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