Panspermia hypotheses propose (for example) that microscopic life-forms
that can survive the effects of space (such as extremophiles)
can become trapped in debris ejected into space after collisions between planets
Solar System bodies that harbor life. Some organisms
may travel dormant for an extended amount of time before colliding randomly with
other planets or intermingling with protoplanetary
disks. Under certain ideal impact circumstances (into a body of water, for
example), and ideal conditions on a new planet's surfaces, it is possible that
the surviving organisms could become active and begin to colonize their new
environment. Panspermia studies concentrate not on how
life began, but on the methods that may cause its distribution in the
Pseudo-panspermia (sometimes called "soft panspermia" or "molecular
panspermia") argues that the pre-biotic organic building-blocks of life
originated in space, became incorporated in the solar nebula from which planets
condensed, and were further—and continuously—distributed to planetary surfaces
where life then emerged (abiogenesis).
From the early 1970s it started to become evident that interstellar dust
included a large component of organic molecules. Interstellar molecules are
formed by chemical reactions within very sparse interstellar or circumstellar
clouds of dust and gas.
The dust plays a critical role in shielding the molecules from the ionizing
effect of ultraviolet
radiation emitted by stars.
The chemistry leading to life
may have begun shortly after the Big Bang, 13.8 billion years ago, during a
habitable epoch when the Universe was only 10 to 17 million years old. Though
the presence of life is confirmed only on the Earth, some scientists think that
extraterrestrial life is not only plausible, but probable or inevitable. Probes
and instruments have started examining other planets and moons in the Solar
System and in other planetary systems for evidence of having once supported
simple life, and projects such as SETI
attempt to detect radio
transmissions from possible extra-terrestrial civilizations.
In an Origins Symposium presentation on April 7, 2009, physicist Stephen Hawking stated
his opinion about what humans may find when venturing into space, such as the
possibility of alien life through the theory of panspermia: "Life could spread
from planet to planet or from stellar system to stellar system, carried on
Three series of astrobiology experiments have been conducted outside the International
Space Station between 2008 and 2015 (EXPOSE)
where a wide variety of biomolecules,
microorganisms, and their spores were exposed to the solar
flux and vacuum of space for about 1.5 years. Some organisms survived in an
inactive state for considerable lengths of time,
and those samples sheltered by simulated meteorite material provide experimental
evidence for the likelihood of the hypothetical scenario of lithopanspermia.
Several simulations in laboratories and in low Earth orbit suggest that
ejection, entry and impact is survivable for some simple organisms. In 2015,
remains of biotic
material were found in 4.1 billion-year-old rocks in Western Australia,
when the young Earth was about 400
million years old.
According to one researcher, "If life arose relatively quickly on Earth … then
it could be common in the universe."
In April 2018 a Russian team published a paper which disclosed that they
found DNA on the exterior of the ISS from land and marine bacteria similar to
those previously observed in superficial micro layers at the Barents and Kara
seas' coastal zones. They conclude "The presence of the wild land and marine
bacteria DNA on the ISS suggests their possible transfer from the stratosphere
into the ionosphere with the ascending branch of the global
atmospheric electrical circuit. Alternatively, the wild land and marine
bacteria as well as the ISS bacteria may all have an ultimate space origin."
In 1903, Svante
Arrhenius published in his article The Distribution of Life in
the hypothesis now called radiopanspermia, that microscopic forms of life can be
propagated in space, driven by the radiation
pressure from stars.
Arrhenius argued that particles at a critical size below 1.5 μm would be
propagated at high speed by radiation pressure of the Sun. However, because its
effectiveness decreases with increasing size of the particle, this mechanism
holds for very tiny particles only, such as single bacterial spores.
The main criticism of radiopanspermia hypothesis came from Iosif Shklovsky and Carl
Sagan, who pointed out the proofs of the lethal action of space radiations
(UV and X-rays)
in the cosmos.
Regardless of the evidence, Wallis and Wickramasinghe argued in 2004 that the
transport of individual bacteria or clumps of bacteria, is overwhelmingly more
important than lithopanspermia in terms of numbers of microbes transferred, even
accounting for the death rate of unprotected bacteria in transit.
Then, data gathered by the orbital experiments ERA, BIOPAN, EXOSTACK
determined that isolated spores, including those of B.
subtilis, were killed by several orders of magnitude if exposed to the
full space environment for a mere few seconds, but if shielded against solar UV,
the spores were capable of surviving in space for up to six years while embedded
in clay or meteorite powder (artificial meteorites).
