Posted on by Fraser Cain

Volcanic Eruption

Strombolian eruption

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The ground beneath your feet feels cool, but you’re actually standing on a thin shell of crust around the much hotter mantle of the Earth. The mantle is under such pressure and temperature that rock squeezes out as a liquid and makes its way to the surface. When the magma reaches the surface, it’s called a volcanic eruption, and can spew out as lava, ash and even large volcanic rocks.

There are actually different kinds of volcanic eruptions, depending on the chemical nature of the magma itself.

The most powerful volcanic eruptions are known as Plinian eruptions, and they involved the explosion ejection of viscous (very thick) lava. A well known example of this is the eruption of Mount Saint Helens in 1980, or Pinatubo in the Philippines.

In a Strombolian eruption, clots of lava blast out of volcano caldera and make arcs through the sky before raining down around the volcano. The lava can continue to stream down the sides of the volcano like tiny rivers causing more damage.

In a Vulcanian eruption, a dense cloud of ash blasts out of the volcano and rises dozens of kilometers into the atmosphere above the peak.

In a Vesuvian eruption, the ash cloud doesn’t rise as high, and forms more of a cauliflower-shaped plume above the volcano peak. This type of volcanic eruption was named after Mount Vesuvius, which destroyed two Roman towns in 79 AD.

During a Pelean eruption, large quantities of ash, rock and dust are blasted out of a central crater and then travel down the slopes of the volcano and hundreds of kilometers per hour. These are one of the most dangerous kinds of volcanic eruptions, as they can lead to a tremendous loss of life to towns and villages near the volcano.

A Hawaiian eruption is when lava comes out of linear vents, and joins together to form streams and rivers of lava. The lava can even come out of the ground at such speed that it creates fountains that erupt for dozens of meters into the air.

Phreatic eruptions are also known as steam blast eruptions, and are caused by expanding steam beneath the ground created when water comes in contact with hot rock or magma.

We have written many articles about volcanoes for Universe Today. Here’s an article about different types of volcanoes, and here’s an article about different types of lava.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

References:
http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/volcanic_landforms/volcano_hazards.html
http://vulcan.wr.usgs.gov/Volcanoes/Italy/description_italy_volcanics.html

Posted on by Anne Minard

A Cold and Wet History on Early Mars?

Mars. Credit: NASA

 

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Even if an early Mars never got above freezing, the brine on its surface could have stayed liquid and supported life, a new study says.

Lead author Alberto G. Fairen, of NASA Ames Research Center in Moffett Field, California, and his colleagues have analyzed the behavior of Martian chemical concentrations found at various mission landing sites, and revealed that warm temperatures wouldn’t have been necessary to support salt-loving life forms.

The authors point out that many features on the Martian surface are believed to have been formed by flowing water and related mineral activity on the surface. Water is a key ingredient for life, but models were having a hard time envisioning a Mars warm enough to support it.

Much evidence has indicated surface temperatures well below freezing.

According to the new study, life may have fared all right anyway.

“Solutes could depress the melting point of water in a frozen Martian environment, providing a plausible solution to the early Mars climate paradox,” the authors write.

Fairen and his colleagues modeled the freezing and evaporation processes of Martian fluids with a composition resulting from the weathering of basalts, as reflected in the chemical compositions at Mars landing sites of Viking 1, Mars Pathfinder, and the rovers Spirit and Opportunity.

“Our results show that a significant fraction of weathering fluids loaded with Si, Fe, S, Mg, Ca, Cl, Na, K and Al remain in the liquid state at temperatures well below 273 K,” or nearly 32 degrees Fahrenheit (zero C), they write.

“This stability against freezing of Martian fluids can explain saline liquid water activity on the surface of Mars at mean global temperatures well below 273 K.”

Photo credit: NASA

Source: Nature

Posted on by Anne Minard

A Benevolent Sort of Asteroid Bombardment?

Celestial impacts can bring life as well as wipe it out, say the authors of a new study out of the University of Colorado at Boulder.

A case in point: the bombardment of Earth nearly 4 billion years ago by asteroids as large as Kansas would not have had the firepower to extinguish potential early life on the planet and may even have given it a boost.

In a new paper in the journal Nature, Oleg Abramov and Stephen Mojzsis report on their study of impact evidence from lunar samples, meteorites and the pockmarked surfaces of the inner planets. The evidence paints a picture of a violent environment in the solar system during the Hadean Eon 4.5 to 3.8 billion years ago, particularly through a cataclysmic event known as the Late Heavy Bombardment about 3.9 billion years ago.

