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  • richardmitnick 4:49 am on December 9, 2016 Permalink | Reply
    Tags: , , , Venus   

    From Science Alert: “NASA has recreated the deadly surface of Venus in Ohio “ 

    ScienceAlert

    Science Alert

    1
    NASA/Wikimedia

    “It’s like hell on Earth”.

    A tiny version of Hell on Earth is hiding in Cleveland, Ohio. Called the Glenn Extreme Environments Rig (GEER), the 14-ton steel chamber can faithfully recreate the toxic, choking, and scorching-hot conditions on the surface of Venus – a once-habitable twin of Earth gone very, very wrong.

    Scientists at the NASA Glenn Research Centre, where GEER is located, have been developing the project for the past five years, and fired it up for the first time in 2014.

    Since then, researchers have lengthened their test runs and exposed all kinds of metals, ceramics, wires, mesh, plating, and electronics to conditions on ‘Venus’ to see what lasts – and what bites the dust.

    “In March 2015, we spent roughly 100 days at the surface of Venus, and the longest single stretch was 42 days,” Lori Arnett, NASA’s facility manager for GEER, told Business Insider.

    Their hope? Learn how to build spacecraft that can last months or even years on Venus instead of being destroyed almost instantly.

    2
    NASA’s GEER chamber. Credit: GEER/NASA Glenn Research Centre

    “One of the last probes to visit Venus was Venera 13 in [1982], and it only survived for about 2 hours and 7 minutes,” said Gustavo Costa, a chemist and materials scientist who’s working with GEER. “Venus is very, very corrosive.”

    Until a modern spacecraft drops through the planet’s thick atmosphere again and explores the surface, GEER is the best way to ask what it’s actually like there.

    “It’s like Hell on Earth,” Costa said. “It’s very harsh.”

    The second planet from the sun was, and still is, very similar to Earth.

    Venus is rocky and has roughly 82 percent the mass and 90 percent the surface gravity of Earth. It also has a persistent atmosphere and orbits in the sun’s ‘habitable zone’ (where water can exist as a liquid).

    Some researchers think the planet once had warm, shallow oceans that were cosy to life for about 2 billion years. That could be about 1.2 billion years long enough for life to emerge and thrive, if you’re using Earth as a scorecard.

    And yet its water vanished, carbon dioxide began clogging up the atmosphere, and – due to runaway global warming – the world was cooked to a crisp.

    3
    The GEER chamber opened up. Credit: GEER/NASA Glenn Research Centre

    In short, Venus today is just about the worst place imaginable to visit in the Solar System, and simultaneously an important analogue to better understand our own planet.

    We know this thanks to nearly two dozen successful missions there, including eight orbiters and 10 landers, most of them launched by the Soviet Union.

    Data beamed back by these spacecraft show Venusian surface air is nearly 97 percent carbon dioxide, about 100 times thicker than Earth’s atmosphere, and is a blistering 864 degrees Fahrenheit (462 degrees Celsius).

    That’s twice the temperature needed to ignite wood and hot enough to melt lead.

    But what it’s actually like to be on the surface, and what happens to materials and spacecraft that dare land there, hasn’t been clear until GEER came along.

    GEER pulls together everything researchers have learned to date about surface conditions on Venus into an 800-litre chamber. A mixing machine combines the known gases on Venus and a powerful heater warms them up.

    “It takes two-and-a-half days to warm up and five days to cool down,” Leah Nakley, GEER’s lead engineer, told Business Insider.

    Costa says one thing he’s come to understand by working with GEER is just how strange the atmosphere of Venus is at the planet’s surface.

    “It’s a supercritical fluid mixture, not just a gas,” Costa said.

    Supercritical fluids behave like a gas and a liquid at the same time.

    If you drink decaffeinated coffee, you benefit from them: supercritical carbon dioxide is typically washed over coffee beans to penetrate deep inside them and dissolve away most of their caffeine.

    This same thing can happen with metals and electronics (below), though, which is not a good thing for spacecraft.

    5
    GEER/NASA Goddard Spaceflight Center; Business Insider

    Normally, rust-proof steel alloys will leach out certain metals to form fans of black minerals, like some Gothic version of a crystal-growing kit.

    Costa says walking around the surface of Venus would feel like walking through air that’s as thick as a pool of water, at a pressure equivalent to being 100 meters (328 feet) underwater, and deadly hot.

    A ‘breeze’ of a few miles per hour would feel more like a gentle wave pushing you around at shore.

    “It’s difficult to imagine this. I guess it’d be like sticking yourself inside a pressure cooker,” he said.

    But the atmosphere of Venus also has trace amounts hydrogen fluoride, hydrogen chloride, hydrogen sulphide, and sulphuric acid, which are all extremely dangerous chemicals.

    “Instead of having water vapour clouds, Venus has sulphuric acid clouds,” he said. “And you have to go through those to even get to the surface. That is terrifying.”

    The next mission to Venus

    6
    DAVINCI/NASA

    Japan is currently the only nation with a spacecraft around Venus, called Akatsuki, though it arrived five years late and is an orbiter, not a lander.

    JAXA/AKATSUKI
    JAXA/AKATSUKI

    The US, meanwhile, hasn’t launched a mission dedicated to Venus since 1989 (the Magellan orbiter) and hasn’t landed anything on the world in more than 45 years.

    However, NASA is currently mulling the launch of a proposed Venus probe called DAVINCI.

    If NASA chooses to fully fund that mission in as part of its Discovery program – GEER is currently being upgraded in part to support researching materials for the descent probe – it would arrive sometime in 2023, parachute down through the atmosphere for 63 minutes, sample gases along the way, and take the highest-resolution images yet of the surface.

    In the past, NASA researchers have also envisioned dropping shiny, nuclear-powered rovers on Venus.

    Such a mission might still be possible if the agency can design more efficient nuclear batteries – and overcome its ongoing shortage of plutonium-238, a rare radioactive material that’s required to fuel such power sources.

    See the full article here .

