NEWS
‘Fixed’ nitrogen found in martian soil By Eric Hand
PHOTO: NASA/JPL-CALTECH/MSSS
O
rganic compounds aren’t the only molecules of life on Earth: Inorganic NO3bearing 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 rover’s 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. Mars’s atmosphere is now just 2% nitrogen (N2), but scientists suspect that it abounded in nitrogen in the past—just as Earth’s atmosphere does today. On Earth, microbes—especially bacteria living in the nodules of legume plants— do the hard work of breaking N2’s triple bonds and turning it into nitrate that can be “fixed” 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 Mars’s ancient past. “In a way, it provides what fertilizer would provide,” says Jennifer Stern, a planetary geochemist at Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. “It’s another support for habitability.” ■
SCIENCE sciencemag.org
CHEMICAL REGULATION
Reform of toxics law is contentious Plan to rewrite 1976 law draws bipartisan support but harsh criticism By Puneet Kollipara
O
f the roughly 80,000 industrial chemicals in commerce in the United States, the Environmental Protection Agency (EPA) has substantially restricted the use of less than 10. That’s just one reason observers on all sides agree that the country’s longstanding chemical testing law is broken. Last week, a U.S. Senate committee set out to fix it, launching what is expected to be a long, contentious effort to rewrite the 1976 Toxic Substances Control Act (TSCA). “There has never been a bipartisan effort with this much potential,” said Senator Tom Udall (D–NM) at an 18 March hearing of the Senate environment committee on a bill (S. 697) that he and 19 other senators, Democratic and Republican, recently rolled out that would revamp the law. Groups that rarely agree share that goal: Environmentalists and regulators decry TSCA because it gives EPA so little clout, while some industry groups complain that TSCA’s flaws have led states to enact a patchwork of laws that complicate compliance. But coming up with a new law that can satisfy everyone won’t be easy. The legislation, co-sponsored by Senator David Vitter (R–LA), has drawn support from industry and the Environmental Defense Fund. Yet other environmental and public health groups, as well as some state officials, complain that Udall’s bill would sometimes prevent states from writing their own tough regulations, fail to adequately accelerate EPA’s efforts to screen potentially dangerous chemicals, and give industry too much voice in agency decisions. The bill “is worse than the current law. We can’t go there,” said Senator Barbara Boxer (D–CA), the top Democrat on the environment panel, at a 17 March press conference. She has offered an alternative bill that she argues would give EPA and state governments stronger oversight power. Nearly 40 years ago, lawmakers approved 27 MARCH 2015 • VOL 347 ISSUE 6229
Published by AAAS
1403
Downloaded from www.sciencemag.org on March 26, 2015
entist at Goddard, reported compounds that, martian soil went through the SAM instruin a preliminary analysis, were consistent ment before the Cumberland sample and with an eight-carbon molecule akin to a benought to have scrubbed the instrument of zoic acid, an 11-carbon alcohol-like molecule, residual contamination. And George Cody, and, most interesting of all, a 10-carbon mola geochemist at the Carnegie Institution for ecule that could be a fatty acid–like carboxScience in Washington, D.C., says that the ylic acid. Glavin is excited that long-chain compound is unlikely to have come from organics can survive in spite of the oxidizing Earth. Fatty acids from biological sources, compounds and UV-rich sunlight. “The fact like technicians’ fingerprints, Cody says, that we see something long means this could tend to have 14, 16, or 18 carbon atoms, not be a good location for 10. Also, if the contamipreservation,” he says. nation were something Other scientists wonlike residual machine der if the compounds oil, smaller chain orcould signify something ganic compounds would more than just good have been detected odds for preservation. In in the background— the case of the 10-carbon molecules that Curiosity fatty acid–like compound, does not see. “You’re talking about The Curiosity team cellular-wall material,” has yet to use any of the says Marc Fries, a curaseven MTBSTFA thimtion scientist at NASA’s Drill hole from the Cumberland site, in bles, or two with another Astromaterials Acquisirock that was an ancient lakebed. type of solvent. Glavin tion and Curation Office says the team is saving at Johnson Space Center in Houston, Texas. them for promising rock formations farther “That’s a potential biogenic molecule.” But up the mountain that Curiosity is now climbit could also be a contaminant, he cautions. ing: clay mineral–bearing deposits that, like Fries notes that a 2014 study by scientists at the Cumberland mudstone, probably formed the Jet Propulsion Laboratory in Pasadena, in water and could be a good location for California, where the rover was assembled, preserving organics. Mahaffy hopes to get a warned that Curiosity could harbor traces of chance to test one of his thimbles soon—and carboxylic acids, which are found in plant and hopes to find even more-tantalizing organic animal oils as well as synthetic lubricants. molecules. “There’s a lot of interesting sites But Glavin points out that six batches of coming along,” he says. ■