Although many believe the bombardment would have sterilized Earth, the new study shows it would have melted only a fraction of Earth’s crust, and that microbes could well have survived in subsurface habitats, insulated from the destruction.

“These new results push back the possible beginnings of life on Earth to well before the bombardment period 3.9 billion years ago,” Abramov said. “It opens up the possibility that life emerged as far back as 4.4 billion years ago, about the time the first oceans are thought to have formed.”

Because physical evidence of Earth’s early bombardment has been erased by weathering and plate tectonics over the eons, the researchers used data from Apollo moon rocks, impact records from the moon, Mars and Mercury, and previous theoretical studies to build three-dimensional computer models that replicate the bombardment. Abramov and Mojzsis plugged in asteroid size, frequency and distribution estimates into their simulations to chart the damage to the Earth during the Late Heavy Bombardment, which is thought to have lasted for 20 million to 200 million years.

The 3-D models allowed Abramov and Mojzsis to monitor temperatures beneath individual craters to assess heating and cooling of the crust following large impacts in order to evaluate habitability. The study indicated that less than 25 percent of Earth’s crust would have melted during such a bombardment.

The CU-Boulder researchers even cranked up the intensity of the asteroid barrage in their simulations by 10-fold — an event that could have vaporized Earth’s oceans. “Even under the most extreme conditions we imposed, Earth would not have been completely sterilized by the bombardment,” said Abramov.

Instead, hydrothermal vents may have provided sanctuaries for extreme, heat-loving microbes known as “hyperthermophilic bacteria” following bombardments, said Mojzsis. Even if life had not emerged by 3.9 billion years ago, such underground havens could still have provided a “crucible” for life’s origin on Earth, Mojzsis said.

Geologic evidence suggests that life on Earth was present at least 3.83 billion years ago, said Mojzsis. “So it is not unreasonable to suggest there was life on Earth before 3.9 billion years ago. We know from the geochemical record that our planet was eminently habitable by that time, and this new study sews up a major problem in origins of life studies by sweeping away the necessity for multiple origins of life on Earth.”

The results also support the potential for microbial life on other planets like Mars and perhaps even rocky, Earth-like planets in other solar systems that may have been resurfaced by impacts, said Abramov.

Source: Eurekalert

Posted on by Tammy Plotner

Flying Saucers? The Fun Is For Real…


On a recent trip to Canada in the great province of Ontario, I found a quiet corner on Lundy’s Lane. I had been enjoying the scenic beauty of Niagara Falls and to break away for the tourist aspect seemed like a welcome respite. How could someone who lives, eats and breathes space 24/7 pass up an opportunity to visit a place like this? The answer was… I couldn’t.

flying_saucer_richard_weissFor any one old enough to remember and still too young to resist, the retro-styling and drive-in atmosphere of this super clean diner was enough to make you smile the moment you stopped in the parking lot. Glittering multi-colored lights and a welcoming glow was all I needed to take a chance. Once inside I was transported back to all of my childhood fantasies, and despite having a well stocked refreshment area – all you really wanted was a cold soda or a milk shake. Why spoil the fun?

menu0001When the menu came, my grin got even wider. There’s nothing that delights me more than a sense of humor… and to combine it with good food makes the experience even more extraordinary. Needless to say, I didn’t just stop by this place on a whim. I’d researched my restaurants in advance and every sample around the family table proved to be just as tasty and well prepared as the reviews promised. The “Jupiter Burgers” were absolutely among the finest I’ve ever eaten and the clam chowder didn’t come out of can, my friends. Even though the hour was late, I had a delightful time talking to the “natives” who were patient with my questions and seemed to enjoy the company as much as we enjoyed theirs!

Right down to the little stuffed aliens…

So what’s a less than serious piece about finding a flying saucer restaurant doing in a serious astronomical webpage like Universe Today? It’s to remind you to take a chance on what you love. If you love astronomy and having dinner in a restaurant shaped like a flying saucer looks like fun? Do it! You may end up in some remote corner of Iowa having the worst cup of coffee you’ve ever tasted… Or you might end up in a quiet corner of Niagara Falls surrounded by your laughing family enjoying diner food at it’s best.

Because the fun is what’s for real…

Thanks to Richard Weiss for the additional image!

Posted on by Anne Minard

New, Deep Image of Virgo Cluster Reveals Galaxy Cut Short in its Youth

Astronomers have peered deep inside the Virgo cluster, and measured the size of one of its most famous members — Messier 87 — with surprising results.

