8004
The G. E. Pease reference is better than the one I cited for general info on its origins
October 12, 2011 at 5:41 pm
Here is the abstract page from an October 2000 article in Science showing that the interior of the ALH84001 meteorite experienced temperatures no higher than 40 C before, during, and after its ejection from Mars.
Here is the abstract page from a November 2007 Science paper showing that relatively small bolide impacts can launch about 10 million 10 cm chunks of Mars rock into space.
Here is the abstract page from a Science article showing that the bolide-induced ejection of small pieces from terrestrial planets (Mercury, Venus, Earth, Mars), following impact, occurs pretty readily and that the meteors can be readily captured by alternative planets due to orbital resonances.
This Wiki article summarizes how a certain class of meteorites are known to be from Mars: They all have unusual isotopic ratios different from other meteorites and different from Earth rocks, but similar to one another and similar to Mars rocks measured by the Viking lander. Some of these meteorites have trapped rare gas inclusions that are virtually identical to the ratios in the Mars atmosphere. Here’s the Science Mag abstract page describing this finding.
At the end, there’s little reason to doubt that rocks get ejected from one planet and captured by another. There’s little reason to doubt this can happen without a large heat shock — at least to the internal part of the rock. And there’s little reason to doubt that the ALH84001 meteorite is from Mars.
The finding is just one data point—but it’s the first and only one to date. “It’s proof that early in the history of Mars……
So, one data point from a blasted rock that was violently ejected from a forming Mars, travelling deep through cold space, and then plunging violently through a non-present-age climate that was probably much thicker than today – PROVES something…. ?
I may be a science noob.. but.. does one data point really prove anything?
Why are they certain that this rock didn’t get ejected from earth and come back in its orbit to impact?? They aren’t. They are simply practicing wishful thinking.
“The meteorite likely originated just below the surface of Mars”
They are not sure?.
Pat writes : “There’s little reason to doubt this can happen without a large heat shock ”
Little reason? The abstract hasn’t given any reason to doubt this whatsoever. It has said that because the rock shows signs of not having been above 40C then it obiously hasn’t been above 40C.
Just what temperature do you then the average rock of this size gets to as it enters our atmosphere and (mostly) burns up?
Let me put this into perspective, Pat. I’ll give you a rock and you can use whatever satellite data you like to tell me where it originated from. How accurate do you think you’ll be? And you’ll have the benefit of “knowing” it came from this planet and not another!
How in the world did this rock get from Mars to earth? Perhaps they have proof that it is a part of the Jeddak of Zodanga’s palace when that city was pretty much destroyed by John Carter and his ally Tars Tarkas.
Pat:
“And there’s little reason to doubt that the ALH84001 meteorite is from Mars.”
And there was little reason to doubt — qualitatively or quantitatively — that burning a substance liberated the phlogistons, leaving the calx behind. It’s an awesome historical narrative to be sure, and one of which I’m fond. But that’s no reason to elevate modern mythology beyond its station in funding season.
Geez, the idiots are out in force today. Next time someone claims that AGW skeptics are anti-science denialists, they can just point to this thread and say “See, told ya.”.
TimTheToolMan says:
October 12, 2011 at 8:58 pm
Just what temperature do you [think] the average rock of this size gets to as it enters our atmosphere and (mostly) burns up?
It is surprising, but most small meteorites don’t burn up. Many meteorites have been found covered with frost (for real, the centers are still very cold). Small rocks tend to reach terminal velocity very quickly. As a result, they don’t even make a dent when they hit the ground. Assuming that a rock comes from Mars, when it enters our atmosphere its speed might be almost the same as the speed of the Earth. As a result, its relative velocity could be very low.
Pat Frank says:
October 12, 2011 at 8:15 pm
And there’s little reason to doubt that the ALH84001 meteorite is from Mars.
====================
Pet peeve of mine. The correct formulation is that there is no evidence that rules out Mars as an origin. I don’t have the link anymore, but back when ALH84001 was a hot issue, there was a paper that analyzed the isotope evidence of origin. It’s clear from the isotope mixes that the SCN meteorites are very unlikely to have originated from the usual sources Earth, the moon or the asteroid belt.
Fine so far.
