WATER WORLD MARS

FROM:  LOS ALAMOS NATIONAL LABORATORY
Water for Future Mars Astronauts?

Diversity of Martian soils leaves Los Alamos scientists thirsty for more

LOS ALAMOS, N.M., Sept. 26, 2013—Within its first three months on Mars, NASA’s Curiosity Rover saw a surprising diversity of soils and sediments along a half-kilometer route that tell a complex story about the gradual desiccation of the Red Planet.

Perhaps most notable among findings from the ChemCam team is that all of the dust and fine soil contains small amounts of water.

“We made this discovery literally with the very first laser shot on the Red Planet,” said Roger Wiens, leader of the ChemCam instrument team. “Every single time we shot at dust we saw a significant hydrogen peak.”

In a series of five papers covering the rover’s top discoveries during its first three months on Mars that appear today in the journal Science, Los Alamos researchers using the rover’s ChemCam instrument team up with an international cadre of scientists affiliated with the CheMin, APXS, and SAM instruments to describe the planet’s seemingly once-volcanic and aquatic history.

Researchers believed the hydrogen seen in the dust was coming from water, a hypothesis that was later corroborated by Curiosity’s SAM instrument, which indicated that all of the soil encountered on Mars contains between 1.5 and 3 percent water. This quantity is enough to explain much of the near-equatorial hydrogen observed beginning in 2001 by Los Alamos’s neutron spectrometer on board the Mars Odyssey spacecraft.

ChemCam also showed that the soils consist of two distinct components. In addition to extremely fine-grained particles that seem to be representative of the ubiquitous Martian dust covering the entire planet’s surface like the fine film that collects on the undisturbed surfaces of a long-abandoned home, the ChemCam team discovered coarser-grained particles up to one millimeter in size that reflected the composition of local rocks. In essence, ChemCam observed the process of rocks being ground down to soil over time.

The ChemCam instrument—which vaporizes material with a high-powered laser and reads the resultant plasma with a spectrometer—has shown a similar composition to fine-grained dust characterized on other parts of the planet during previous Martian missions. ChemCam tested more than 100 targets in a location named Rocknest and found that the dust contained consistent amounts of water regardless of the sampling area.

What’s more, the Rover dug into the soils at Rocknest to provide scientists with the opportunity to sample the newly unearthed portion over the course of several Martian days. The instrument measured roughly the same tiny concentration of water (about 2 percent) in the surface soils as it did in the freshly uncovered soil, and the newly excavated area did not dry out over time—as would be expected if moist subsurface material were uncovered.

The water signature seen by Curiosity in the ubiquitous Martian dust may coincide with the tiny amount of ambient humidity in the planet’s arid atmosphere. Multiple observations indicate that the flowing water responsible for shaping and moving the rounded pebbles encountered in the vicinity of the rover landing area has long since been lost to space, though some of it may still exist deep below the surface of the planet at equatorial locations (water ice is known to exist near the surface at the poles).

Despite the seemingly small measurements of water in the Martian environment, the findings nevertheless are exciting.

“In principle it would be possible for future astronauts to heat the soil to derive water to sustain them,” said Wiens.

While at Rocknest, scientists were also able to test samples that had been characterized by ChemCam with two other instruments aboard the rover: CheMin, a miniaturized apparatus partially developed at Los Alamos that uses X-rays to determine the composition of materials; and SAM, a tiny oven that melts samples and identifies the composition of gases given off by them. The analyses by all three instruments indicate that Mars likely has a volcanic history that shaped the surface of the planet.

A fourth instrument, the Alpha Particle X-ray Spectrometer (APXS), provides additional insights into the volcanic diversity on Mars. APXS analyzed a rock called Jake Matijevic—named in honor of a deceased Jet Propulsion Laboratory Mars engineer—and found that it is one of the most Earth-like rocks yet seen on the Red Planet. The rock’s enrichment in sodium, giving it a feldspar-rich mineral content, makes it very similar to some rocks erupted on ocean islands on Earth. ChemCam contributed to the characterization of Jake_M.

The Curiosity Rover is scheduled to explore Mars for another year at least. In the coming months, Curiosity will travel to Mount Sharp, a towering peak nearly three miles in elevation. Mount Sharp appears to contain layers of sedimentary history dating back several billion years. These layers are like pages of a book that could teach researchers much about the geologic and climate history of the Red Planet.

