(Press-News.org) CAMBRIDGE, Mass-- At first glance, Mars' clouds might easily be mistaken for those on Earth: Images of the Martian sky, taken by NASA's Opportunity rover, depict gauzy, high-altitude wisps, similar to our cirrus clouds. Given what scientists know about the Red Planet's atmosphere, these clouds likely consist of either carbon dioxide or water-based ice crystals. But it's difficult to know the precise conditions that give rise to such clouds without sampling directly from a Martian cloud.
Researchers at MIT have now done the next-best thing: They've recreated Mars-like conditions within a three-story-tall cloud chamber in Germany, adjusting the chamber's temperature and relative humidity to match conditions on Mars — essentially forming Martian clouds on Earth.
While the researchers were able to create clouds at the frigid temperatures typically found on Mars, they discovered that cloud formation in such conditions required adjusting the chamber's relative humidity to 190 percent — far greater than cloud formation requires on Earth. The finding should help improve conventional models of the Martian atmosphere, many of which assume that Martian clouds require humidity levels similar to those found on Earth.
"A lot of atmospheric models for Mars are very simple," says Dan Cziczo, the Victor P. Starr Associate Professor of Atmospheric Chemistry at MIT. "They have to make gross assumptions about how clouds form: As soon as it hits 100 percent humidity, boom, you get a cloud to form. But we found you need more to kick-start the process."
Cziczo says the group's experimental results will help to improve Martian climate models, as well as scientists' understanding of how the planet transports water through the atmosphere. He and his colleagues have reported their findings in Journal of Geophysical Research: Planets.
Seeding Martian clouds
The team conducted most of the study's experiments during the summer of 2012 in Karlsruhe, Germany, at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility — a former nuclear reactor that has since been converted into the world's largest cloud chamber.
The facility was originally designed to study atmospheric conditions on Earth. But Cziczo realized that with a little fine-tuning, the chamber could be adapted to simulate conditions on Mars. To do this, the team first pumped all the oxygen out of the chamber, and instead filled it with inert nitrogen or carbon dioxide — the most common components of the Martian atmosphere. They then created a dust storm, pumping in fine particles similar in size and composition to the mineral dust found on Mars. Much like on Earth, these particles act as cloud seeds around which water vapor can adhere to form cloud particles.
After "seeding" the chamber, the researchers adjusted the temperature, first setting it to the coldest temperatures at which clouds form on Earth (around minus 81 degrees Fahrenheit). Throughout the experiment, they cranked the temperature progressively lower, eventually stopping at the chamber's lowest setting, around minus 120 Fahrenheit — "a warm summer's day on Mars," Cziczo says.
By adjusting the chamber's relative humidity under each temperature condition, the researchers were able to create clouds under warmer, Earth-like temperatures, at expected relative humidities. These observations gave the researchers confidence in their experimental setup as they attempted to grow clouds at temperatures that approached Mars-like conditions.
Dialing the temperature down
Over a week, the group created 10 clouds, with each cloud taking about 15 minutes to form. The chamber is completed insulated, so the researchers used a system of lasers, which beam across the chamber, to detect cloud formation. Any clouds that form scatter laser light; this scattering is then detected and recorded by computers, which display the results — the size, number, and composition of cloud particles — for scientists outside the chamber.
By analyzing this data over the following six months, the researchers found that clouds that grew at the lowest temperatures required extremely high relative humidity in order for water vapor to form an ice crystal around a dust particle. Cziczo says it's unclear why Martian clouds need such humid conditions to take shape, but hopes to investigate the question further.
Toward that end, the group plans to return to Germany next fall, when the chamber will have undergone renovations, enabling it to perform cloud experiments at even lower temperatures — conditions that may more closely mimic the icy atmosphere on Mars.
"If we want to understand where water goes and how it's transported through the atmosphere on Mars, we have to understand cloud formation for that planet," Cziczo says. "Hopefully this will move us toward the right direction."
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PROVIDENCE, R.I. [Brown University] — Home-delivered meals bring not only food to seniors but also the opportunity to remain in their homes. A new study by Brown University public health researchers projects that if every U.S. state in the lower 48 expanded the number of seniors receiving meals by just 1 percent, 1,722 more Medicaid recipients avoid living in a nursing home and most states would experience a net annual savings from implementing the expansion.
