Did Life Originate from Space ?
This theory proposes that life originated out there and was brought to Planet Water on a
meteorite or some other heavenly body.
While there is no evidence of living things on these bodies there is evidence of organic molecules.
What this says is that the primeval soup is everywhere and that it is raining down upon our planet.
Whether this is only the precursors of life or the remnants of life itself out there, remains to
be answered.
Certainly it shown that the building blocks for life are tumbling through the
universe.
The evidence for these building blocks or life remnants is summarized below.
Evidence of Life Coming from Space: The Murchison Meteorite
A meteorite, that landed near Murchison, in Victoria, Australia on 28 September 1969, turned
out to contain a variety of organic molecules including:
=> purines and pyrimidines
=> polyols - compounds with hydroxyl groups on a backbone of 3 to 6 carbons such as
glycerol and glyceric acid. Sugars are polyols
=> amino acids
Six of the amino acids found are present in all living things
=> Glycine, Glutamic acid, Alanine, Valine, Aspartic acid
but the others
=> Isovaline, Norvaline, Proline, N-methylalanine, N-ethylglycine
are not normally found in living matter here on earth.
The same amino acids and their relative proportions were quite similar to the products formed in
Miller's experiments.
The question is: were these molecules simply terrestrial contaminants that got into the
meteorite after it fell to earth?
It appear that this was not the case:
=> Some of the samples were collected on the same day it fell and subsequently handled with
great care to avoid contamination.
=> The polyols contained the isotopes carbon-13 and hydrogen-2 (deuterium) in greater amounts
than found here on earth.
=> The samples lacked certain amino acids that are found in all earthly proteins.
=> Only L amino acids occur in earthly proteins, but the amino acids in the meteorite contain
both D and L forms (although L forms were slightly more prevalent).
Evidence of Life Coming from Space: The ALH84001 meteorite
This meteorite arrived here from Mars. It contained not only a variety of organic molecules,
including polycyclic aromatic hydrocarbons, but - some claim - evidence of microorganisms
as well.
Furthermore, there is evidence that its interior never rose about 40° C during its fiery
trip through the earth's atmosphere. Live bacteria could easily survive such a trip.
Evidence of Life Coming from Space: Organic molecules in interstellar space
Astronomers, using infrared spectroscopy, have identified a variety of organic molecules
in interstellar space, including:
=> methane (CH4),
=> methanol (CH3OH),
=> formaldehyde (HCHO),
=> cyanoacetylene (HC3N) (which in spark-discharge experiments is a precursor to the
pyrimidine cytosine).
=> polycyclic aromatic hydrocarbons
=> as well as such inorganic building blocks as carbon dioxide (CO2),
carbon monoxide (CO), ammonia (NH3), hydrogen sulfide (H2S), and
hydrogen cyanide (HCN).
Evidence of Life Coming from Space: Laboratory Synthesis of Organic Molecules Under
Conditions Mimicking Outer Space
There have been several reports of producing amino acids and other organic molecules by
taking a mixture of molecules known to be present in interstellar space such as:
=> ammonia (NH3)
=> carbon monoxide (CO)
=> methanol (CH3OH) and
=> water (H2O)
=> hydrogen cyanide (HCN)
and exposing it to
=> a temperature close to that of space (near absolute zero)
=> intense ultraviolet (UV) radiation.
This is Miller's experiment and many other versions of it.
The Bottom Line: Precursors in Outer Space? - Yes Life in Outer Space? - Not So Far
The primeval soup rains down upon us and there is evidence of organic molecules out there
in space.
But when and where the life that appeared on planet water, first developed remains to be
answered.
If life did arrive from space, questions still remain about how it arose or was created
out there?
Evolution pathway and links to the atmosphere - These are the keys to understanding
Life as we know it