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July 30, 2018 by Bill Steigerwald, NASA’s Goddard Space Flight Center
https://phys.org/news/2018-07-mars-terraforming-present-day-technology.html
Science fiction writers have long featured terraforming, the process of creating an Earth-like or habitable environment on another planet, in their stories. Scientists themselves have proposed terraforming to enable the long-term colonization of Mars. A solution common to both groups is to release carbon dioxide gas trapped in the Martian surface to thicken the atmosphere and act as a blanket to warm the planet.
However, Mars does not retain enough carbon dioxide that could practically be put back into the atmosphere to warm Mars, according to a new NASA-sponsored study. Transforming the inhospitable Martian environment into a place astronauts could explore without life support is not possible without technology well beyond today’s capabilities.
Although the current Martian atmosphere itself consists mostly of carbon dioxide, it is far too thin and cold to support liquid water, an essential ingredient for life. On Mars, the pressure of the atmosphere is less than one percent of the pressure of Earth’s atmosphere. Any liquid water on the surface would very quickly evaporate or freeze.
Proponents of terraforming Mars propose releasing gases from a variety of sources on the Red Planet to thicken the atmosphere and increase the temperature to the point where liquid water is stable on the surface. These gases are called “greenhouse gases” for their ability to trap heat and warm the climate.
“Carbon dioxide (CO2) and water vapor (H2O) are the only greenhouse gases that are likely to be present on Mars in sufficient abundance to provide any significant greenhouse warming,” said Bruce Jakosky of the University of Colorado, Boulder, lead author of the study appearing in Nature Astronomy July 30.
Although studies investigating the possibility of terraforming Mars have been made before, the new result takes advantage of about 20 years of additional spacecraft observations of Mars. “These data have provided substantial new information on the history of easily vaporized (volatile) materials like CO2 and H2O on the planet, the abundance of volatiles locked up on and below the surface, and the loss of gas from the atmosphere to space,” said co-author Christopher Edwards of Northern Arizona University, Flagstaff, Arizona.
The researchers analyzed the abundance of carbon-bearing minerals and the occurrence of CO2 in polar ice using data from NASA’s Mars Reconnaissance Orbiter and Mars Odyssey spacecraft, and used data on the loss of the Martian atmosphere to space by NASA’s MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft.
“Our results suggest that there is not enough CO2 remaining on Mars to provide significant greenhouse warming were the gas to be put into the atmosphere; in addition, most of the CO2 gas is not accessible and could not be readily mobilized. As a result, terraforming Mars is not possible using present-day technology,” said Jakosky.Although Mars has significant quantities of water ice that could be used to create water vapor, previous analyses show that water cannot provide significant warming by itself; temperatures do not allow enough water to persist as vapor without first having significant warming by CO2, according to the team. Also, while other gases such as the introduction of chloroflorocarbons or other fluorine-based compounds have been proposed to raise the atmospheric temperature, these gases are short-lived and would require large-scale manufacturing processes, so they were not considered in the current study.
The atmospheric pressure on Mars is around 0.6 percent of Earth’s. With Mars being further away from the Sun, researchers estimate a CO2 pressure similar to Earth’s total atmospheric pressure is needed to raise temperatures enough to allow for stable liquid water. The most accessible source is CO2 in the polar ice caps; it could be vaporized by spreading dust on it to absorb more solar radiation or by using explosives. However, vaporizing the ice caps would only contribute enough CO2 to double the Martian pressure to 1.2 percent of Earth’s, according to the new analysis.
Another source is CO2 attached to dust particles in Martian soil, which could be heated to release the gas. The researchers estimate that heating the soil could provide up to 4 percent of the needed pressure. A third source is carbon locked in mineral deposits. Using the recent NASA spacecraft observations of mineral deposits, the team estimates the most plausible amount will yield less than 5 percent of the required pressure, depending on how extensive deposits buried close to the surface may be. Just using the deposits near the surface would require extensive strip mining, and going after all the CO2 attached to dust particles would require strip mining the entire planet to a depth of around 100 yards. Even CO2 trapped in water-ice molecule structures, should such “clathrates” exist on Mars, would likely contribute less than 5 percent of the required pressure, according to the team.
Carbon-bearing minerals buried deep in the Martian crust might hold enough CO2 to reach the required pressure, but the extent of these deep deposits is unknown, not evidenced by orbital data, and recovering them with current technology is extremely energy intensive, requiring temperatures above 300 degrees Celsius (over 572 degrees Fahrenheit). Shallow carbon-bearing minerals are not sufficiently abundant to contribute significantly to greenhouse warming, and also require the same intense processing.