Though minimal protection is required to shelter a spore against UV radiation,
exposure to solar UV and cosmic ionizing radiation of unprotected DNA, break it
up into its bases.
Also, exposing DNA to the ultrahigh vacuum of space alone is sufficient to cause
DNA damage, so the transport of unprotected DNA or RNA during interplanetary
flights powered solely by light pressure is extremely unlikely.
The feasibility of other means of transport for the more massive shielded spores
into the outer Solar System – for example, through gravitational capture by
comets – is at this time unknown.
Based on experimental data on radiation effects and DNA stability, it has
been concluded that for such long travel times, boulder-sized rocks which are
greater than or equal to 1 meter in diameter are required to effectively shield
resistant microorganisms, such as bacterial spores against galactic cosmic
These results clearly negate the radiopanspermia hypothesis, which requires
single spores accelerated by the radiation pressure of the Sun, requiring many
years to travel between the planets, and support the likelihood of
interplanetary transfer of microorganisms within asteroids
or comets, the
so-called lithopanspermia hypothesis.
Lithopanspermia, the transfer of organisms in rocks from one planet to
another either through interplanetary or interstellar space, remains
speculative. Although there is no evidence that lithopanspermia has occurred in
the Solar System, the various stages have become amenable to experimental
Planetary ejection — For lithopanspermia to occur, researchers have
suggested that microorganisms must survive ejection from a planetary surface
which involves extreme forces of acceleration and shock with associated
temperature excursions. Hypothetical values of shock pressures experienced by
ejected rocks are obtained with Martian meteorites, which suggest the shock
pressures of approximately 5 to 55 GPa, acceleration of
3 Mm/s2 and jerk
of 6 Gm/s3 and post-shock temperature increases of about 1 K
to 1000 K.
To determine the effect of acceleration during ejection on microorganisms,
rifle and ultracentrifuge methods were successfully used under simulated outer
Survival in transit — The survival of microorganisms has been
studied extensively using both simulated facilities and in low Earth orbit. A
large number of microorganisms have been selected for exposure experiments. It
is possible to separate these microorganisms into two groups, the human-borne,
and the extremophiles.
Studying the human-borne microorganisms is significant for human welfare and
future manned missions; whilst the extremophiles are vital for studying the
physiological requirements of survival in space.
Atmospheric entry — An important aspect of the lithopanspermia
hypothesis to test is that microbes situated on or within rocks could survive
hypervelocity entry from space through Earth's atmosphere (Cockell, 2008). As
with planetary ejection, this is experimentally tractable, with sounding
rockets and orbital vehicles being used for microbiological experiments.B.
subtilis spores inoculated onto granite
domes were subjected to hypervelocity atmospheric transit (twice) by launch to
a ∼120 km altitude on an Orion two-stage rocket. The spores were shown to
have survived on the sides of the rock, but they did not survive on the
forward-facing surface that was subjected to a maximum temperature of
In separate experiments, as part of the ESA STONE experiment, numerous
organisms were embedded in different types or rocks and were mounted in the
heat shield of six Foton
re-entry capsules. During reentry, the rock samples were subjected to
temperatures and pressure loads comparable to those experienced in
The exogenous arrival of photosynthetic
microorganisms could have quite profound consequences for the course of
biological evolution on the inoculated planet. As photosynthetic organisms
must be close to the surface of a rock to obtain sufficient light energy,
atmospheric transit might act as a filter against them by ablating the surface
layers of the rock. Although cyanobacteria
have been shown to survive the desiccating, freezing conditions of space in
orbital experiments, this would be of no benefit as the STONE experiment
showed that they cannot survive atmospheric entry.
Thus, non-photosynthetic organisms deep within rocks have a chance to survive
the exit and entry process. (See also: Impact
survival.) Research presented at the European Planetary Science Congress
in 2015 suggests that ejection, entry and impact is survivable for some simple
Thomas Gold, a professor of
astronomy, suggested in 1960
the hypothesis of "Cosmic Garbage", that life on Earth might have originated
accidentally from a pile of waste
products dumped on Earth long ago by extraterrestrial beings.