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  • richardmitnick 4:11 pm on October 22, 2016 Permalink | Reply
    Tags: , , , Idunn Mons volcano, Venus   

    From DLR: “Recently active lava flows on the eastern flank of Idunn Mons on Venus” 

    DLR Bloc

    German Aerospace Center

    18 October 2016

    Manuela Braun
    German Aerospace Center (DLR)
    Corporate Communications, Editor, Human Space Flight, Space Science, Engineering
    Tel.: +49 2203 601-3882
    Fax: +49 2203 601-3249

    Dr. Jörn Helbert
    Deutsches Zentrum für Luft- und Raumfahrt (DLR) – German Aerospace Center
    Tel.: +49 30 67055-319
    Fax: +49 30 67055-384

    1
    Elevation model of Idunn Mons
    2
    Area characterized by recent volvanic activity
    3
    Five lava flow units identified during mapping process

    The European Space Agency’s (ESA) Venus Express mission has provided a great amount of data from the surface and atmosphere of Earth’s inner twin planet.

    ESA/Venus Express
    ESA/Venus Express

    Among these observations was the mapping of the southern hemisphere of Venus in the near infrared spectral range using the VIRTIS (Visible and InfraRed Thermal Imaging Spectrometer) instrument. However, the thick and permanent cloud cover of Venus limits the achievable resolution, similar to observing a scene through fog. Using a numerical model, planetary researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) pushed the limits of the data resolution. With this new technique, the emissivity anomalies were analysed on the top and eastern flank of Idunn Mons, a volcano with a diameter of 200 kilometres at its base situated in the southern hemisphere of Venus. These anomalies provide an indication of geologically recent volcanism in this area. “We could identify and map distinctive lava flows from the top and eastern flank of the volcano, which might have been recently active in terms of geologic time,” says Piero D’Incecco, the DLR planetary researcher who presented these results at the joint 48th meeting of the American Astronomical Society’s Division for Planetary Sciences (DPS) and 11th European Planetary Science Congress in Pasadena, California.

    “With our new technique we could combine the infrared data with much higher-resolution radar images from the NASA Magellan mission, having been in orbit about Venus from 1990 until 1992.

    4
    NASA/Magellan

    It is the first time that – combining the datasets from two different missions – we can perform a high resolution geologic mapping of a recently active volcanic structure from the surface of a planet other than Earth.” This study will also provide motivation for future projects focused on the exploration of Venus, as for example the NASA Discovery VERITAS mission proposal or the ESA EnVision M5 mission proposal that – in combining high-resolution radar and near-infrared mapping – will extend the frontiers of our current knowledge of the geology of Venus.

    Search for location and extent of the lava flows

    From 2006 until 2014 the ESA Venus Express probe analysed the atmosphere and surface of Earth’s twin planet. VIRTIS has provided data that indicates the occurrence of recent volcanic activity on Venus. DLR scientists Piero D’Incecco, Nils Müller, Jörn Helbert and Mario D’Amore selected the eastern flank of Idunn Mons – Imdr Regio’s single large volcano – as the study area, since it was identified in VIRTIS data as one of the regions with relatively high values of thermal emissivity at one micron wavelength.

    Using the capabilities of specific techniques developed in the Planetary Spectroscopy Laboratory group at DLR in Berlin, the study intends to identify location and extent of the sources of such anomalies, thus the lava flows responsible for the relatively high emissivity observed by VIRTIS over the eastern flank of Idunn Mons. Therefore the lava flow units on the top and eastern flank of Idunn Mons are mapped, varying the values of simulated one micron emissivity assigned to the mapped units. For each configuration, the total mismatch as root mean square error in comparison with the VIRTIS observations is calculated. In the best-fit configuration, the flank lava flows are characterised by high values of one micron simulated emissivity. Hence, the lava flow units on the eastern flank on Idunn Mons are likely responsible for the relatively high one micron emissivity anomalies observed by VIRTIS. This result is supported by the reconstructed post-eruption stratigraphy, displaying the relative dating of the mapped lava flows, that is independent of the 1 micron emissivity modelling. Values of average microwave emissivity extracted from the lava flow units range around the global mean, which is consistent with dry basalts.

    See the full article here .

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    DLR Center

    DLR is the national aeronautics and space research centre of the Federal Republic of Germany. Its extensive research and development work in aeronautics, space, energy, transport and security is integrated into national and international cooperative ventures. In addition to its own research, as Germany’s space agency, DLR has been given responsibility by the federal government for the planning and implementation of the German space programme. DLR is also the umbrella organisation for the nation’s largest project management agency.

    DLR has approximately 8000 employees at 16 locations in Germany: Cologne (headquarters), Augsburg, Berlin, Bonn, Braunschweig, Bremen, Goettingen, Hamburg, Juelich, Lampoldshausen, Neustrelitz, Oberpfaffenhofen, Stade, Stuttgart, Trauen, and Weilheim. DLR also has offices in Brussels, Paris, Tokyo and Washington D.C.

     
  • richardmitnick 7:21 am on August 10, 2016 Permalink | Reply
    Tags: , , , Venus   

    From SA: “Hellish Venus Might Have Been Habitable for Billions of Years” 

    Scientific American

    Scientific American

    August 10, 2016
    Shannon Hall

    1
    Maat Mons is displayed in this three-dimensional perspective view of the surface of Venus. Credit: NASA/JPL

    Venus is—without a doubt—Earth’s toxic sibling. Although both worlds are similar in size and density, our planetary neighbor has temperatures so high they can melt lead, winds that whip around it some 60 times faster than the planet itself rotates and an atmosphere that slams down with more than 90 times the pressure found on Earth’s atmosphere. But there have been a few tantalizing hints that billions of years ago Venus might have been more akin to Earth’s twin. In addition to their comparable sizes, the worlds also formed close together, which suggests that they are made out of the same bulk of materials. The big difference is their proximity to the sun. Because Venus is roughly 41 million kilometers closer, it receives twice as much sunlight as Earth. But a few billion years ago a slightly fainter sun might have allowed for a relatively cool Venus, one where liquid water could have pooled in vast oceans that were friendly to life.

