Transpermia 

Microbes hitching a lift between planets on rocks blasted into space by impacts. Did life originate on Mars (or Venus) and hop to the Earth billions of years ago?

Contents

[Swapping Rocks][News] [Carl Sagan's speculations] [ Jay Melosh's 1998 Papers] ["5th Miracle" by Paul Davies][Venus] [Nanobes]   [Panspermia] [Rocks between stars] [Research in the1960s] [More links] [Updates] [Genesis radio show] [Transpermia paper] [Extremophiles][Hot springs from impacts][Water/ice on Mars]

This mechanism was recently given the name "lithopanspermia" (rock-across-seeding?) , which I find rather unimaginative. Oliver Morton came up with the term "Transpermia".

26 Aug 08 TPS: Support The Planetary Society Phobos LIFE Project - urgent request for donations to send microbes on a round trip to the Martian moon to test the transpermia hypothesis.

29 Jul 10 AMEC2010: Potential for microbe colonisation of Mars by rocks launched into space by the Chicxulub impact - paper by Michael Paine. Youtube video of the presentation (no audio) + Updates:

• 11 Dec 2012 BBC: Dinosaur asteroid 'sent life to Mars'
  
• 14 Apr 15 BBC: Evidence of liquid water found on Mars (strengthens my speculation) +
  
• 29 Sep 15: NASA Confirms Evidence That Liquid Water Flows on Today’s Mars
• 3 Mar 17 Uni Arkansas: Is Anything Tough Enough to Survive on Mars? + NASA: Microbes Could Survive Thin Air of Mars.
• 13 Jan 18 Science ($): Exposed subsurface ice sheets in the Martian mid-latitudes + Gizmodo: Water Might Be Easier To Find On Mars Than We Thought [maybe there is near-surface ice covering 30% of Mars instead of the 1% assummed in my calculations in 2010]
• 26 Jul 18 ABC: Mars has a vast liquid water lake beneath its southern pole, scientists believe + The Conversation: Discovered: a huge liquid water lake beneath the southern pole of Mars + Science: Liquid water spied deep below polar ice cap on Mars (strengthens the case for Earth-life reaching liquid water on Mars but see the Science article about the  challenge  of cold , salty water)
  
• 25 Oct 18 SciAm: Oxygen-Rich Liquid Water May Exist on Mars - Brines suffused with the life-giving gas could offer hope for past and even present microbes on the Red Planet, according to a new study [further strengthens the case for Earth-microbes reaching habitable conditions on Mars]
• August 2024: A new astrobiology book covers many of the topics set out below - The Secret Life of the Universe by Nathalie Cabrol. New Scientist review: Top astrobiologist explores the possibilities of alien life
• 18 Oct 24 JPL: Could Life Exist Below Mars Ice? NASA Study Proposes Possibilities + Nature: Potential for photosynthesis on Mars within snow and ice [but, for Transpermia, there is less likelihood of photosynthesising microbes surviving a journey from Earth to Mars (or vice versa)]

Translations of the following are available: Belorussian, Ukrainian, Boongoo, Swedish etc (you will have to search for them - I don't link to pages that I don't understand!)

Swapping Rocks - Exchange of Surface Material Among the Planets

by H Jay Melosh. (Reproduced with his permission)

Extract from the July 1994 issue of Planetary Report
 



The returning Apollo 11 astronauts' triumphal reception in July 1969 was somewhat delayed by a strict and lengthy biological quarantine. In those days, no one was certain that the Moon was entirely sterile. No one knew whether the lunar rocks might harbor deadly microorganisms. One wonders whether the level of concern would have been as high if scientists had known that dozens of lunar rocks had been lying in the Antarctic ice for thousands of years, or that about 10 small fragments of the Moon must fall onto Earth's surface every year. Unfortunately for the astronauts, the first lunar meteorite was not recognized until 1982. Before that time, no one seriously believed that nearly unaltered rocks could be blasted off the surface of one planet and later fall onto the surface of another.

Now, however, not only do we know that lunar rocks occasionally fall to Earth, but we are also reasonably certain that a group of nine meteorites, the so-called SNCs (for Shergony, Nakhla and Chassigny, named after the sites where they landed), originated on the planet Mars. Although all of the lunar meteorites were collected long after they fell, four of the SNCs were observed dropping from the sky. In 1911, a piece of Nakhla, which fell near Alexandria, Egypt, killed a dog, scoring the only known fatality (of a mammal) caused by a meteorite. [update: more recent work suggests otherwise]


The total flux of martian material falling onto Earth has been estimated at about half a ton per year. Under these circumstances, it may seem silly to worry about hypothetical martian organisms contaminating Earth, since martian material has evidently rained down on our planet throughout its history. Although a good case can be made for limiting modern biological contamination of Mars by terrestrial spacecraft, the discovery of Mars rocks on Earth brings up the immediate question of whether Earth rocks have been ejected into space, eventually to fall onto Mars, thus closing the circle of potential contamination.

Blasting Rocks off Planets

Only a few years ago, the question, "Can rocks be launched from the surface ofa major planet or satellite by natural processes?" would have been answered with a resounding no by experts on both impact and volcanism, the only geological processes known to eject solid material at high velocities. The existence of the lunar and SNC meteorites has, however, forced these experts to rethink the mechanics of ejection. Although volcanic eruptions still seem incapable of achieving planetary escape velocity, the ejecta from large impacts are not so limited.

Older work on the maximum velocities achieved by impact ejecta focused on the relationship between the pressure in the shock wave generated by the impact and the velocity of material just behind the shock. Measured directly in laboratory experiments, the shock pressure needed to accelerate material to planetary escape velocities--2.4 kilometers per second (about 5,000 miles per hour) for the Moon, and 5.0 kilometers per second (about 11,000 miles per hour) for Mars, implying pressures of 0.44 and 1.5 megabars (a megabar equals 1 million times Earth's atmospheric pressure at sea level) for lunar and martian basalts, respectively-would have been high enough to melt or even vaporize the ejected rock. Yet study of the lunar meteorites indicates that their ejection was accompanied by no more than about 0.2 megabar of shock, and the most highly shocked martian meteorites (which contain pockets of once-melted glass) still indicate only about 0.4 megabar.

The problem with the pressure-velocity relationship is that it applies only to material completely engulfed by the shock wave. Very close to the target surface, however, the ambient pressure is zero. No matter how strong the impinging shock wave, the free surface can never be raised to a pressure higher than zero. This effectively shields surface rocks from strong compression. However, the pressure increases very rapidly with depth below the surface, which translates into a powerful acceleration that throws lightly shocked surface rocks our at speeds comparable to the original impactor's speed.

An experiment performed several years ago by Andy Gratz and colleagues at the Lawrence Livermore Laboratory has verified the general correctness of this model. An aluminum projectile about the size of a penny was fired at a granite block at about 4 kilometers per second (9,000 miles per hour). Material from the face of the block was ejected at about 1 kilometer per second (2,000 miles per hour). This material was caught in a foam cylinder and, upon analysis. proved to be composed of millimeter-size, lightly shocked fragments of granite.

Furthermore, blocks up to a meter in diameter from the uppermost limestone layer surrounding the 24-kilometer diameter (l5-mile) Ries impact crater in southern Germany have been found nearly 200 kilometers away in Switzerland. Although they were not actually ejected from Earth, these blocks again show a combination of low shock damage (less than 10 kilobars. 10,000 times Earth's atmospheric pressure at sea level) and high ejection velocity (1.4 kilometers per second or about 3,000 miles per hour). Thus, current theory, experiment and observation all agree in indicating that a small quantity of material near the surface surrounding the site of an impact is ejected at high speed while suffering little shock damage.

Impacts such as the one that created the 180-kilometer diameter (110-mile) Chicxulub crater in Yucatan 65 million years ago (and incidentally caused a profound extinction that wiped out the dinosaurs, among others) may have launched millions of rock fragments 10 meters (30 feet) or more in diameter into interplanetary space. Of these fragments, a small fraction, perhaps 1 in 500, would have been so lightly shocked that internal temperatures remained below 100 degrees Celsius (212 degrees Fahrenheit). Higher temperatures would presumably kill any microorganisms present in the rock, but a few thousand of the ejected rocks, those originating nearest the free surface, could have carried viable organisms into interplanetary space. Although such impacts are fortunately rare at the present time (the only comparable craters known are the 1.85-billion-year-old Sudbury crater in Ontario and the 1.97-billion-year-old Vredefon crater in South Africa), the much higher cratering rate early in solar system history during the period of late heavy bombardment that lasted up to about 3.8 billion years ago would have made ejection of microorganisms a much more common occurrence at that time.