Directed panspermia concerns the deliberate transport of microorganisms in
space, sent to Earth to start life here, or sent from Earth to seed new
planetary systems with life by introduced
species of microorganisms on lifeless planets. The Nobel prize winner Francis
Crick, along with Leslie
Orgel proposed that life may have been purposely spread by an advanced
but considering an early "RNA
world" Crick noted later that life may have originated on Earth. It
has been suggested that 'directed' panspermia was proposed in order to
counteract various objections, including the argument that microbes would be
inactivated by the space environment and cosmic radiation
before they could make a chance encounter with Earth.
Conversely, active directed panspermia has been proposed to secure and expand
life in space.
This may be motivated by biotic ethics that values, and seeks to propagate, the
basic patterns of our organic gene/protein life-form. The
panbiotic program would seed new planetary systems nearby, and clusters of new
stars in interstellar clouds. These young targets, where local life would not
have formed yet, avoid any interference with local life.
For example, microbial payloads launched by solar sails at speeds up to
0.0001 c (30,000 m/s) would reach targets at 10 to 100 light-years
in 0.1 million to 1 million years. Fleets of microbial capsules can be aimed at
clusters of new stars in star-forming clouds, where they may land on planets or
captured by asteroids and comets and later delivered to planets. Payloads may
for diverse environments and cyanobacteria
similar to early microorganisms. Hardy multicellular organisms (rotifer cysts)
may be included to induce higher evolution.
The probability of hitting the target zone can be calculated from
where A(target) is the cross-section of the target area, dy
is the positional uncertainty at arrival; a -- constant (depending on
units), r(target) is the radius of the target area; v the velocity
of the probe; (tp) the targeting precision (arcsec/yr); and d the
distance to the target, guided by high-resolution astrometry of 1x10−5
arcsec/yr (all units in SIU). These calculations show that relatively near
target stars(Alpha PsA, Beta Pictoris) can be seeded by milligrams of launched
microbes; while seeding the Rho Ophiochus star-forming cloud requires hundreds
of kilograms of dispersed capsules.
Directed panspermia to secure and expand life in space is becoming possible
because of developments in solar
sails, precise astrometry,
and microbial genetic
engineering. After determining the composition of chosen meteorites, astroecologists performed
laboratory experiments that suggest that many colonizing microorganisms and some
plants could obtain many of their chemical nutrients from asteroid and cometary
However, the scientists noted that phosphate (PO4) and nitrate (NO3–N)
critically limit nutrition to many terrestrial lifeforms.
With such materials, and energy from long-lived stars, microscopic life planted
by directed panspermia could find an immense future in the galaxy.
A number of publications since 1979 have proposed the idea that directed
panspermia could be demonstrated to be the origin of all life on Earth if a
distinctive 'signature' message were found, deliberately implanted into either
the genome or
the genetic code of the first
microorganisms by our hypothetical progenitor.
In 2013 a team of physicists claimed that they had found mathematical and semiotic
patterns in the genetic code which they think is evidence for such a
This claim has been refuted by biologist PZ
Myers who said, writing in Pharyngula:
Unfortunately, what they’ve so honestly described is good old honest
garbage ... Their methods failed to recognize a well-known functional
association in the genetic code; they did not rule out the operation of
natural law before rushing to falsely infer design ... We certainly don’t need
to invoke panspermia. Nothing in the genetic code requires design. and the
authors haven’t demonstrated otherwise.
In a later peer-reviewed article, the authors address the operation of
natural law in an extensive statistical test, and draw the same conclusion as in
the previous article.
In special sections they also discuss methodological concerns raised by PZ Myers
and some others.
Pseudo-panspermia (sometimes called soft panspermia, molecular panspermia or
quasi-panspermia) proposes that the organic molecules used for life originated
in space and were incorporated in the solar nebula, from which the planets
condensed and were further —and continuously— distributed to planetary surfaces
where life then emerged (abiogenesis).
From the early 1970s it was becoming evident that interstellar dust consisted of
a large component of organic molecules. The first suggestion came from Chandra
Wickramasinghe, who proposed a polymeric composition based on the molecule
Interstellar molecules are formed by chemical reactions within very sparse
interstellar or circumstellar clouds of dust and gas. Usually this occurs when a
molecule becomes ionized, often as the result of an
interaction with cosmic
rays. This positively charged molecule then draws in a nearby reactant by
electrostatic attraction of the neutral molecule's electrons. Molecules can also
be generated by reactions between neutral atoms and molecules, although this
process is generally slower.
The dust plays a critical role of shielding the molecules from the ionizing
effect of ultraviolet radiation emitted by stars.