    A new study recently accepted in Geophysical Research Letters suggests that not only was Venus habitable in the distant past, it could have remained habitable for billions of years. Michael Way from NASA’s Goddard Institute for Space Studies and his colleagues applied the first three-dimensional climate model—the same computer simulations used to predict human-caused climate change on Earth—to early Venus. Because previous research only looked at one-dimensional climate models on Venus (which consider incoming and outgoing radiation but do not visualize the complexities, like clouds, within an atmosphere), the results are a huge step forward compared with previous studies, scientists say. “There’s a real difference between a back-of-the-envelope calculation and actually plugging it into a more sophisticated model,” says Jason Barnes, an astronomer from the University of Idaho, who was not involved in the study.

    The team first simulated how the Venusian climate might have looked 2.9 billion years ago. Such an ancient date required the researchers to make a few educated guesses about the early planet, such as assuming it had a shallow ocean just 10 percent the volume of that on Earth today. But the results were clear—2.9 billion years ago the second rock from the sun could have had a balmy Earth-like temperature that hovered around 11 degrees Celsius. The team then ran the model for a later Venus some 715 million years ago and found that even under the sun’s heightened heat, the planet would have warmed by only 4 degrees Celsius since that earlier time. Such a slight increase in temperature would have allowed the planet’s liquid ocean to persist for billions of years.

    What allowed Venus to stay wet for so long? According to the models, clouds played a key role. They likely piled up on the dayside of the planet, acting as a bright shield that reflects incoming sunlight, and never formed on the nightside, letting heat radiate off into space. “To me the real takeaway message is that Venus could have been habitable for a significant period of time, and time is one of the key ingredients to being able to originate life on a planet,” says Lori Glaze, an astronomer at NASA Goddard Space Flight Center who was not involved in the study. This suggestion adds a new element to the question of habitability: time. “Habitability is not something that’s static,” says David Grinspoon, an astronomer from the Planetary Science Institute and a co-author of the paper. “It’s not just a question of a point in space, it’s a point in space and time and how long a planet could potentially retain oceans, and if that’s long enough to be considered a good candidate to have had an origin and evolution of life.”

    Those cool conditions, however, depend on whether Venus looked the same in its youth as it does today—although the researchers added an ocean, they kept Venus’s present-day topography intact—and whether it has always spun as slowly as it does now, taking 243 Earth days to complete a single rotation. Because the answers to both questions are fairly uncertain, the research team also modeled what Venus’s climate would have looked like 2.9 billion years ago if it had an Earth-like topography or spun at a slightly faster pace. The differences were huge. With mountain ranges and ocean basins similar to Earth’s, the temperature was 12 degrees warmer than with Venus’s topography. And if the rotation rate was 16 Earth days, the temperature skyrocketed 45 degrees higher than the level with its current rotation rate. The cloud pattern that kept the climate cool only formed if the planet was rotating slugglishly.

    This result has vast implications for the world of exoplanets. “The community should be careful about ignoring worlds that are very close to their stars, like Venus-type worlds,” Way says. If a few key characteristics such as an exoplanet’s topography and rotation rate are just right, then the inner edge of the habitable zone—the region in a solar system where conditions conducive to life can arise—will be closer to the host star than is usually thought. The finding is especially important given that these close-in worlds are much easier to observe and characterize than other types of planets. The much-anticipated James Webb Space Telescope—often referred to as Hubble’s successor—for example, will likely only study worlds that hug their host stars, making observations of planets with wider orbits like Mars or even Earth out of the question. Or as Ravi Kopparapu, an astronomer at The Pennsylvania State University puts it: “The closest to Earth we can get with the James Webb Space Telescope is Venus around cool stars.”

    But Glaze could not contain her excitement about the latest study because of the light it sheds on a rock back home. “Venus is the planet next door, the sister next door, and it’s so surprising how little we know,” she says. “We know Mars so much better than we do Venus. Those [plus Earth] are our three terrestrial planets in our own backyard. If we don’t understand those three planets and what makes them the same and what makes them different, we’re going to be hard-pressed to interpret the new planets that we’re discovering outside our own solar system.” Luckily, there are two Venus missions currently in competition for potential flight: One is a geophysical mission, which would map the planet in higher resolution than before. The other is one led by Glaze herself that would measure the makeup of the Venusian atmosphere and even return samples to Earth. Both could shed light on what Venus looked like in the past. “There is still more important data that we need to collect in order to put tighter constraints on these models, and we have the ability to collect those data now. We just need the missions,” Glaze says.

    See the full article here .

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    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

     
  • richardmitnick 8:52 am on June 21, 2016 Permalink | Reply
    Tags: , , , Venus, Why Doesn't Venus Have Water? Blame Electric Wind   

    From CosmosUp: “Why Doesn’t Venus Have Water? Blame Electric Wind” 

    CosmosUp bloc

    CosmosUp

    21, Jun 2016
    No writer credit found

    Venus, our nearest neighbor, is one of the most inhospitable places in the solar system, it’s surface is often said to resemble the classical images of Hell, a really awful place that will kill you in less than 10 seconds.

    Right now, Venus is more than 800°F (426&deg:C) on a normal day, that is hot enough to melt lead; with an atmosphere composed primarily of carbon dioxide (96.5%) — about 90 times denser than Earth’ is — and much higher surface atmospheric pressure, Venus is a place of extremes, definitely not a friendly planet for humanity.

    But at some point in the past, more than 4 billion years ago, Venus wasn’t a desolate wasteland but actually a cool place as some scientists believe.

    Venus is often thought of as Earth’s twin sister because of its size, mass and gravity and there’s evidence that once it contained oceans of water.

    But, as the surface’ temperature of the planet rose to 470°C, all the water boiled away presumably as vapor, into the atmosphere.

    Nowadays, the atmosphere of the planet has 10,000 to 100,000 times less water than Earth’s atmosphere.. Something had to remove all that steam, so where is that water today?

    Previous studies theorized that the solar wind as the likely suspect, but now, a new research reveal that Venus is far more hellish than we previously thought.

    1
    Venus is the planet most like Earth in terms of its size and gravity, and evidence suggests it once had oceans of water that boiled away to steam long ago, with surfaces temperatures of around 460°C (860°F)

    Electric Wind to blame?

    According to a new study published in the journal Geophysical Research Letters, unexpectedly strong electric wind sucked oxygen out into space, thus stripped Venus of its oceans.