‘Fixed’ nitrogen found in martian soil By Eric Hand
PHOTO: NASA/JPL-CALTECH/MSSS
O
rganic compounds aren’t the only molecules of life on Earth: Inorganic NO3bearing 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 rover’s 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. Mars’s atmosphere is now just 2% nitrogen (N2), but scientists suspect that it abounded in nitrogen in the past—just as Earth’s atmosphere does today. On Earth, microbes—especially bacteria living in the nodules of legume plants— do the hard work of breaking N2’s triple bonds and turning it into nitrate that can be “fixed” 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 Mars’s ancient past. “In a way, it provides what fertilizer would provide,” says Jennifer Stern, a planetary geochemist at Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. “It’s another support for habitability.” ■
SCIENCE sciencemag.org
CHEMICAL REGULATION
Reform of toxics law is contentious Plan to rewrite 1976 law draws bipartisan support but harsh criticism By Puneet Kollipara
O
f the roughly 80,000 industrial chemicals in commerce in the United States, the Environmental Protection Agency (EPA) has substantially restricted the use of less than 10. That’s just one reason observers on all sides agree that the country’s longstanding chemical testing law is broken. Last week, a U.S. Senate committee set out to fix it, launching what is expected to be a long, contentious effort to rewrite the 1976 Toxic Substances Control Act (TSCA). “There has never been a bipartisan effort with this much potential,” said Senator Tom Udall (D–NM) at an 18 March hearing of the Senate environment committee on a bill (S. 697) that he and 19 other senators, Democratic and Republican, recently rolled out that would revamp the law. Groups that rarely agree share that goal: Environmentalists and regulators decry TSCA because it gives EPA so little clout, while some industry groups complain that TSCA’s flaws have led states to enact a patchwork of laws that complicate compliance. But coming up with a new law that can satisfy everyone won’t be easy. The legislation, co-sponsored by Senator David Vitter (R–LA), has drawn support from industry and the Environmental Defense Fund. Yet other environmental and public health groups, as well as some state officials, complain that Udall’s bill would sometimes prevent states from writing their own tough regulations, fail to adequately accelerate EPA’s efforts to screen potentially dangerous chemicals, and give industry too much voice in agency decisions. The bill “is worse than the current law. We can’t go there,” said Senator Barbara Boxer (D–CA), the top Democrat on the environment panel, at a 17 March press conference. She has offered an alternative bill that she argues would give EPA and state governments stronger oversight power. Nearly 40 years ago, lawmakers approved 27 MARCH 2015 • VOL 347 ISSUE 6229
Published by AAAS
1403
Downloaded from www.sciencemag.org on March 26, 2015
entist at Goddard, reported compounds that, martian soil went through the SAM instruin a preliminary analysis, were consistent ment before the Cumberland sample and with an eight-carbon molecule akin to a benought to have scrubbed the instrument of zoic acid, an 11-carbon alcohol-like molecule, residual contamination. And George Cody, and, most interesting of all, a 10-carbon mola geochemist at the Carnegie Institution for ecule that could be a fatty acid–like carboxScience in Washington, D.C., says that the ylic acid. Glavin is excited that long-chain compound is unlikely to have come from organics can survive in spite of the oxidizing Earth. Fatty acids from biological sources, compounds and UV-rich sunlight. “The fact like technicians’ fingerprints, Cody says, that we see something long means this could tend to have 14, 16, or 18 carbon atoms, not be a good location for 10. Also, if the contamipreservation,” he says. nation were something Other scientists wonlike residual machine der if the compounds oil, smaller chain orcould signify something ganic compounds would more than just good have been detected odds for preservation. In in the background— the case of the 10-carbon molecules that Curiosity fatty acid–like compound, does not see. “You’re talking about The Curiosity team cellular-wall material,” has yet to use any of the says Marc Fries, a curaseven MTBSTFA thimtion scientist at NASA’s Drill hole from the Cumberland site, in bles, or two with another Astromaterials Acquisirock that was an ancient lakebed. type of solvent. Glavin tion and Curation Office says the team is saving at Johnson Space Center in Houston, Texas. them for promising rock formations farther “That’s a potential biogenic molecule.” But up the mountain that Curiosity is now climbit could also be a contaminant, he cautions. ing: clay mineral–bearing deposits that, like Fries notes that a 2014 study by scientists at the Cumberland mudstone, probably formed the Jet Propulsion Laboratory in Pasadena, in water and could be a good location for California, where the rover was assembled, preserving organics. Mahaffy hopes to get a warned that Curiosity could harbor traces of chance to test one of his thimbles soon—and carboxylic acids, which are found in plant and hopes to find even more-tantalizing organic animal oils as well as synthetic lubricants. molecules. “There’s a lot of interesting sites But Glavin points out that six batches of coming along,” he says. ■