A 2008 analysis of 12C/13C isotopic ratios of organic
compounds found in the Murchison
meteorite indicates a non-terrestrial origin for these molecules rather than
terrestrial contamination. Biologically relevant molecules identified so far
include uracil, an RNA nucleobase, and xanthine.
These results demonstrate that many organic compounds which are components of
life on Earth were already present in the early Solar System and may have played
a key role in life's origin.
In August 2009, NASA scientists identified one of the fundamental chemical
building-blocks of life (the amino acid glycine)
in a comet for the first time.
In August 2011, a report, based on NASA
studies with meteorites
found on Earth,
was published suggesting building blocks of DNA
(adenine, guanine and
molecules) may have been formed extraterrestrially in outer space.
In October 2011, scientists reported that cosmic
dust contains complex organic
matter ("amorphous organic solids with a mixed aromatic-aliphatic
structure") that could be created naturally, and rapidly, by stars.
One of the scientists suggested that these complex organic compounds may have
been related to the development of life on Earth and said that, "If this is the
case, life on Earth may have had an easier time getting started as these
organics can serve as basic ingredients for life."
In August 2012, and in a world first, astronomers at Copenhagen
University reported the detection of a specific sugar molecule, glycolaldehyde, in a
distant star system. The molecule was found around the protostellar binary IRAS
16293-2422, which is located 400 light years from Earth.
Glycolaldehyde is needed to form ribonucleic acid, or
RNA, which is
similar in function to DNA. This finding suggests that
complex organic molecules may form in stellar systems prior to the formation of
planets, eventually arriving on young planets early in their formation.
In 2013, the Atacama
Large Millimeter Array (ALMA Project) confirmed that researchers have
discovered an important pair of prebiotic molecules in the icy particles in interstellar
space (ISM). The chemicals, found in a giant cloud of gas about 25,000
light-years from Earth in ISM, may be a precursor to a key component of DNA and
the other may have a role in the formation of an important amino acid. Researchers
found a molecule called cyanomethanimine, which produces adenine, one of the four nucleobases
that form the "rungs" in the ladder-like structure of DNA. The other molecule,
is thought to play a role in forming alanine,
one of the twenty amino acids in the genetic code. Previously, scientists
thought such processes took place in the very tenuous gas between the stars. The
new discoveries, however, suggest that the chemical formation sequences for
these molecules occurred not in gas, but on the surfaces of ice grains in
NASA ALMA scientist Anthony Remijan stated that finding these molecules in an
interstellar gas cloud means that important building blocks for DNA and amino
acids can 'seed' newly formed planets with the chemical precursors for life.
In March 2013, a simulation experiment indicate that dipeptides (pairs of
amino acids) that can be building blocks of proteins, can be created in
In May 2016, the Rosetta Mission team reported the presence of glycine, methylamine and
ethylamine in the coma of 67P/Churyumov-Gerasimenko.
This, plus the detection of phosphorus, is consistent with the hypothesis that
comets played a crucial role in the emergence of life on Earth.
It is estimated that space travel over cosmic distances would take an
incredibly long time to an outside observer, and with vast amounts of energy
required. However, there are reasons to hypothesize that faster-than-light
interstellar space travel might be feasible. This has been explored by NASA
scientists since at least 1995.
on extraterrestrial sources of illnesses
Hoyle and Wickramasinghe have speculated that several outbreaks of illnesses
on Earth are of extraterrestrial origins, including the 1918
flu pandemic, and certain outbreaks of polio and mad cow
disease. For the 1918 flu pandemic they hypothesized that cometary dust brought the virus
to Earth simultaneously at multiple locations—a view almost universally
dismissed by experts on this pandemic. Hoyle also speculated that HIV came from outer space.
After Hoyle's death, The
Lancet published a letter
to the editor from Wickramasinghe and two of his colleagues,
in which they hypothesized that the virus
that causes severe
acute respiratory syndrome (SARS) could be extraterrestrial in origin and
not originated from chickens. The Lancet subsequently published three
responses to this letter, showing that the hypothesis was not evidence-based,
and casting doubts on the quality of the experiments referenced by
Wickramasinghe in his letter.
A 2008 encyclopedia notes that "Like other claims linking terrestrial disease to
extraterrestrial pathogens, this proposal was rejected by the greater research
In April 2016, Jiangwen Qu of the Department of Infectious Disease Control in
China presented a statistical study suggesting that "extremes of sunspot
activity to within plus or minus 1 year may precipitate influenza pandemics."
