moleculas orgnanicas en marte
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articulo científicoTRANSCRIPT
7182019 Moleculas orgnanicas en Marte
httpslidepdfcomreaderfullmoleculas-orgnanicas-en-marte 121402 27 MARCH 2015 bull VOL 347 ISSUE 6229 sciencemagorg SCIENC
By Eric Hand in The Woodlands Texas
For almost 40 yearsmdashever since NASArsquos
Viking missionsmdashlanders and rovers
have searched the desiccated soil of
Mars for the carbon-bearing organic
compounds that would be essential for
any Earth-like life Last week here at
the Lunar and Planetary Science Conference
scientists working with NASArsquos Curiosity
rover announced a major milestone in that
search They reported the most definitive de-
tections of organic molecules yet along with
hints of heavier longer-chain molecules re-
sembling those in cell wallsThe detected molecules do not necessarily
indicate past or present life on Mars They
could also have come from asteroid impacts
or rocks that burbled up from Marsrsquos mantle
But they at least show that fragile organic
materials can survive in the inhospitable
environmentmdashwhich bodes well for searches
for clearer indicators of past life
ldquoWe are all excited about itrdquo says Paul
Mahaffy a scientist at the Goddard Space
Flight Center in Greenbelt Maryland and
principal investigator for the Sample Analy-
sis at Mars (SAM) instrument on Curiosity which made the detections ldquoThe fact that
there are any organic compounds in the near
surface at all is very promisingrdquo It suggests
he says that ldquobiosignaturesrdquo if any exist
might survive billions of years to be detected
today in spite of the harsh surface conditions
Marsrsquos soil is known to be filled with harsh
oxidizers like perchlorate which break down
organic molecules Ultraviolet (UV) light at
the surface can also destroy organics as can
cosmic rays The Viking landers may have
detected organic molecules in the form of
chloromethanes but in such tiny quantitiesmdash
about 15 parts per billionmdashthat the team wasnever confident about making a claim
The Curiosity team is now making a claim
with gusto having detected chlorobenzenemdash
a six-carbon molecule in an aromatic ring
structuremdashat levels of up to 300 parts per
billion They have also detected smaller two-
three- and four-carbon chains in the alkane
family at lesser abundances The results
were posted online on 4 March in advance
of publication in the Journal of Geophysical
Research Planets
The organics come from a sample that Cu-
riosity collected nearly 2 years ago by drillin
65 centimeters into a mudstonemdashharden
sediment from an ancient lakemdashat a si
called Cumberland The SAM team took
long to announce their finding in part b
cause they wanted to be sure they had n
been fooled by contamination from lea
age in their ldquowet labsrdquo which hold thimbl
fuls of a solvent called MTBSTFA used
isolating organic molecules The SAM teahas now controlled for this backgroun
contamination and they have not seen th
chloro benzene at subsequent sampli
sitesmdashevidence that the Cumberland dete
tion was real
Curiosity scientists suspect that the chl
robenzene arose when organic molecul
reacted with perchlorate in the soil as th
sample was baked in SAMrsquos ovens To p
down the precursor molecules the SA
team decided not to use any of their preciou
thimbles instead they took advantage of th
leaked MTBSTFA They baked a sample fro
Cumberland to drive off any perchloraand then exposed it to ambient MTBSTF
inside the onboard lab for 2 days The so
vent makes organic molecules much mo
volatile and thus more likely to be detect
by SAMrsquos mass spectrometer before they r
act with anything else (like perchlorate) ldquo
gives them lsquowingsrsquo so they can fly through th
instrument unimpededrdquo Mahaffy says Aft
the exposure the team slowly started heatin
the sample again ldquoThatrsquos when this beautif
set of rich organics showed uprdquo
At the meeting Danny Glavin a SAM s
I N D EP T H
Mars rover finds long-chain organic compoundsComplex carbon molecules show that clues to past lifemdashifanymdashcould survive harsh martian conditions
PLANETARY SCIENCE Curiosityrsquos lab carries quartz sample cups (white) an
