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.
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
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."
Andrew Carleen | EurekAlert!
Water cooling for the Earth's crust
22.11.2017 | Helmholtz Centre for Ocean Research Kiel (GEOMAR)
Retreating permafrost coasts threaten the fragile Arctic environment
22.11.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy