Martian Meteorite ALH 84001 Revisited. New evidence of Martian biology?

[Brian T]

http://spaceflightnow.com/news/n0911/24marslife/

Does anyone else remember this bit from 1996? NASA announced that a meteorite found in Antarctica was actually from the surface of Mars. About 4 billion years ago, a meteor impact on Mars kicked up ejecta with enough force to achieve escape velocity, and after drifting in space for about 16 million years, it landed here on Earth. As if that wasn't crazy enough, then NASA says that the Martian meteorite might contain evidence of fossilized bacteria...from Mars. They backed down on that claim in the face of competing hypotheses, and they didn't quite have enough evidence at the time to make a compelling case. Now after 13 years of further study with better equipment, here's the kicker.

They may have been right all along.

This seems like it's from a reputable source. I've seen this article cited by a few other websites, but no official (i.e. NASA) confirmation just yet. I'll be interested to see if this pans out. So far, every internet rumors about major announcements tend to be anticlimactic, and it would be really cool for something of this magnitude to be announced.

I'm trying not to hold my breath too much. Your thoughts?

[Bynaus]

About 4 billion years ago, a meteor impact on Mars kicked up ejecta with enough force to achieve escape velocity, and after drifting in space for about 16 million years, it landed here on Earth.

That doesn't make any sense.

The rock that formed the ALH 84001 meteorite formed (crystalized) 4 billion years ago. But the impact that flung it into interplanetary space happend only 16 million years ago.

The debate has been going on for more than a decade now, with a majority rejecting the claims of a minority.

The abstract of the related paper (http://dx.doi.org/10.1016/j.gca.2009.05.064) is very conservative and doesn't even use the word "life"...

[marsbug]

Why doesn't that make sense? Mars has no plate tectonics, a rock that forms on the surface when the planet is forming will sit there until something happens to it.

This paper from the team that made the original find in '96 is a round up of their ongoing work, and references many papers including the one linked by Bynaus above. They don't claim to have definitive proof of life on mars. They do claim that they can show a number of lines of evidence still hold up, and that more recent data has ruled out the alternative explanantions for what they've found. It's a NASA published paper, so what you make of it depends on what you think of NASA peer review processes.

EDIT: I'm not implying anything about NASA's review process, I just wanted to aknowledge that they have a crisis in manned spaceflight right now, and it will be suggested that this is a grab for attention to try and bolster the case for spending money on MSF to Mars. I honestly don't think they would- it's too crudely transparent and the last thing they need is a damaging backlash. But i thought it'd be worth pointing out that the thought crossed my mind. END EDIT

The majority attacking the arguments of the minority is how science, especially a find/theory of this importance and controvosy, is supposed to work. That doesn't make them wrong, it means that they haven't been shown to be wrong or right yet, the debate is ongoing. The NASA paper isn't claiming iron clad proof of life on mars either:

In summary, the original hypothesis that features in ALH84001 may be the result of early microbial life on Mars
remains robust and is further strengthened by the presence of abundant biomorphs in other martian meteorites. These
biomorphs, while not completely definitive for microbial life, are clearly associated with martian aqueous alteration
(iddingsite) and are nearly identical to terrestrial biomorphs known to be formed by microbial activity.

I don't have the expertise to asses what they've found, but I think it means the question is still open. To quote the paper linked by Bynaus:

This origin does not exclude the possibility that a fraction is consistent with formation by biogenic processes, as proposed in previous studies.

My bolding.

I think the thing to do is wait for the offical announcment, and try not to expect anything definitive... I think this is one of those things that will never be wholly put to bed.

[RGClark]

Why doesn't that make sense? Mars has no plate tectonics, a rock that forms on the surface when the planet is forming will sit there until something happens to it.

Bynaus was referring to Brian T's phrasing in his post, which implied the meteor impact occurred 4 billion years ago. It was the rock itself that formed 4 billion years ago and the impact only occurred 16 million years ago.


Bob Clark

[marsbug]

Ah, right. Sorry Bynaus I read through the quote too fast!

[Brian T]

Oops. Looks like I made a mistake with the timeline there, my apologies. I guess that's what happens when I try to type a synopsis too fast. Yay, reading comprehension.

But to echo what others have said, I'm also going to wait for official word on this. Even if it is confirmed, it will probably be along the lines of, "Evidence so far doesn't rule out the possibility that this might be biologic". I'm not expecting anyone to flat out say, "This is 100% unimpeachable, proof positive of Martian biology." I'll take Sagan's mantra to heart here - "Extraordinary claims require extraordinary evidence."

In either case, it's one of the most interesting things to pop onto my radar in quite some time.

[Kawarthajon]

To me it just makes sense that they would find something like this. If life arose on earth so soon after it's formation, why wouldn't it on other planets/moons too? I agree that we have to wait for the full report to come out and this question will be ongoing for decades until we can plant a human or robot on Mars capable of bringing back lots of samples.

It seems like the crux of the paper's argument for life was the purity of the deposits and their similarities to our bacteria. It is really fascinating to me that, if this is really bacteria, that it makes deposits similar to bacteria on Earth. That suggests to me that the bacteria themselves were somewhat similar.