The most lightly shocked rocks ejected at high speed are necessarily those closest to the free surface. The surface is also the place where biological activity is highest, so that a large impact on Earth, or on an earlier life-harboring Mars, would be very likely to throw rocks that might contain microorganisms into interplanetary space. Larger organisms, even if present, would be unlikely to survive the 10,000 g accelerations accompanying the launch process.

Current cratering calculations indicate that large lmpacts even on Venus, despite its dense atmosphere, could eject surface rocks into interplanetary space. Meteorites from Venus have not yet been discovered, but there appears to be no reason why they might not someday be found on Earth. Large impacts on all of the terrestrial planets are thus capable of ejecting lightly shocked surface rocks into interplanetary space. If there should be microorganisms on the surfaces of these planets, then they too have a chance of journeying to another planet.

Between the Planets

Ejecta from even the largest, fastest impacts do not travel fast enough to make a direct trip from one planet to another. In general, the quantity of ejecta is largest at the lowest ejection velocities, so most planetary ejecta move relatively slowly with respect to the planet they escape (naturally, a much larger quantity of ejecta moves still more slowly and ends up falling back onto the planet of origin). The way that an ejecta fragment from, say, Mars eventually reaches Earth is by a series of encounters with Mars as it and the fragment orbit the Sun. Occasionally such a fragment comes too close to Mars and ends up falling back onto the planet after some rime in space. However, it is much more likely to miss Mars and recede into interplanetary space, but not before Mars' gravity has deflected the fragment and changed its orbit.

After a long series of such encounters. a few fragments' orbits get "pumped up" sufficiently to cross Earth's orbit. Then the more massive Earth takes over this cosmic volleyball game. changing the orbit still more, until the fragment may become Venus crossing. Sometimes the fragment is deflected all the way out to Jupiter or Saturn, which themselves may eject it from the solar system entirely. At any stage of this random walk through the solar system, the fragment may actually hit one of the planets, ending its journey.

Natural orbital perturbations thus supply the means for rocks ejected from one planer to spread throughout the solar system and eventually fall onto another planet (or leave the solar system entirely). This is presumably how the SNC meteorites reached Earth. Any microorganism contained in these rocks would thus have an opportunity to colonize the new planet, if it was able to survive both the journey and the fall to its destination.

Surviving the journey

Can microorganisms survive long exposure to the space environment? This question is of paramount importance for the transfer of viable microorganisms from one planet to another, since even dormant organisms might not be able to survive a long trip. Furthermore, cosmic rays, ultraviolet light or even radiation from the enclosing rocks might kill the organisms along the way.

Many microorganisms stand up surprisingly well to the space environment. Subjected to high vacuum, some bacteria quickly dehydrate and enter a state of suspended animation from which they are readily revived by contact with water and nutrients. Medical laboratories routinely use high vacuums for preservation of bacteria. Viable microorganisms were recovered from pans of the Surveyor 3 camera system after three years exposure to the lunar environment. However, these instances of preservation have only been tested over times approaching decades, not over the tens to hundreds of millions of years necessary for interplanetary travel.

Nature, however, has been kind enough to give us several instances of really long-term preservation of viable microorganisms. Chris McKay of NASA Ames Research Center has extracted microorganisms preserved for perhaps as long as 3 million years from deep cores in the Siberian permafrost. Even more impressive is the discovery of bacteria that were preserved for some 255 million years in salt beds of Permian age discovered at a site in New Mexico. Dehydrated by contact with salt and protected from radiation by the salt's low content of radioactive elements, these ancient bacteria demonstrated their viability by causing the decay of fish that had been packed with the salt.

Living bacteria can tolerate extremely high radiation doses, far higher than any multicellular organism can withstand. They can resist the effects of radiation largely because of active DNA repair systems. It is less clear that a dormant bacterium could tolerate large amounts of radiation. However, if the microorganisms happened to be living in cracks or pores of rocks that were ejected as large blocks, the rock itself might provide adequate shielding against both cosmic rays and ultraviolet light. Since it requires about 3 meters (about 10 feet) of rock to shield against high-energy galactic cosmic rays, if the impact event were to throw out rock fragments of about 10 meters (30 feet) diameter or larger, a significant interior volume would be protected against this radiation. Ultraviolet light can be screened by only a few microns of silicate dust, so the interiors of large ejecta blocks might be excellent havens for spacefaring bacteria.

Entering a New World

When a meteorite strikes the surface of an airless body like the Moon at high speed, it creates a shock wave in both the target rocks and in the meteorite that converts most of its initial kinetic energy into heat, melting or even vaporizing the original meteorite. Organisms inside such a meteorite would have little chance of surviving the impact. However, if the planet has an atmosphere. the meteorite might be slowed sufficiently that it strikes the ground at terminal velocity, perhaps only a few hundred meters per second, which microorganisms could easily survive.

The fate of a meteorite entering a planetary atmosphere depends largely upon its initial size and speed. Small meteorites, smaller than a few centimeters, burn up in Earth's atmosphere. Very large ones, a kilometer or more in diameter, traverse it without slowing and make craters. Meteorites of intermediate sizes, a few meters to tens of meters, however, are significantly slowed by the atmosphere. Buffeted by kilobars of aerodynamic pressure, they break up in the atmosphere (as did the famous Peekskill meteorite that disintegrated over the eastern United States on October 9, 1992) and may eventually fall to the ground in a shower of small fragments. Even on the modem Mars, with its tenuous atmosphere, meter-size meteorites are greatly slowed before striking the surface.

This scenario of slowing and breakup of intermediate-size meteorites is nearly ideal for the dispersion of microorganisms onto the new planet. Whether or not these organisms can survive and multiply depends, of course, on conditions at their new home. It seems unlikely that terrestrial organisms arriving on the modern Mars or Venus would survive. However, in the past conditions may have been much more hospitable on Mars at least, and perhaps at that time microorganisms from Earth found a home on Mars, or vice versa.

The current impact-exchange rates among the terrestrial planets are relatively low. However, during the era of heavy bombardment, when most of the visible craters on the Moon and Mars formed, cratering rates were thousands of times higher than current rates. Blue-green algae were apparently present on Earth as early as 3.5 billion years ago. and life may have been present even earlier, overlapping the period of heavy bombardment. Given the possibility of exchange of life among the planets by large impacts, we may have to regard the terrestrial planets not as biologically isolated, but rather as a single ecological system with components, like islands in the sea, that occasionally communicate with one another.

Although this scenario is highly speculative, it may be testable: If sample returns from former lake deposits on Mars should contain evidence of the existence of a microbiota, it may be possible to extract organic molecules from the samples. If familiar terrestrial molecules such as DNA, RNA and proteins are discovered, and especially if a genetic code similar to that of terrestrial organisms is found, then it would provide very strong verification of the idea that Earth and Mars have exchanged microorganisms in the past. Naturally, any such test requires that we be very careful not to contaminate the samples beforehand with terrestrial organic molecules.

H. Jay Melosh is a professor of planetary science at the Lunar and Planetary Laboratory at the University of Arizona. His latest book, Impact Cratering: A Geologic Process, has been published by Oxford University Press.



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Update: 24 June 97 - having just read a back issue of Planetary Report!

In an article titled "Some mysteries of Planetary Science" in the May/June 1988 issue of Planetary Report, Carl Sagan wrote:

A very recent and interesting analysis by H.J. Melosh at the University of Arizona shows that in the course of generating a l00-kilometer impact crater, debris can be transferred from Mars to Earth or vlce versa; the chunks being transported are big enough that anything inside them does not suffer significant radiation damage from the solar wind or solar ultraviolet light or cosmic rays during the roughly million-year time scale it takes to be ejected from the one world and swept up by the other. This has a serious biological implication. It suggests that on time scales of tens to hundreds of millions of years microorganisms from Earth arrive at Mars.

Is this true? If they survive the journey, would they survive the martian environment? And if we go to Mars looking for microbes and find one, is it indigenous, or is it some contaminant from Earth? How do we find out? And then there's even the remote possibility that a long time ago terrestial microbes got transported to Mars, sat around and maybe proliferated a while, and then another big impact on Mars ejected their remote descendants back to Earth. How much did they change in the meantime?

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Update May 98: Chris Chyba's paper "The Origin of Life in a Cosmic Context" in the newly published book "Carl Sagan's Universe" discusses the possibility of "panspermia" between Mars, Earth and Venus. 

