Posted on by Nancy Atkinson

Mars ‘Hide and Seek’ Ice Cap Affected by Winds and Water

Mars northern polar ice cap. Credit: ESA

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Mars has permanent ice caps at both poles composed mostly of solid carbon dioxide, and mysteriously, a large portion of the northern cap disappears early in the northern Martian spring followed later by its sudden reappearance. Scientists may have solved this mystery, saying that strong winds and Mars’ active water cycle may play a part in ‘come and go’ polar cap.

Earlier this year, another group of scientists from the University of Texas found that so-called katabatic winds — a wind that carries high density air from a higher elevation down a slope under the force of gravity – were responsible for the formation of giant swirls or troughs in the northern polar cap, as well as a huge chasm that is also visible. Those winds may also play a part in the regeneration of the ice cap.

Seasonal ice deposits play a major role in the water cycle of the planet. Every Martian year, alternatively during northern and southern winter, a significant part of the atmosphere condenses on the surface in the form of frost and snow. These seasonal ice deposits, which can be up to one meter thick, are mainly composed of carbon dioxide with minor amounts of water and dust. During spring, the deposits sublimate becoming a substantial source of water vapor, in particular in the northern hemisphere of the planet.

Sudden reappearance of the carbon dioxide ice signature between 'solar longitudes' 59.2 degrees and 60.2 degrees (which corresponds to a time lapse of approximately two Martian days) in the spiral troughs structure of the North polar cap. Credit: ESA

Dr. Bernard Schmitt and Mr. Thomas Appéré analyzed data taken with the OMEGA instrument on board ESA’s Mars Express, honing in on two northern Martian regions. Before the Mars Express mission, scientists monitored the evolution of the seasonal deposits by looking at the albedo (reflectivity) and temperature changes of the surface, as the ice deposits appear much brighter and are colder than the surrounding defrosted terrains.

The first Martian region that the scientists observed is located on Gemina Lingula, a Northern plateau, where a peculiar evolution of the carbon dioxide ice deposits was observed.

“During spring the ice signature disappeared from our data, but the surface temperature was still cold enough to sustain plenty of CO2 ice,” said Schmitt. “We concluded that a thick layer of something else, either dust or water ice was overlaid. If it was dust then it would also hide water ice and the surface of the planet would become darker. None of these happened so we concluded that a layer of water ice was hiding the CO2 ice. We had to wait until the weather gets warm enough on Mars for the water to vaporize as well, and then the carbon dioxide signatures re-appeared in our data.”

Soon after spring sunrise, the solar radiation hitting the surface of Mars warms enough the CO2 ice lying on the top layer to cause it to vaporize. But the water ice needs higher temperatures to sublimate, so a fine grained layer of water ice gradually forms hiding the carbon dioxide ice still lying beneath it.

“A layer only 2 tenths of a millimeter thick is enough to completely hide the CO2 ice. Also some water that has been vaporized at lower, warmer, Martian latitudes condenses as it moves northward and may be cold trapped on top of the CO2 ice,” said Appéré.

The second region analyzed by the team is located in the spiral troughs structure of the North permanent cap. A similar situation was observed but the carbon dioxide ice re-appeared very quickly here after its initial disappearance.

“This hide-and-seek game didn’t make much sense to us. It wasn’t cold enough for CO2 ice to condense again, neither warm enough for water ice to sublimate,” said Schmitt.

(a) Simulation of katabatic (downhill) winds. Colour bar: friction velocity from 0.1 to 0.6 m/s. (b) Localization of regions where early disappearances (blue) and sudden reappearances (orange) of the carbon dioxide ice signature are observed. Credit: ESA

“We concluded that somehow the water ice layer was removed,” said Appéré. “The topography of the North permanent Martian cap is well-suited to entail the formation of strong katabatic winds.”

Another scientist, Dr. Aymeric Spiga, used a model to simulate those winds and he indeed confirmed the sudden re-appearances of CO2 ice where strong katabatic winds blow.