Although the surface of Mars is inhospitable to known forms of life today, features that resemble dry riverbeds and mineral deposits that only form in the presence of liquid water provide evidence that, in the distant past, the Martian climate supported liquid water at the surface. But solar radiation and solar wind can remove both water vapor and CO2 from the Martian atmosphere. Both MAVEN and the European Space Agency’s Mars Express missions indicate that the majority of Mars’ ancient, potentially habitable atmosphere has been lost to space, stripped away by solar wind and radiation. Of course, once this happens, that water and CO2 are gone forever. Even if this loss were prevented somehow, allowing the atmosphere to build up slowly from outgassing by geologic activity, current outgassing is extremely low; it would take about 10 million years just to double Mars’ current atmosphere, according to the team.
Another idea is to import volatiles by redirecting comets and asteroids to hit Mars. However, the team’s calculations reveal that many thousands would be required; again, not very practical.
Taken together, the results indicate that terraforming Mars cannot be done with currently available technology. Any such efforts have to be very far into the future.
More information: Bruce M. Jakosky et al. Inventory of CO2 available for terraforming Mars, Nature Astronomy (2018). DOI: 10.1038/s41550-018-0529-6
-http://dccomicsextendeduniverse.wikia.com/wiki/World_Engine-
The World Engine was an ancient piece of Kryptonian technology designed to terraform uninhabitable worlds into ones with identical atmospherics and topography of Krypton.
Female mice are immune to cognitive damage from space radiation
August 20, 2018 by Nicoletta Lanese, University of California, San Francisco
https://medicalxpress.com/news/2018-08-female-mice-immune-cognitive-space.html
Humankind still dreams of breaking from the bounds of Earth’s atmosphere and venturing to the moon, Mars and beyond. But once astronauts blast past the International Space Station, they become exposed to one of the many dangers of deep space: galactic cosmic radiation.
The effects of deep space radiation are difficult to study in humans, namely because the last people to blast beyond Earth’s magnetic field were Apollo astronauts. But scientists can simulate the extraterrestrial hazard in mice. Now, new NASA-funded research from UC San Francisco suggests that female space travelers may perhaps fare better than males in the face of cosmic radiation: while male mice show significant cognitive decline and brain structure changes when exposed to simulated cosmic radiation, female mice do not.
“We can see stark differences in the female responses, from behavioral read-outs down to the cellular and molecular level, when compared to the male counterparts,” said Karen Krukowski, Ph.D., postdoctoral researcher and first author of the new study. “We did not expect to see a difference – it was a bit surprising.”
The research – conducted in the lab of UCSF neuroscientist Susanna Rosi, Ph.D., and published online August 11, 2018 in Brain, Behavior and Immunity – raises new questions about why female mice are immune to the effects of cosmic radiation, and could lead to the development of treatments to protect human space travelers of both sexes, the authors say.
“Thanks to NASA, we are planning on doing further research to understand the specific mechanisms behind these profound differences,” said Rosi, professor of physical therapy and rehabilitation and of neurological surgery, and member of the UCSF Weill Institute for Neurosciences. “Based on recent evidence, we believe that cells known as microglia protect the female brain against insults such as deep space radiation. Understanding what makes these cells more resistant could be key to pinpointing specific treatments.”
NASA aims to launch a mission to Mars by 2030 and wants to prepare for potential obstacles their astronauts may encounter along the way. One danger lies just outside the protective bubble of our planet’s magnetic field, past the International Space Station bound in low Earth orbit. This celestial hazard is known as galactic cosmic radiation – high energy protons and charged nuclei that mainly come from outside our solar system and even from other galaxies. These particles can whiz straight through the hull of a spaceship, as well as any human housed inside, potentially causing serious health problems.
As humankind launches into deep space, it is essential that scientists understand how galactic cosmic radiation could impact future long-haul astronauts of both sexes – especially considering over forty percent of the most recent class of astronauts is female.
Prior studies of mice exposed to simplified simulations of isolated components of space radiation –such as protons or nuclei of helium, oxygen, titanium or silicon atoms – found that exposure to these highly-charged particles induces short- and long-term cognitive decline. But these studies were primarily conducted with male rodents.
“We wanted to understand if there are any sex differences in response to deep space exposure,” Rosi said.
By simply including both sexes in their study, the researchers learned that female mice are protected from the cognitive problems induced by space radiation in male mice. (The paper’s original title was “I am Woman, Watch Me Soar.”)
In the new work, researchers at the Brookhaven National Laboratory in New York exposed mice to a newly designed “GCR cocktail” – a combination of protons, helium and oxygen developed by Tamako Jones and Gregory Jones at Loma Linda University. Exposing mice to a mixture of particles better simulates conditions astronauts will experience in deep space.
Back at UCSF, scientists evaluated the irradiated animals’ sociability, social memory, anxiety-like behaviors and memory. Irradiated males interacted significantly less with other mice, had difficulty recognizing familiar mice and objects, and showed greater aversion to exploring open, well-lit spaces. But irradiated females behaved as if they had not encountered radiation at all.