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Update August 1998: A more up-to-date version of this topic has just been published in a journal called "The Sciences", a publication of the New York Academy of Sciences. The citation is:
Melosh, H. J. (1998) Blast Off, The Sciences 38, no. 4, 40-46.

Jay Melosh is also participating in a gigantic collaboration to do a careful analysis of the transfer of viable microorganisms from one planet to another that will be published soon in Icarus:
Mileikowsky, C., Cucinotta, F., Wilson, J. W., Horneck, G., Lindgrin, L., Melosh, H. J., Rickman, H. and Valtonen, M. (1998) Natural transfer of viable microbes in space, Part 1: From Mars to Earth and Earth to Mars, submitted to Icarus. (not published as at May 1999) - Paul Davies: "It turns out to be even easier than we thought to cross-contaminate the planets."

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Update Nov 1998: See also Scientific American, February 1984, page 55 "Message from the Moon" which discusses the hypothesis (now verified) that the "SNC" meteorites came from Mars. In the article Jay Melosh explains the mechanism whereby rocks can be ejected into orbit by large impacts. Interestingly, it was another meteorite (ALH84001) found in the Allan Hills of Antartica in 1982 that confirmed the idea that rocks can be ejected, intact, from planetary surfaces - it came from Mars. However, the idea goes back to at least the 1960's - for example, Carl Sagan's popular science book Planets refers to the possibility of rocks from Earth seeding the Moon with microbiotic life.


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Update September 1998: See the New Scientist article Survivors from Mars by Paul Davies and the new book 'The Fifth Miracle': Chapter 9
"Did Earthlife come from mars?" discusses impacts on Mars sending microbes to Earth. If it did...you and I...could be descended from Martians.
"Did Earthlife go to Mars?" discusses the reverse: It is therefore inevitable that life from Earth has reached Mars ... that is why I am certain that there was life on Mars in the past, and may well be life there today.
Amazon link.

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Nanobes

• Interplanetary transfer of organisms via meteoroids - the Nanobes survived the vacuum and intense radiation of the electron microscope (c.f. space travel) and the hot, pressurised environment 5 km below the seabed (c.f. planetary ejection due to a cosmic impact and subsequent re-entry) and
• "Nanofossils" in Martian meteorite ALH84001. Until now it was thought by many scientists that "organisms" around 20 nanometres - the size of the nanofossils - were too small for "life"!

Nanobe Links
 
• Press release from Queensland University (no longer works!) UQ scientists discover new, tiny organisms.
• 22 Mar 1999: BBC item Do nanobacteria rule Earth and Mars?
• 25 Mar 1999: ABC TV Quantum "Deep Bacteria" featuring an interview with Paul Davies. Paul's comment on the Queensland University discovery, if verified - "Mommentous"
• MSNBC "Nanobes add to debate over life in Universe"
• 27 Mar 1999: New Scientist editorial
• Guardian 20 Mar 1999 Small is beautiful as nanobes reveal we are not alone Physicist Paul Davies asks if tiny 'microbe' is missing link between life and non-life
• 30 Jun 00 ABC Science Show "Nanobes".
• 21 Dec 01 ABC: More evidence for 'nanobes' An Australian researcher may have quietly strengthened the evidence for extra-terrestrial life this week
• Nanobac.com - Finnish site researching developing uses for nanobacteria.
• NANOBES: Images and Links - Microscopy-UK
• Wikipedia: Nanobes
• Apr 06: Anya Yago from UQ is analysing the DNA believed to be associated with nanobes.
• Micscape Magazine: NANOBES: About Philippa Uwins and the Discovery Team 
• American Mineralogist 1998: Novel nano-organisms from Australian sandstones.
• New Scientist ($):
• Mean microbes - 11 July 1998
• Tiny wonders - 27 March 1999
• The Martians in your kidneys - 21 August 1999
• 
  
• Extreme organisms - 30 March 2002
• Nanobacteria revelations provoke new controversy - 19 May 2004
• Are nanobacteria alive or just strange crystals? - 22 May 2004
• 23 Aug 06: Nanobac Pharmaceuticals Inc. Announces Agreement To Validate Proof That Nanobacteria Promote Gallstones + 2 Nov 06: Live Video of Calcifying Nanoparticles - "real-time tracking of calcifying nanoparticles (CNPs) at a size
  of around 100 nanometers..." + Links to scientific publications.
• Feb 05 Kidney Int.(abs): A potential cause for kidney stone formation during space flights: enhanced growth of nanobacteria in microgravity
• 3 Jan 07 Science ($): Lineages of Acidophilic Archaea Revealed by  Community Genomic Analysis - "it may be necessary to reconsider existing paradigms for the minimum requirements for life..." Nanobes by another name?
• 12 Jan 07 EPSL ($): Impact of micro-organisms activity on the natural remanent magnetization of the young oceanic crust.
• Carlton College: Nanobacteria and Nanobes- Are They Alive?
• 6 Jun 08 NewSci: Nanoscope peers beyond the limits of light - maybe they will look for nanobes?
• 24 Aug 21 New Scientist ($): Artificially stripped-back cell is still able to rapidly evolve
  
  

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Panspermia - British astronomers Fred Hoyle and Chandra Wickramasinghe propose that "comets, which are largely made of water-ice, carry bacterial life across galaxies and protect it from radiation damage along the way. One aspect of this research program, that space contains organic compounds, has been pursued by others as well. After initial resistance, it is now generally accepted that space contains the "ingredients" of life. This development could be the first hint of a huge paradigm shift. But mainstream science has not accepted the hard core of panspermia, that whole cells seeded life on Earth."
Note that this concerns interstellar panspermia and is a different issue to the transfer of microbes between planets within the Solar System.


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Research in the 1960s

The possibility of fossilized life being found in meteorites goes back to at least 1961 when several scientists covered this topic:
• G Claus & B Nagy in Nature, 192:594 (1961)
• B Nagy, WG Menschein & DJ Henneset Ann NY Acad Sci 93:25 (1961)
• HC Urey "Lifelike forms in Meteorites", Science, 137:625-628, Aug 24, 1962.
References from Encyc Brit., 1965. (if they are available online somewhere please let me know)


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Organic Molecules in Space Found

Yahoo - January 12 2000 (copied here because of limited lifespan of Yahoo news stories)
 By PAUL RECER AP Science Writer

 ATLANTA (AP) - A primordial soup of complex organic chemicals that could be the
 precursors of life is cooked up very quickly after the birth of stars, new research suggests.

 ``Life could have had an easier time starting than we thought before,'' astronomer Sun Kwok
 said Wednesday at a national meeting of the American Astronomical Society.

 Kwok, of the University of Calgary, Canada, said a study by the Infrared Space Observatory
 showed that large organic molecules evolve within only a few thousand years from chemicals
 in the cloud-like envelope surrounding some stars.

 The conclusion is based on the infrared spectra readings of short-lived, carbon-rich stars that
 are engulfed in clouds of gas and dust. Kwok said the clouds are rich in some of the most
 advanced organic molecules ever detected in outer space.

 ``There is no doubt now that such complex molecules exist and the stars are able to make them
 with no difficulty,'' said Kwok.

 Such chemicals would eventually be ejected into interstellar space, he said, which makes it
 possible that they could end up on planets such as Earth where, under the right conditions, life
 could have evolved.

 Among the chemicals detected was acetylene, a building block for benzene and other aromatic
 molecules that, in turn, can form complex hydrocarbons, the chemical stuff of life.

 Kwok said it is possible that amino acids could be manufactured around stars, but this
 molecule, essential to life, cannot be detected by the current generation of space telescopes.

 The Infrared Space Observatory is operated by the European Space Agency.

 Another international team has made calculations that suggest that life could have arisen on
 Mars and then been transferred to Earth by meteorites jolted away from the surface of Mars
 by asteroid impacts.

 A team of astronomers from nine institutions and five countries made a serious study of the
 possibility and found that, if life ever existed on Mars, then there could have been up to five
 trillion life-bearing rocks from Mars that landed on Earth over the last four billion years.

 ``The question is, are we really Martians?'' said Mauri Valtonen of the Turku Observatory in
 Turku, Finland.

 The international team also studied the possibility of life-carrying asteroids from solar systems
 beyond the sun landing on the Earth and found the probability of this to be very low.

 ``The ancestral cell for life on Earth must have originated somewhere in our own solar
 system,'' said Curt Mileikowsky, an astronomer of the Royal Institute of Technology in
 Stockholm, Sweden, and a leader of the research team.