ldquowet labrdquo cups with solvent (silver)
Published by AAAS
7182019 Moleculas orgnanicas en Marte
httpslidepdfcomreaderfullmoleculas-orgnanicas-en-marte 22
NEW
27 MARCH 2015 bull VOL 347 ISSUE 6229 140SCIENCE sciencemagorg
P H O T O N A S A J P L 983085 C A L T E C H M S S S
entist at Goddard reported compounds that
in a preliminary analysis were consistent
with an eight-carbon molecule akin to a ben-
zoic acid an 11-carbon alcohol-like molecule
and most interesting of all a 10-carbon mol-
ecule that could be a fatty acidndashlike carbox-
ylic acid Glavin is excited that long-chain
organics can survive in spite of the oxidizing
compounds and UV-rich sunlight ldquoThe fact
that we see something long means this could be a good location for
preservationrdquo he says
Other scientists won-
der if the compounds
could signify something
more than just good
odds for preservation In
the case of the 10-carbon
fatty acidndashlike compound
ldquoYoursquore talking about
cellular-wall materialrdquo
says Marc Fries a cura-
tion scientist at NASArsquos
Astromaterials Acquisi-tion and Curation Office
at Johnson Space Center in Houston Texas
ldquoThatrsquos a potential biogenic moleculerdquo But
it could also be a contaminant he cautions
Fries notes that a 2014 study by scientists at
the Jet Propulsion Laboratory in Pasadena
California where the rover was assembled
warned that Curiosity could harbor traces of
carboxylic acids which are found in plant and
animal oils as well as synthetic lubricants
But Glavin points out that six batches of
martian soil went through the SAM instru-
ment before the Cumberland sample and
ought to have scrubbed the instrument of
residual contamination And George Cody
a geochemist at the Carnegie Institution for
Science in Washington DC says that the
compound is unlikely to have come from
Earth Fatty acids from biological sources
like techniciansrsquo fingerprints Cody says
tend to have 14 16 or 18 carbon atoms not10 Also if the contami-
nation were something
like residual machine
oil smaller chain or-
ganic compounds would
have been detected
in the backgroundmdash
molecules that Curiosity
does not see
The Curiosity team
has yet to use any of the
seven MTBSTFA thim-
bles or two with another
type of solvent Glavinsays the team is saving
them for promising rock formations farther
up the mountain that Curiosity is now climb-
ing clay mineralndashbearing deposits that like
the Cumberland mudstone probably formed
in water and could be a good location for
preserving organics Mahaffy hopes to get a
chance to test one of his thimbles soonmdashand
hopes to find even more-tantalizing organic
molecules ldquoTherersquos a lot of interesting sites
coming alongrdquo he says
By Eric Hand
Organic compounds arenrsquot the only molecules of life on Earth Inorganic NO
3-
bearing chemicals known as nitrates are also crucial for living organisms and
make up a key component of fertilizers Now in a study published this week in
the Proceedings of the National Academy of Sciences the NASA Curiosity rover
team reports detecting nitrates on Mars
The chemicals turned up in scoops of windblown dust as well as samples drilled
out of a mudstone thought to have been made from lakebed deposits billions of
years old The roverrsquos onboard lab Sample Analysis at Mars heated the rock dust
to release gases and ran them through a mass spectrometer which spotted the
molecular signature of nitrogen Marsrsquos atmosphere is now just 2 nitrogen (N 2) but scientists suspect that it abounded in nitrogen in the pastmdashjust as Earthrsquos
atmosphere does today
On Earth microbesmdashespecially bacteria living in the nodules of legume plantsmdash
do the hard work of breaking N 2rsquos triple bonds and turning it into nitrate that can
be ldquofixedrdquo in the soil Rover scientists say things probably happened differently on
Mars where the energy of asteroid impacts could have done the fixing in a flash
Regardless the discovery shows nitrate would have been available as a nutrient
in Marsrsquos ancient past ldquoIn a way it provides what fertilizer would providerdquo says
Jennifer Stern a planetary geochemist at Goddard Space Flight Center in Greenbelt