    “We found that the electric wind, which people thought was just one small cog in a big machine, is in fact this big monster that’s capable of sucking the water from Venus by itself,

    said Glyn Collinson.

    3
    When water molecules rise into the upper atmosphere, sunlight breaks the water into hydrogen ions

    It’s amazing, shocking,

    added Collinson

    We never dreamt an electric wind could be so powerful that it can suck oxygen right out of an atmosphere into space. This is something that has to be on the checklist when we go looking for habitable planets around other stars.”

    Just as every planet has a gravity field, the force that holds together everything in the universe, some scientists suspect that every planet with an atmosphere is also surrounded by a weak electric field.

    While the force of gravity is responsible of holding down the atmosphere of the planet, the electric force can help to push the upper layers of the atmosphere off into space.

    So far, we have not been able to detect it even in our own planet, but scientists believe its there, but these electric fields are very, very weak.

    Venus is different. Its electric field is enormous, so strong that it can accelerate even the heavier ions to speeds fast enough to escape the planet’s gravity.

    “If you were unfortunate enough to be an oxygen ion in the upper atmosphere of Venus then you have won a terrible, terrible lottery.”

    said Collinson.

    Hunting for other worlds

    These new results may have implications and information that could help us to understand other worlds around the solar system and beyond.

    “We’ve been studying the electrons flowing away from Titan [a moon of Saturn] and Mars as well as from Venus, and the ions they drag away to space,”

    said Andrew Coates, who leads the electron spectrometer team at University College London in the U.K.

    Astronomers will also have to take the electric field of a planet into account when trying to figure out a star’s habitable zone

    “Even a weak electric wind could still play a role in water and atmospheric loss at any planet,

    co-author on the study Alex Glocer said in the statement.

    It could act like a conveyor belt, moving ions higher in the ionosphere where other effects from the solar wind could carry them away.”

    See the full article here .

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  • richardmitnick 12:40 pm on June 13, 2016 Permalink | Reply
    Tags: , , JAXA Akatsuki, , Venus   

    From Phil Plait at Slate: “Akatsuki Reveals a Hot, Dynamic Venus” 

    SLATE

    slate.com

    June 13 2016
    Phil Plait

    1
    A highly unusual infrared view of Venus, taken by the Japanese Akatsuki probe. ISAS/JAXA

    That stunning image above really threw me for a moment. If I hadn’t seen the caption first, it seriously would’ve taken me a second or two to figure out what planet it must be.

    That’s Venus. Honestly, I’ve never seen an image of our sister planet that looks anything quite like that (well, maybe just a little; see below). Usually Venus just looks, well, white. In visible light, at least, the kind our eyes see. Sometimes you can see subtle features, but nothing like this.

    That shot was taken by the Japanese Akatsuki (“Dawn”) spacecraft, which entered Venus orbit in late 2015.

    JAXA AKATSUKI
    JAXA AKATSUKI

    This part is amazing: It was launched in March 2010 and arrived at Venus in December of that year, but due to a thruster misfiring it wound up not going into orbit around Venus initially. It orbited the Sun for five years, and incredibly engineers were able to insert it into Venus orbit using only its attitude control thrusters, very low thrust rockets used normally just to change the spacecraft’s angle to the planet. By doing so, they saved the mission.

    And now Akatsuki is returning science to Earth. The image above is a combination of two infrared shots at wavelengths of 1.735 microns (shown as red) and 2.26 microns (shown as blue); a pseudo-green frame was crated combining the two together. The color choice is a bit odd, since usually the longer wavelength image is shown as red. But who am I to argue with such a phenomenal image?

    The bright white crescent on the left is the day side of Venus, and the orange band is actually twilight; the ridiculously thick atmosphere of Venus (90 times the pressure of Earth’s atmosphere at ground level!) spreads out the sunlight, causing a wide band of scattered sunlight.*

    But it’s the structure of the clouds on the night side of the planet that’s so amazing. The two different wavelengths used are sensitive to different sized cloud particles in Venus’ atmosphere and really show the atmospheric structure.

    Venus is really odd: It rotates extremely slowly, taking 243 days to spin just once! The atmosphere, however, moves much more rapidly. At least, in the troposphere it does, up to a height of about 65 kilometers. It super-rotates, going around the planet faster than the planet spins. This effect is strongest at the equator, and decreases toward the poles. You can see that in the image; the sideways V-shape to the clouds reveals that.

    In fact, I mentioned that the IR image does look a little like another one of Venus I’ve seen, in this case what it looks like in the ultraviolet:

    3
    Venus in ultraviolet light. ISAS/JAXA

    That image was also taken by Akatsuki as it reached Venus orbit. You can also see the unusual pattern in the clouds there. Previous UV images have shown this as well.

    The folks at the Japanese space agency JAXA also released this fascinating short animation showing the cloud motion:

    4
    ISAS/JAXA

    That was taken in the infrared, four images taken four hours apart each. The motion you see is almost entirely due to the clouds super-rotating; Venus hardly spun at all during that time (the spacecraft was about 360,000 kilometers from the planet at the time, so its orbital velocity is low, and doesn’t contribute much to the motion seen either).

    Akatsuki is still warming (haha) to its task at Venus. One of the most interesting things I’m waiting for is lightning data. Yes, seriously! Akatsuki has a Lightning and Airglow Camera that hopefully will settle a decades-long debate over whether Venus has lightning or not. That camera will be returning data pretty soon, so that’ll be nice to see.

    Venus is such a fascinating place. Far hotter than Earth, an atmosphere that’s almost entirely carbon dioxide, tremendous surface pressure, a thick crust covered in volcanic features … it’s so close to being another Earth yet misses by a country kilometer. What happened? Why is it not Earth’s twin, but Earth’s evil twin? We’re still trying to figure that out, and Akatsuki will help tremendously.

    Update, June 13, 2016: Mark McCaughrean, senior space adviser for the European Space Agency, reminded me that the ESA Venus Express probe also took amazing images of Venus.

    ESA/Venus Express
    ESA/Venus Express

    To be honest, this simply slipped my mind! I’ve thought about this before; we’ve had so many missions to so many planets now that it can be hard to remember them all. What times we live in! I’ve written about Venus Express many times, and because why not, here’s NASA’s Magellan mission, too.