The association with Mars is derived from — as I recall — seven gases whose Martian isotope mixes were measured by the Viking Lander and whose isotope mixes in ALH84001 can be measured. This results in a lovely chart (without error bars) that shows a near perfect match. The problem is that the Mars atmosphere error limits for four of the seven gases are very broad. Virtually any rock from anywhere will “fit”. The isotope mix for one of the other gases varies a lot among the dozen or so SCN rocks. (how can that be if they are from the same source?). So we’re left with a two point match, not a seven point match.
The chart used to “establish” origin is very persuasive. But it might not be great science. Proof by Powerpoint as it were. The evidence doesn’t rule out Mars as a source. It might even suggest Mars. But proof of origin? I think not. It will please me no end if, in the long run, ALH84001 turns out to be from someplace other than Mars.
>>
The meteorite likely originated just below the surface of Mars. About 16 million years ago, another meteorite struck the area, blasting it off into space before it landed on Earth about 13,000 years ago.
<<
>>
The meteorite likely started out tens of meters below the Martian surface and was blown off when another meteorite struck the area, blasting the piece of Mars toward Earth.
<<
This is bad use of terminology and one of my pet peeves. The term “meteorite” refers to the mineral/material that survives a meteor impact. Saying that a meteorite struck something is nonsense. If someone wants to refer to the pre-impact object, then the correct term is “meteoroid.”
Jim
captainfish says:October 12, 2011 at 8:45 pm
I may be a science noob.. but.. does one data point really prove anything?
——————————————————
Historically, many things have been proven by just one data point (datum). The ones that immediately come to mind are the Michaelson-Morley interferometer experiment proving the non-existence of the luminiferous aether. The aberrations in the orbit of Mercury about the sun cannot be explained by Newtonian physics. Therefore, the physics, not the data must be wrong. Existence can always be proven by a single thing. So tell yourself honestly, if a flying saucer sat down in your front yard and little green men came out and granted press interviews for a week, would you say we need a hundred more landings to prove the existence of flying saucers and little green men?
Personally, I am still waiting for the AGW enthusiasts to explain the complete non-correlation between CO2 concentration and global temperatures going back a few hundred million years. Here’s one of many references: http://www.biocab.org/carbon_dioxide_geological_timescale.html To me, this one inconvenient plot shows that a doubling of CO2 will not lead to runaway temperatures. It didn’t happen in the past when CO2 was higher, why should it now?
The easily verifiable fact that the IPCC changed the temperature record for the past 1000 years tells me that they are cooking the books and are not to be trusted. Look it up for yourself. AR1 shows the medieval warm period and the little ice age, but AR3 has those historical temperatures flattened out. Lord Turnbull’s paper “A Really Inconvenient Truth” shows this and more. It’s a clickable pdf on this web page: http://www.thegwpf.org/gwpf-reports.html
So tell yourself honestly, if a flying saucer sat down in your front yard and little green men came out and granted press interviews for a week, would you say we need a hundred more landings to prove the existence of flying saucers and little green men?
Actually, to a true-blue scientist, he would be doubtful. He would ask them questions and conduct analysis of them and compare his results to other “known” results before coming to the conclusion that they were little green martians … or just little green men conducting a scam.
Don K says (October 12, 2011 at 11:32 pm): “The association with Mars is derived from — as I recall — seven gases whose Martian isotope mixes were measured by the Viking Lander and whose isotope mixes in ALH84001 can be measured.”
According to the article, the rock spent most of its 4 billion years on Mars before being blasted into space some 16 million years ago. So I assume the isotope ratios in the rock would be fixed from its formation 4 billion years ago, and we’re assuming the isotope ratios in the Martian atmosphere haven’t changed since then?
Robert writes “It is surprising, but most small meteorites don’t burn up.”
Well that may be the case but this one isn’t exactly small so its going to be travelling quite quickly…and then its only got to get to 18C internally and whats to say the structure didn’t internally form here on earth anyway? Or if the meteorite got close to the sun at some stage or any number of other plausible explanations as to its “18C” state at some stage.
The whole argument is so thin as to be speculation. There are so many massive assumptions surrounding the actual evidence and predicting Mars’ temperature!
THe soil temperature NOW is reported to be as high as 20°C and since the atmospheric pressure is so low and is nearly saturated w/ H2O vapor it acts as an insulating layer to minimize heat loss. So……
and we’re assuming the isotope ratios in the Martian atmosphere haven’t changed since then?