Maryland and lead author of the study ldquoItrsquos another support for habitabilityrdquo
lsquoFixedrsquo nitrogen found in martian soil
Drill hole from the Cumberland site in
rock that was an ancient lakebed
Reform oftoxics law is
contentiousPlan to rewrite 1976 lawdraws bipartisan supportbut harsh criticism
CHEMICAL REGULATION
By Puneet Kollipara
O
f the roughly 80000 industri
chemicals in commerce in the Unite
States the Environmental Prote
tion Agency (EPA) has substantial
restricted the use of less than 1
Thatrsquos just one reason observeon all sides agree that the countryrsquos lon
standing chemical testing law is broke
Last week a US Senate committee set o
to fix it launching what is expected to be
long contentious effort to rewrite the 19
Toxic Substances Control Act (TSCA)
ldquoThere has never been a bipartisan e
fort with this much potentialrdquo said Senat
Tom Udall (DndashNM) at an 18 March hearin
of the Senate environment committee on
bill (S 697) that he and 19 other senator
Democratic and Republican recently rolle
out that would revamp the law Groups th
rarely agree share that goal Environmetalists and regulators decry TSCA becau
it gives EPA so little clout while some i
dustry groups complain that TSCArsquos flaw
have led states to enact a patchwork of law
that complicate compliance
But coming up with a new law that ca
satisfy everyone wonrsquot be easy The legisl
tion co-sponsored by Senator David Vitt
(RndashLA) has drawn support from indust
and the Environmental Defense Fund Y
other environmental and public heal
groups as well as some state officials com
plain that Udallrsquos bill would sometimes pr
vent states from writing their own tougregulations fail to adequately accelera
EPArsquos efforts to screen potentially dange
ous chemicals and give industry too muc
voice in agency decisions The bill ldquois wor
than the current law We canrsquot go there
said Senator Barbara Boxer (DndashCA) the to
Democrat on the environment panel at
17 March press conference She has offere
an alternative bill that she argues wou
give EPA and state governments strong
oversight power
Nearly 40 years ago lawmakers approv
Published by AAAS
7182019 Moleculas orgnanicas en Marte
httpslidepdfcomreaderfullmoleculas-orgnanicas-en-marte 22
NEW
27 MARCH 2015 bull VOL 347 ISSUE 6229 140SCIENCE sciencemagorg
P H O T O N A S A J P L 983085 C A L T E C H M S S S
entist at Goddard reported compounds that
in a preliminary analysis were consistent
with an eight-carbon molecule akin to a ben-
zoic acid an 11-carbon alcohol-like molecule
and most interesting of all a 10-carbon mol-
ecule that could be a fatty acidndashlike carbox-
ylic acid Glavin is excited that long-chain
organics can survive in spite of the oxidizing
compounds and UV-rich sunlight ldquoThe fact
that we see something long means this could be a good location for
preservationrdquo he says
Other scientists won-
der if the compounds
could signify something
more than just good
odds for preservation In
the case of the 10-carbon
fatty acidndashlike compound
ldquoYoursquore talking about
cellular-wall materialrdquo
says Marc Fries a cura-
tion scientist at NASArsquos
Astromaterials Acquisi-tion and Curation Office
at Johnson Space Center in Houston Texas
ldquoThatrsquos a potential biogenic moleculerdquo But
it could also be a contaminant he cautions
Fries notes that a 2014 study by scientists at
the Jet Propulsion Laboratory in Pasadena
California where the rover was assembled
warned that Curiosity could harbor traces of
carboxylic acids which are found in plant and
animal oils as well as synthetic lubricants
But Glavin points out that six batches of
martian soil went through the SAM instru-
ment before the Cumberland sample and
ought to have scrubbed the instrument of
residual contamination And George Cody
a geochemist at the Carnegie Institution for
Science in Washington DC says that the
compound is unlikely to have come from
Earth Fatty acids from biological sources
like techniciansrsquo fingerprints Cody says
tend to have 14 16 or 18 carbon atoms not10 Also if the contami-
nation were something
like residual machine
oil smaller chain or-
ganic compounds would
have been detected
in the backgroundmdash
molecules that Curiosity