    5
    Magellan imaged more than 98% of Venus at a resolution of about 100 meters.

    Magellan mission to Venus spacecraft
    NASA/Magellan mission to Venus spacecraft

    See the full article here .

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    Slate is a daily magazine on the Web. Founded in 1996, we are a general-interest publication offering analysis and commentary about politics, news, business, technology, and culture. Slate’s strong editorial voice and witty take on current events have been recognized with numerous awards, including the National Magazine Award for General Excellence Online. The site, which is owned by Graham Holdings Company, does not charge for access and is supported by advertising revenues.

     
  • richardmitnick 8:45 am on May 7, 2015 Permalink | Reply
    Tags: , , , Venus   

    From SFSU: Venus 

    SFSU bloc

    San Fransisco State University

    Why is Venus interesting?

    Venus is often referred to as Earth’s “sister planet”. This is because it is relatively close and is of similar size and mass as the Earth. It also has a substantial cloudy atmosphere which is effective at reflecting sunlight, giving it a bright appearance in our morning and evening skies. Any similarities to Earth end there. Venus has a mean surface temperature of 462°C (863°F), the result of a runaway greenhouse in its primarily carbon dioxide atmosphere. With a surface atmospheric pressure 92 times that on Earth and clouds of sulfuric acid, Venus can be aptly described as the epitome of uninhabitable.

    How is Venus related to the search for habitable planets?

    The search for exoplanets is largely motivated by answering the question: Is our solar system common? Venus and Earth formed under very similar conditions and probably had water delivered to their surfaces in the same way. However, at some point in their histories, the evolution of their surfaces and atmospheres diverged dramatically! To understand the history of the Earth, we must also understand the tenuous gap that separates the Earth from a runway greenhouse, such as that which exists on Venus. That understanding will come from determining the frequency of Venus-like planets as well as possible habitable planets like the Earth.

    Could we mistake a “Venus” for an “Earth”?

    The main method that is currently used to detect terrestrial-size planets is the transit method, mostly using data from NASA’s Kepler telescope.

    NASA Kepler Telescope
    Kepler

    The main property of an exoplanet we measure using these data is the size of the exoplanet. Since Venus and Earth are approximately the same size (Venus is only 5% smaller), we cannot distinguish between Venus and Earth based solely on size. However, we do know that Venus receives almost twice the amount of energy from the Sun than the Earth does. We can use this information to define a new region where we can hunt for potential analogs to the Venus in our solar system.

    1

    What is the “Venus Zone”?

    In the same way that the “Habitable Zone” is the region around a star where a planet similar to Earth could have liquid water on the surface, the Venus Zone is the region around a star where the atmosphere of a planet like Earth would likely be pushed into a runaway greenhouse producing surface conditions similar to those found on Venus. The below figure shows the Venus Zone (red) and Habitable Zone (blue) for stars of different temperatures. The outer boundary of the Venus Zone is the “Runaway Greenhouse” line which is calculated using climate models of Earth’s atmosphere. The inner boundary (red dashed line) is estimated based on where the stellar radiation from the star would cause the atmosphere of the planet to erode and disappear relatively quickly. The pictures of Venus shown in this region represent planet candidates detected by NASA’s Kepler space telescope.

    3

    How common are Venus-type planets?

    Our analysis of Kepler data detected 43 planets in their star’s Venus Zone. These planets have sizes that are between 50% and 140% the size of the Earth. Using all of the available Kepler data and our knowledge of how many stars have planets, we estimate that approximately 32% of small low-mass stars have terrestrial planets that are potentially like Venus. For stars like our Sun, this number rises to 45%. This is the first estimate for how common our sister-planet is in the universe.

    How can we know for certain if these planets are like Venus?

    Unfortunately it is presently beyond our reach to know for sure if indeed these planets have a runaway greenhouse type of atmosphere. That will require a detailed spectroscopic analysis of the atmospheres to determine the molecular abundances present, such as the dominance of the carbon dioxide spectral lines that we see for Venus’s atmosphere. The transit detection method is far more sensitive to short period-planets than long-period planets, meaning that we can detect a Venus-analog much easier than an Earth-analog. Upcoming space telescopes, such as the Transiting Exoplanet Survey Satellite (TESS) will be efficient Venus detectors in the same way that Kepler is. However, the host stars of planets detected via TESS will be significantly brighter than those found with Kepler, enabling detailed follow-up observations with the James Webb Space Telescope (JWST) due to be launched in 2018. Thus there is a strong chance that we will have our first confirmation of a runaway greenhouse atmosphere on an exoplanet within the next 10 years.

    NASA TESS
    TESS

    NASA James Webb Telescope
    Webb

    Where can I find the scientific publication and related data?

    The science paper On the Frequency of Potential Venus Analogs from Kepler Data has been accepted for publication in the Astrophysical Journal Letters and can be found here.

    See the full article here.

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    San Francisco State University (commonly referred to as San Francisco State, SF State and SFSU) is a public comprehensive university located in San Francisco, California, United States. As part of the 23-campus California State University system, the university offers 118 different Bachelor’s degrees, 94 Master’s degrees, 5 Doctoral degrees including two Doctor of Education, a Doctor of Physical Therapy, a Ph.D in Education and Doctor of Physical Therapy Science, along with 26 teaching credentials among six academic colleges.

     
  • richardmitnick 6:23 am on January 3, 2015 Permalink | Reply
    Tags: , , , Venus   

    From New Scientist: “‘Super-powered oven’ suggests Venus once had continents” 

    NewScientist

    New Scientist

    02 January 2015
    Adam Mann

    VENUS is Earth’s bad-tempered and secretive twin. Despite being similar to Earth in size and mass, Venus is a noxious pressure cooker with surface temperatures that can melt lead. What’s more, it hides its surface in perpetual clouds of sulphuric acid – despite decades of spacecraft visits, no one really knows what Venus’s surface rocks are made of.

    That’s beginning to change, thanks to a powerful oven in a lab in Germany. Jörn Helbert at the DLR Institute for Planetary Research in Berlin and colleagues have used it to make the first analogue studies of Venus’s surface. The results could help explain how Earth’s twin went bad.