The giant elliptical galaxy isn’t quite as giant as previously believed.

This deep image of the Virgo Cluster, obtained by Chris Mihos of Case Western Reserve University and his colleagues using the university’s Burrell Schmidt telescope, shows the diffuse light between the galaxies belonging to the cluster. North is up, east to the left. The dark spots indicate where bright foreground stars were removed from the image.

At a distance of approximately 50 million light-years, the Virgo Cluster is the nearest galaxy cluster. It is located in the constellation of Virgo (the Virgin) and is a relatively young and sparse cluster. The cluster contains many hundreds of galaxies, including giant and massive elliptical galaxies, as well as more homely spirals like our own Milky Way.

Using ESO’s Very Large Telescope, astronomers have succeeded in measuring the size of giant galaxy Messier 87 and were surprised to find that its outer parts have been stripped away by still unknown effects. The galaxy also appears to be on a collision course with another giant galaxy in this very dynamic cluster.

The new observations reveal that Messier 87’s halo of stars has been cut short, with a diameter of about a million light-years, significantly smaller than expected, despite being about three times the extent of  the halo surrounding our Milky Way. Beyond this zone only few intergalactic stars are seen.

This research is presented in a paper to appear in Astronomy and Astrophysics: “The Edge of the M87 Halo and the Kinematics of the Diffuse Light in the Virgo Cluster Core,” led by Michelle Doherty at the Max-Planck-Institute for Extraterrestrial Physics in Garching, Germany.

“This is an unexpected result,” said study co-author Ortwin Gerhard. “Numerical models predict that the halo around Messier 87 should be several times larger than our observations have revealed. Clearly, something must have cut the halo off early on.”

The team used FLAMES, the super-efficient spectrograph at ESO’s Very Large Telescope at the Paranal Observatory in Chile, to make ultra-precise measurements of a host of planetary nebulae in the outskirts of Messier 87 and in the intergalactic space within the Virgo Cluster of galaxies, to which Messier 87 belongs. FLAMES can simultaneously take spectra many sources, spread over an area of the sky about the size of the Moon.

The observed light from a planetary nebula in the Virgo Cluster is as faint as that from a 30-Watt light bulb at a distance of about 6 million kilometres (about 15 times the Earth–Moon distance). Furthermore, planetary nebulae are thinly spread through the cluster, so even FLAMES’s wide field of view could only capture a few tens of nebulae at a time.

“It is a little bit like looking for a needle in a haystack, but in the dark,” said team member Magda Arnaboldi. “The FLAMES spectrograph on the VLT was the best instrument for the job.”

The astronomers have proposed several explanations for the discovered “cut-off” of Messier 87’s, such as collapse of dark matter nearby in the galaxy cluster. It might also be that another galaxy in the cluster, Messier 84, came much closer to Messier 87 in the past and dramatically perturbed it about a billion years ago. “At this stage, we can’t confirm any of these scenarios,” said Arnaboldi. “We will need observations of many more planetary nebulae around Messier 87.”

One thing the astronomers are sure about, however, is that Messier 87 and its neighbor Messier 86 are falling towards each other. “We may be observing them in the phase just before the first close pass,” said Gerhard. “The Virgo Cluster is still a very dynamic place and many things will continue to shape its galaxies over the next billion years.”

Source: ESO. A PDF version of the paper is available here. 

Posted on by Nancy Atkinson

New International Astronauts Introduced

Simonetta Di Pippo, center, with the new ESA astronauts. Credit: ESA

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ESA proudly presented today six new astronauts from five different European countries who will soon begin training for missions to the International Space Station. The last time ESA selected astronauts, back in the early 1990’s, those astronauts were not guaranteed to have any actual flights in space. But the astronauts introduced today, which include three military pilots, two engineers, and one scientist, are slated to be part of at least seven opportunities to fly on a 6-month increment on the ISS. Additionally, an ESA official said he also hopes they can be part of an international lunar exploration program.

“This is the culmination of a life- long dream,” said Andreas Mogensen, Denmark’s first-ever astronaut. “Your parents and teachers always tell you to dream big, and to follow your dream. But no one tells you what it is like to achieve that dream. I think we’re all in a stsate of shock, but we just have to enjoy the moment. I’m absolutely thrilled to be sitting here today.”

In addition to Mogensen, the other astronauts are:

Samantha Cristoforetti, Italy
Alexander Gerst, Germany
Luca Parmitano, Italy
Timothy Peake, UK
Thomas Pesquet, France

Bios and pictures of the new astronauts.