does not see
The Curiosity team
has yet to use any of the
seven MTBSTFA thim-
bles or two with another
type of solvent Glavinsays the team is saving
them for promising rock formations farther
up the mountain that Curiosity is now climb-
ing clay mineralndashbearing deposits that like
the Cumberland mudstone probably formed
in water and could be a good location for
preserving organics Mahaffy hopes to get a
chance to test one of his thimbles soonmdashand
hopes to find even more-tantalizing organic
molecules ldquoTherersquos a lot of interesting sites
coming alongrdquo he says
By Eric Hand
Organic compounds arenrsquot the only molecules of life on Earth Inorganic NO
3-
bearing chemicals known as nitrates are also crucial for living organisms and
make up a key component of fertilizers Now in a study published this week in
the Proceedings of the National Academy of Sciences the NASA Curiosity rover
team reports detecting nitrates on Mars
The chemicals turned up in scoops of windblown dust as well as samples drilled
out of a mudstone thought to have been made from lakebed deposits billions of
years old The roverrsquos onboard lab Sample Analysis at Mars heated the rock dust
to release gases and ran them through a mass spectrometer which spotted the
molecular signature of nitrogen Marsrsquos atmosphere is now just 2 nitrogen (N 2) but scientists suspect that it abounded in nitrogen in the pastmdashjust as Earthrsquos
atmosphere does today
On Earth microbesmdashespecially bacteria living in the nodules of legume plantsmdash
do the hard work of breaking N 2rsquos triple bonds and turning it into nitrate that can
be ldquofixedrdquo in the soil Rover scientists say things probably happened differently on
Mars where the energy of asteroid impacts could have done the fixing in a flash
Regardless the discovery shows nitrate would have been available as a nutrient
in Marsrsquos ancient past ldquoIn a way it provides what fertilizer would providerdquo says
Jennifer Stern a planetary geochemist at Goddard Space Flight Center in Greenbelt
Maryland and lead author of the study ldquoItrsquos another support for habitabilityrdquo
lsquoFixedrsquo nitrogen found in martian soil
Drill hole from the Cumberland site in
rock that was an ancient lakebed
Reform oftoxics law is
contentiousPlan to rewrite 1976 lawdraws bipartisan supportbut harsh criticism
CHEMICAL REGULATION
By Puneet Kollipara
O
f the roughly 80000 industri
chemicals in commerce in the Unite
States the Environmental Prote
tion Agency (EPA) has substantial
restricted the use of less than 1
Thatrsquos just one reason observeon all sides agree that the countryrsquos lon
standing chemical testing law is broke
Last week a US Senate committee set o
to fix it launching what is expected to be
long contentious effort to rewrite the 19
Toxic Substances Control Act (TSCA)
ldquoThere has never been a bipartisan e
fort with this much potentialrdquo said Senat
Tom Udall (DndashNM) at an 18 March hearin
of the Senate environment committee on
bill (S 697) that he and 19 other senator
Democratic and Republican recently rolle
out that would revamp the law Groups th
rarely agree share that goal Environmetalists and regulators decry TSCA becau
it gives EPA so little clout while some i
dustry groups complain that TSCArsquos flaw
have led states to enact a patchwork of law
that complicate compliance
But coming up with a new law that ca
satisfy everyone wonrsquot be easy The legisl
tion co-sponsored by Senator David Vitt
(RndashLA) has drawn support from indust
and the Environmental Defense Fund Y
other environmental and public heal
groups as well as some state officials com
plain that Udallrsquos bill would sometimes pr
vent states from writing their own tougregulations fail to adequately accelera
EPArsquos efforts to screen potentially dange
ous chemicals and give industry too muc
voice in agency decisions The bill ldquois wor
than the current law We canrsquot go there
said Senator Barbara Boxer (DndashCA) the to
Democrat on the environment panel at
17 March press conference She has offere
an alternative bill that she argues wou
give EPA and state governments strong
oversight power
Nearly 40 years ago lawmakers approv
Published by AAAS