    “We want to go back in time and say, what are the evolutionary steps of Venus? Where did it diverge and become Venus instead of Earth?” Helbert says. He presented his research at the American Geophysical Union in San Francisco on 16 December.

    There are a few ways to peek beneath Venus’s veil. Orbital maps made with radar, which can cut through the cloud layer, show that our planetary neighbour mainly consists of volcanic plains where lava once flowed and then cooled. On Earth, such flows generally leave behind basaltic rocks. Samples from the Soviet-era Venera landers, which detected basalt in the ground around their landing sites, suggest the same is true on Venus. But they could not tell what exists further away.

    Venera Lander
    Venera Landers

    More recently, an atmosphere-sensing instrument on the European Space Agency’s Venus Express spacecraft – called the visible and infrared thermal imaging spectrometer (VIRTIS) – created a rough map of the southern hemisphere. The blistered rocks of Venus glow with infrared light, emitting spectra according to their composition. Helbert wanted to use that data to tease out which minerals make up the surface.

    ESA Venus Express
    ESA/Venus Express

    ESA VIRTIS  Visible and Infrared Thermal Imaging Spectrometer

    But there was a problem. Scientists know the spectra of rocks at earthly temperatures – but Venus is a scorching 460 °C. So the researchers built a special electric heating chamber to interpret the Venus Express data.

    “It’s a bit like an electric stovetop in your kitchen, just super-powered,” Helbert says. The team cooked a wide range of rocks, including basalt, anorthosite and haematite and matched the resulting spectra with VIRTIS data.

    The results suggest that the oldest surfaces on Venus could be made of granite, which on Earth forms through tectonic activity. That might mean Venus once had continents. Many geologists think tectonic activity requires the presence of water, which could mean Venus once had oceans and, perhaps, could have hosted life.

    “This kind of data… provides a fantastic way to peek to the surface from orbit, so we can do actual mineralogy from orbit like a real geologist,” says Thomas Widemann at the Paris Observatory in France.

    Widemann is now working with Helbert to build an instrument specifically for orbital composition scans. It could fly on a future Venus mission, such as ESA’s planned EnVision mission or the NASA proposal known as VERITAS.

    See the full article here.

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  • richardmitnick 10:29 pm on November 30, 2014 Permalink | Reply
    Tags: , , , , , Venus   

    From SPACE.com: “How Far Away is Venus?” 

    space-dot-com logo

    SPACE.com

    November 16, 2012
    Nola Taylor Redd

    How far is Venus from Earth?

    v
    Global radar view of the surface from Magellan radar imaging between 1990 and 1994

    NASA Magellan
    NASA/Magellan

    Venus is the closest planet to Earth (it’s also the most similar in size). But its proximity to our planet depends on the orbits of both. The two planets travel in ellipses around the sun, and so the distance between them is constantly shifting. At its farthest, Venus lies 162 million miles (261 million kilometers) away.

    Venus takes 224.7 Earth days to travel around the sun. It makes its closest approach to Earth about once every 584 days, when the planets catch up to one another. On average, it is 25 million miles (40 million km) away at this point, though it can reach as close as 24 million miles (38 million km).

    How far is Venus from the sun?

    All of the planets orbit the sun in an ellipse, rather than a circle, but Venus has the most circular orbit of the planets. On average, the distance to Venus from the sun is 67 million miles (108 million km). At its closest (perihelion), it is only 66.7 million miles away (107 million km); at its farthest (aphelion), only 67.7 million miles (108.9 million km) separate the two.

    Venus isn’t the brightest planet in the sky because it is the closest to the sun; Mercury bears that honor. But unlike Mercury, Venus has a thick, cloudy atmosphere that reflects the light better than Mercury’s rocky surface (it also keeps the planet piping hot). This causes it to stand out, brighter than any star even at its dimmest.

    Phases of Venus

    When Italian astronomer Galileo Galilei studied Venus with a telescope, he was astonished to find that it had phases. Like the moon, these phases depended on where the planet and the sun lay in relationship to the Earth. The phases of Venus were used as evidence that Venus, like the other planets, orbited the sun rather than the Earth in the Copernican model of the solar system.

    Transits of Venus

    Because Venus lies inside of the orbit of the Earth, it periodically transits, or crosses, the sun, blocking out a portion of the star. If the planets traveled within the same plane of the solar system, this would happen on a frequent basis. Instead, Venus has an orbit that is inclined by 3.4 degrees with respect to Earth, so sometimes it tends to pass outside of the range.

    Transits occur in pairs every 243 years; the pairs are separated by eight years. The last transit of the 21st century occurred on June 5 and 6, 2012 (its partner passing took place in 2004). Other transits occurred in 1639 (the first one scientifically observed; its companion transit was missed), 1761 and 1769, and 1874 and 1882. Ancient cultures such as the Greeks, the Mayans, and the Chinese charted the motion of Venus, but records indicate no clues as to transits. [PHOTOS: Transit of Venus 2012 in Pictures]

    Combining information about Venus’ 1639 transit with the principle of parallax allowed for the most accurate estimates of the distance from the Earth to the sun at the time.

    How long does it take to get to Venus?

    The time it takes to travel to Venus depends not only on what speed a rocket can obtain but also on the path a spacecraft travels. Space agencies frequently use gravity boosts from moons, the sun, and other planets to accelerate a craft without using fuel.

    In 1962, NASA’s Mariner 2 became the first spacecraft to send back information from another planet. Launched on August 27, 1962, it performed a flyby of the planet on Dec. 14, having taken less than four months to reach Venus.

    NASA Mariner 2
    NASA/Mariner 2

    The Soviet Union launched Venera 7 on Aug. 17, 1970. On Dec. 15 of that same year, it landed on Venus and became the first spacecraft to send back information from another planet. It took slightly more time to reach Venus than Mariner 2, but still fell short of the four-month mark.

    USSR Venera 7
    USSR Venera 7

    The most recent terrestrial visitor Venus was NASA’s Magellan spacecraft, which took up orbit around the shining planet. Launched on May 4, 1989, it began its orbital insertion movement on Aug. 7, 1990, having taken a more roundabout trip after scheduling issues following the Challenger disaster. Magellan mapped the surface of Venus in depth.

