More Light Shed On Possibility of Life On Mars

More Light Shed On Possibility of Life On Mars

STONY BROOK, NY, December 9, 2013 – Humankind is by nature inquisitive, especially about the prospect of life on other planets and whether or not we are alone. The aptly named Curiosity, a NASA Mars rover, has been scouring that planet’s surface as a potential habitat for life, either past or present. Stony Brook Department of Geosciences professors Scott McLennan and Joel Hurowitz just revealed some exciting findings, as lead and co-authors of six papers that appeared in the December 9 online issue of Science.

Self portrait of "Curiosity," a NASA Mars rover, taken on the outcrops that are being published in the Dec. 9, 2013 online edition of the journal "Science." The rover landed on August 5, 2012 in Gale Crater on Mars on a two-year primary mission. Photo Credit  NASA/JPL-Caltech/MSSS

Self portrait of “Curiosity,” a NASA Mars rover, taken on the outcrops that are being published in the Dec. 9, 2013 online edition of the journal “Science.” The rover landed on August 5, 2012 in Gale Crater on Mars on a two-year primary mission.
Photo Credit NASA/JPL-Caltech/MSSS

“We have determined that the rocks preserved there represent an ancient geological environment that was habitable for microbial life,” says McLennan, who was selected as a Participating Scientist for the NASA Mars Science Laboratory rover mission. Adds Hurowitz, “Curiosity carried out the work in an area on Mars called Yellowknife Bay, within Gale crater. The rover fully characterized this environment in terms of its geological and geochemical relationships.”

This meticulous representation is crucial to understanding whether Mars was theoretically habitable. A major model of Martian history posits that the planet had fresh water to generate clay minerals—and possibly support life—more than 4 billion years ago, but experienced a drying phenomenon that changed the conditions to more acidic and briny. A key question about the clay minerals at Yellowknife Bay was whether they formed early in Martian history—up on the crater rim where the bits of rock originated—or later, down where the bits were carried by flowing water and deposited.

Professor McLennan and his co-authors determined that the chemical elements in the rocks indicate the particles were carried by rivers into Yellowknife Bay without experiencing much chemical weathering until sometime after they were deposited. If the weathering that turns some volcanic minerals into clay minerals had happened in the source regions where the sedimentary particles were generated, a loss of elements that readily dissolve in water—especially calcium and sodium—would be expected. The evidence indicates that did not occur, and that much of the geochemical “action” took place late in the history of the rocks found in Yellowknife Bay.

The clay-bearing Yellowknife Bay habitat, thought to be an ancient lakebed, consisted of water that was neither too acidic nor too salty, and had the right mix of elements to be an energy source for life. The energy source would have been similar to that used by many primitive rock-eating microbes on Earth—a mixture of sulfur- and iron-bearing minerals of the type that allow for the ready transfer of electrons, not unlike a simple battery.

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Joel A. Hurowitz, Research Associate Professor in the Department of Geosciences at Stony Brook University.

“This demonstrates that the geological environments on early Mars were conducive for life,” McLennan says. “It justifies further investigations to determine if life actually existed on Mars. The age of these rocks is perhaps a little younger than thought was likely to contain such environments. This means that the current paradigm for the evolution of surface conditions on Mars may require some reinterpretation.”

The Mars Science Laboratory mission is part of NASA’s Mars Exploration Program for long-term robotic exploration of the red planet. The rover landed on August 5, 2012 in Gale Crater on Mars on a two-year primary mission. The four central objectives are to assess biological potential, characterize the geology of the landing region, investigate planetary processes that are relevant to past habitability—including the role of water, and describe the broad spectrum of surface radiation.

The record of the climate and geology of Mars is contained in the rock and soil formations, structure, and chemical composition. Curiosity scoops samples from the soil, drills them from rocks, and observes the geological and radiation environment around the rover. Its onboard laboratory ingests and analyzes the samples in an attempt to detect the chemical building blocks of life—especially different forms of carbon—and assess what the Martian surface environment was like in the past.

Hurowitz marvels at the remarkable state of preservation of these rocks, despite their great antiquity. “Finding ancient sedimentary rock that hasn’t been ‘chewed to pieces’ is exceedingly difficult to do on Earth,” he says. “But such rocks appear to be commonplace on Mars, making it an excellent target for understanding the early history of watery terrestrial planets in our Solar System and beyond.”

Curiosity is currently traversing over 5 miles from Yellowknife Bay to the base of Mount Sharp in the center of Gale crater, which has always been the prime target for the mission. “It is expected to arrive sometime in 2014, when it will begin the exploration of this 5 km high mountain that consists of layered rocks,” Hurowitz says.

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Scott M. McLennan, Professor in the Department of Geosciences at Stony Brook University

During the first three months of the landed mission, Professors McLennan and Hurowitz worked out of the Jet Propulsion Laboratory in Pasadena, CA, where the science and engineering team operated the rover on “Mars time,” because a Martian day, or “sol,” is approximately 40 minutes longer than an Earth day. McLennan’s role is both as Participating Scientist and, operationally, as a Long Term Planning Lead.