This is just the first step in figuring out exactly how the polar cap disappears and reappears on Mars.

“To decipher the present and past water cycles on Mars and improve our weather models on the planet, one needs to have a good understanding of the seasonal ice deposits dynamics, how they change in space and time,” said Schmitt. “We are confident that our results will make a significant contribution in this direction.”

Source: European Planetary Science Congress

Posted on by Nancy Atkinson

Watch the Effects of Earthquakes Just Hours After They Occur

Princeton University has developed software that can produce realistic “movies” of earthquakes based on complex computer simulations, and these visualizations will be available on the internet within hours of a disastrous upheaval. For example, this video of a 5.7 scale Earthquake off the coast of Peru occurred yesterday, September 22, 2010. “In our view, this could truly change seismic science,” said Princeton’s Jeroen Tromp, a professor of geosciences and applied and computational mathematics, who led the effort. “The better we understand what happens during earthquakes, the better prepared we can be. In addition, advances in understanding seismic waves can aid basic science efforts, helping us understand the underlying physics at work in the Earth’s interior. These visualizations, we believe, will add greatly to the research effort.”

Continue reading “Watch the Effects of Earthquakes Just Hours After They Occur”

Posted on by Fraser Cain

Moved Servers… Again

Hey everyone, just to let you know that we’ve gone ahead and moved Universe Today to a whole new server: Amazon’s giant cloud server. Apparently “Publisher of Universe Today” means that I’m constantly scrambling to make the technical infrastructure function; I’m going to change my title to “Webmaster”. The previous solution just wasn’t working out, with this mysterious “no available nodes” error. The administration interface for posting stories was even more frustrating, often becoming unusable. So, we moved again – I’m hoping you didn’t even notice. But I think you’ll feel a tremendous speed boost.

As always, please drop me an email at [email protected] if you experience any problems or notice any bugs.

Fraser

Posted on by Nancy Atkinson

Lightning Storms on Venus Similar to Those On Earth

Artists impression of lightning storms on Venus. Credit: ESA

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Venus is a world not for the faint of heart. On its surface you’d have to endure high temperatures and intense air pressures, plus within the thick, sulfuric acid-laced atmosphere there are actually lightning storms. These storms are surprisingly similar to lightning storms on Earth, despite the great differences between the atmospheres of the two planets. “Venus and Earth are often called twin planets because of their similar size, mass, and interior structure,” said Dr. Christopher Russell from the University of California, who presented his findings at the European Planetary Science Congress in Rome this week. “The generation of lightning is one more way in which Venus and Earth are fraternal twins.”

Scientists have known there was lightning on Venus since the early planetary missions such as the Venera and Pioneer Venus Orbiter missions, and more recently the Galileo spacecraft reported evidence for optical and electromagnetic waves from Venus that could be produced by lightning. This was also confirmed by ground telescopes capturing lighting flashes at Venus.

Now, the Venus Express spacecraft, in orbit around Venus, has been studying Venus’ lightning in detail with its magnetometer, looking at the rates of discharge, the intensity and the spatial distribution in the magnetic field at altitudes between 200 and 500 km.

Russell said the Venus electromagnetic signals associated with lightning discharges are stronger than terrestrial signals in this frequency band because the background magnetic field is much weaker and the waves travel more slowly, but the electromagnetic energy flux is similar to that on Earth.

“Short strong pulses of the signals expected to be produced by lightning were seen almost immediately upon arrival at Venus, despite the generally unfavorable magnetic field orientation for entry of the signals into the Venus ionosphere at the altitude of the Venus Express measurements,” said Russell.

The observed electromagnetic waves are strongly guided by the Venusian magnetic field and they can only be detected by the spacecraft when the magnetic field tilts away from the horizontal by more than 15 degrees. This is quite unlike the situation on Earth, where the lightning signals are aided in their entry into the ionosphere by the nearly vertical magnetic field.