 In their calculations, the astronomers considered how frequently Mars would have been hit by
 asteroids that blasted rock away from the Red Planet and sent it flying toward Earth. Although
 only a few asteroids from Mars have been found on Earth, the team calculated that tons of
 Martian rock is here.

 The team also calculated the pressure, temperature, acceleration and radiation a microbe
 would have to endure to survive such a journey from Mars to Earth.

 At least two well-known microbes, Deinococcus radiodorans and Bacillus subtilis, said
 Mileikowsky, would be capable of surviving the trip. He said the microbes have been tested in
 laboratories and found to be highly resistant to heat, radiation and acceleration forces.

 Mileikowsky said the microbe would have to be near the core of a Mars rock to be protected
 enough to survive the journey through the vacuum of space and endure the searing fall to
 Earth.

 ``If the size (of the rock) is more than a football,'' he said, ``heat would not have time to get
 inside.''

 The astronomers estimated that up to one and one-half percent of the microbes inside such a
 rock would survive.

 The existence of life on Mars is now unlikely, but astronomers say that early in solar system
 history the planet had water, an atmosphere and mild temperatures. For this reason, it is
 believed that life could have once existed there. Scientists at the Johnson Space Center in
 Houston say they have found evidence that life once existed inside a Martian asteroid, but the
 conclusions are controversial.

 Early in solar system history, it is also calculated that up a trillion Earth rocks were blasted into
 space and traveled to Mars. This means that life from Earth could have once seeded Mars.

 ``Because of the heavy traffic between Earth and Mars, we couldn't decide which came first,''
 Martian life on Earth, or the reverse, said Mileikowsky.


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Panspermia and exchange of rocks between planetary systems

After reading the excellent paper by Curt Mileikowsky and co. 'Risks threatening viable transfer of microbes between bodies in our solar systm', Planetary and Space Science 48 (2000) 1107-1115 http://www.elsevier.com/inca/publications/store/2/0/0/ I wondered whether planetary systems could *quickly* exchange rocks, and therefore microbes. The Mileikowsky paper seems to suggest that it is extremely unlikely that DNA-based organisms could survive in space for millions of years (they use 100,000 years *flight time* as a limit for calculating the quantity of viable organisms exchanged between Earth and Mars). Assuming this is the case then the current distances to the nearest stars make survival aboard meteoroids ejected from the Earth extremely unlikely (comets may be a different matter - but I won't enter that debate). The other problem is the poor chances of actually encountering a planetary system after drifting through space for millions of years.

There is however a mechanism that might increase the chances of exhange of rocks between planetary system - THE STARS MIGHT COME TO US.In 1981 Jack Hills published a paper 'Comet showers and the steady-state infall of comets from the Oort cloud'. He was looking at a possible cause of comet bombardments. As part of this work he derived estimates of the mean time between stars passing within a given distance of our Sun. I don't know if there have been updates to these estimates but here is a summary of his work:
Minimum distance between        Mean interval
star and Sun (au)               (years)
500au                           5 billion
1,000au                         1 billion
5,000au                         40 million
10,000au                        10 million
This suggests that over the lifetime of the Earth about 4 star systems may have come within 1,000au of the Sun. It would be interesting to work out the odds of a microbe-bearing Earth rock finding its way into this region of the solar system (perhaps through encounters with Mars and/or Jupiter - the estimate is that several hundred kilograms of Earth rocks reach the surface of Mars each years so a reasonable number must just miss Mars and receive a slingshot to the outer solar system). Then the odds of it being "picked up" by a passing star and landing on a suitable planet - all within, say, 1 million years. No doubt they are extremely poor odds - but it would just take one successful exchange for panspermia to succeed.
One positive factor in this speculation is that it would take several years for the star to pass "through" the solar system. During this time there may be a major bombardment of the Earth by comets disturbed from the Oort cloud. The number of launches of rocks bearing microbes would therefore increase during this period (the delay in comets reaching the inner solar system may defeat this idea).

Michael Paine 5 Dec 2000

P.S. Jay Melosh advises that he is looking at this possibility for a forthcoming article in Icarus.

Updates

• 17 Mar 01: SpaceDaily: All Aboard the Meteor Express of Life
• 9 Apr 01 New Scientist: Wish upon a star - Life may spread in space when star systems pass close by.
• 4 May 01 Comment: Jay Melosh's work may have been misunderstood. His calculation of a few dozen extra-solar meteoroids landing on Earth over 4 billion years (or vice versa) means the chances of a microbe making it are very slim - the combined odds of an ejected rock actually hosting lifeforms and the chances of them surviving the journey must get into the millions (if not billions) to one against. In other words there is a very slim chance that Earth was seeded in this way but it is highly unlikely that the galaxy is teeming with life via this mechanism.
• July 01: Poster paper on Transpermia refers to Melosh's work.
• 8 May 03 Astrobiology (journal): Exchange of Meteorites (and Life?) Between Stellar Systems - H. J. Melosh
  

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More links & news

• Astrobiology links.
• The Martian underground was safe place for early life - Stanford University Press Release 30 Nov 1998
• NASA Meteorites from Mars.
• Life on Earth 3,800 million years ago - from Nature, 1996
• Radiation beating bug offers cancer clues - BBC, 18 Nov 1999 - a strain of pink bacteria that can survive 1.5 million rads of gamma irradiation, a dose 3,000 times more than would kill a human
• The Deep Hot Biosphere - by Tom Gold
• Conjecture about life on Mars - by Michael Paine
• Your ancestors may have been Martian extremophiles - by Michael Paine in Explorezone (also at Space.com)
• The Martians in Your Kidneys by Neil Boyce, New Scientist, 21 August 1999 (contents only).
• Life at the Limit by J Kelly Beatty, Sky & Telescope, September 1999 (contents only)
• Interplanetary Infestations by Paul Davies, Sky & Telescope, September 1999 (contents only).
• "Extremophiles" by by Michael T. Madigan and Barry L. Marrs, Scientific American, April 1997.
•  Zapping Mars Rocks with Gamma Rays. PSR, Dec 1999.
• Astrobiology Journal.
• Nature Vol 419 24 Oct 2002: Earth’s lunar attic by Clarke Chapman -  Rocks blasted long ago from the surface of Earth and other planets may be preserved on the Moon. Although hard to identify, they could hold a unique record of the chemical history of the planets and even evidence of life.
  

News (latest at bottom)