======
I believe so. The only obvious reasons for the ratios to change would be radioactive decay and “leakage” of gases to space at lower rates for heavier isotopres. I’m pretty sure there is a term for that. Can’t remember it.
I would think corrections for radioactive changes, if any, would be straightforward. But I sure could be wrong.
Because of Mars’ low gravity, I think the modern atmosphere is dominated by heavy gases where the amount of fractionation between different isotopes is presumably small. The light gases would long since have been lost? I could be wrong about that also.
A naive question: How do they know it came from Mars?
I bet the calderas of the Martian volcanoes were alot warmer than 64F at one time…..
Is everyone here happy with the remarkable notion that the piece of rock came from Mars? Isn’t the earth a pretty small target both in size and gravitationally to have drawn the chunk here. Is the science also settled on this. Re carbonate surviving the entry into the earths atmosphere. Calcium carbonate calcines at 850C about your oven cleaning temp. So we had the outer skin of this meteorite at about 2000C during passage through the atomosphere and microscopic textures survived a few inches inside! Also, couldn’t these guys at least have identified the carbonate involved. An orangy carbonate sounds to me like a rare-earth fluorcarbonate (like bastnaseite) or if not a carbonate, a rare earth phosphate. I want to believe this fantastic story – can someone convince me of this being a chunk of Mars. Oh, and I am a bit suspicious of the very accurate 64 degree temp on Mars that is recorded therein. I’m afraid I have been proxyfied silly.
“Researchers at the California Institute of Technology (Caltech) have directly determined the surface temperature of early Mars…”
and
[The method] “allows for a direct measurement of temperature.”
Seems to me that a “direct” measurement would be to take a Tardis to early Mars and read a thermometer. Measuring the isotope discrimination sounds like an indirect method (accurate though it may be).
Tim, if the rock had heated above 40 C it would not have retained its magnetism. That magnetism was caused by the magnetic field of Mars, which polarized the magnetic domains as the rock originally cooled. Radiodating of the rock gave its age as 4.1 billion years or so, which is when it solidified and when its magnetic domains were polarized.
The origin of the rock was determined by its isotopic composition, and from rare gases trapped in related meteorites. Those rare gases were in proportions identical to those in the Mars atmosphere. The proportions of rare gases in the Mars atmosphere are known from measurements taken by the Viking lander. Satellite data played no part in anything.
You seem to be displaying a naive skepticism that apparently isn’t informed by the facts of the case itself.
Plenty of meteorites don’t burn up or get heated through when passing through the atmosphere, by the way. Stone is a poor conductor. The surface can get heated and ablate away without necessarily heating the interior. The same process worked for the Mercury, Gemini, and Apollo astronauts, recall.
There was intelligent life on Mars.
How do we know?
There was once liquid water on the planet, and with all other ingredients there we know life was inevitable. Life plus time = intelligent life.
How do we know there was liquid water on the planet?
Because we know the temperature was right for it during a certain period.
How do we know this?
Because we found a calibrated thermometer sticking out of a martian rock.
🙂
Don K, you raised valid points. The abstract page for the original report about the isotopic signature of Martian gases in the EETA79001 meteorite is here. Looking at that paper, they did indeed report measurement error bars. It looks like a careful piece of work. Their error bars show the measurements supported a valid discrimination between Earth and Mars.
I also looked up the original 1977 JGR mass spectrometry report of Owen, et al, on the composition of the Martian atmosphere from the Viking lander data. That abstract page is here. They also reported measurement error bars — of order (+/-)10-20% of the measurement value and included baseline scans.
The upshot is that the isotope work is empirically credible, and the trapped meteoric gases can be assigned to Mars.
Question, if stone is a bad conductor of heat, the why are stones used in sauna houses? And, don’t some meteoroids explode in our atmosphere due to the friction and heating? And, weren’t our space capsules a bit more intelligently covered with heat dissipating materials than stone? But, I think the main question is, if they are sure that the martian surface got to 64F 4 billion years ago… then that means it never got above 64F during its formation and bombardment phase?
Shouldn’t a rock that is FORMING during the planet’s formation stage, be a bit more hotter than 64F? 64F is a bit chilly in my book.
Again, I am a science noob so I am obviously missing something here.
The Catalogue of Meteorites, kept and updated periodically by the British Museum of Natural History, London, since 1847, is worth a look. The fifth edition of the catalog(ue) was published in 2000, “includes the names of all well-authenticated meteorites known up to December 1999 (22,507 in total), even if no material has been preserved.”
