Organic molecules found in diverse space places
By Ker Than, SPACE.com

A two-year survey of enormous interstellar dust clouds has turned up
eight organic molecules in two different regions of space. One is a
stellar nursery awash in light while the other is a cold, starless void.
The finding, detailed in the current issue of Astrophysical Journal,
supports other recent studies suggesting molecules important for life
commonly form in the gas and dust clouds that condense to form stars and
planets.

The molecules were discovered using the Robert C. Byrd Green Bank
Telescope (GBT), a large radio telescope located in West Virginia.
"Finding eight [organic] molecules in the space of two years is quite
remarkable," said study leader Jan Hollis of NASA Goddard Space Flight
Center.

Life molecules
The newly discovered molecules are made up of 6 to 11 atoms each and are
classified as organic because they contain carbon.
Five of the molecules were discovered in Sagittarius B2(N), a
star-forming dust cloud located 26,000 light-years from Earth near the
center of the Milky Way Galaxy. This stellar nursery is the largest
known repository of complex interstellar molecules.
The other three molecules were found in the Taurus Molecular Cloud
(TMC-1), located only 450 light-years away. TMC-1 is starless; it is
cold and dark and has a temperature of only 10 degrees above absolute
zero.

"The discovery of these large organic molecules in the coldest regions
of the interstellar medium has certainly changed the belief that large
organic molecules would only have their origins in hot molecular cores,"
said study team member Anthony Remijan of the National Radio Astronomy
Observatory (NRAO). "It has forced us to rethink the paradigms of
interstellar chemistry."
Just because a molecule is organic does not mean that it is made by
living things. In fact, many of the newly spotted molecules are
poisonous to organisms on Earth, Hollis said. But one of the molecules
found in Sagittarius B2(N), called acetamide, contains a type of
chemical bond important for linking together amino acids, the molecular
building blocks of proteins.
Made up of 9 atoms, acetamide "is the largest molecule found in space
that has that bond," Hollis told SPACE.com.

Space tumbleweeds
The molecules are thought to form by two main mechanisms. In the first,
simple chemical reactions add an atom to a molecule that is stuck to the
surface of a dust grain afloat in space. The second method involves
chemical reactions between neutral molecules and highly reactive
molecules called radicals.
Once formed, the molecules are shaken loose from their dust-grain homes
by rapidly moving shock waves. As the freed molecules tumble
end-over-end in space, they can emit or absorb radiation at precise
radio frequencies unique to each type of molecule. Astronomers identify
the molecules based on these radio frequencies.

Within a dust cloud, thousands of billions of molecules undergo the same
types of rotation, emitting and absorbing the same radio frequencies.
The end result is a signal strong enough to be detected by instruments
on Earth.
The newfound molecules bring the total number of biologically-relevant
molecules found in interstellar space to 141. Scientists have previously
found benzene, a ring-shaped carbon molecule important for life on
Earth, around stars and intact amino acids in meteorites that have
crash-landed on Earth.
Even more complex molecular creations might be possible in space,
experiments suggest. In one study, scientists simulated deep space
conditions in the laboratory and created small structures resembling
cell walls in living organisms.

A case for extraterrestrial life
Taken together, the findings suggest that the chemical ingredients
necessary for life began taking shape long before our planet was formed.
Many scientists now accept the notion that ancient meteorites and comets
helped jumpstart life on our planet by bringing a significant amount of
water, organic molecules and even amino acids to early Earth.
Scientists now think those imprisoned organic molecules were likely
created in the massive dust and gas clouds that eventually coalesced
into planets and stars, comets and meteorites. Dust clouds are thought
to form when events such as novas and supernovas caused chemical
elements and molecules created during thermonuclear reactions inside
stars to be ejected into space.

Hollis says his team plans to keep using the Green Bank Telescope to
continue searching for other biologically-significant molecules.
"From a research and astrobiology point of view, it's been a goldmine,"
he said.