Could life have survived a fall to Earth?

Sep 12, 2013
Asteroid impacting Earth's oceans. Credit: NASA/Don Davis

(Phys.org) —It sounds like science fiction, but the theory of panspermia, in which life can naturally transfer between planets, is considered a serious hypothesis by planetary scientists. The suggestion that life did not originate on Earth but came from elsewhere in the universe (for instance, Mars), is one possible variant of panspermia. Planets and moons were heavily bombarded by meteorites when the solar system was young, throwing lots of material back into space. Meteorites made of Mars rock are occasionally found on Earth to this day, so it is quite plausible that simple life forms like yeasts or bacteria could have been carried on them.

Yet serious questions remain for supporters of this theory. Would even the hardiest life forms be able to survive an impact which ejects the rock into space? Could they live through the freezing temperatures and deadly radiation of space? And could they enter the atmosphere and hit the surface of the Earth without being killed?

New research presented at the European Planetary Science Congress at UCL aims to answer the final question, of whether entry and impact is survivable for simple organisms. Using frozen samples of Nannochloropsis oculata, a type of single-celled ocean-dwelling algae, Dina Pasini (University of Kent) set out to test the conditions which early life would have had to survive if it did indeed travel through space.

Using a two-stage light gas gun, which can accelerate objects up to very high speeds, Pasini fired frozen of Nannochloropsis into water and tested the samples to see if any had survived.

"As you might expect, increasing the speed of impact does increase the proportion of algae that die," Pasini explains, "but even at 6.93 kilometers per second, a small proportion survived. This sort of impact velocity would be what you would expect if a hit a planet similar to the Earth."

As well as surviving freezing and impacts, like those experienced when rocks are ejected from planets or hit them, there are good reasons to think that the other problems faced by panspermia are not insurmountable either. Ice and rocks can provide protection against radiation, especially if the organism is deeply embedded inside. What is more, heating caused by entry into the atmosphere is unlikely to heat anything more than a thin layer around the outside of rocks, forming what is known as a 'fusion crust.'

This research suggests that panspermia, while certainly not proven, is not impossible either.

"Our research raises several questions," Pasini says. "If we find on another planet, will it be truly alien or will it be related to us? And if so, did it spawn us or did we spawn it? We cannot answer these questions just now, but the questions are not as farfetched as one might assume."

Explore further: Analysis of Sutter's Mill fragments reveals organic compounds not seen in other meteorites

Provided by European Planetary Science Congress

4.6 /5 (16 votes)

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Birger
not rated yet Sep 12, 2013
...and since nearly all star systems are born in groups (star associations), a meteorite ejected from a world in one planetary system will have a non-zero chance of making it to another planetary system in the same star association, provided it happens during the first 500 million years.
So if life forms early in one system, on a world with low enough escape velocity to allow impact ejecta to escape you could even get interstellar panspermia.
deatopmg
1 / 5 (12) Sep 12, 2013
or maybe a contaminating microorganism was inadvertently or purposely left here after a visit by ??? Just another vanishingly small probability.
RealScience
4 / 5 (8) Sep 12, 2013
Um, Freethinking, I haven't seen evolutionists coming to the conclusion that life can't start from non-life...

Some journalists inflate minor changes in theories or that we don't yet know the details into headline stories of major problems, but that is bad journalism and does not reflect on the science. Quite the contrary, science has plenty of hypotheses for the details how life arose, and needs to weed out those that didn't happen to find the way that became life-as-we-know-it.

Recent work shows that the proton gradient needed for life as we know it to be a natural consequence of alkaline hydrothermal vents, making starting life energetically 'downhill' rather than an uphill struggle, but the case for 'white smokers' is far from settled and there are many other viable hypotheses.

Free your thinking from your current rigid belief system and at least look with an open mind at what evolutionists actually think, rather than stating that they think what you want them to think.
Torbjorn_Larsson_OM
4.3 / 5 (6) Sep 12, 2013
One should distinguish between transpermia, that is local life transfer between planets, and earlier panspermia hypotheses, which are pervasive interstellar seeding.