He discussed possible mechanisms of epidemic initiation and early spread,
including speculation on primary causation by externally derived viral variants
from space via cometary dust.
A meteorite originating from
Mars known as ALH84001
was shown in 1996 to contain microscopic
structures resembling small terrestrial nanobacteria. When the
discovery was announced, many immediately conjectured that these were fossils and
were the first evidence of extraterrestrial
life — making headlines around the world. Public interest soon started to
dwindle as most experts started to agree that these structures were not
indicative of life, but could instead be formed abiotically from organic molecules.
However, in November 2009, a team of scientists at Johnson Space
Center, including David McKay, reasserted that there was "strong evidence
that life may have existed on ancient Mars", after having reexamined the
meteorite and finding magnetite
On May 11, 2001, two researchers from the University
of Naples claimed to have found viable extraterrestrial bacteria inside a
meteorite. Geologist Bruno D'Argenio and molecular biologist Giuseppe Geraci
claim the bacteria were wedged inside the crystal structure of minerals, but
were resurrected when a sample of the rock was placed in a culture medium.
An Indian and British team of researchers led by Chandra Wickramasinghe
reported on 2001 that air samples over Hyderabad, India,
gathered from the stratosphere by the Indian
Space Research Organisation (ISRO) on Jan 21, 2001, contained clumps of
Wickramasinghe calls this "unambiguous evidence for the presence of clumps of
living cells in air samples from as high as 41 km, above which no air
from lower down would normally be transported".
Two bacterial and one fungal species were later independently isolated from
these filters which were identified as Bacillus simplex, Staphylococcus pasteuri and
Engyodontium album respectively.
Pushkar Ganesh Vaidya from the Indian Astrobiology Research Centre reported in
2009 that "the three microorganisms captured during the balloon experiment do
not exhibit any distinct adaptations expected to be seen in microorganisms
occupying a cometary niche".
In 2005 an improved experiment was conducted by ISRO. On April 20, 2005, air
samples were collected from the upper atmosphere at altitudes ranging from
20 km to more than 40 km.
The samples were tested at two labs in India. The labs found 12 bacterial and
6 different fungal species in these samples. The fungi were Penicillium
sp. and Tilletiopsis albescens. Out of the 12 bacterial samples,
three were identified as new species and named Janibacter hoylei (after
Hoyle), Bacillus isronensis (named after ISRO) and Bacillus
aryabhattai (named after the ancient Indian mathematician, Aryabhata). These three new
species showed that they were more resistant to UV radiation than
Some other researchers have retrieved bacteria from the stratosphere since
Atmospheric sampling by NASA in 2010 before and after hurricanes, collected
314 different types of bacteria; the study suggests that large-scale
convection during tropical storms and hurricanes can then carry this material
from the surface higher up into the atmosphere.
Another proposed mechanism of spores in the stratosphere is lifting by
weather and Earth magnetism up to the ionosphere
into low Earth orbit, where Russian astronauts retrieved DNA
from a known sterile exterior surface of the International Space Station.
The Russian scientists then also speculated the possibility "that common
terrestrial bacteria are constantly being resupplied from space."
On January 10, 2013, Chandra
Wickramasinghe found fossil diatomfrustules in what he thinks
is a new kind of carbonaceous meteorite called Polonnaruwa
that landed in the North Central Province of Sri Lanka on 29 December
Early on, there was criticism that Wickramasinghe's report was not an
examination of an actual meteorite but of some terrestrial rock passed off as
Wickramasinghe's team remark that they are aware that a large number of
unrelated stones have been submitted for analysis, and have no knowledge
regarding the nature, source or origin of the stones their critics have
examined, so Wickramasinghe clarifies that he is using the stones submitted by
the Medical Research Institute in Sri Lanka.
In response to the criticism from other scientists, Wickramasinghe performed
analyses to verify its meteoritic origin. His analysis revealed a 95% silica and 3% quartz content,
and interpreted this result as a "carbonaceous
meteorite of unknown type".
In addition, Wickramasinghe's team remarked that the temperature at which
sand must be heated by lightning to melt and form a fulgurite (1770 °C) would
have vaporized and burned all carbon-rich organisms and melted and thus
destroyed the delicately marked silica frustules of the diatoms,
and that the oxygen isotope data confirms its meteoric origin.