• 31 Dec 1999 BBC: Bugs in Space "Astrobiologists are to test whether life from Mars could have survived a journey to Earth by hiding inside meteorites..."
• 14 Jan 2000 Space.com: Did bacteria survive the trip to Mars?
• 26 Jan 2000 Space.com: How comets might seed planets.
• 28 Jan 2000 Explorezone: Deadly radiation could power life on Europa. Based on Christopher Chyba's article in Nature (not available online). Also at MSNBC, BBC. Europa Exobiology Page of Mark Elowitz. Possibility of Life on Europa by Charles Tritt. NASA's Europa fact sheet.
• 2 Feb 2000:  FOSSILISED BACTERIA FOUND IN METEORITES, RUSSIAN  SCIENTISTS CLAIM.(CC) See also a 1997 report FOSSILIZED LIFE FORMS IN THE MURCHISON METEORITE.and AAO Press Release A Clue to the Origin of Life (amino acids in the meteorite) and criticism of the claims  of Fossilized Bacteria Found in Ancient Meteorite (Space.com by Michael Paine)
• Microbial mats and stromatolites - NASA
• Life from a dirty snowball - NASA
• Bacteria in the Tatahouine meteorite: nanometric-scale life in rocks  Earth and Planetary Science Letters 175 (2000). 1.6Mb PDF.
• MICROBES IN A MARTIAN METEORITE? AN UPDATE ON THE CONTROVERSY by Allan Treiman, Sky & Telescope, April 1999 (at Britannica.com). Also Treiman's Mars Meteorite page at NASA.
• 6 Mar 2000 Nature: Resurrecting life on Mars?
• 23 Mar 2000: New method of finding nannobacteria in rust could be used on Mars ocks. Also NANNOBACTERIA The University of Texas at Austin Department of Geological Sciences and Life's Rusty Old Debate (SpaceDaily).
• 10 May 2000 Space.com: To Seed the Heavens with Life: Panspermia In Reverse.
• 10 May 2000 SpaceDaily: CSIRO Team Brings Back Deep Ocean Life Sample.
• 21 May 2000 Space.com: New Find Proves Life Can Thrive in Hostile Conditions.(CSIRO)
• 25 May 2000 PSRD: Liquid water on Mars: The story from meteorites... these two studies of weathering products in Martian meteorites suggest that small amounts of water were available near the surface of Mars during the past several hundred million years.
• 3 Jun 2000: Australian ABC Radio's Science Show - Nanobes, Tiny Diamonds (from asteroid impacts) and Core Rock.
• 9 Jun 2000 ABC: New Evidence of Life’s Origins Researchers have found what they believe are fossils 3.2 billion years old, suggesting that life on Earth originated in volcano-heated ocean depths where sunlight never entered.
• NASA's Exobiology Strategy from 1995!
• 13 Jul 2000 BBC: TOUGH MICROBES DISCOVERED AT THE SOUTH POLE.
• 18 Jul 2000 SpaceDaily: Viking Data May Hide New Evidence For Life + The Need For Mars Mission Exobiologists. However see also (not online)  'Did Viking Discover Life on Mars' by Viking Biology Leader Harold Klein, Origins of Life and Evolution of the Biosphere, 29: 625-631, 1999: [the assertion that] results of  the Labelled Release experiment are analogous to those observed with terrestrial organisms...is found to be implausible.
• Science@NASA The Sagan Criteria for Life Revisited
• 27 Jul 2000 BBC: Hot-spring bug goes into space. Also SPACE 'BUGS' TO TEST ALIEN MICROBE THEORY.(UT)
• 16 Aug 2000 DER SPIEGEL: Zwerge im Zahnschmelz - in German - interview with Philippa Uwins about 'nanobes'.
• 25 Aug 2000 Science: Life as We Don't Know It - There are two main groups of theories for the origin of life on Earth, the prebiotic  broth theories and the hydrothermal theories, exemplified by the iron-sulfur world  theory. In his Perspective, Wächtershäuser discusses the report by Cody et al.,  which provides key support for the latter proposal. Also BBC.
• 1 Sep 2000 Space.com: Life Amidst Glaciers Thrives and Survives and New Clues About Martian Meteorites Baffle Scientists. Also Discovery: Meteorites Could Reveal Martian Life.
• 28 Oct 2000 Caltech: New results on Martian meteorite support hypothesis that life can jump between planets + links + PDF of Science paper: Our results also indicate that major impact events are capable of  moving rocks from the surface of Mars to the surface of Earth without subjecting them to temperatures high enough to cause thermal sterilization of eukarya or bacteria. Dynamic simulations of martian impact events indicate that materials can be launched into a wide variety of orbits. Although most of the ~1 ton of martian rocks which land on Earth each year have spent several million years inspace, one in 10^7 of the arriving rocks will have made the journey in less than a year . Every million years, ;10 rocks larger than 100 g are transferred in just 2 to 3 years . Bacterial spores, as well as microorgan-isms within rocks, can survive in deep space for more than 5 years. These results indicate that it may not be necessary to protect Earth’s present biosphere by quarantining rocks retrieved by a Mars sample return mission . Conditions are appropriate to allow low-temperature rocks and, if present, microorganisms from Mars to be transported to Earth throughout most of geological time. +Scientific American news item.
• Meteorite! Nov 2000 has an excellent article 'Early asteroid impacts and the origin of terrestrial life' by Andrew Glikson.
• 1 Nov 2000 Space.com: The New Case for Panspermia + Q&As with Chandra Wickramasinghe and Jay Melosh.
• 30 Nov 2000: The September issue of Planetary and Space Science has several excellent papers concerning life on Mars. In particular, one covers the possibility of exchange of life between Mars and Earth. You can download PDFs from http://www.elsevier.com/inca/publications/store/2/0/0/ BUT the free download finishes on 1st December 2000.
• 1 Dec 2000 BBC: Lunar meteorites reveal life's troubles. - new evidence confirms the Earth was heavily bombarded 4 billion years ago.
• 6 Dec 2000: Ideas about exchange of rocks between planetary systems posted.
• 8 Dec 2000 Space.com: Catastrophe, Mother of Evolution: Life Survived Early Bombardment.
• 13 Jan 2001 Planetary Report: Life from Space? - Testing Panspermia with Martian Meteorite ALH84001 (not online)
• 13 Jan 2001 Australian ABC Radio National: The Genesis Factor - origin of life discussion by Paul Davies. First episode noon today (repeated 1pm Monday). Second episode, including TPSAVC contribution, at noon on Saturday 20th January. Transcripts and Real Time audio.
• 17 Mar 01 SpaceDaily: All Aboard the Meteor Express of Life (interstellar transfers) Also New Scientist Galactic hitchhikers - Microbes could fly across the Galaxy aboard a fleet of meteorites.
• 9 Apr 01 Space.com: Star-Hopping Travelers Could Sow Seeds of Life.
• 30 Apr 01 ENN: Do asteroids contain seeds of life?
• 13 Jun 01 SpaceDaily: Life's Rocky Road Between Worlds (Paper on transpermia by Michael Paine - copy here). Criticism of the rock exchange idea by John Michael Williams.
• 15 Jun 01: EPSL: Survival of bacteria exposed to extreme acceleration: implications for panspermia.
• 29 Aug 01 SciAm: From Mars to Earth in a Meteorite? ...the temperature at ALH84001's core never exceeded 40 degrees Celsius en route from the Red Planet
• 5 Oct 01 New website: Australian Centre for Astrobiology.
• 30 Oct 01 Guardian: Invaders that rock the world - Are we really descendants of bacteria that rode on cosmic cannon balls, asks Matthew Genge.
• 17 Dec 01 Stanford Uni: Geophysicist studies life in the early solar system - Norman Sleep discusses transpermia as a possible mechanism for surviving asteroid bombardment. Presented at AGU.
• 22 Dec 01: MarsBugs website with newsletter.
• 11 Jan 02 New Scientist: Life from Mars (space experiments confirm hardiness of bacteria and chances of transpermia)
• 28 Jan 02 NASA AI: Bugs from Hell.
• 29 Jan 02 BBC: Martian rocks bonanza. NASA report.
• 10 Apr 02 NAI Conference abstract: A thin meteorite layer protects bacterial spores in space.
• 22 Apr 02 SFC: Shooting for the moon - Lunar surface may hold evidence that asteroids crashed into Earth.
• 2 May 02 Nature: New bug found on bug - Marine microbe sets miniaturization records. (haven't they heard of Nanobes?)
• 19 Oct 02 NASA: Earth rocks on the Moon (See also   Carl Sagan's Planets)
• 24 Oct 02 BBC: Martian rock 'does contain [fossilized] life'
• 25 Oct 02 Nature: Earth's lunar attic (PDF copy) - see also 19 Oct. Icarus paper by Armstong et al.
• 4 Nov 02 SpaceDaily: Bacterial Blasting Across Space - firing bacteria out of guns to test survival chances.
• 5 Nov 02 Guardian: It's true, men really are from Mars
• 9 Nov 02 Space.com: Why a Mars Rock Hits Earth Every Month (New work by Jay Melosh and colleagues reported in Science (subs required) - Transpermia is even more likely than first thought)
• 27 Nov 02 Space.com: Surviving Space: How Bugs Might Travel Between Planets. + Astrobiology magazine: Surviving the Final Frontier.
• 18 Dec 02 New Scientist: [Earth?] Microbes from edge of space revived (CC)
• 18 Dec 02 Astrobiology magazine: Minimalist Life. Nanoarchaeum - what a dull name for Nanobes! (see also 2 May)
• 30 Jan 03 Astrobiology Magazine: Hitch-Hiker's Guide to Biology's Second Datum - transpermia experiments aboard the Shuttle.
• 31 Jan 03 Telegraph ($): Is this how life on Earth began? Faraday Prize lecture by Paul Davies.(CC)
• 6 Feb 03: Look out for a forthcoming article in Astrobiology by Jay Melosh and co-workers that calculates the highly improbable chance of an Earth rock reaching a terristrial planet in another solar system.
• 10 Apr 03 NAI:  Hitchhikers May Have Thumbed A Ride to Mars (on spacecraft, not meteoroids)
• 2 May 03 BBC: Worms survived Columbia disaster.
• 8 May 03 UCLA:MARS, PANSPERMIA, AND THE ORIGIN OF LIFE: WHERE DID IT ALL BEGIN? 
• 8 May 03 Astrobiology (journal): Exchange of Meteorites (and Life?) Between Stellar Systems - H. J. Melosh
  