When clouds form, on Earth or Venus, the energy that the Sun has deposited in the air can be released in a very powerful electrical discharge. As cloud particles collide, they transfer electrical charge from large particles to small, and the large particles fall while the small particles are carried upward. The separation of charges leads to lightning strokes. This process is important for a planetary atmosphere because it raises the temperature and pressure of a small portion of the atmosphere to a very high value so that molecules can form, which would not otherwise occur at standard atmospheric temperatures and pressures. This is why some scientists have speculated that lightning may have helped life to arise on Earth.

“We have analyzed 3.5 Earth-years of Venus lightning data using the low-altitude Venus Express data, which is about 10 minutes per day,” Russell said. “By comparing the electromagnetic waves produced at the two planets, we found stronger magnetic signals on Venus, but when converted to energy flux we found very similar lightening strength,” said Russell. Also it seems that lightning is more prevalent on the dayside than at night, and happens more often at low Venusian latitudes where the solar input to the atmosphere is strongest.”

Source: European Planetary Science Congress

Posted on by Nancy Atkinson

Where In The Universe Challenge #119

Here’s this week’s image for the Where In The Universe Challenge, to test your visual knowledge of the cosmos. You know what to do: take a look at this image and see if you can determine where in the universe this image is from; give yourself extra points if you can name the instrument responsible for the image. We’ll provide the image today, but won’t reveal the answer until later this week. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.

UPDATE: Answer has been posted below.

This week’s WITU challenge image was a cropped version of an image I took in March 2010 of space shuttle Discovery during a midnight rollout to the launchpad. A unique silhouette shadow formed up in the clouds from the Xenon lights shining of the shuttle stack. The effect only lasted a short time, but I was able to capture it with my Fuji Finepix S2000. Here is the full image, below, which was featured on the popular Astronomy Picture of the Day website this week. I’m usually known for my words and not my pictures, so it was an honor to have an image I took posted on such a well-regarded website.

You can read the full story about how I captured the image on my personal blog, and see more images of the shadow, some of which I think might be better than this one, however the effect is more subtle.

You all made me feel very good that so many of you recognized this week’s WITU as my APOD image!

Full image of the silhouette shadow that formed on the clouds during Discovery's rollout in March 2010. Image: Nancy Atkinson
Posted on by Nancy Atkinson

Oppy’s New Meteorite Find (in 3-D!)

'Oileán Ruaidh' - the new rock found by the Opportunity rover. It could be another meteorite. Credit: NASA/JPL-Caltech/Cornell University. 3-D by Stuart Atkinson

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The Opportunity rover has done it again — found another strange-looking rock sitting on Meridiani Planum, and it looks like another meteorite. “The dark color, rounded texture and the way it is perched on the surface all make it look like an iron meteorite,” said Matt Golombek from the MER science team. Unofficially named “Oileán Ruaidh” (pronounced ay-lan ruah), which is the Gaelic name (translated: Red Island) for an island off the coast of northwestern Ireland. The rock is about the size of a toaster: 45 centimeters (18 inches) wide from the angle at which it was first seen. Stu Atkinson has posted some enhanced images of the rock on his website, Road to Endeavour, which I have nabbed and posted here. Thanks Stu! The 3-D version above looks awesome with the red/green glasses. And look for more detailed images of the rock on his site soon, as Opportunity comes in for a closer look. UPDATE: As promised, Stu has provided an enhanced close-up of this rock, below.

Close up of a rock on Mars, possibly another meteorite. Credit: NASA/JPL/Cornell, enhanced by Stu Atkinson

Here’s an extreme close-up of Oileán Ruaidh, and it certainly has that “iron meteorite” look about it. It almost looks like the head of a craggy old snapping turtle!

