Meteorite experiment deals blow to 'bugs from space' theory

"deals blow to 'bugs from space' theory"
Nonsense. Smearing some bacteria on the rear surface of two tiny pieces or rock has no relevance to the panspermia theory. Bacteria are found living thousands of feet below the earths surface in the interstices naturally present. When the experiment has been repeated and shows that all bacteria -or bacterial spores - have been killed in the center of a 10Km wide space rock, that would be more relevant. Bad science.

Actually the more I think about it the more of a no-brainer it seems. Unless you're talking about a huge rock (with a lot of surrounding insulation) the heat really would be too intense for any kind of life as we know it to survive.

Admittedly I've never been a fan of panspermia, and quite frankly always considered it fringe science....so it may just be my bias showing through.

Yes but say a bolder sized peace comes into the atmosphere and explodes partway down sending some of its mass back towards space thus slowing its decent. Brakes up again smaller peace ejects the same. now moving far slower then burn up rate.
brakes open releasing spores microbes etc. that are very light in now thick atmosphere float slowly down alive. Providing the vacuum and hard radiation of space had not killed them.

If on future mars missions we find life or signs of earlier life on mars that resembles life as we know it, it would be conclusive to say pan-spermia happened.

Until then its an interesting theory that may or may not have happened.

Unfortunatly the only thing this article suggests is that small meteorites are unlikely to spread life around.For some reason i suspect funding wouldnt allow the 10km rock experiment:D

Size matters.
Too small and the meteor burns up in the atmosphere.
Too large and the meteorite is vaporized on impact.

I have seen photos of meteorites that range in size from softballs to basket balls that left only small (less than 1m) craters if any at all. These meteorites could be porous or have deep fissures and still be large enough to insulate the interior from the heat of passing through the atmosphere. I can envision a scenario where just such a rock lands in water, snow or ice and is rapidly cooled before the interior of the meteor was heated via conduction and said space germs are cooked. Such a thermal shock could also further fracture the rock releasing the travelers to their new environment (we must assume it's not toxic to them).

"deals blow to 'bugs from space' theory"
Nonsense. Smearing some bacteria on the rear surface of two tiny pieces or rock has no relevance to the panspermia theory. Bacteria are found living thousands of feet below the earths surface in the interstices naturally present. When the experiment has been repeated and shows that all bacteria -or bacterial spores - have been killed in the center of a 10Km wide space rock, that would be more relevant. Bad science.

Yeah the test is not conclusive but its some result at least. They should try bigger ones with bacteria placed in the center.

Very large rocks have huge kinetic energy and are vaporised on impact - nothing will survive in those.

To me the main problem with panspermia is that it doesn't solve any problems, instead it creates new ones - the life still had to start somewhere, and on top of that it also had to make an exceedingly improbable journey to Earth.

I think the reason behind panspermia is a desire some people have for a more romantic way in which life came about as well as the fact that it is more compatible with purposeful creation (by aliens, god, AI, or whatever). No trace of such a deliberate creation on Earth can be troubling for proponents of some such theories, with panspermia they can claim the creation took place elsewhere.

We have already successfully returned E. coli from NEO behind a heatshield. Too much design consideration opens the experiment to criticism.

I know this is a stupid question, but is there a reason the process must take place on an actual re-entry vehicle?
Wouldn't it be cheaper to simulate in a blast furnace or something?
Or is the abrasive nature of the entry also a factor?
I realize the questions may appear novice, but I'll admit I'm no astrobiologist.

This experiment is highly flawed and proves nothing. Meteors spin as they travel through the atmosphere, as I once was very fortunate to observe from 50 - 75', exposing more than one surface to heating and therefore dispersing the heat.

many of the points above are valid and point out that the experiment is highly flawed.

...or maybe someone just didn't wipe their feet or take off their shoes (like my wife is always telling me) when they stepped on the surface 4 billion yrs ago.

I don't like panspermia either but it does have the advantage of meaning that life would only need to develop on one planet and any collisions large enough to litter the solar system would effectively seed the habital zone of the galaxy as it went around spitting off rocks due to orbital influences.

I know this is a stupid question, but is there a reason the process must take place on an actual re-entry vehicle?
Wouldn't it be cheaper to simulate in a blast furnace or something?
Or is the abrasive nature of the entry also a factor?
I realize the questions may appear novice, but I'll admit I'm no astrobiologist.

Well it has to be as close to the real thing as possible, it would be very hard to precisely recreate all aspects of reentry like proper pressure profile, changing atmospheric concentration, shockwaves, abrasion, etc.

Besides no matter how hard you tried some critics would never be convinced its good enough.

(At least I think those are the reasons I'm not astrobiologist either)

All that's been shown is evidence that extraterrestrial rocks smaller than my butt are unlikely to be ferrying microbes.

I dont know why people are such fans of life coming from outerspace!!