Pennsylvania would see the greatest net savings – $5.7 million – as Medicaid costs for nursing home care dropped ...
LA JOLLA, CA—October 7, 2013—Chemists at The Scripps Research Institute (TSRI) have devised a new technique for connecting drug molecules to antibodies to make advanced therapies.
Antibody-drug conjugates, as they're called, are the basis of new therapies on the market that use the target-recognizing ability of antibodies to deliver drug payloads to specific cell types—for example, to deliver toxic chemotherapy drugs to cancer cells while sparing most healthy cells. The new technique allows drug developers to forge more stable conjugates than are possible with current ...
Philadelphia, PA, October 7, 2013 – The recognition of a causal link between mutations in BRCA1 and BRCA2 genes and increased risk of developing breast and ovarian cancer has intensified the demand for genetic testing. Identifying mutations in these large genes by conventional methods can be time consuming and costly. A report in the November issue of the Journal of Molecular Diagnostics describes a new technique using second-generation sequencing technology that is as sensitive as the standard methodology but has the potential to improve the efficiency and productivity ...
Scientists from the Wildlife Conservation Society and the Kenyan Marine and Fisheries Research Institute have achieved a milestone in Africa: they've helped build a better fish trap, one that keeps valuable fish in while letting undersized juvenile fish and non-target species out.
By modifying conventional African basket traps with escape gaps, the marine researchers have proven that the new traps catch larger fish, allow more undersized and non-target fish to escape, increase profits, and—most importantly—minimize the impact of fishing on coastal reef systems. The findings, ...
Researchers from the University of Illinois at Urbana-Champaign have developed a new approach with applications in materials development for energy capture and storage and for optoelectronic materials.
According to Charles Schroeder, an assistant professor in the Department of Chemical and Biomolecular Engineering, the results show that peptide precursor materials can be aligned and oriented during their assembly into polypeptides using tailored flows in microfluidic devices.
The research was a collaboration between the labs of Schroeder and William Wilson, a research ...
This news release is available in French. Researchers at the Sainte-Justine University Hospital Center and University of Montreal have discovered that the genomic signature inherited by today's 6 million French Canadians from the first 8,500 French settlers who colonized New France some 400 years ago has gone through an unparalleled change in human history, in a remarkably short timescale. This unique signature could serve as an ideal model to study the effect of demographic processes on human genetic diversity, including the identification of possibly damaging mutations ...
Relapses after treatment for Leishmania infection may be due to a greater infectivity of the parasite rather than drug resistance, as has been previously thought, according to a study published in mBio®, the online open-access journal of the American Society for Microbiology.
Visceral leishmaniasis, also called kala-azar, is a parasitic disease that strikes 400,000 people every year and kills around 1 in 10 of its victims. The disease has proven difficult to treat, in part because a large percentage of patients who take the drug of choice, miltefosine, relapse after treatment, ...
San Diego, CA, October 8, 2013 – A new study published in the American Journal of Preventive Medicine indicates that motor vehicle crashes can be hazardous for pregnant women, especially if they are not wearing a seat belt when the accident occurs.
Trauma is a leading cause of maternal and fetal morbidity and mortality. Blunt abdominal trauma is of particular concern to a pregnant woman and her fetus since it can directly and indirectly harm fetal organs as well as shared maternal and fetal organ systems. Car crashes are responsible for most injuries requiring hospitalization ...
WORCESTER, MA -- In a new study published by the American Journal of Preventive Medicine, UMass Medical School behavioral psychologist and weight loss expert Sherry Pagoto, PhD, and colleagues find that mobile apps to help people lose weight are lacking when it comes to strategies for changing behaviors.
"Apps do include evidence-based behavioral strategies, but only a narrow range," said Dr. Pagoto, associate professor of medicine at UMass Medical School. "Strategies that often were missing are ones that help patients with adherence and motivation."
In the study "Evidence-based ...
Brain training games, apps, and websites are popular and it's not hard to see why — who wouldn't want to give their mental abilities a boost? New research suggests that brain training programs might strengthen your ability to hold information in mind, but they won't bring any benefits to the kind of intelligence that helps you reason and solve problems.
The findings are published in Psychological Science, a journal of the Association for Psychological Science.
"It is hard to spend any time on the web and not see an ad for a website that promises to train your brain, ...