• 13 May 03; How about Venus? ScienceDaily 21 Jan 01: Study Suggests Venus Could Have Been Wet Planet. + NS: Venus may surprise us and emerge as a haven for life.
• 5 Jun 03 Icarus (abstract): Reseeding of early earth by impacts of returning ejecta during the late heavy bombardment
• 15 Sep 03 DPS: Did Venus Experience One Great Transition or Two?, + NewSci: Venus possibly habitable for billions of years (CA) - Venus is another possibility for transpermia.
• 18 Sep 03 NAI: Chomping on Nano-Nuggets
• 14 Dec 03: Max K. Wallis and N.C. Wickramasinghe, Cardiff Centre for Astrobiology, "Interstellar transfer of planetary microbiota," to appear in Monthly Notices of the Royal Astronomical Society, [17 page PDF], accepted October 2003 + W.M. Napier, Armagh Observatory, "A Mechanism for Interstellar Panspermia," to appear in Monthly Notices of the Royal Astronomical Society [6 page PDF, image format], accepted October 2003. (CA)
• 11 Feb 04 Astrobiology (Vol 3, No4): Does Lifes Rapid Appearance Imply a Martian Origin? (Paul Davies)
• 9 May 04 GCA abstract: Petrology and shock metamorphism of the olivine-phyric shergottite [Martian meteorite] Yamato 980459 - Evidence for a two-stage cooling and a single-stage ejection history - Its near surface position allowed the ejection from the planet's surface already by a single impact event and at relatively low shock pressures.
• 11 May 04 CCNet: Impact ejection from Earth by Max Wallis.
• 21 May 04 NewSci: Nanobacteria revelations provoke new controversy (but no mention of Australian research) + Nanobac Life Sciences Inc. "is the world leader in the research of degenerative diseases stemming from Nanobacterial infections." + AJP - Heart and Circulatory Physiology:Evidence of Nanobacterial-like Structures in Human Calcified Arteries and Cardiac Valves.
• 25 May 04 LPS 2004; METEORITES FROM MARS – CONSTRAINTS FROM NUMERICAL MODELING. N. Artemieva and B.
  Ivanov.(PDF)
• 27 May 04 Space.com: Survival of the Smallest: Mini-Microbes Redefine Extreme Living - American Society for Microbiology 104th General Meeting.
  
• 14 Dec 04 Space.com: Life-Swapping Scenarios for Earth and Mars
• 1 Mar 05 Space.com: Astronauts: Taking it in the Kidneys - nanobacteria were found to multiply five times faster in microgravity compared to normal gravity on Earth + Kidney International: A potential cause for kidney stone formation during space flights: Enhanced growth of nanobacteria in microgravity.
  
• 5 May 05 UT: DID LIFE ARRIVE BEFORE THE SOLAR SYSTEM EVEN FORMED? - research from Princeton and the University of Michigan. Astrobiology Preprint.
• 24 Jun 05 Nature: Timescales of shock processes in chondritic and martian meteorites - martian meteorites with similar, recent ejection ages may have originated from the same few square kilometres on Mars.
• 31 Jul 05 Glaciers on Mars - a safe landing for hitchhiking microbes from Earth - new discussion paper
• 15 Sep 05 Space.com: Scientists Reconsider Habitability of Saturn's Moon. And Titan's thick atmosphere would assist transpermia by providing a gentler landing.
• 15 Sep 05 Astrobiology Journal (abs): Impact Seeding and Reseeding in the Inner Solar System "Early bacterial life on Earth could have been safeguarded from any purported impact-induced extinction by temporary refuge in space" + Lithopanspermia in Star-Forming Clusters (thanks Paul Davies)
• 2 Nov 05 SciAm: Did Life Come from Another World?
• 19 Mar 06 BBC: Earth could seed Titan with life + 37th LPSC - Meteoroid transfer to Europa and Titan (not Triton)+ BACTERIAL SPORES SURVIVE HYPERVELOCITY LAUNCH BY SPALLATION: IMPLICATIONS FOR LITHOPANSPERMIA
• 12 May 06 SpaceDaily: Survival In Space Takes A Hardy Bug.
• 9 Dec 06 New Scientist ($): Looking for Life, Searching the Solar System: Book review.
• 11 Dec 06 Meteoritics & Planetary Science ($): Nature of the Martian uplands: Effect on Martian meteorite age distribution and secondary cratering - Martian meteorites (MMs) have been launched from an estimated 5-9 sites on Mars within the last 20 Myr...
• 20 Jan 07 Icarus: Experimental evidence for the potential impact ejection of viable microorganisms from Mars and Mars-like planets - The survival of Bacillus subtilis and Xanthoria elegans up to 45 GPa and of Chroococcidiopsis sp. up to 10 GPa supports the possibility of transfer of life inside meteoroids between Mars and Earth...
• 2 Mar 07 SciAm ($): March 1907! Panspermy - "..life can be transmitted from one heavenly body to another by minute germs propelled by the pressure of light..." - Prof Svante Arrhenius.
• 18 Apr 07 TPS: Life Experiment: Phobos - In an ambitious new initiative, the Society is studying the possibility of sending a collection of living organisms on a three-year trip to the Martian moon Phobos and back to Earth. This will be  test of the Transpermia Hypothesis. Donations are sought.
• 28 Jul 07 Cosmos Magazine Issue 16 (contents listing only): Children of Mars - essay by Paul Davis
• 10 Aug 07 Universe Today: An Experiment to Test Panspermia.
• 15 Aug 07 Icarus ($): Crater clusters on Mars: Shedding light on martian ejecta launch conditions.
• 21 Sep 07 New Sci ($): Moon's gentle surface could hide life's secrets (ancient Earth rocks scattered to the Moon)
• 24 Oct 07 BBC: Life from Mars theory put to test
• 5 Dec 07 SciAm ($): Are Aliens Among Us? - In pursuit of evidence that life arose on Earth more than once, scientists are searching for microbes that are radically different from all known organisms - by Paul Davies
• 21 Mar 08 Microbial Rock Inhabitants Survive Hypervelocity Impacts on Mars-Like Host Planets: First Phase of Lithopanspermia Experimentally Tested (PDF) + Life Forms Ejected on Asteroid Impact Could Survive to Reseed Earth, (thanks COSMIC ANCESTRY )
• 22 Apr 08 Nature: Nanobacteria theory takes a hit.
• 16 May 08 Space.com: Space Rocks Could Reseed Life on Earth (see also Your Ancestors May Be Martian)
• 12 Aug 08 Space.com: [hypothetical] Microbes Could Travel from Venus to Earth (via solar wind). See Venus.
• 26 Aug 08 TPS: Support The Planetary Society Phobos LIFE Project - urgent request for donations to send microbes on a round trip to the Martian moon to test the transpermia hypothesis.
• 5 Sep 08 NewSci: Interstellar 'slowball' could have carried seeds of life
• 17 Sep 08 Space.com: Eight-Legged Space Survivor Gives 'Panspermia' New Life. See also Your Ancestors May Be Martian. 
• 29 Sep 08 SpaceDaily: Stone-6 Artificial Meteorite Shows Martian Impactors Could Carry Traces Of Life.
• 1 Oct 08 NewSci: Martian fossils may be hiding inside white rocks
• 17 Oct 08 Space.com: 'Alien' Water Bears Amaze Scientists - gives more credence to the theory of panspermia
• 2 Nov 08 Space.com: Cold Storage: Moon Might Preserve Alien Life - maybe, but most meteoroids are travelling at interplanetary speeds and so vaporise on impact with the airless Moon.
• 30 Dec 08 TPS Planetary Report Nov/Dec 2008: Our Phobos LIFE Biomodule passes tests (page 16). Donations sought for this experiment. See also the May/June 08 issue.
• 22 Feb 09 UT: Arizona Scientist: We Could All Be Martians - Jay first proposed this in the early 1990s - see also Space.com: Your ancestors may be Martian (1999)
• 6 Mar 09 UT: Life on Ceres: Could the Dwarf Planet be the Root of Panspermia?
• 14 Mar 09 New Scientist: Second Genesis: The search for shadow life (see also Finding a Second Sample of Life on Earth)
• 10 Apr 09 NewSci: DNA analysis may be done on Mars for first time - NASA has bought into the possibility that life may have once travelled between the two planets...
• 6 Jun 09 Space.com: [Hitchhiking] Microbes Would Find Scarce Shelter on Mars (except on a glacier?)
• 15 Oct 09 NewSci: Like a foaming stone: Life began in rock (nanobes?)
• 31 Dec 09 SciAm ($): The Rise and Fall of Nanobacteria - makes a convincing case that nanobacteria (or nanobes) are not alive but are often extraordinary reactions between minerals and protein molecules that exhibit "life-like" crystal growth such as budding. Disappointingly there is no mention of the work by Philippa Uwins
• 26 Feb 10 Space.com: Scientists Build Gun to Mimic Meteorite Crash.
• 8 May 10 Icarus ($): Testing the survival of microfossils in artificial martian sedimentary meteorites during entry into Earth’s atmosphere: The STONE 6 experiment - living organisms probably need to be protected by at least 5 cm of rock in order to be shielded from the intense heat of entry.
• 13 May 10 Astrobiology Science Conference 2010:
• TOWARDS A GENERAL THEORY OF LITHOPANSPERMIA
• DIRECTED EVOLUTION OF BACILLUS SUBTILIS TOWARDS HYPOBARIC GROWTH
• SULFATE-REDUCING BACTERIA AS A MODEL FOR LIFE IN THE MARTIAN SUBSURFACE
• Methanogens: A Model for Life on Mars
• Biotoxicity of Mars Analog Soils: Microbial Dispersal into Desiccated Soils Versus Emplacement in Salt or Ice Inclusion Fluids
• Terrestrial Microorganism and Biomarker Survival as a Function of Depth in a Mars Analog Regolith after Exposure to Mars Surface Conditions
• Habitability Potential of Ceres, a Warm Icy Body in the Asteroid Belt
• Early Mars: A Warm Wet Niche for Life
• Active Igneous and Hydrothermal Activity During the Early-Middle Amazonian: Inferences from the Chassignite and Nakhlite Meteorites and Implications for Astrobiology
• The Habitability of the Phoenix Landing Site: An Evaluation of Mission Results
• The Habitability Potential of Mars 
• The Search for Sustainable Subsurface Habitats on Mars
• Martian Debris-covered Glaciers: Seeking “Signs of Life” in a ~100 My Old Deep-Freeze
• Exploring Martian Impact Craters: Why They are Important for the Search for Life 
• PANSPERMIA: A PROMISING FIELD OF RESEARCH
• 29 Jul 10 AMEC2010: Potential for microbe colonisation of Mars by rocks launched into space by the Chicxulub impact - paper by Michael Paine. Youtube video of the presentation (no audio)
• 1 Mar 11 UT: Meteorites May Have Delivered First Ammonia for Life on Earth + BBC: Meteorite 'could have carried nitrogen to Earth'.
• 14 Mar 11 Acta Astronautica: Survival of dormant organisms after long-term exposure to the space environment .
• 24 Aug 11 BBC: Impacts 'more likely' to have spread life from Earth.
• 6 Jan 13 Icarus ($): Survival of yeast spores in hypervelocity impact events up to velocities of 7.4 km s−1 - "...extreme shocks during transfer across space are not necessarily sterilising."
• 24 Mar 13 New Scientist: Curiosity's discoveries hint at life's cradle on Mars (strengthens the case for microbe colonisation of Mars by rocks launched into space from Earth )
• 2 May 13 SciAm: The Long and Arduous Quest to Find Flowing Water on Mars May Be Over (boosts the case for microbe colonisation of Mars by rocks launched from Earth)
• 29 Aug 13 BBC: Earth life 'may have come from Mars' (see also Your ancestors may be Martian)
• 18 Oct 13 NASA: NASA Rover Confirms Mars Origin of Some Meteorites
• 20 Nov 13 NewSci ($): Meteor impact trapped ancient swamp plants in glass
• 12 Dec 14 Inquisitr: Life On Mars Found?[No!] Tissint Meteorite May Show Evidence Of Organic Life [chemicals!] In Space (thanks Paul Curnow) +  Livescience: Experts Cast Doubt on Meteorite Study's Claims of Martian Life.
• 3 Apr 15 Icarus: Dynamics of escaping Earth ejecta and their collision probability with different Solar System bodies.
• 31 Oct 15 Panspermia.org: A fossil on Mars resembles one on Earth? (thanks Brig Klyce)
• 16 Dec 16 ABC: Oldest water on Earth found in Canada could provide clues to hidden life on Mars
• 18 Jan 17 Astrobiology Magazine: Microbes Could Survive Thin Air of Mars (strengthens case for Potential for microbe colonisation of Mars by rocks launched into space by the Chicxulub impact  )
• 19 Apr 17 NG: 7 Alien 'Earths' May Be Swapping Life via Meteorites (thanks Paul Curnow)
• 22 May 17 NewSc ($): Microbes might thrive after crash-landing on board a meteorite.
• 14 Jul17 Space.com: Life on TRAPPIST-1 Planets? Rock-Swapping May Boost Odds.
• 18 Aug 17 Radio Canada: Could evidence of life on Mars be found in a crater? + Meteorite Impacts Could Have Fostered Life on Early Earth + Osinski blog Jul 2016: Heading to the Haughton impact structure, Nunavut
  