What makes it so difficult to believe that life originated on Earth instead of Mars?

if it could originate on Mars, it could ALSO originate on Earth.

in fact, it could have very well originated on Earth and being transported TO MARS aboard Earth rocks expelled from Earth due to a big impact.

I'm assumming you mean 927 celsius to 1700 Farrenheit.

deatopmg said:

Meteors spin as they travel through the atmosphere, as I once was very fortunate to observe from 50 - 75', exposing more than one surface to heating and therefore dispersing the heat.

You observed a meteor (in flight) from 50 to 75 feet away? Sure... right...

I dont know why people are such fans of life coming from outerspace!!

What makes it so difficult to believe that life originated on Earth instead of Mars?

if it could originate on Mars, it could ALSO originate on Earth.

in fact, it could have very well originated on Earth and being transported TO MARS aboard Earth rocks expelled from Earth due to a big impact.

Right... but either way its still panspermia, at least within our solar system. If it is true that life developed on one planet and then seeded another, then wouldn't you find that rather interesting?

Anyway, *WE* are outer space from the perspective of Mars.

If on future mars missions we find life or signs of earlier life on mars that resembles life as we know it, it would be conclusive to say pan-spermia happened.

Unless you count the possibility that our Mars landers have already contaminated Mars with Earth grown life.

A second question, WRT this experiment, is how long did they leave the Chroococcidiopsis exposed to vacuum? Anything coming from Mars would be exposed to vacuum and solar radiation for at least 6 months (and more likely years.)

This experiment was a waste of time to begin with.

Not many people if any would expect that a rock that small would not be cooked on re-entry.

And cooking will kill bacteria.

Whether Panspermia exists or not this experiment proves nothing except that cooking does in fact kill bacteria something we already knew.

Even if Panspermia is proved as feasable it does not prove that life on Earth originated elswhere.

There is nothing on the books that says life cannot be created in more than one location.

I dont know why people are such fans of life coming from outerspace!!

What makes it so difficult to believe that life originated on Earth instead of Mars?

I think it's partly because life appears to have come out of "nowhere" very soon after the Earth formed.

Pretty much everyone agrees that there have been cyanobacteria at least as long as 3.5 billion years, and some evidence seems to indicate that they have been around for 3.8 billion years. That's the time when the fiery Hadean period ended and life as we know it became possible. The problem is that cyanobacteria are actually very complex organisms and the Calvin cycle they use to release oxygen requires lots and lots of evolution. Would cyanobacteria have evolved on Hadean Earth? I wouldn't bet on it.

Here's Wikipedia's entry for Calvin Cycle:
http://en.wikiped...in_cycle

if it could originate on Mars, it could ALSO originate on Earth.

in fact, it could have very well originated on Earth and being transported TO MARS aboard Earth rocks expelled from Earth due to a big impact.

As far as I know, there are three points that would make the reverse case more likely:
1. Earth is bigger and has stronger gravity, which makes it take in more rocks from space.
2. The weaker gravity of Mars means a large meteor impact on it's surface sends more rocks to space.
3. The conditions for life on Mars apparantly became favorable before they did on Earth.

Pretty much everyone agrees that there have been cyanobacteria at least as long as 3.5 billion years, and some evidence seems to indicate that they have been around for 3.8 billion years. That's the time when the fiery Hadean period ended and life as we know it became possible. The problem is that cyanobacteria are actually very complex organisms and the Calvin cycle they use to release oxygen requires lots and lots of evolution. Would cyanobacteria have evolved on Hadean Earth? I wouldn't bet on it.

According to (sourced) wiki article on hadean period liquid water already existed on Earth as early as 4.4 billion years ago (BYA).

Cyanobacteria article says the earliest evidence for life seems to be from 3.5 BYA but it is not identified as cyanobacteria which are phototrophic, evidence shows that photosynthesis evolved before 2.5 BYA but there is no proof when exactly.
All in all there is no conflict as those dates leave enough time for evolution to do its magic.

http://en.wikiped...i/Hadean
http://en.wikiped..._history

One other thing is that today's cyanobacteria are almost certainly completely different from those which first evolved.

Just as todays combustion engines are nothing like the first steam engines, the primitive life metabolism was nothing like today's sophisticated biochemical masterpiece.

Calvin cycle should be thought of as a most recent incarnation in a series of metabolic engines of increasing complexity developed during evolution.

3. The conditions for life on Mars apparantly became favorable before they did on Earth.

What makes you think so? So far it seems possible that they never became favorable on Mars.

Most ill-conceived "experiment" based on totally conflated premises. Firstly, species such as micrococcus radiodurans and M. radiophilus which can withstand 2Mrad of radiation and enzymatically repair their own genetic damage, and terrestrial hyperthermophilic bacteria which can withstand up to 306 C would have been more suitable here. Forgotten are two facts - their panspermic taxonomic precursors would have been far more resistant to the exigencies of interstellar journeys than evolutionary later ones that would have adapted to a terrestrial econiche - such adaptation clearly being a rapid process as ratified in the biostratigraphic record beginning shortly after crustal solidification in the Hadean Period; secondly, embedding in a heat-shield would appear to be a poor substitute for cometary or meteoric ingress modelling.