Of interest is the country-by-country tally:
http://www.nhm.ac.uk/research-curation/research/projects/metcat/search//metsPerCountry.dsml
A few readers seem to be skeptical about how meteorites are found and differentiated from earth rocks. Since it’s the basic question a neophyte like myself would ask, it deserves to be answered. I’m not a geologist, but I’ll posit the following breathtaking theory explaining why so many meteorites are discovered in these locations. 1) Softest landing 2) Easiest viewing
Of the total cache of meteorites officially “discovered”, Antarctica wins at a walk with 19,884.
There’s a funny picture of Roberta Score belly-down on the ice, her face inches from her famous discovery. With a pair of binoculars, it’s obvious that you can see a black dot from miles away.
Next most fruitful meteorite fields seem to be the Sahara desert (see North African countries like Libya); U.S. appears to be the third best (I’m guessing tilled farmland in winter months, before crops come up).
Do meteorites have any value?
Pat Frank, hang in there!
“The upshot is that the isotope work is empirically credible, and the trapped meteoric gases can be assigned to Mars.”
Pat Frank
====================
Don’t have any problem with that, and I tried to say that. What I’m saying is that the isotope mixture is consistent with Mars as a source. It may suggest Mars as a source. But it does not rule out most of the dozens of other potential sources in the solar system because we have no idea what the isotope mixtures on Mercury, Venus, the Jovian moons, etc are — and probably won’t until we drag some rocks back from them and analyze the material.
Shouldn’t a rock that is FORMING during the planet’s formation stage, be a bit more hotter than 64F? 64F is a bit chilly in my book.
Captianfish
=========================
I’m not an expert on this, but I think the significance of 64F is twofold:
1. 64F is too cold for any of the proposed mechanisms for nodule formation except precipitation from a body of water — a process that seems not too likely in a world that is cooling from an initial molten state. But it is possibly consistent with a period slightly later with a cooled planet surrounded by a thick greenhousing atmosphere that has subsequently been lost. I’m not sure that I find the first part of that entirely persuasive, but …
2. 64F is rather warmer than one might expect on a planet twice the distance of the Earth from the sun. Theories of stellar evolution seem pretty plausible, and they say that the sun should have been somewhat cooler 4.5B years ago not warmer. The presumably rather dimmer sun is also a problem for those trying to figure out the Earth’s history. In the Earth’s case it is exacerbated by plate tectonics that have erased essentially all of the Earth’s early sedimentary history.
There 5 reasons why many believed/believe that the Martian meteorite showed real signs of ancient life, here a quote from MarsNews.com:
”
The scientists talked their reasoning for the discovery — they had four independent lines of evidence which, when taken together as a whole, ancient life on Mars is the logical conclusion.
Do these orange carbonate globs contain the remains of millions of ancient Martian lifeforms?
(Courtesy Science Magazine)
1) Carbonate globules
The carbonate patterns form a unique signature of life, and the density and compostion of the carbonate patterns is consistent with how terrestrial bacteria operate. Carbonate by itself, however, is abundant in non-living materials.
2)Polycyclic aromatic hydrocarbons (PAHs)
Organic compounds usually created by bacteria were present in the meteorite. There has been much controversy about whether or not the PAHs are contaminants from the Antarctic environment, or are present from Mars.
3) Magnetite globules
These globules are created by bacteria on Earth as well as some chemical processes. However, the distinctive tear-shape in the Martian evidence is only created by bacteria. Some scientists are still not conviced.
4) Microscopic fossil-like structures
The most dramatic evidence of all, pictures were shown at the press conference of worm-like structures present in the meteorite. While they are much smaller than terrestrial bacteria, they look very similar, but could also just be mineral structures. More pictures have been created since then. The initial skepticism about them has partially been silenced by recent discoveries of similar terrestrial fossils of similar (nanobacterial) scale.
Are these worm-like structures fossilised Martian bacteria? (Courtesy NASA/JSC)
5) All of these features occur within a few hundred-thousandths of an inch together. The most logical conclusion is that it’s ancient bacteria (life!). Immediately, other scientists disputed the findings, and a grand debate continues to this day. Neither side has convinced the other and there is abundant evidence both for and against Mars life in the meteorite.