They were selected following a Europe-wide recruitment process that started last year, which saw 8,413 valid applications. They are the first new recruits to join the European Astronaut Corps since 1992 under this second-ever astronaut selection carried out by ESA.

The earliest any of the new astronauts could fly to space would be 2013, said ESA Director General Jean-Jacques Dordain. The new recruits will begin general astronaut training in September, which lasts for 18 months. After they receive flight assignments, astronauts then train for two years prior to flying in space.

“We are at a turning point in ESA’s human spaceflight activities. Last year, with the launch of the Columbus laboratory and the Jules Verne Automated Transfer Vehicle, ESA became a fully-fledged member of the International Space Station partnership. We are now entering a new phase of utilisation of the unique capabilities offered by the ISS and preparation for international exploration of the Moon and beyond,” said Dordain.

“This is a very important day for human spaceflight in Europe,” said Simonetta Di Pippo, ESA Director of Human Spaceflight. “These young men and women are the next generation of European space explorers. They have a fantastic career ahead, which will put them right on top of one of the ultimate challenges of our time: going back to the Moon and beyond as part of the global exploration effort.”

British journalists at the press conference expressed excitement but surprise that a UK citizen was chosen, as Britain does not contribute financially to ESA’s human spaceflight program. But Dourdain said that Peake’s qualifications stood out. “We took the best candidates, it didn’t matter which country they were from.”

Source: ESA, press conference

Posted on by Nancy Atkinson

Astronauts Release Hubble — Watch the Video


After five spacewalks on consecutive days to bring new life to the Hubble Space Telescope, astronauts on space shuttle Atlantis said goodbye to the venerable observatory, releasing it back to its orbital home. Watching it float out of the cargo bay was a bittersweet moment for everyone involved with the mission, and space enthusiasts, too, as even though Hubble is in great shape and now set to look out farther than ever before, this is that last time humans will visit, touch and care for the world’s most famous telescope. “It’s a sad moment but a great moment, because we put the Hubble in the best posture and and best performance in can be in,” said Jon Morse, NASA Astrophysics division director.
Continue reading “Astronauts Release Hubble — Watch the Video”

Posted on by Nancy Atkinson

Flying Carpets in Space: Yes. Folding Laundry: No

Japanese astronaut Koichi Wakata demonstrating a 'magical flying carpet' Photo: GETTY

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Astronauts in orbit have said it time and time again: some things are easier in the microgravity environment in space, other things are harder. Japanese astronaut Koichi Wakata, current resident of the International Space Station recently gave a video demonstration of a few odd tasks in space, showing how simple, everyday jobs here on Earth, such as folding laundry and using eye drops, can become difficult in space. But he also proved how one “impossible” action for us landlubbers is fairly simple to do on board the ISS. He soared on a magic carpet.

Wakata filmed 16 different tasks in space as part of a series of zero-gravity challenges submitted by the public.

Albeit, he couldn’t use just any carpet; it had to be magic. Or in this case, a carpet with a little rigidity worked the best, and he had one more secret to his success: adhesive tape (not sure if it was duct tape). Here’s the video clip of posted by the Japan Aerospace Exploration Agency (Jaxa).

Wakata is shown gliding smoothly, after a fashion, through a cabin of the International Space Station, as if snowboarding.

“I flew on this magic carpet by using adhesive tape so that the soles of my feet stayed on it,” the 45-year-old astronaut said. The tasks were selected from ideas sent to the space agency by hundreds of members of the Japanese public, from nursery school pupils to a 90-year-old man. Wakata performed the tasks in the Japanese laboratory Kibo (Hope) of the ISS on May 15. He also filmed a series of other tasks in April, including push-ups.

He handled the awkward task of folding laundry in microgravity, struggling with a shirt and then, for added difficulty, the floating arms and legs of a blue space overall. Finally, a bungee cord was necessary to keep the uncooperative overall from unfolding.

Tackling another challenge, Wakata showed how to use eye drops in zero gravity, squeezing out a tiny ball of liquid and letting it perch at the tip of the container before carefully bringing it to his eye.