What if a rock fragment from Mars that contained living oragisims was in space for 10 year before it entered the Earths atmosphere, at a temperature of 3 degrees above absolute zero would the organism be able to survive the trip?

bacteria pulled from 100 million year old salt deposits were found to revive by simply adding water. I dont have the source at the moment, but you can google it, its quite interesting.

some bacteria seem to have been built for interstellar travel: survive radiation, vaccuum and cold of space, repair its DNA, and survive millions of years in a sort of hibernation.

stupid experiment though, smearing bacteria on the back of a rock? c'mon

Gotta redo the Spore Intro now.

According to (sourced) wiki article on hadean period liquid water already existed on Earth as early as 4.4 billion years ago (BYA).

The Hadean period, which lasted up to billion years, was a time when there was very little crust on Earth and so the first oceans were extremely hot (estimates vary between 80C and 100C), not to mention all the other types of hazards like radiation and chemicals. That's dangerous for organisms without DNA damage repair molecules and definitely too much for the molecules behind photosynthetic reactions.

Cyanobacteria article says the earliest evidence for life seems to be from 3.5 BYA but it is not identified as cyanobacteria which are phototrophic, evidence shows that photosynthesis evolved before 2.5 BYA but there is no proof when exactly.

The oldest known stromatolite fossils (photosynthetic cyanobacteria) are approximately 3.5 billion years old:
http://www.ucmp.b...ofr.html

One other thing is that today's cyanobacteria are almost certainly completely different from those which first evolved.

There's still no denying that oxygenic photosynthesis requires a very complex set of molecules to work.

Forgotten are two facts - their panspermic taxonomic precursors would have been far more resistant to the exigencies of interstellar journeys than evolutionary later ones that would have adapted to a terrestrial econiche

1. What makes you state this as a "fact"?

2. Why would they be more adapted to space? This would imply an organism evolving IN space as opposed to an organism evolving on a planet and being broadcast through space.

The above comments mostly covered it. A great example of how PhysOrg readers can spot a clunker.

But there are two other sillynesses to the study: 1) Life could have entered when the atmosphere was vastly thinner or thicker; 2) The study assumes that it's common for material in space to carry life. But it might be only one-in-a-million. The end result, after millions of hits, would be the same.

The Hadean period, which lasted up to billion years, was a time when there was very little crust on Earth and so the first oceans were extremely hot (estimates vary between 80C and 100C), not to mention all the other types of hazards like radiation and chemicals. That's dangerous for organisms without DNA damage repair molecules and definitely too much for the molecules behind photosynthetic reactions.

Todays life can exist in such conditions, early life could have been even more tolerant. As for radiation most of it would be attenuated by water.

There's still no denying that oxygenic photosynthesis requires a very complex set of molecules to work.

The oxygenic photosynthesis is complex, but photosynthesis when it first appeared was most likely much simpler based on something like a bacteriorhodopsin molecule - a single protein capable of converting light energy into chemical energy (proton gradient). Oxygen only started to accumulate at the end of archean period 2.5 billion years ago.
http://en.wikiped...hodopsin

I CANNOT UNDERSTAND WHY SMALL METEORITES WOULD EVER HAVE BEEN SERIOUSLY CONSIDERED AS BIOLOGICAL ARKS.
LARGER ONES PERHAPS.
THE MOST PROBABLE SOURCE WOULD BE DUST PARTICLES THAT WOULD TEND TO FLOAT OR DRIFT DOWN, THUS AVOIDING THE HEAT OF RE-ENTRY AND AVOID BEING COOKED.
SPACE DUST AND COMET DUST COULD BE SOURCES
I THINK IT IS PREMATURE TO WRITE THIS POSSIBILITY OFF ON A SINGLE 2 CM SAMPLING
FRED HOYLE AND A SRI LANKAN ASSOCIATE WROTE AN INTERESTING BOOK ON PANDEMICS AS HAVING POSSIBLE ORIGINS FROM SPACE DEBRIS OF SOME SORT. A TRIP TO ONES LIBRARY MIGHT PROVE INTERESTING

They should try a rock half the size of present day earth made of iron (which became earth's core) and filled with carefully controlled living conditions (water and atmosphere) for the pan sperm... or not...
Of course there could be a god. Nahhhh, that would be too simple

THOSE LAMEBRAINS PROBABLY USED LIVE BACTERIA INSTEAD OF GRAM-POSITIVE SPORES. BUT SCREW THE DETAILS, CHRISTIAN SCIENCE MUST MOVE ON. TAKE THAT, YOU SMARTY-PANTS INTELLECTUALS!

One thing overlooked is a real meteorite would have spent less time burning its way through the atmosphere than a re-entering spacecraft, some of them are going 4 or 5 times as fast, so a given size rock would have less internal heating in the first place. Also it is 1700 F not C.