Download Impacts from space can form building blocks of life

Impacts from space can form building blocks of life
Czech researchers who simulated conditions prevalent on Earth under a hail of asteroids and comets
billions of years ago in laboratory with a powerful laser , showed that chemical reactions that took
place under the heat and pressure extremes caused by these impacts could have synthesized the
organic compounds which form RNA, believed to be the first molecule to encode genetic information
essential for the life forms to emerge and replicate themselves.
In the experiment conducted at the J. Heyrovsky Physical Chemistry Institute in Prague, a solution
containing formamide, a mineral thought to abound in the crust of early Earth, and clay was bombarded
by laser pulses spaced by a third of a nanosecond. In the solution subjected to intense pressure caused
by laser pulses, temperature peaks in excess of 4200⁰C and high-energy radiation including ultraviolet
and X-rays, adenine, guanine, cytosine
and uracil, the four nucleobases which
make up the RNA were seen to form
together.
RNA is believed to be the molecule
bearing the genetic code before the
DNA which contains thymine instead
of uracil and is present in the nucleus
of every cell in organisms. Formamide,
produced when hydrogen cyanide
reacts with water, contains atoms of
hydrogen, nitrogen, carbon and oxygen
which are essential for life.
The Earth, currently about 4.6 billion
years old, had come under an intense
bombardment by meteorites along
with its moon and other inner solar
system planets Mecury, Venus and
Mars four billion years ago. This
barrage of planetsimals of every size,
let loose as aresult of gravitational
interactions between the gas giant
planets of the outer solar system and
lasted 150 million years, is called the
Late Heavy Bombardment. Though
many scientists believe that these
impacts and their devastating effects
should have stamped off any fledging
life, the work of Czech scientists show
that such impacts can also create the
molecules crucial for life.
The ice and rock debris disk immediately after the formation of the
sun (left), the destabilisation of the disk due to the gravitational tugof-war between gas giant planets (center) and the solar system after
the Late Heavy Bombardment according to a computer simulation
(right).
With Jupiter’s migration inward and Saturn’s outward as a result of gravitational
jostling between gas giant planets shortly after the formation of the solar
system, the disk of debris left from the sun’s formation had become unstable ,
unleashing a torrent of asteroids and comets onto the inner solar system. And
when the orbital periods of Jupiter and Saturn entered into resonance at the end
of the process, the disk underwent a second wave of ripples with debris either
raining down on inner planets and moons once again, or getting catapulted
outward to form the Kuiper Belt and the Oort Cloud.
In the closing stages of this epoch called the Late Heavy Bombardment, the
Earth, the Moon and other inner planets Mercury, Venus and Mars had been
pummeled by a mixed bag of meteorites of varying sizes, including giant
asteroids and comets.While the vestiges of this cataclysmic bombardment were
largely erased from Earth’s surface by new crust constantly rising and spreading
as result of the movement of tectonic plates, the devastation it caused is clearly
visible on the surfaces of other planets, moons and other objects of the inner
solar system in the form of craters some of which are hundreds of kilometers
accross.
Raşit Gürdilek
REFERENCES:
“From hell on Earth, to life’s building
blocks”, Science, 12 December 2014
TAGS:
RNA, meteorite, formamide, life, nucleobases, adenine , guanine cytosine, uracil l
Artist’s
impression of
the impacts
sustained by
the Moon
during the Late
Heavy
Bombardment
(top) and the
present day
surface of the
moon
pockmarked by
craters
(bottom).