Wickramasinghe's team also argues that since living diatoms require nitrogen fixation
to synthetize amino acids, proteins, DNA, RNA and other life-critical
biomolecules, a population of extraterrestrial cyanobacteria
must have been a required component of the comet (Polonnaruwa meteorite)
In 2013, Dale Warren Griffin, a microbiologist working at the United
States Geological Survey noted that viruses are the most numerous entities on
Earth. Griffin speculates that viruses evolved in comets and on other planets
and moons may be pathogenic to humans, so he proposed to also look for viruses
on moons and planets of the Solar System.
A separate fragment of the Orgueil
meteorite (kept in a sealed glass jar since its discovery) was found in 1965 to
have a seed capsule embedded in it, whilst the original glassy layer on the
outside remained undisturbed. Despite great initial excitement, the seed was
found to be that of a European Juncaceae
or Rush plant that had been glued into the fragment and camouflaged using coal dust.
The outer "fusion layer" was in fact glue. Whilst the perpetrator of this hoax
is unknown, it is thought that they sought to influence the 19th century debate
generation — rather than panspermia — by demonstrating the transformation of
inorganic to biological matter.
Until the 1970s, life was thought to depend on its
access to sunlight. Even life in the
ocean depths, where sunlight cannot reach, was believed to obtain its
nourishment either from consuming organic detritus rained down from the surface
waters or from eating animals that did.
However, in 1977, during an exploratory dive to the Galapagos Rift in the
deep-sea exploration submersible Alvin,
scientists discovered colonies of assorted creatures clustered around undersea
volcanic features known as black
It was soon determined that the basis for this food chain is a form of bacterium
that derives its energy from oxidation
of reactive chemicals, such as hydrogen
sulfide, that bubble up from the Earth's interior. This chemosynthesis
revolutionized the study of biology by revealing that terrestrial life need not
be Sun-dependent; it only requires water and an energy gradient in order to
It is now known that extremophiles,
microorganisms with extraordinary capability to thrive in the harshest
environments on Earth, can specialize to thrive in the deep-sea,
ice, boiling water, acid, the water core of nuclear reactors, salt crystals,
toxic waste and in a range of other extreme habitats that were previously
thought to be inhospitable for life.
Living bacteria found in ice core samples retrieved from 3,700 metres
(12,100 ft) deep at Lake
Vostok in Antarctica,
have provided data for extrapolations to the likelihood of microorganisms
surviving frozen in extraterrestrial habitats or during interplanetary
Also, bacteria have been discovered living within warm rock deep in the Earth's
Although computer models suggest that a captured meteoroid would typically
take some tens of millions of years before collision with a planet,
there are documented viable Earthly bacterial spores that are 40 million years
old that are very resistant to radiation,
and others able to resume life after being dormant for 25 million years,
suggesting that lithopanspermia life-transfers are possible via meteorites
exceeding 1 m in size.
The discovery of deep-sea ecosystems,
along with advancements in the fields of astrobiology,
and discovery of large varieties of extremophiles, opened up a new avenue in
astrobiology by massively expanding the number of possible extraterrestrial
habitats and possible transport of hardy microbial life through vast
The question of whether certain microorganisms
can survive in the harsh environment of outer space has intrigued biologists
since the beginning of spaceflight, and opportunities were provided to expose
samples to space. The first American tests were made in 1966, during the Gemini
IX and XII
missions, when samples of bacteriophage
T1 and spores of Penicillium
roqueforti were exposed to outer space for 16.8 h and 6.5 h,
Other basic life sciences research in low
Earth orbit started in 1966 with the Soviet biosatellite program Bion and the U.S. Biosatellite
program. Thus, the plausibility of panspermia can be evaluated by examining
life forms on Earth for their capacity to survive in space.
The following experiments carried on low
Earth orbit specifically tested some aspects of panspermia or
The survival of spores treated with the vacuum of space, however shielded
against solar radiation, is substantially increased, if they are exposed in
multilayers and/or in the presence of glucose
All spores in "artificial meteorites", i.e. embedded in clays or simulated Martian soil, are
The decrease in viability of the microorganisms could be correlated with
the increase in DNA
The purple membranes, amino acids and urea were not measurably affected by
the dehydrating condition of open space, if sheltered from solar radiation.