I don't really buy the whole panspermia argument of how life got to earth because it doesn't seem to me that bacteria would be able to survive an impact that would launch it into space, a trip that lasted millions or even hundreds of thousands through space to a new planet/moon, survive impact on the new planet/moon and so on. My thinking is that the life would have to emerge independently with essentially the same building blocks.

If that is the case and this is really an example of life, then WOW!!!!!!!!!!!!!!!!!!!!!!!!1

[cosmocrazy]

To me it just makes sense that they would find something like this. If life arose on earth so soon after it's formation, why wouldn't it on other planets/moons too? I agree that we have to wait for the full report to come out and this question will be ongoing for decades until we can plant a human or robot on Mars capable of bringing back lots of samples.

It seems like the crux of the paper's argument for life was the purity of the deposits and their similarities to our bacteria. It is really fascinating to me that, if this is really bacteria, that it makes deposits similar to bacteria on Earth. That suggests to me that the bacteria themselves were somewhat similar.

I don't really buy the whole panspermia argument of how life got to earth because it doesn't seem to me that bacteria would be able to survive an impact that would launch it into space, a trip that lasted millions or even hundreds of thousands through space to a new planet/moon, survive impact on the new planet/moon and so on. My thinking is that the life would have to emerge independently with essentially the same building blocks.

If that is the case and this is really an example of life, then WOW!!!!!!!!!!!!!!!!!!!!!!!!1

I agree, if the conditions once long ago on Mars were indeed similar to those experienced here on Earth then why should life, as we know it, not form there also? If life here on Earth started the way is currently believed to have done, then all you require is liquid water and the right consistency of elements. Based on current evidence Mars does appear to have had/or have those basic fundamentals.

[newmac]

http://www.timesonline.co.uk/tol/new...cle6934078.ece

Yes Virginia; there is life on Mars.

[eburacum45]

Two things occur to me;
!/ Evidence of life on Mars four billion years ago is not the same thing as evidence of life on Mars now. The environment has changed very much since that time. Life that existed then may very well not persist today.

2/If life emerged on Mars and on Earth that suggests that the emergence of life (abiogenesis) is a very common event, as it seems to occurred on two adjacent planets with quite different characteristics in a relatively short space of time. However there is a chance that only one event of abiogenesis occurred, and life was transferred from one planet to another shortly afterwards. Since there was still plenty of meteoric bombardment going on in that period, 4Gya, the chances of such a ballistic transfer is not zero.

But the chance of life successfully coming from Mars to Earth is greater than the other way round, simply because of Mars' lower escape velocity. So it is quite possible that life originated on the red planet, and we are all Martians.

[Kawarthajon]

eburacum45 - I agree with you that it is unlikely that Mars has life today, unless it lives underground in very limited ecosystems.

I think panspermia is too far fetched a theory though. I do agree that life would be more likely to come from Mars to Earth if it did, but I just don't think that bacteria can survive in space for hundreds of thousands or millions of years, not to mention surviving the impact that pushed it into space and the landing on Earth. I know that bacteria can survive for thousands of years, but tens or hundreds of thousands - even millions?

[IsaacKuo]

If we're talking interstellar panspermia, then a survival time of hundreds of thousands or millions of years is required. But if we're just talking about a Mars->Earth transfer, the survival time requirement may only be a few months.

In order to ever reach Earth, a Mars ejecta would need to be on an Earth crossing orbit. Otherwise, it will simply orbit the Sun in an orbit relatively near Mars--eventually it will hit Mars again.

Any ejecta on an Earth crossing orbit would cross 1AU within a few months. Earth might not be there on the first pass, of course, so it could be centuries or thousands of years before it hits Earth (unless it hits Mars or the Moon first). But it will get it's first shot at the Earth within a few months.

[marsbug]

There is a good critisicm of the report on the comments section of the universe today article. I've tried to register to post my own comments but for some reason the registration e-mailnever arrives in my account! So I'll repeat the gist of it here:

Second, and no minor point IMHO: the team has failed to test the most important character. (I think, looking at "archae-biology" papers.) Chemically deposited magnetites tend to have a log-normal distribution from simple growth processes. Biological magnetites tend to have a normal distribution with a truncation, as they grow in biological organisms that tend to have a normal size distribution when they die and moreover are inhibited in growth when they hit the magnetosome membrane.

[Arguing that alien life won't have analogous cell structures, they should at least have a membrane and if so also display a normal size distribution. And preferably have a sub-compartment of some kind, or crystal growth will eventually kill them.]

When I go back to 1997, the group have identified the need for a test in a conference paper.

And 2000 they presented a very competent paper, looking at magnetite images and skilfully transforming their 2D representation into 3D format. (I wouldn't know how to do this before. But recognizes the need after having worked with statistics on inclusions in steel factory products – which luckily happens to be rather spherical and easy to treat.)