• 18 Aug 17 Astrobiology (14:6:2014): Survival of Organic Materials in Hypervelocity Impacts of Ice on Sand, Ice, and Water in the Laboratory "... exogenous delivery of complex organic molecules [not viable microbes] from icy impactors is a viable source of such material..."
• 30 Apr 18 Cosmos: Viruses, ET and the octopus from space: the return of panspermia.
• 25 May 18 Pansperrmia.org: A fossil on Mars resembles one on Earth (see 2018 update)
• 6 Aug 18 Forbes (thanks Panspermia.org): Earth, Mars, And The Theory Of 'Swapping Spit' (note that transit times of much less than 1 million years are possible. Also exchange of microbes with Europa is possible but unlikely due to hypervelocity impacts)
• 6 Aug 18 Mars.Daily: Russia Plans to Send Capsule With Microorganisms to Mars [and back, via Phobos]
• 28 Apr 19 Space.com: Life May Have Evolved Before Earth Finished Forming.
• 10 May 19 Space.com: Could There Be Life on Mars Today [see also this 2010 paper]
• 8 Jul 19 Havard News: Spreading seeds of life (panspermia across the Milky Way)
• 19 Aug 19 SciAm: Tardigrades Were Already on the Moon.
• 19 Aug 19 AJAA: Lithopanspermia – The Terrestrial Input During the Past 550 Million Years. [the estimated flux is much less than that estimated by Wallis, as used in my Mars paper]
• 25 Sep 20 Astrobiology: Transfer of Life Between Earth and Venus with Planet-Grazing Asteroids
• 20 Feb 21 The Conversation: As the Perseverance rover lands on Mars, there’s a lot we already know about the red planet from meteorites found on Earth
• 24 May 21 Air & Space: Could We Really All Be Martians? - Considering the likelihood of an exchange of microbes between Earth and Mars.
  
• 24 May 21 Astrobiology ($$!): Life on Mars: Independent Genesis or Common Ancestor? + Uninhabitable and Potentially Habitable Environments on Mars: Evidence from Meteorite ALH 84001.
• 2 Jul 22 Salon: Why some scientists believe life may have started on Mars + Astrobiology: Resolving the History of Life on Earth by Seeking Life As We Know It on Mars (thanks COSMIC ANCESTRY)
• 27 Sep 22 Nature: Geological diversity and microbiological potential of lakes on Mars.
• 4 Feb 23 UT: A Martian Meteorite Contains Organic Compounds. The Raw Ingredients for Life? (annoying ads - reader view recommended)
• 30 Aug 24 New Scientist ($): Strange meteorites have been traced to their source craters on Mars.
  

• New Scientist 13 Sep 2003: Shocked into life by Gordon Osinski "The hydrothermal systems active today are volcanic, for example, in Yellowstone National Park in Wyoming. But given that impact craters can also provide the two most important components of a hydrothermal system – heat and water – it seems that volcanoes are not the only contenders for giving life a place to stay..."
  