Plasmid DNA, however, suffered a significant amount of strand breaks under
BIOPAN is a
multi-user experimental facility installed on the external surface of the
descent capsule. Experiments developed for BIOPAN are designed to
investigate the effect of the space environment on biological material after
exposure between 13 and 17 days.
The experiments in BIOPAN are exposed to solar and cosmic radiation, the space
vacuum and weightlessness, or a selection thereof. Of the 6 missions flown so
far on BIOPAN between 1992 and 2007, dozens of experiments were conducted, and
some analyzed the likelihood of panspermia. Some bacteria, lichens (Xanthoria
geographicum and their mycobiont cultures, the black Antarctic
microfungi Cryomyces minteri and Cryomyces antarcticus), spores,
and even one animal (tardigrades)
were found to have survived the harsh outer space environment and cosmic
The German EXOSTACK
experiment was deployed on 7 April 1984 on board the Long
Duration Exposure Facility statellite. 30% of Bacillus subtilisspores
survived the nearly 6 years exposure when embedded in salt crystals, whereas 80%
survived in the presence of glucose, which stabilize the structure of the
cellular macromolecules, especially during vacuum-induced dehydration.
If shielded against solar UV,
spores of B. subtilis were capable of surviving in space for up to 6
years, especially if embedded in clay or meteorite powder (artificial
meteorites). The data support the likelihood of interplanetary transfer of
microorganisms within meteorites, the so-called lithopanspermia
mission is an orbital astrobiology
experiment by Japan that is currently investigating the possible interplanetary
transfer of life, organic
compounds, and possible terrestrial particles in low Earth orbit. The
Tanpopo experiment is taking place at the Exposed Facility located on the
exterior of Kibo
module of the International
Space Station. The mission will collect cosmic
dusts and other particles for three years by using an ultra-low density
silica gel called aerogel.
The purpose is to assess the panspermia hypothesis and the possibility of
natural interplanetary transport of life and its precursors.
Some of these aerogels will be replaced every one or two years through 2018.
Sample collection began in May 2015, and the first samples were be returned to
Earth in mid-2016.
Panspermia is often criticized because it does not answer the question of the
of life but merely places it on another celestial body. It was also
criticized because it was thought it could not be tested experimentally.
Wallis and Wickramasinghe argued in 2004 that the transport of individual
bacteria or clumps of bacteria, is overwhelmingly more important than
lithopanspermia in terms of numbers of microbes transferred, even accounting for
the death rate of unprotected bacteria in transit.
Then it was found that isolated spores of B. subtilis were killed
by several orders of magnitude if exposed to the full space environment for a
mere few seconds. These results clearly negate the original panspermia
hypothesis, which requires single spores as space travelers accelerated by the
radiation pressure of the Sun, requiring many years to travel between the
planets. However, if shielded against solar UV, spores of Bacillus subtilis
were capable of surviving in space for up to 6 years, especially if embedded in
clay or meteorite powder (artificial meteorites). The data support the
likelihood of interplanetary transfer of microorganisms within meteorites, the so-called lithopanspermia hypothesis.
^A variation of the panspermia hypothesis is necropanspermia which astronomer Paul Wesson describes as follows: "The
vast majority of organisms reach a new home in the Milky Way in a technically
dead state … Resurrection may, however, be possible." Grossman,
Lisa (2010-11-10). "All Life on Earth Could Have Come From Alien Zombies". Wired. Retrieved 10
^Hoyle, F. and Wickramasinghe, N.C. (1981). Evolution from Space. Simon & Schuster Inc., NY, and J.M. Dent and
Son, London (1981), ch3 pp. 35–49.
^ abKlyce, Brig (2001).
"Panspermia asks new questions". In Kingsley, Stuart A; Bhathal, Ragbir. The Search for Extraterrestrial Intelligence (SETI) in the Optical Spectrum
III. Proc. SPIE. The Search for Extraterrestrial Intelligence
(SETI) in the Optical Spectrum III. 4273. p. 11. Bibcode:2001SPIE.4273...11K. doi:10.1117/12.435366.
^ abcThe DNA of bacteria of the World Ocean and the
Earth in cosmic dust at the International Space Station. T.V.
Grebennikova, A.V. Syroeshkin, E.V. Shubralova, O.V. Eliseeva, L.V. Kostina,
N.Y. Kulikova, O.E. Latyshev, M.A. Morozova, A.G. Yuzhakov, I.A. Zlatskiy,
M.A. Chichaeva, O.S. Tsygankov. (PDF). 2017.