Unfortunately they stop right before actually doing a statistical test, unless again I missed something. They are eyeballing figures in a log diagram and trying to convince the reader that the ALH84001 magnetites are akin to a biological sample from a magnetotactic bacteria, and they are, and also that they aren't log-normal distributed, which is more uncertain despite their "helpful" sketch of one such distribution.

I think that this is the paper they are referring to.The statistical analysis concerning the normal and log normal distributions of width/length ratios is what i think is being reffered to in the comment ( it's on page 18), and I think he's right, although they show that there are similarities, and that the ALH84001 samples have a truncuation, as far as I can tell, they don't actually mention whether the distribution is log-normal or not. I don't recall this being mentioned in any of the recent papers metioned in above posts either. My knowledge of statistics is shaky at best, so would anyone else like to venture an opinion?

My own best guess is that the distribution was inconclusive, somewhere between one and the other, and 'needed more analysis/work'. Peer reviewers will often ask authours to cut material that is uncompleted or inconclusive, saying things like 'this data should not be submitted until conclusions can be drawn from it'

[iquestor]

So when is NASA going to comment????

[01101001]

So when is NASA going to comment????

What are you looking for?

NASA Press Release: New Study Adds to Finding of Ancient Life Signs in Mars Meteorite

JSC : Johnson Space Center
NASA : well, NASA

“In this study, we interpret our results to suggest that the in situ inorganic hypotheses are inconsistent with the data, and thus infer that the biogenic hypothesis is still a viable explanation,” said lead author Thomas-Keprta, senior scientist for Barrios Technology at JSC.

“We believe that the biogenic hypothesis is stronger now than when we first proposed it 13 years ago,” said Gibson, NASA senior scientist.

In addition to the new paper on ALH84001, the JSC team has published a paper that identifies shapes or morphologies in Martian meteorites that resemble known microfossil and microbial shapes in samples from Earth. These new shapes, seen with a scanning electron microscope, are termed biomorphs because of their close resemblance to known, biologically produced features on Earth. The biomorphs observed in the meteorites will be the focus of the JSC team with more detailed studies, including chemical and isotopic analyses.

“The evidence supporting the possibility of past life on Mars has been slowly building up during the past decade,” said McKay, NASA chief scientist for exploration and astrobiology, JSC. “This evidence includes signs of past surface water including remains of rivers, lakes and possibly oceans, signs of current water near or at the surface, water-derived deposits of clay minerals and carbonates in old terrain, and the recent release of methane into the Martian atmosphere, a finding that may have several explanations, including the presence of microbial life, the main source of methane on Earth."

More there.

[iquestor]

What are you looking for?

NASA Press Release: New Study Adds to Finding of Ancient Life Signs in Mars Meteorite

JSC : Johnson Space Center
NASA : well, NASA



More there.

Awesome link!!!!

SInce there seem to be strong resemblances to earth organisms, if these are found to be biological artifacts, I assume the next argument will be whether they share a common origin with earth life, ie panspermia. We wont know that until we find some living examples on Mars to compare them to.


SO, who is excited about this? I know I am!

[borman]

Regarding one of the links on the NASA page with links to the full paper

New Study Adds to Finding of Ancient Life Signs in Mars Meteorite

http://www.nasa.gov/centers/johnson/...meteorite.html

One of the links gives a graphic condensed view of the main points:



THE “LIFE ON MARS” HYPOTHESIS

http://www.nasa.gov/centers/johnson/...fe_on_mars.pdf

The view on pages 41-42 is that pure siderite makes pure magnetite upon heating while impure siderite heats to make impure magnetite. There is no pure siderite in ALH84001, but some of the magnetite is pure. Hence some of the magnetite came from somewhere else than the rock itself.

Perhaps a next step would be to determine if some of the unkinked chains of magnetite crystals discussed in a Freidman paper are made of the pure magnetite rather than the impure magnetite. If these are composed of the pure kind of magnetite, it would suggest that the crystals arrived as a chain. This is not the energy state favored by single crystals which would flow individually in a clump rather than a chain. A chain would need a constraint to retain chain structure during transport. A good candidate is a cellular membrane to maintain structure during presumably fluid transport to prevent a collapse into a clump.
Chains of magnetite crystals in the meteorite ALH84001: Evidence of biological origin
http://www.pnas.org/content/98/5/217...4-47ccd352c8fe

[borman]

Possible Martian biosignatures spreading to other meteorites

Three Martian meteorites triple evidence for Mars life

http://www.spaceflightnow.com/news/n1001/09marslife/

[Paul Scott Anderson]

Possible Martian biosignatures spreading to other meteorites

Three Martian meteorites triple evidence for Mars life

http://www.spaceflightnow.com/news/n1001/09marslife/

I saw that yesterday also; the three meteorites (ALH84001, Nakhla, Y000593) had also been referenced before with the previous news update last November. For anyone who may have missed it:

http://www.nasa.gov/centers/johnson/...ain_7441-1.pdf

The further studies this year should be very interesting and I will be paying close attention!

Paul

[newmac]

http://www.nasa.gov/centers/johnson/...e246437_hi.jpg