    NASA Magellan
    NASA/ Magellan

    See the full article here.

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  • richardmitnick 2:20 pm on October 19, 2014 Permalink | Reply
    Tags: , , , , , , Venus   

    From astrobio.net: “Rediscovering Venus to Find Faraway Earths “ 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 19, 2014
    fa
    Contact:
    Lyndsay Meyer
    The Optical Society
    +1.202.416.1435
    lmeyer@osa.org

    New optical device designed to measure gravitational pull of a planet should speed the search for Earth-like exoplanets.

    Astronomers Chih-Hao Li and David Phillips of the Harvard-Smithsonian Center for Astrophysics want to rediscover Venus—that familiar, nearby planet stargazers can see with the naked eye much of the year.

    Granted, humans first discovered Venus in ancient times. But Li and Phillips have something distinctly modern in mind. They plan to find the second planet again using a powerful new optical device installed on the Italian National Telescope that will measure Venus’ precise gravitational pull on the sun. If they succeed, their first-of-its-kind demonstration of this new technology will be used for finding Earth-like exoplanets orbiting distant stars.

    Italian National Telescope Galileo
    Italian National Telescope Galileo Internal
    Galileo Italian National Telescope

    “We are building a telescope that will let us see the sun the way we would see other stars,” said Phillips, who is a staff scientist at the Harvard-Smithsonian Center for Astrophysics. He and Li, a research associate at the Center for Astrophysics, will describe the device in a paper to be presented at The Optical Society’s (OSA) 98th Annual Meeting, Frontiers in Optics, being held Oct. 19-23 in Tucson, Arizona, USA. Li is the lead author of the paper, which has 12 collaborators.

    Astronomers have identified more than 1,700 exoplanets, some as far as hundreds of light years away. Most were discovered by the traditional transit method, which measures the decrease in brightness when a planet orbiting a distant star transits that luminous body, moving directly between the Earth and the star. This provides information about the planet’s size, but not its mass.

    Li and Phillips are developing a new laser-based technology known as the green astro-comb for use with the “radial velocity method,” which offers complementary information about the mass of the distant planet.

    From this information, astronomers will be able to determine whether distant exoplanets they discover are rocky worlds like Earth or less dense gas giants like Jupiter. The method is precise enough to help astronomers identify Earth-like planets in the “habitable zone,” the orbital distance “sweet-spot” where water exists as a liquid.

    Better Precision with a Laser

    The radial velocity method works by measuring how exoplanet gravity changes the light emitted from its star. As exoplanets circle a star, their gravitation tugs at the star changing the speed with which it moves toward or away from Earth by a small amount. The star speeds up slightly as it approaches Earth, with each light wave taking a fraction of a second less time to arrive than the wave before it.

    To an observer on Earth, the crests of these waves look closer together than they should, so they appear to have a higher frequency and look bluer. As the star recedes, the crests move further apart and the frequencies seem lower and redder.

    astro
    The astro-comb calibrates the Italian National Telescope’s HARPS-Nspectrograph using an observation of the asteroid Vesta. The top figure is a colorizedversion of the raw HARPS-N spectrum, showing the astro-comb calibration dottedlines and the sun’s spectrum reflected off Vesta as mostly solid vertical lines.The middle figure shows the raw data converted to a very precise standard one-dimensionalplot of spectral intensity vs. wavelength. The very regular astro-comb calibrationspectrum is below below. Credit: David Phillips

    This motion-based frequency change is known as the Doppler shift. Astronomers measure it by capturing the spectrum of a star on the pixels of a digital camera and watching how it changes over time.

    Today’s best spectrographs are only capable of measuring Doppler shifts caused by velocity changes of 1 meter per second or more. Only large gas giants or “super-earths” close to their host stars have enough gravity to cause those changes.

    The new astro-comb Li, Phillips and their colleagues are developing, however, will be able to detect Doppler shifts as small as 10 centimeters per second—small enough to find habitable zone Earth-like planets, even from hundreds of light years away.

    “The astro-comb works by injecting 8,000 lines of laser light into the spectrograph. They hit the same pixels as starlight of the same wavelength. This creates a comb-like set of lines that lets us map the spectrograph down to 1/10,000 of a pixel. So if I have light on this section of the pixel, I can tell you the precise wavelength,” Phillips explained.

    “By calibrating the spectrograph this way, we can take into account very small changes in temperature or humidity that affect the performance of the spectrograph. This way, we can compare data we take tonight with data from the same star five years from now and find those very small Doppler shifts,” he said.

    Seeing Green

    Li and his co-researchers pioneered the astro-comb several years ago, but it only worked with infrared and blue light. Their new version of the astro-comb lets astronomers measure green light—which is better for finding exoplanets.

    “The stars we look at are brightest in the green visible range, and this is the range spectrographs are built to handle,” Phillips said.

    Building the green astro-comb was a challenge, since the researchers needed to convert red laser light to green frequencies. They did it by making small fibers that convert one color of light to another.

    pla
    A slowly rotating planet is not guaranteed to be habitable, as is evident when looking at the inhospitable Venus. Credit: NASA/JPL/Caltech

    “Red light goes in and green light comes out,” Phillips said. “Even though I see it every day and understand the physics, it looks like magic.”

    The researchers plan to test the green astro-comb by pointing it at our sun, analyzing its spectrum to see if they can find Venus and rediscover its characteristic period of revolution, its size, its mass and its composition.

    “We know a lot about Venus, and we can compare our answers to what we already know, so we are more confident about our answers when we point our spectrographs at distant stars,” Li said.

    The Harvard-Smithsonian team is installing this device on the High-Accuracy Radial Velocity Planet Searcher-North (HARPS-N), a new spectrograph designed to search for exoplanets using the Italian National Telescope.

    “We will look at the thousands of potential exoplanets identified by the Kepler satellite telescope by the transit method. Together, our two methods can tell us a lot about those worlds,” Li said.

    And, because he will have already discovered Venus, he will be more certain of the answers.

    See the full article here.