This looks at hypervelocity (shock) impacts. Small meteorites achieve terminal velocity before impact, so no shock heat and pressure.

If one goes through all the rates from the impact rates of then Mars to the survival rates of spores in crack inhabited rocks on the one hand, and compare with the abiogenesis rates that hydrothermal vents requires, it is immediately apparent that evolution of local life is more likely.

Even for the case that Mars had life earlier (rapid formation; no later sterilizing Moon creating impactor), and the "delivery line" was filled up with deliveries as Earth became habitable.
Torbjorn_Larsson_OM
4.2 / 5 (5) Sep 12, 2013
@RealScience: Actually I think the creationist gap for magic was closed 2012 by those smokers as Lane & Martin published their homology between pH modulated AHV chemistry and early chemoautotrophs. Yes, Russell makes much hay of the proton gradient too. And we can also add the relative CHNOPS frequencies in cells and Archean ocean water.

All these trait homologies means a phylogeny, and I haven't seen a peer criticism of L&M. So a) we know for certain life evolved out of terrestrial planet geochemistry, and b) since evolution theory rejects other mechanisms than evolutionary, the gap where creationists wanted to insert their magic is henceforth closed.

PS. I love the creationist thinking of adding factors pulled out from their asses ("really really..."). Reminds me of the rather insanely untestable open ended Rare Earth hypothesis, where you also can add bayesian factors freely to get any probability you wish between 0 and 1. (All original RE factors are now known wrong though.)
Captain Stumpy
1 / 5 (11) Sep 13, 2013
a) we know for certain life evolved out of terrestrial planet geochemistry


@ Torbjorn_Larsson_OM

so why all the hub-ubb? is this just sensationalism?
not being a smart alek... really curious... is it because of the lack of peer criticism of L&M? I have seen more than a few articles of late (in various places) about transpermia
RealScience
3.7 / 5 (3) Sep 13, 2013
@Torbjorn - White smokers naturally having proton gradients similar to those that drive key chemical reactions of life, and a pore size similar to common bacterial cell sizes, with those pore naturally concentrating nucleotides and naturally accumulating lipid membranes, and the proton gradient making nucleotide chains energetically favorable, is pretty convincing and that white smokers are likely to be shown to be the origin of life as we know it.

But while white smokers are probable, it is currently far from a 5-sigma conclusion. Warm ponds, tidal pools, clays, mica and pyrites have also been shown to have suitable concentrating mechanisms, and ponds, sunlight, lightning, waves, meteors and black smokers are capable of adding energy, and lipid membranes have been shown to be self forming under a variety of conditions, so although white smokers currently have the most complete set of attributes there are plenty of other viable mechanisms, especially in combination.
antialias_physorg
5 / 5 (4) Sep 13, 2013
If we find life on another planet, will it be truly alien or will it be related to us?

I guess that one will only be answerable when we find life on other planets - and when we do any kind of spculation up and to that point will be moot. So that part of the reseach doesn't tell us much.

The fact that you can have biological samples remain viable under high speed impact is certainly interesting, though.

Yup, since evolutionists are coming to the realization that life can't start from nothing given the earth has been around a really...

You missed the point of the article. Completely.

By idea of Fred Hoyle some viruses may fall from sky all the time.

Virus panspermia would be pointless - as a virus requires a (non-virus) host. You can't start off life on a planet with a virus.
RealScience
3.7 / 5 (3) Sep 13, 2013
@Captain: Panspermia and Transpermia are not mutually exclusive with white-smoker chemistry producing life precursors and nurturing incipient life. It is clear to those in this field that life could start on earth (probably in a variety of ways), and it also appears that life could survive inside a meteorite long enough to travel between planets (although between stars is much harder), so it becomes a race between numerous viable ways for life-on-earth to start on earth, with the wild card of life arriving here before it can start here.