• Asteroids - now for the good news
• New Scientist: Asteroid impact craters could cradle life
  
• Astrobiology Magazine ($) Impact-Generated Endolithic Habitat Within Crystalline Rocks of the Haughton Impact Structure, Devon Island, Canada + (2009) Evidence of Ancient Hot Springs on Mars (Published article here) +
  
• NASA Paper ANCIENT HYDROTHERMAL SPRINGS IN ARABIA TERRA, MARS - but Nature: Supervolcanoes within an ancient volcanic province in Arabia Terra, Mars suggests a volcanic origin for hot springs instead of an impact event
  
• PSI: RECOGNITION  CRITERIA  OF  SPRING DEPOSITS ON  MARS  AT  ALL  SCALES:  EVIDENCE  FROM THE DALHOUSIE SPRINGS ANALOG (AUSTRALIA)
• 4 Aug 17 SciAm ($): Life on Earth Came from a Hot Volcanic Pool, Not the Sea, New Evidence Suggests - Deep oceans were thought to hold life's origins. New evidence points instead to an active volcanic landscape [but impact craters are often associated with similar hydrothermal systems and are much more frequent than volcanoes on rocky planets.]
• 18 Apr 19 LiveScience: The First Known Interstellar Meteor May Have Hit Earth in 2014 [meteor (light) characteristics suggests an interstellar trajectory of this (est) 1m diameter object - no meteorite (rock) has been found.
• 9 Sep 19 The Conversation: Tiny specks in space could be the key to finding martian life.
• 1 Oct 19 Cosmos: Earliest life found in ancient Aussie rocks.
• 21 Nov 19 Phys.org: First detection of sugars in meteorites gives clues to origin of life - but see Fossilized Bacteria Found in Ancient Meteorite.
• 29 Jul 23 New Scientist ($): Meteorite left Earth then landed back down after round trip to space (lifeboats in space?)
• 15 Nov 23 The Conversation: Did this chemical reaction create the building blocks of life on Earth?
  

Extremophiles

• NAS: Evaluating the Biological Potential in Samples Returned from Planetary Satellites and Small Solar System Bodies .
• SciAm: Extremophiles.
• UNSW: Extremophiles (methanogens)
• Viking data still causing a stir.
• 28 Sep 02 New Scientist: Tough Earth bug may be from Mars + 9 Dec 95: Doomsday bacteria thrive on radiation.
• 16 Aug 03 BBC: Microbe breaks temperature record (121C!). NSF press release.
• 6 Nov 04: Scanned letter from Harold (Chuck) Klein concerning the possibility of airborne microscopic life on Mars - from the Viking project in 1974 (200K GIF).
• 25 Jul 05 NewSci (subs): Thriving ecosystem discovered under Antarctic ice (Dr Ishman's web page) - the ecosystem is fed by subterranean chemical energy rather than by photosynthesis. + LiveScience: Ice Shelf Collapse Reveals New Undersea World
• 5 Aug 05 NewSci: Life underground, down under - Beneath the arid surface of Western Australia are hundreds of limestone deposits honeycombed with small holes and filled with water. Each of these deposits is teeming with life.
• 5 Aug 05 Space.com: Extremophiles: Not So Extreme?
• 3 Sep 06 New Scientist ($): Russian scientists argue that a mysterious radiation-proof microbe may have evolved on Mars.
• 3 May 08 NewSci: Interview: The man who found Mars on Earth - Chris McKay "It's fashionable these days for astrobiologists to talk about how rugged and hardy life is, and how it can survive in all the most amazing places. In fact, I have formed the opposite impression. Life is dangling on a fragile thread, and that thread is liquid water. We have searched for organisms that could do without it. No joy..."
• 26 Jun 08 NewSci: The most extreme life-forms in the universe [on Earth?].
• 30 Jul 08 Space.com: Unique Habitat Found Inside Earth.
• 20 Sep 08 Space.com: Earth Hot Spots Spark Alien Ideas - see also Your ancestors may be Martian
• 17 Oct 08 NewSci: DNA of gold-mine bug may be key to alien life.
• 28 Feb 09 NewSci: Lost world of extremophiles hides beneath Great Lakes.
• 23 Dec 09 NewSci: Microbes survive 30,000 years inside a salt crystal.
• 18 Oct 10 NewSci ($): Arctic bugs may have the longest life-cycle on Earth  - with a hibernation period of up to 100 million years, [thermophile] bacteria discovered on the Arctic sea floor may have the longest life cycle of any known organism. Perfect for transpermia!
• 3 Dec 10 NewSci: Arsenic-eating bacteria point to new life forms.
• 8 Dec 10 Nature: Microbe gets toxic response - Researchers question the science behind last week's revelation of arsenic-based life
• 6 Apr 11 Nature: Antarctic microbes live life to the extreme.
• 2 jun 11 SciAm: Newly Discovered Microscopic Worm Thrives in Gold Mines a Kilometer Underground.
• 16 May 12 TPS: Earth's toughest life could survive on Mars.
• 30 May 12 NewSci: Buried microbes exist at limit between life and death
• 25 Jun 12 SpaceDaily: The toughest life on Earth.
• 18 Dec 12 NewSci ($): Loneliest bug on Earth… has a friend.
  
• 29 Apr 13 NewSci ($): Deep life: Strange creatures living far below our feet.
• 10 Dec 13 NewSci: The 19 superbugs that rule Earth's hidden depths
• 18 Sep 14 Wikipedia: Dendrogramma - "an early branch on the tree of life, with similarities to the 600 million-year-old extinct Ediacara fauna."
• 13 May 15 NewSci: Rock-forming microbes may be suited for life on other planets.
• 2 Sep 15 ABC Science: Evolution of complex life on Earth, take 2?
• 6 Apr 16 NewSci: Artificial cell designed in lab reveals genes essential to life - breaks record for smallest genome... Science: Synthetic microbe lives with fewer than 500 genes
  
• 26 May 16 SciAm: Maybe Life in the Cosmos Is [extremely] Rare After All - The conclusion that the universe is teeming with biology is based on an unproved assumption + EPSL ($): Dense microbial community on a ferromanganese nodule from the ultra-oligotrophic South Pacific Gyre - deep sea life, but did they also search for a shadow biosphere?
• 3 Mar 17 Uni Arkansas: Is Anything Tough Enough to Survive on Mars? + NASA: Microbes Could Survive Thin Air of Mars.
• 4 Dec 17 NewSci: Scorching hot springs house extreme life and a future ocean.
• 17 Jan 18 Cosmos: Some species of bacteria produce methane - US research uncovers previously unknown greenhouse gas pathway
• 13 Nov 18 New Scientist: Why lichen may be the perfect factories for making rocket fuel on Mars + Microbes might thrive after crash-landing on board a meteorite.
• 11 Dec 18 The Guardian: Scientists identify vast underground ecosystem containing billions of micro-organisms [ Are they looking for naobes?]
• 3 Jan 19 SciAm: What a Newfound Kingdom Means for the Tree of Life - Neither animal, plant, fungus nor familiar protozoan, a strange microbe foretells incredible biodiversity yet to be discovered.
• 25 Jan 19 The Guardian: Tardigrades: Earth’s unlikely beacon of life that can survive a cosmic cataclysm - Microscopic creatures reassure scientists complete eradication of life on the planet is extremely unlikely
• 8 Feb 19 NewSci: The ancestor of all creatures on Earth lived a lukewarm lifestyle.
• 19 Aug 19 NewSci: Deep-sea microbe could answer one of evolution's biggest mysteries.
• 12 May 20 ScienceAlert: Scientists Find The First Animal That Doesn't Need Oxygen to Survive.
• 13 Sep 20 Frontiers in Microbiology ($): DNA Damage and Survival Time Course of Deinococcal Cell Pellets During 3 Years of Exposure to Outer Space.
• 13 Sep 20 PNAS ($(: Mechanism of water extraction from gypsum rock by desert colonizing microorganisms.
• 23 Oct 20 Science: Deep abiotic weathering of pyrite [...and the role of microorganisms in the oxidation process]
• 9 Nov 20 EurekaAlert: Microbial space travel on a molecular scale.
• 21 Feb 22 ScienceAlert: A Mysterious Desert Bacterium Has Evolved Its Own, Unique Ability to Photosynthesize.
• 27 Oct 22 Space.com: Extremophiles on Mars could survive for hundreds of millions of years (increases the odds for live microbes in my estimates)
• 12 Mar 23 The Conversation: Electricity from thin air: an enzyme from bacteria can extract energy from hydrogen in the atmosphere (Mars had atmospheric hydrogen in the early days of the solar system)
• 18 Dec 23 New Scientist ($): The unlikely extremophiles lurking in your kitchen [the dishwasher might be a good analogy for conditions on early Earth!]
• 21 Jan 24 New Scientist ($): We finally know how tardigrades can survive extreme conditions.
• 25 Jun24 The Conversation: Some of Earth’s most ancient lifeforms can live on hydrogen.
• 4 Jul 24 New Scientist ($): Moss that survives deep freeze and radiation could live on Mars.
• 12 Oct 24 New Scientist ($): Living microbes found deep inside 2-billion-year-old rock.
  

See also bibliography for Rocks from Space.




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This web page prepared by Michael Paine (home page) email: mpainesyd!gmail.com (replace ! with @)
Created in October 1996.

Australian Spaceguard Survey
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This page prepared in association with the TPS Australian Volunteers.