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  • richardmitnick 9:43 am on September 16, 2014 Permalink | Reply
    Tags: , , , , , , Venus   

    From astrobio.net: “NASA Research Helps Unravel Mysteries Of The Venusian Atmosphere” 

    Astrobiology Magazine

    Astrobiology Magazine

    NASA Research Helps Unravel Mysteries Of The Venusian Atmosphere
    Sep 15, 2014
    Source: NASA
    Karen C. Fox NASA’s Goddard Space Flight Center, Greenbelt, Md.

    two
    Earth and Venus – worlds apart. Credits: Earth: NASA; Venus: Magellan Project/NASA/JPL

    Underscoring the vast differences between Earth and its neighbor Venus, new research shows a glimpse of giant holes in the electrically charged layer of the Venusian atmosphere, called the ionosphere. The observations point to a more complicated magnetic environment than previously thought – which in turn helps us better understand this neighboring, rocky planet.

    Planet Venus, with its thick atmosphere made of carbon dioxide, its parched surface, and pressures so high that landers are crushed within a few hours, offers scientists a chance to study a planet very foreign to our own. These mysterious holes provide additional clues to understanding Venus’s atmosphere, how the planet interacts with the constant onslaught of solar wind from the sun, and perhaps even what’s lurking deep in its core.

    “This work all started with a mystery from 1978,” said Glyn Collinson, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is first author of a paper on this work in the Journal of Geophysical Research. “When Pioneer Venus Orbiter moved into orbit around Venus, it noticed something very, very weird – a hole in the planet’s ionosphere. It was a region where the density just dropped out, and no one has seen another one of these things for 30 years.”

    NASA Pioneer Venus Orbiter
    NASA/Pioneer Venus Orbiter

    Until now.


    New research shows giant holes in Venus’ atmosphere – which serve as extra clues for understanding this planet so different from our own. Image Credit: NASA’s Goddard Space Flight Center/G. Duberstein

    Collinson set out to search for signatures of these holes in data from the European Space Agency’s Venus Express. Venus Express, launched in 2006, is currently in a 24-hour orbit around the poles of Venus. This orbit places it in much higher altitudes than that of the Pioneer Venus Orbiter, so Collinson wasn’t sure whether he’d spot any markers of these mysterious holes. But even at those heights the same holes were spotted, thus showing that the holes extended much further into the atmosphere than had been previously known.

    ve
    ESA/Venus Express

    The observations also suggested the holes are more common than realized. Pioneer Venus Orbiter only saw the holes at a time of great solar activity, known as solar maximum. The Venus Express data, however, shows the holes can form during solar minimum as well.

    Interpreting what is happening in Venus’s ionosphere requires understanding how Venus interacts with its environment in space. This environment is dominated by a stream of electrons and protons – a charged, heated gas called plasma — which zoom out from the sun. As this solar wind travels it carries along embedded magnetic fields, which can affect charged particles and other magnetic fields they encounter along the way. Earth is largely protected from this radiation by its own strong magnetic field, but Venus has no such protection.

    What Venus does have, however, is an ionosphere, a layer of the atmosphere filled with charged particles. The Venusian ionosphere is bombarded on the sun-side of the planet by the solar wind. Consequently, the ionosphere, like air flowing past a golf ball in flight, is shaped to be a thin boundary in front of the planet and to extend into a long comet-like tail behind. As the solar wind plows into the ionosphere, it piles up like a big plasma traffic jam, creating a thin magnetosphere around Venus – a much smaller magnetic environment than the one around Earth.

    ve
    Venus Express aerobraking. Credit: ESA

    Venus Express is equipped to measure this slight magnetic field. As it flew through the ionospheric holes it recorded a jump in the field strength, while also spotting very cold particles flowing in and out of the holes, though at a much lower density than generally seen in the ionosphere.

    The Venus Express observations suggest that instead of two holes behind Venus, there are in fact two long, fat cylinders of lower density material stretching from the planet’s surface to way out in space. Collinson said that some magnetic structure probably causes the charged particles to be squeezed out of these areas, like toothpaste squeezed out of a tube.

    The next question is what magnetic structure can create this effect? Imagine Venus standing in the middle of the constant solar wind like a lighthouse erected in the water just off shore. Magnetic field lines from the sun move toward Venus like waves of water approaching the lighthouse. The far sides of these lines then wrap around the planet leading to two long straight magnetic field lines trailing out directly behind Venus. These lines could create the magnetic forces to squeeze the plasma out of the holes.

    But such a scenario would place the bottom of these tubes on the sides of the planet, not as if they were coming straight up out of the surface. What could cause magnetic fields to go directly in and out of the planet? Without additional data, it’s hard to know for sure, but Collinson’s team devised two possible models that can match these observations.

    In one scenario, the magnetic fields do not stop at the edge of the ionosphere to wrap around the outside of the planet, but instead continue further.

    “We think some of these field lines can sink right through the ionosphere, cutting through it like cheese wire,” said Collinson. “The ionosphere can conduct electricity, which makes it basically transparent to the field lines. The lines go right through down to the planet’s surface and some ways into the planet.”

    ct
    Venus cloud tops. Credit: ESA/MPS/DLR/IDA

    In this scenario, the magnetic field travels unhindered directly into the upper layers of Venus. Eventually, the magnetic field hits Venus’ rocky mantle – assuming, of course, that the inside of Venus is like the inside of Earth. A reasonable assumption given that the two planets are the same mass, size and density, but by no means a proven fact.

    A similar phenomenon does happen on the moon, said Collinson. The moon is mostly made up of mantle and has little to no atmosphere. The magnetic field lines from the sun go through the moon’s mantle and then hit what is thought to be an iron core.

    In the second scenario, the magnetic fields from the solar system do drape themselves around the ionosphere, but they collide with a pile up of plasma already at the back of the planet. As the two sets of charged material jostle for place, it causes the required magnetic squeeze in the perfect spot.

    Either way, areas of increased magnetism would stream out on either side of the tail, pointing directly in and out of the sides of the planet. Those areas of increased magnetic force could be what squeezes out the plasma and creates these long ionospheric holes.

    Scientists will continue to explore just what causes these holes. Confirming one theory or the other will, in turn, help us understand this planet, so similar and yet so different from our own.

    See the full article here.

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