Behavioral changes in the irradiated males corresponded to physical alterations in their brains. Most notably, microglia – resident immune cells of the brain and spinal cord – became very active following radiation. The boosted activity was measured in the hippocampus, a brain structure integral to learning and memory.
Corresponding with the observed microglial activation, the researchers found that the number of synaptic connections in the male hippocampus fell significantly. Landing docks for the excitatory neurotransmitter glutamate, which are known as AMPA receptors, were also greatly depleted in the hippocampus. Again, these changes were only seen in irradiated male mice – females were completely spared.
Microglia have both a “resting” and “active” state, and the active state often ignites inflammation in the surrounding tissue. Research suggests that female mice have more resting microglia than males, and in response to trauma, these microglia induce significantly less inflammation. Instead, female microglia appear to promote neuroprotective effects.
In a prior study, Rosi’s lab was able to “reset” microglia in the brains of male mice to a less inflammatory state and found that this prevented loss of cognitive functions, restoring memory function to levels similar to what is seen in unexposed animals. In that study, the researchers exposed the mice to a single highly-charged ion, then eliminated nearly all of their microglia using a drug that blocks a signal vital to microglial survival. After two weeks, the mice were taken off the drug, and their microglia levels naturally rebounded.
Months later, the animals were tested and were found to be protected from radiation-induced cognitive deficits. The research demonstrated that by resetting the immune system early on after radiation exposure it is possible to prevent long-term deficits.
Rosi’s lab is currently testing a more complex combination simulating galactic cosmic ray exposure to determine the differences between male and female microglia and whether resetting the immune system can prevent loss of cognitive function. Eventually, this research could lead to viable protective treatments for astronauts on the Mars voyage.
More information: Karen Krukowski et al. Female mice are protected from space radiation-induced maladaptive responses, Brain, Behavior, and Immunity (2018). DOI: 10.1016/j.bbi.2018.08.008
Journal reference: Brain, Behavior, and Immunity
Provided by: University of California, San Francisco
Mars likely to have enough oxygen to support life: study
October 22, 2018 by Marlowe Hood
https://phys.org/news/2018-10-mars-oxygen-life.html
Salty water just below the surface of Mars could hold enough oxygen to support the kind of microbial life that emerged and flourished on Earth billions of years ago, researchers reported Monday.
In some locations, the amount of oxygen available could even keep alive a primitive, multicellular animal such as a sponge, they reported in the journal Nature Geosciences.
“We discovered that brines”—water with high concentrations of salt—”on Mars can contain enough oxygen for microbes to breathe,” said lead author Vlada Stamenkovic, a theoretical physicist at the Jet Propulsion Laboratory in California.
“This fully revolutionises our understanding of the potential for life on Mars, today and in the past,” he told AFP.
Up to now, it had been assumed that the trace amounts of oxygen on Mars were insufficient to sustain even microbial life.
“We never thought that oxygen could play a role for life on Mars due to its rarity in the atmosphere, about 0.14 percent,” Stamenkovic said.
By comparison, the life-giving gas makes up 21 percent of the air we breathe.
On Earth, aerobic—that is, oxygen breathing—life forms evolved together with photosynthesis, which converts CO2 into O2. The gas played a critical role in the emergence of complex life, notable after the so-called Great Oxygenation Event some 2.35 billion years ago.
But our planet also harbours microbes—at the bottom of the ocean, in boiling hotsprings—that subsist in environments deprived of oxygen.
“That’s why—whenever we thought of life on Mars—we studied the potential for anaerobic life,” Stamenkovic.
The new study began with the discovery by NASA’s Curiosity Mars rover of manganese oxides, which are chemical compounds that can only be produced with a lot of oxygen.
Curiosity, along with Mars orbiters, also established the presence of brine deposits, with notable variations in the elements they contained.
A high salt content allows for water to remain liquid—a necessary condition for oxygen to be dissolved—at much lower temperatures, making brines a happy place for microbes.
Depending on the region, season and time of day, temperatures on the Red Planet can vary between minus 195 and 20 degrees Celsius (minus 319 to 68 degrees Fahrenheit).
The researchers devised a first model to describe how oxygen dissolves in salty water at temperatures below freezing.
A second model estimated climate changes on Mars over the last 20 million years, and over the next 10 million years.
Taken together, the calculations showed which regions on the Red Planet are most likely to produce brine-based oxygen, data that could help determine the placement of future probes.
“Oxygen concentrations [on Mars] are orders of magnitude”—several hundred times—”greater than needed by aerobic, or oxygen-breathing—microbes,” the study concluded.
“Our results do not imply that there is life on Mars,” Stamenkovic cautioned. “But they show that the Martian habitability is affected by the potential of dissolved oxygen.”
More information: Vlada Stamenković et al. O2 solubility in Martian near-surface environments and implications for aerobic life, Nature Geoscience (2018). DOI: 10.1038/s41561-018-0243-0
Journal reference: Nature Geoscience
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