Torbjorn is betting on the most favored horse in the race, and pointing out that even if transpermia is possible, it has extra hurdles in its path.
RealScience
4 / 5 (4) Sep 13, 2013
@freethinking: Not even particularly close.

Life-as-we-know-it WILL come from no life if you have the chemicals for life, processes that produce life precursors, processes that concentrate life precursors, and have an energy source that drives stringing life precursors into long chains.
Alkaline hydrothermal vents have all of these attributes.
The time required depends on the volume that one has of such conditions and on how well areas of that volume mix, and on temperature.

The time required for large volumes is SMALL, at most a few hundred million years.

In spite of only having a few decades and experimenting with tiny volumes, we have made good progress toward showing that it is possible, and in figuring out important steps and details. While we are far from replicating the whole process, we have even already replicated a few of the key steps.

(P.S. To be fair, were you there when your version of genesis supposedly happened and can you repeat it to prove it scientifically?)

JohnGee
2.1 / 5 (11) Sep 13, 2013
When scientists are actually capable of creating life from scratch in the lab, the creationists will just move the goal posts. They'll say the Earth wasn't a lab, or they will become terrorists and try to murder those pursuing that work.
Gmr
3 / 5 (10) Sep 13, 2013
JohnGee - I predict instead that they will turn it into a triumph for their side, proving that it takes "an intelligence" to make life.
Captain Stumpy
1.3 / 5 (12) Sep 13, 2013
RealScience
I see, thanks. I am currently thinking similarly, (betting on a local genesis rather than transpermia) but I am also willing to look at other points of view, especially with good data.
as Antialias put it "The fact that you can have biological samples remain viable under high speed impact is certainly interesting, though." that was actually something that stood out most to me in this article. speaks to the hardiness of life. it also opens doors of thought about where life can exist.
RealScience
3.7 / 5 (3) Sep 13, 2013
@Cap'n - I, too, keep an open mind to transpermia and panspermia (and I'll even look at more exotic theories IF someone provides a modicum of evidence).

And remember that transpermia works both ways - it is almost certain that some life-bearing rocks have been blasted from earth and landed on Mars, too, so this article has bearing on whether earth-based life forms have colonize Mars at some point.

It will be great when we actually find life forms elsewhere, especially if they are not from the same genesis as earth life and we finally have a sample size larger than one.
Captain Stumpy
1.3 / 5 (12) Sep 13, 2013
i totally agree. new life from a new genesis... that would be awesome.

i figured trans/panspermia would work both ways...

i keep coming back to the fact that life could be so hardy to live not only through a energetic event, but then through the vacuum of space and irradiation, till another energetic event happens, and still be viable. ok, so we prove one energetic event, but with the drop in viable organisms they would have to rebound after exiting the atmosphere and thrive, at least to an amount that would survive the next energetic event. i really think that this is the reason that i prefer the local genesis over them.... that combination of events. but i am open minded still

any speculation on what forms new life might take? or if they may be based upon something other than carbon? just fun speculation? :-)
dtxx
1.7 / 5 (12) Sep 13, 2013
FT is giving that straw man a fierce beating. Even if we found strong enough proof for everyone to agree life started on another planet and traveled here, that only moves the location of where abiogenesis took place. This article is not about the very beginnings of life, but only suggests a mechanism for how it may have taken root on this planet. Even with transpermia or panspermia, it still had to start somewhere.

Yup, since evolutionists are coming to the realization that life can't start from nothing...