”
My comment:
Especialy the PAH´s, Magnetite globules etc. and then the proximity of more “signs” in such a small small area… What kind of known geological mechanism could bring about all these different typical for life in the same spot??
I have not read all findings on this, but I havent seen no solid theory of how these findings should have ended in the same spot due to geological processes. So far I do not have the impression that this dispute has found a broadly accepted conclusion.
or?
K.r. Frank
K.r. Frank
=======
If it will help any, much of the controversy about evidence of life in ALH84001 revolves around rodlike structures that resemble likely very ancient terrestrial bacterial fossils found a few decades ago by Bill Schopf in West Australia. Schopf himself was skeptical about ALH84001 feeling that the evidence for biological origin was insufficient to be sure and that the various possibly microbial structures themselves were so tiny that there probably was not enough room inside them for both a cell and an enclosing cell wall.
See http://library.thinkquest.org/19455/alh84001_analysis.htm
and also “The emergence of life on Earth: a historical and scientific overview By Iris Fry p227” accessible through Google Books.
captainfish says: October 13, 2011 at 7:23 am
Actually, to a true-blue scientist, he would be doubtful. He would ask them questions and conduct analysis of them and compare his results to other “known” results before coming to the conclusion that they were little green martians … or just little green men conducting a scam.
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You mean that good science includes skepticism and invents further tests to prove or disprove alternative theories? Of course. A number of us repeatedly point out here that climate science as practiced by the “in crowd” does not act like real science in that they reject alternative theories and hide their data, communications, and computer models.
On that previous subject, I actually have a bit of experience with little green men. In 1973, I was investigating a rash of UFO sightings that had happened a few years previously in Newfield, New York. One example was a lady who called the police because there were little green men in her back yard. The police came to investigate, and sure enough, her neighbors’ kids were dressed in green and playing in her back yard. After the rash of sightings, a pilot admitted he started the whole thing by shutting down his airplane engine and flashing his landing light as he glided over the valley before restarting his engine on the far side of the next hill.
captainfish says: October 13, 2011 at 10:50 am
Question, if stone is a bad conductor of heat, the why are stones used in sauna houses?
Because of the cheap heat capacity and resistance to the environment, not their thermal conductivity. Meteor entries take less than a few minutes from hitting the atmosphere to hitting the ground. The poor thermal conductivity is what keeps them cold inside. A sauna uses the stones’ heat for hours, not minutes.
And, don’t some meteoroids explode in our atmosphere due to the friction and heating?
Some do, some don’t. Depends on their composition. Comet materials frequently explode, asteroid belt remnants usually fall intact.
And, weren’t our space capsules a bit more intelligently covered with heat dissipating materials than stone?
Stone would make an acceptable reentry heat shield; but you’re right, the chosen materials were far lighter. Ablative materials are typically used on ballistic reentries (Mercury, Gemini, Apollo, warheads, etc) and thermal insulators are used on lifting reentries (Space Shuttle, BOR-4, X-37).
But, I think the main question is, if they are sure that the martian surface got to 64F 4 billion years ago… then that means it never got above 64F during its formation and bombardment phase?
Can’t answer that one; I’m not a Mars Geologist. We do seem to have some knowledgeable people in this thread though.
Thank you Dan, Don K and Frank. I appreciate the patient teaching.
My small brain did a bit of research.
Mars escape velocity is about 11,000 MPH, so this rock was accelerated to escape velocity by an incoming projectile yet was not destroyed.
Pretty amazing if true.
Anyone care to convince a skeptic ?
There is nothing unusual or remarkable about debris being imparted with escape velocities by large impactors. You can see examples of local crater debris and sub-orbital debris on the surfaces of Luna, Mars, and the Earth. Although the rock at and adjacent to the point of impact may be vaporized and melted, much of the rock debris on the periphery of the impact remains unmelted. NASA reports about the apparent Martian meteorites “All twelve also show evidence of shock heating, presumably as a result of the impact which ejected them into space.”
It is also quite normal for a meteorite of this type to become a bolide upon entry into the Earth’s atmosphere, exploding as a consequence of the rapid heating and expansion of the exterior portions of the rock. The interior fragments of the rock can then fall to Earth at relatively low speeds with little or no evidence of heating or scorching experienced by the outer portions of the original meteor. Examine the collections of meteorites and their individual stories.
NASA:
I wonder how NASA knows that Mars is the only place where that shock-heating could have occurred?