Opportunity's panoramic camera's view of a dark rock that may be an iron meteorite. Image Credit: NASA/JPL-Caltech/Cornell University, enhanced by Stuart Atkinson

Read more about the rock at JPL’s website.

Posted on by Jerry Coffey

What Is Water Made Of

Water
Water

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The answer to ‘what is water made of’ is as easy as you want it to be. Do you want to just do some superficial research or do you want to look a little deeper? Superficially, pure, distilled water is composed of 2 hydrogen atoms and 1 oxygen atom. If the sample of water is not ‘pure’, the composition of the sample can be different.

Salt water obviously contains salt, but it can contain many other trace elements. Fresh water from different sources will contain different elements and minerals. These come from the rocks the water washes over and the pollutants from farms and industry. The water that you drink will contain several additives used for purification plus the fluoride that is added for our health. Rain water will have any number of pollutants that have accumulated in the atmosphere.

At high temperatures and pressures, like those in the interior of giant planets, scientists think that water exists as ionic water in which the molecules break down into a soup of hydrogen and oxygen ions, and at even higher pressures as superionic water in which the oxygen crystallizes but the hydrogen ions float around freely within the oxygen lattice.

There are many interesting facts about water. Water is a tasteless, odorless liquid. The natural color of water and ice is slightly blue, although water appears colorless in small quantities. Ice also appears colorless, and water vapor is essentially invisible as a gas. Since the water molecule is not linear and the oxygen atom has a higher electronegativity than hydrogen atoms, water carries a slight negative charge. As a result, water has a electrical dipole moment. Water can form a large number of intermolecular hydrogen bonds(four). These factors lead to to water’s high surface tension and capillary forces. Water is often referred to as the universal solvent. All major cellular components are dissolved in water. Water is at its maximum density at 3.98°C. Oddly, it becomes less dense when it is cooled down to its solid form, ice. It expands to occupy 9% greater volume in this solid state, which accounts for the fact of ice floating on liquid water.

Water covers the majority of our planet and can be found in one form or another throughout the known universe. No matter where you are on Earth, water affects you in some way each day.

We have written many articles about water for Universe Today. Here’s an article about the density of water, and here’s an article about the water on Earth.

If you’d like more info on Water, check out NASA’s Water, Water, Everywhere!. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Source: Wikipedia

Posted on by Nancy Atkinson

Titan Weather Report for Spring: Still Cold, but Clearing Skies

Left: T43 flyby of Titan - 12 May 2008 – VIMS images a large cloud that caps the north pole of Titan (yellowish tones). Right: T63 flyby of Titan - 12 December 2009 – VIMS still observes a huge cloud system at 40°S (yellowish tones) and the north pole of Titan free of clouds, a few months after the equinox. Credit: NASA/JPL/University of Arizona/University of Nantes/ University of Paris Diderot

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The beauty of an extended space mission is that scientists can make long term observations and find out things we’ve never known before. The Cassini spacecraft’s Visual and Infrared Mapping Spectrometer (VIMS) instrument has been monitoring clouds on Titan continuously since the spacecraft went into orbit around Saturn in 2004, and a team led by Sébastien Rodriguez (AIM laboratory – Université Paris Diderot) has used more than 2,000 VIMS images to create the first long-term study of Titan’s weather. Are they ready to make a weather forecast? They say Titan’s northern hemisphere is set for mainly fine spring weather, with polar skies clearing since the equinox in August last year.

Together with Saturn in its 30-years orbit around the Sun, Titan has seasons that last for 7 terrestrial years. The team has observed significant atmospheric changes between July 2004 (early summer in the southern hemisphere) and April 2010, the very start of northern spring. The images showed that cloud activity has recently decreased near both of Titan’s poles. These regions had been heavily overcast during the late southern summer until 2008, a few months before the equinox.