So if your god is the first cause of the universe, and your god is a sentient life form who brought us to life, then at some point life still came from the "nothing" prior to your god. But, I have to give FT credit for being unintentionally truthful. It really is true life "can't start from nothing." If there was no matter or energy, we sure woudn't be here. But with the frequency of his posts, FT would find even Aquinas and S. Clarke telling him to STFU already.
RealScience
4 / 5 (4) Sep 13, 2013
@Cap'n - Asimov wrote a great article on other plausible life solvent / structural molecule combinations, starting from very low temperatures and ending up at very high ones. While there have been a few refinements since then, it is still the best all-in-one-place summary I have seen. It is called "Not as We Know it - The Chemistry of Life".
RealScience
3.7 / 5 (3) Sep 14, 2013
@Franklins - your post is an example of what a post should be - on-topic, short, readable (and correct). I don't know why others are voting you down on that post (habit, I guess).
Captain Stumpy
1.6 / 5 (13) Sep 14, 2013
@RealScience
the search I did keep giving me the book "Asimov on Chemistry"... that is one I don't have. but I am looking for it, especially now.

Asimov is one of my favorite writers. I am trying to collect his works (non-fiction) but they are not always so easy to come by. most people have his fiction, but I was always more interested in his non-fict writing more.

one of his that is my favorite: the Relativity of Wrong
RealScience
4 / 5 (4) Sep 14, 2013
@cap'n: I agree - Asimov's non-fiction is first rate (and his fiction is good, too).
"The Relativity of Wrong" is a new one for me - thanks, and I'll keep my eyes open for it.

Here is a link to a group of articles that includes "Not as We Know It":
http://www.bigear...9all.htm
RealScience
4 / 5 (6) Sep 14, 2013
I guess, because they're religious idiots, unable to think in independent way

@Franklins:
No, most of them would actually agree with what you wrote in THAT post, so it is clear that they voted without reading the post.

You have written multiple long posts on many threads, often poorly edited and sometimes off topic, and to protest this 'noise' some readers have gotten into the habit of giving all your posts a '1'. Some of them (lite/open, for example) even appear to have automated scripts that do so.

But automatic voting dilutes the useful information added by carefully considered voting, so effectively they are adding noise to protest the noise you often add, which is silly. It is counterproductive to vote on a post without at least reading enough of it to pass judgement on that specific post.

So keep your posts to the point and on topic, think before you write and edit after you write, and maybe the 'reflex raters' will stop being so lazy and use feedback wisely.

Captain Stumpy
1.3 / 5 (12) Sep 14, 2013
Here is a link to a group of articles that includes "Not as We Know It":
http://www.bigear...9all.htm


@RealScience THANKS for the link... reading it now!

Franklins... IMHO "noise" is your constant posting of what some to consider off-topic, and the issues with translation, as you seem to me to be bi-lingual and that english is not your first language, that some tune you out immediately and down-vote. i have caught myself doing this.

i have changed the way i vote. since there is no shortage of down-voters, i simply dont vote (as of late) unless i agree, then i choose a degree and represent how much i agree, and try to never go below 3. been working so far. i dont agree, i dont vote.
robweeve
1 / 5 (12) Sep 14, 2013
the planet was seeded by others who came here on purpose
Lurker2358
1 / 5 (10) Sep 15, 2013
The "Ancient Aliens" guys love this stuff. They probably think we came from the Orion constellation, since they are obsessed with the fact that most of the world's ancient cultures were obsessed with that constellation.

When you say "Betelguese" three times, it may seem as though nothing happens, but Ancient Aliens theorists probably believe Thetons show up and eat your soul, and then hide in your sperm to infect their next host.

Now if you've named your peter "Pan" then you have "Pan-spermia".

There, I can borrow someone elses nonsense, and make up some of my own.
RealScience
4.2 / 5 (5) Sep 15, 2013
@freethinking - where do you get these strange ideas about people who think that life evolves?

First, many believers in various gods (including Christians) also believe in evolution.

Second, I know many atheists, and I have never met one yet who says that NO evidence would EVER lead them to believe in God (although I have read of such atheists).

Although I certainly don't currently believe in a man-in-the-sky God, if there were one he could certainly provide evidence to convince me if he wanted to.

On the other hand I have seen quite a few anti-evolution creationists says no evidence would ever convince them. Try looking in a mirror, as you sure sound like one. And who are you to tell your God that he can't use evolution to create new species if he wants to? If you believe that god created us, then take a truly open-minded look at the evidence of how he did it.