Source: The Telegraph

Posted on by Nancy Atkinson

Cosmologists Improve on Standard Candles Measurement

The warm colors in this diagram stand for strong correlations of the brightness ratios between two wavelengths and a Type Ia supernova's absolute magnitude. (Diagram colors are unrelated to those in the spectrum itself.) Wavelengths are in nanometers. The upper left triangle shows correlations with uncorrected magnitudes; at lower right are correlations using color-corrected data. Credit: Nearby Supernova Factory

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Cosmologists have found a new and quicker technique that establishes the intrinsic brightness of Type Ia supernovae more accurately than ever before. These exploding stars are the best standard candles for measuring cosmic distances and are the tools that made the discovery of dark energy possible. An international team has found a way to do the job of measuring stellar distances in just a single night as opposed to months of observations by simply measuring the ratio of the flux (visible power, or brightness) between two specific regions in the spectrum of a Type Ia supernova. With this new method, a supernova’s distance can be determined to better than 6 percent uncertainty.

Using classic methods, which are based on a supernova’s color and the shape of its light curve – the time it takes to reach maximum brightness and then fade away – the distance to Type Ia supernovae can be measured with a typical uncertainty of 8 to 10 percent. But obtaining a light curve takes up to two months of high-precision observations. The new method provides better correction with a single night’s full spectrum, which can be scheduled based on a much less precise light curve.

Members of the international Nearby Supernova Factory (SNfactory), a collaboration among the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, a consortium of French laboratories, and Yale University, searched the spectra of 58 Type Ia supernovae in the SNfactory’s dataset and found the key spectroscopic ratio.

The new brightness-ratio correction appears to hold no matter what the supernova’s age or metallicity (mix of elements), its type of host galaxy, or how much it has been dimmed by intervening dust.

Team member Stephen Bailey from the Laboratory of Nuclear and High-Energy Physics (LPNHE) in Paris, France, says that the SNfactory’s library of high-quality spectra is what made his successful results possible. “Every supernova image the SNfactory takes is a full spectrum,” he says. “Our dataset is by far the world’s largest collection of excellent Type Ia time series, totaling some 2,500 spectra.”

The most accurate standardization factor Bailey found was the ratio between the 642-nanometer wavelength, in the red-orange part of the spectrum, and the 443-nanometer wavelength, in the blue-purple part of the spectrum. In his analysis he made no assumptions about the possible physical significance of the spectral features. Nevertheless he turned up multiple brightness ratios that were able to improve standardization over current methods applied to the same supernovae.

SNfactory member Rollin Thomas of Berkeley Lab’s Computational Research Division, who analyzes the physics of supernovae, says, “While the luminosity of a Type Ia supernova indeed depends on its physical features, it also depends on intervening dust. The 642/443 ratio somehow aligns those two factors, and it’s not the only ratio that does. It’s as if the supernova were telling us how to measure it.”

The Nearby Supernova Factory describes the discovery of the new standardization technique in an article in the forthcoming issue of the journal Astronomy & Astrophysics, and the abstract is available online.

Source: Berkeley

Posted on by Nancy Atkinson

Herschel Phones Home — Literally

ESA's 35-metre deep-space ground station at New Norcia, Australia. Credit: ESA

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For the first time in spaceflight history, a satellite has used mobile phone technology to radio back to Earth. The Herschel spacecraft – which launched on May 14, called home two days later using the same technology used in GSM mobile phone networks to send test data to ESA’s deep space tracking station. “Herschel’s 1.5-Mbps test transmission – roughly the same data rate provided by a home broadband Internet connection – was picked up at ESA’s ESTRACK station at New Norcia, Australia, on Saturday, as the satellite was travelling some 280 000 km from Earth,” said John Dodsworth, the Herschel-Planck Flight Operations Director.

This marks the first-ever use of Gaussian Minimum Shift Keying (GMSK) modulation in space. GMSK is commonly used in Global System for mobile Communication (GSM) mobile phone networks due to its very efficient use of bandwidth and power.

Plot showing Herschel's mobile phone call received at New Norcia station
Plot showing Herschel's mobile phone call received at New Norcia station

In a typical GSM mobile phone network, the same technology transmits data at a somewhat lower speed. The Planck spacecraft that was launched along with Herschel also uses GMSK technology, and its transmission capability will be tested later during the satellite’s commissioning phase.

During their missions, the GMSK-based radio links will be used by both spacecraft to transfer data gathered by their scientific instruments and on-board subsystems, providing information on flight status and overall health.

The development was driven by the need to use bandwidth more efficiently in view of the growing number of ESA missions that require X-band communications via the Agency’s deep space ground stations.

The GSM standard is the most popular modulation standard for mobile phone networks in the world. According to the GSM Association, terrestrial GSM networks now cover more than 80% of the world’s population in more than 212 countries and territories – and will soon extend 1.5 million kms further to L2, Herschel and Plank’s final orbital destination.

Source: ESA