^ abHorneck, G;
Rettberg, P; Reitz, G; Wehner, J; Eschweiler, U; Strauch, K; Panitz, C;
Starke, V; Baumstark-Khan, C (2001). "Protection of Bacterial Spores in Space,
a Contribution to the Discussion on Panspermia". Origins of life and
evolution of the biosphere : the journal of the International Society for
the Study of the Origin of Life. 31 (6): 527–47. Bibcode:2002ESASP.518..105R. PMID11770260.
Cucinotta, F. A.; Wilson, J. W.; Gladman, B; Horneck, G; Lindegren, L; Melosh,
J; Rickman, H; Valtonen, M; Zheng, J. Q. (2000). "Natural Transfer of Microbes
in space, part I: from Mars to Earth and Earth to Mars". Icarus. 145 (2): 391–427. Bibcode:2000Icar..145..391M. doi:10.1006/icar.1999.6317.
Karen; Cockell, Charles S. (2010). "Experimental methods for studying
microbial survival in extraterrestrial environments". Journal of
Microbiological Methods. 80 (1): 1–13. doi:10.1016/j.mimet.2009.10.004.
Baglioni, P.; Borruat, G.; Brandstätter, F.; et al. (2002). "Do meteoroids of
sedimentary origin survive terrestrial atmospheric entry? The ESA artificial
meteorite experiment STONE". Planetary and Space Science. 50
(7–8): 763–772. Bibcode:2002P&SS...50..763B. doi:10.1016/S0032-0633(02)00018-1.
S.; Brack, André; Wynn-Williams, David D.; Baglioni, Pietro; et al. (2007).
"Interplanetary Transfer of Photosynthesis: An Experimental Demonstration of a
Selective Dispersal Filter in Planetary Island Biogeography". Astrobiology. 7 (1): 1–9. Bibcode:2007AsBio...7....1C. doi:10.1089/ast.2006.0038.
(2008). "From Fossils to Astrobiology – A Roadmap to Fata Morgana?". In
Seckbach, Joseph; Walsh, Maud. From Fossils to Astrobiology: Records of
Life on Earth and the Search for Extraterrestrial Biosignatures. 12. p. xvii. ISBN1-4020-8836-1.
Stephen (2002), If the universe is teeming with aliens, where is everybody?
Fifty solutions to the Fermi paradox and the problem of extraterrestrial
life, Copernicus, Springer, OCLC50164852.
(Sep 1995). "Some Thoughts on the Implications of Faster-Than-Light
Interstellar Space Travel". Quarterly Journal of the Royal Astronomical
Society. 36 (3): 205. Bibcode:1995QJRAS..36..205C.
Geraci, Giuseppe & del Gaudio, Rosanna (March 2001). "Microbes in rocks
and meteorites: a new form of life unaffected by time, temperature, pressure".
Rendiconti Lincei. 12 (1): 51–68. doi:10.1007/BF02904521.
^De La Torre
Noetzel, Rosa (2008). "Experiment lithopanspermia: Test of interplanetary
transfer and re-entry process of epi- and endolithic microbial communities in
the FOTON-M3 Mission". 37th COSPAR Scientific Assembly. Held 13–20 July
2008. 37: 660. Bibcode:2008cosp...37..660D.
Ingemar Jönsson; Elke Rabbow; Ralph O. Schill; Mats Harms-Ringdahl; et al. (9
September 2008). "Tardigrades survive exposure to space in low Earth orbit". Current Biology.
18 (17): R729–R731. doi:10.1016/j.cub.2008.06.048.
Scalzi; Laura Selbmann; Laura Zucconi; Elke Rabbow; et al. (1 June 2012).
"LIFE Experiment: Isolation of Cryptoendolithic Organisms from Antarctic
Colonized Sandstone Exposed to Space and Simulated Mars Conditions on the
International Space Station". Origins of Life and Evolution of
Biospheres. 42 (2–3): 253–262. Bibcode:2012OLEB...42..253S. doi:10.1007/s11084-012-9282-5.
Lux-Endrich, Astrid; Panitz, Corinna; Horneck, Gerda (January 2015). "Survival
of Spores of Trichoderma longibrachiatum in Space: data from the Space
Experiment SPORES on EXPOSE-R". International Journal of Astrobiology. 14 (Special Issue 1): 129–135. Bibcode:2015IJAsB..14..129N. doi:10.1017/S1473550414000408.