SCIENTISTS FIND THE DESTINATION OF CHARCOAL

At NSF's Florida Coastal Everglades LTER site, charcoal is part of the dissolved organic carbon. Credit: Wikimedia Commons

 

FROM: NATIONAL SCIENCE FOUNDATION
Where Does Charcoal, or Black Carbon, in Soils Go?
Scientists have uncovered one of nature's long-kept secrets--the true fate of charcoal in the world's soils.

The ability to determine the fate of charcoal is critical to knowledge of the global carbon budget, which in turn can help understand and mitigate climate change.

However, until now, researchers only had scientific guesses about what happens to charcoal once it's incorporated into soil. They believed it stayed there.

Surprisingly, most of these researchers were wrong.

The findings of a new study that examines the result of charcoal once it is deposited into the soil are outlined in a paper published this week in the journal Science.

The international team of researchers was led by scientists Rudolf Jaffe of Florida International University and Thorsten Dittmar of the German Max Planck Society.

"Most scientists thought charcoal was resistant," says Jaffe. "They believed that once it was incorporated into soils, it stayed there. But if that were the case, soils would be black."

Charcoal, or black carbon, is a residue generated by combustion including wildfires and the burning of fossil fuels.

When charcoal forms, it is usually deposited into the soil.

"From a chemical perspective, no one really thought it dissolved, but it does," Jaffe says.

"It doesn't accumulate for a long time. It's exported into wetlands and rivers, eventually making its way to the oceans."

It all started with a strange finding in the Everglades.

At the National Science Foundation (NSF) Florida Coastal Everglades Long-Term Ecological Research (LTER) site--one of 26 such NSF LTER sites in ecosystems around the world--Jaffe studied the glades' environmental chemistry.

Dissolved organic carbon is known to be abundant in wetlands such as the Everglades and plays a critical role in the ecology of these systems.

Jaffe wanted to learn more about what comprised the organic carbon in the Everglades.

He and colleagues discovered that as much as 20 percent of the total dissolved organic carbon in the Everglades is charcoal.

Surprised by the finding, the researchers shifted their focus to the origin of the dissolved charcoal.

In an almost serendipitous scientific journey, Dittmar, head of the Max Planck Research Group for Marine Geochemistry at the University Oldenburg in Germany, was also tracing the paths of charcoal, but from an oceanographic perspective.

To map out a more comprehensive picture, the researchers joined forces. Their conclusion is that charcoal in soils is making its way into the world's waters.

"This study affirms the power of large-scale analyses made possible through international collaborations," says Saran Twombly, program director in NSF's Division of Environmental Biology, which funded the research along with NSF's Directorate for Geosciences.

"What started out as a puzzling result from the Florida Everglades engaged scientists at other LTER sites in the U.S., and eventually expanded worldwide," says Twombly. "The result is a major contribution to our understanding of the carbon cycle."

Fire is probably an integral part of the global carbon cycle, says Dittmar, its effects seen from land to sea.

The discovery carries significant implications for bioengineering, the scientists believe.

The global carbon budget is a balancing act between sources that produce carbon and sources that remove it.

The new findings show that the amount of dissolved charcoal transported to the oceans is keeping pace with the total charcoal generated by fires annually on a global scale.

While the environmental consequences of the accumulation of black carbon in surface and ocean waters are currently unknown, Jaffe said the findings mean that greater consideration should be given to carbon sequestration techniques.

Biochar addition to soils is one such technique.

Biochar technology is based on vegetation-derived charcoal that is added to agricultural soils as a means of sequestering carbon.

As more people implement biochar technology, says Jaffe, they should take into consideration the potential dissolution of the charcoal to ensure that these techniques are environmentally friendly.

Jaffe and Dittmar agree that there are still many unknowns when it comes to the environmental fate of charcoal, and both plan to move on to the next phase of the research.

They've proved where charcoal goes.

Now they'd like to answer how that happens, and what the environmental consequences are.

The more scientists can understand the process and the environmental factors controlling it, says Jaffe, the better the chances of developing strategies for carbon sequestration and mitigating climate change.

The research was also conducted at NSF's Bonanza Creek; Konza Prairie; Hubbard Brook; Coweeta; and Georgia Coastal Ecosystems LTER sites, and at other locations around the world.

Other authors of the paper are: Yan Ding of Florida International University; Jutta Niggemann of the Max Planck Research Group for Marine Geochemistry; Anssi Vahatalo of the University of Helsinki; Aron Stubbins of the Skidaway Institute of Oceanography in Savannah, Georgia; Robert Spencer of the Woods Hole Research Center in Massachusetts; and John Campbell of the USDA Forest Service.

-NSF-