“Over the past six years, we’ve found that clouds appear clustered in three distinct latitude regions of Titan: large clouds at the north pole, patchy cloud at the south pole and a narrow belt around 40 degrees south. However, we are now seeing evidence of a seasonal circulation turnover on Titan – the clouds at the south pole completely disappeared just before the equinox and the clouds in the north are thinning out. This agrees with predictions from models and we are expecting to see cloud activity reverse from one hemisphere to another in the coming decade as southern winter approaches,” said Dr Rodriguez.

Fractional cloud coverage in Titan’s atmosphere integrated between July 2004 and April 2010. Black areas are cloud free and yellow are fully covered. Credit: NASA/JPL/University of Arizona/University of Nantes/ University of Paris Diderot

The team has used results from the Global Climate Models (GCMs) developed by Pascal Rannou (Institut Pierre Simon Laplace) to interpret the evolution of the observed cloud patterns over time. Northern polar clouds of ethane form in the Titan’s troposphere during the winter at altitudes of 30-50 km by a constant influx of ethane and aerosols from the stratosphere. In the other hemisphere, mid- and high-latitudes clouds are produced by the upwelling from the surface of air enriched in methane. Observations of the location and activity of Titan’s clouds over long periods are vital in developing a global understanding of Titan’s climate and meteorological cycle.

In Feburary 2010, the Cassini mission was extended to a few months past Saturn’s northern summer solstice in May 2017. This means that Rodriguez and his team will be able to observe the seasonal changes right the way through from mid-winter to mid-summer in the northern hemisphere.

“We have learned a lot about Titan’s climate since Cassini arrived in at Saturn but there is still a great deal to learn. With the new mission extension, we will have the opportunity to answer some of the key questions about the meteorology of this fascinating moon,” said Rodriguez.

Rodriguez presented the results at the European Planetary Science Congress 2010 in Rome.

Source: European Planetary Science Conference

Posted on by Jon Voisey

Electric Resistance May Make Hot Jupiters Puffy

The Sun’s magnetic field

One of the surprises coming from the discoveries of the class of exoplanets known as “Hot Jupiters” is that they are puffed up beyond what would be expected from their temperature alone. The interpretation of these inflated radii is that extra energy must be being deposited in the regions of the atmosphere with large amounts of circulation. This extra energy would be deposited as heat, causing the atmosphere to expand. But from where was this extra energy coming? New research is suggesting that ionized winds passing through magnetic fields may create this process. Continue reading “Electric Resistance May Make Hot Jupiters Puffy”

Posted on by Nancy Atkinson

New Discovery at the Large Hadron Collider?

Image of a 7 TeV proton-proton collision in CMS producing more than 100 charged particles. Credit: CERN

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Scientists at the Large Hadron Collider reported today they apparently have discovered a previously unobserved phenomenon in proton-proton collisions. One of the detectors shows that the colliding particles appear to be intimately linked in a way not seen before in proton collisions. The correlations were observed between particles produced in 7 TeV collisions. “The new feature has appeared in our analysis around the middle of July,” physicist Guido Tonelli told fellow CERN scientists at a seminar to present the findings from the collider’s CMS (Compact Muon Solenoid) detector.

The scientists said the effect is subtle and they have performed several detailed crosschecks and studies to ensure that it is real. It bears some similarity to effects seen in the collisions of nuclei at the RHIC facility located at the US Brookhaven National Laboratory, which have been interpreted as being possibly due to the creation of hot dense matter formed in the collisions.

CMS studies the collisions by measuring angular correlations between the particles as they fly away from the point of impact.

The scientists stressed that there are several potential explanations to be considered and the they presented their news to the physics community at CERN today in hopes of “fostering a broader discussion on the subject.”

“Now we need more data to analyze fully what’s going on, and to take our first steps into the vast landscape of new physics we hope the LHC will open up,” said Tonelli.

Proton running at the Large Hadron Collider is scheduled to continue until the end of October, during which time CMS will accumulate much more data to analyze. After that, and for the remainder of 2010, the LHC will collide lead nuclei.

Source: CERN