Research Associate Professor Hurowitz is a Mars Science Laboratory Co-Investigator and also a Long Term Planning Lead. Hurowitz, co-author on all but one of the papers published in Science, was selected to be on the panel at the December 9 press conference—coordinated by the Jet Propulsion Laboratory and NASA, and held at the American Geophysical Union conference in San Francisco—where the findings were announced.

Both Hurowitz and McLennan are also science team members for the Mars Exploration Rovers Spirit and Opportunity that landed on Mars in 2004. Contact with the Spirit rover was lost in 2010, but Opportunity is still fit and currently exploring Endeavour Crater on the Meridiani Plains, over 5,000 miles to the west of where Curiosity is operating.

Their work highlights the fact that Stony Brook faculty working in the planetary sciences—Professors McLennan and Hurowitz working with Curiosity, and others such as Tim Glotch (planetary geology, remote sensing, Martian surface mineralogy), Deanne Rogers (planetary geology, remote sensing), and Hanna Nekvasil (planetary crustal evolution on Mars, Earth and the Moon)—are at the cutting edge of planetary science research, evaluating data returned from missions to Mars and the Moon and performing research in the laboratory.

Their research is also crucial for the openings it offers to eager researchers on the Stony Brook campus. Says McLennan, “This work provides unique opportunities for Stony Brook students and post-docs to be involved in such crucial planetary science undertakings.”

 

http://www.stonybrook.edu/content/first-papers-curiosity.html

Abstract: http://www.sciencemag.org/cgi/content/abstract/science.1244734?ijkey=Fl8TZW7wu5t4k&keytype=ref&siteid=sci

Reprint: http://www.sciencemag.org/cgi/rapidpdf/science.1244734?ijkey=Fl8TZW7wu5t4k&keytype=ref&siteid=sci
Editors note: Original article can be found here. 

 

Too much of a good thing? How drinking too much water can kill

Too much of a good thing? How drinking too much water can kill

DAVID BENTLEY, THE UNIVERSITY OF ADELAIDE

“The low risk of suffering from hyponatremia by eliminating water intake is far outweighed by the gains of improving exercise performance by drinking the correct amount of water, regularly.”
Image: Geber86/iStockphoto


FRIDAY, 28 SEPTEMBER 2012

Drinking enough water is very important during long periods of physical activity or recreational pursuits. But there are rare instances when too much fluid intake can be harmful, and even lead to death.
Earlier this week, the ABC reported on the unfortunate death of a bushwalker in Tasmania’s north western ranges. The coroner’s report said the most likely cause of death was an “exercise-related medical condition caused by drinking too much water during prolonged exertion.”

This condition is known as hyponatremia, which quite literally means low (hypo), sodium in the blood (natremia). Hyponatremia is relatively common among people with certain disease conditions and among athletes, such as marathon runners. But it’s very important to recognise that harm and risk of death due to hyponatremia are very low.
Sodium (Na) is an important nutrient obtained from a normal diet. Sodium levels in the body are impacted by the intake of salt, which is contained in a variety of common foods. It’s unlikely that the bushwalker died because of low dietary intake of sodium because only a small amount is required for our body to function, even during exercise. Indeed, scientific reports indicate that marathon runners diagnosed with hyponatremia don’t have low sodium levels in their blood.

The coroner’s report outlined that the deceased bushwalker had a swollen brain (cerebral edema), which in his opinion was due excessive water intake. But how can water lead to death due to hyponatremia?
Excessive or low water intake and excessive or low sodium intake can initiate a series of hormonal reactions largely mediated by the antidiuretic hormone. These reactions lead to either retention of water or its elimination from the body through urine. This process maintains a normal level of fluid and blood volume in our body.

A dramatic increase in water ingestion leads to a so-called “water intake overload”, which may be associated with a decrease in the volume of circulating blood, even though total body fluid volume is greater. This can, in turn, lead to abnormal accumulation of fluid in the body or edema (swollen brain). Decreased blood volume stimulates the release of the antidiuretic hormone, which leads to further water retention and a worsening of the condition.
Blood pressure is an important way of regulating oxygen delivery to all of the body, including the muscles and brain. And oxygen is important for keeping our muscles moving during exercise. The oxygen supply to the brain influences decision-making processes and cognitive functioning. Irregular blood pressure can lead to low oxygen levels. When combined with cerebral edema (as suggested by the coroner’s report), this can lead to confusion, disorientation, and unconsciousness.

While common in pathological states, hyponatremia occurs less frequently in healthy exercising adults. There are reports of marathon runners having hyponatremia but in nearly all cases, the condition can be treated and dangerous situations avoided.
The low risk of suffering from hyponatremia by eliminating water intake is far outweighed by the gains of improving exercise performance by drinking the correct amount of water, regularly. The recommended intake of fluid is generally small – in the range of 150ml to 200ml for every 15 to 20 minutes of exercise.
Exercising adults should know about effective fluid and dietary intake before and during sport or exercise. While these are influenced by severity (walking versus running), duration and environmental conditions (hot or cold, dry or humid) of exercise, the simple recommendation for avoiding fatigue (due to dehydration) as well as hyponatremia, is for people who are exercising to drink according to thirst, that is, before, during and after exercise.
Editor’s Note: This article was originally published by The Conversation, here, and is licenced as Public Domain under Creative Commons. See Creative Commons – Attribution Licence.