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  • richardmitnick 6:38 am on June 20, 2015 Permalink | Reply
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    From Space.com: “What is a Wormhole?” 

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    A model of ‘folded’ space-time illustrates how a wormhole bridge might form with at least two mouths that are connected to a single throat or tube. Credit: edobric | Shutterstock

    A wormhole is a theoretical passage through space-time that could create shortcuts for long journeys across the universe. Wormholes are predicted by the theory of general relativity. But be wary: wormholes bring with them the dangers of sudden collapse, high radiation and dangerous contact with exotic matter.

    Wormhole theory

    In 1935, physicists Albert Einstein and Nathan Rosen used the theory of general relativity to propose the existence of “bridges” through space-time. These paths, called Einstein-Rosen bridges or wormholes, connect two different points in space-time, theoretically creating a shortcut that could reduce travel time and distance.

    Wormholes contain two mouths, with a throat connecting the two. The mouths would most likely be spheroidal. The throat might be a straight stretch, but it could also wind around, taking a longer path than a more conventional route might require.

    Einstein’s theory of general relativity mathematically predicts the existence of wormholes, but none have been discovered to date. A negative mass wormhole might be spotted by the way its gravity affects light that passes by.

    Certain solutions of general relativity allow for the existence of wormholes where the mouth of each is a black hole. However, a naturally occurring black hole, formed by the collapse of a dying star, does not by itself create a wormhole.

    Exotic matter, which should not be confused with dark matter or antimatter, contains negative energy density and a large negative pressure. Such matter has only been seen in the behavior of certain vacuum states as part of quantum field theory.

    If a wormhole contained sufficient exotic matter, whether naturally occurring or artificially added, it could theoretically be used as a method of sending information or travelers through space.

    Wormholes may not only connect two separate regions within the universe, they could also connect two different universes. Similarly, some scientists have conjectured that if one mouth of a wormhole is moved in a specific manner, it could allow for time travel. However, British cosmologist Stephen Hawking has argued that such use is not possible. [Weird Science: Wormholes Make the Best Time Machines]

    “A wormhole is not really a means of going back in time, it’s a short cut, so that something that was far away is much closer,” NASA’s Eric Christian wrote.

    Although adding exotic matter to a wormhole might stabilize it to the point that human passengers could travel safely through it, there is still the possibility that the addition of “regular” matter would be sufficient to destabilize the portal.

    Today’s technology is insufficient to enlarge or stabilize wormholes, even if they could be found. However, scientists continue to explore the concept as a method of space travel with the hope that technology will eventually be able to utilize them.

    See the full article here.

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  • richardmitnick 8:57 am on March 26, 2015 Permalink | Reply
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    From Space.com: “The Strangest Black Holes in the Universe” 2013 But Interesting 

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    July 08, 2013
    Charles Q. Choi

    Black holes are gigantic cosmic monsters, exotic objects whose gravity is so strong that not even light can escape their clutches.

    The Biggest Black Holes
    Credit: Pete Marenfeld

    Nearly all galaxies are thought to harbor at their cores supermassive black holes millions to billions of times the mass of our sun. Scientists recently discovered the largest black holes known in two nearby galaxies.

    One of these galaxies, known as NGC 3842 — the brightest galaxy in the Leo cluster nearly 320 million light years away — has a central black hole containing 9.7 billion solar masses. The other, NGC 4889, the brightest galaxy in the Coma cluster more than 335 million light years away, has a black hole of comparable or larger mass.

    NGC 4889
    Credit: Sloan Digital Sky Survey, Spitzer Space Telescope
    Sloan Digital Sky Survey Telescope
    SDSS telescope

    NASA Spitzer Telescope

    The Smallest Black Hole
    Credit: NASA/Goddard Space Flight Center/CI Lab

    The gravitational range, or “event horizon,” of these black holes is about five times the distance from the sun to Pluto. For comparison, these blaVck holes are 2,500 times as massive as the black hole at the center of the Milky Way galaxy, whose event horizon is one-fifth the orbit of Mercury.

    The smallest black hole discovered to date may be less than three times the mass of our sun. This would put this little monster, officially called IGR J17091-3624, near the theoretical minimum limit needed for a black hole to be stable. As tiny as this black hole may be, it looks fierce, capable of 20 million mph winds (32 million kph) — the fastest yet observed from a stellar-mass black hole by nearly 10 times.

    Cannibalistic Black Holes
    Credit: X-ray: NASA/CXC/SAO/G.Fabbiano et al; Optical: NASA/STScI

    NASA Chandra schematic

    NASA Hubble Telescope
    NASA/ESA Hubble [not in notes but in credit]

    Black holes devour anything unlucky enough to drift too close, including other black holes. Scientists recently detected the monstrous black hole at the heart of one galaxy getting consumed by a still larger black hole in another.

    The discovery is the first of its kind. Astronomers had witnessed the final stages of the merging of galaxies of equal mass — so-called major mergers — but minor mergers between galaxies and smaller companions had long eluded researchers.

    Using NASA’s Chandra X-ray Observatory, investigators detected two black holes at the center of a galaxy dubbed NGC3393, with one black hole about 30 million times the mass of the sun and the other at least 1 million times the mass of the sun, separated from each other by only about 490 light-years.

    Bullet-shooting Black Hole
    Credit: Greg Sivakoff/University of Alberta

    Black holes are known for sucking in matter, but researchers find they can shoot it out as well. Observations of a black hole called H1743-322, which harbors five to 10 times the mass of the sun and is located about 28,000 light-years from Earth, revealed it apparently pulled matter off a companion star, then spat some of it back out as gigantic “bullets” of gas moving at nearly a quarter the speed of light.

    The Oldest Known Black Hole
    Credit: ESO/M. Kornmesser

    The oldest black hole found yet, officially known as ULAS J1120+0641, was born about 770 million years after the Big Bang that created our universe. (Scientists think the Big Bang occurred about 13.7 billion years ago.)

    The ancient age of this black hole actually poses some problems for astronomers. This brilliant enigma appears to be 2 billion times the mass of the sun. How black holes became so massive so soon after the Big Bang is difficult to explain.

    The Brightest Black Hole
    Credit: HST

    Although the gravitational pulls of black holes are so strong that even light cannot escape, they also make up the heart of quasars, the most luminous, most powerful and most energetic objects in the universe.

    As supermassive black holes at the centers of galaxies suck in surrounding gas and dust, they can spew out huge amounts of energy. The brightest quasar we see in the visible range is 3C 273, which lies about 3 billion light-years away.

    Rogue Black Holes
    Credit: David A. Aguilar (CfA)

    When galaxies collide, black holes can get kicked away from the site of the crash to roam freely through space. The first known such rogue black hole, SDSSJ0927+2943, may be approximately 600 million times the mass of the sun and hurtle through space at a whopping 5.9 million mph (9.5 million kph). Hundreds of rogue black holes might wander the Milky Way.

    Middleweight Black Holes
    Credit: NASA

    Scientists have long thought that black holes come in three sizes — essentially small, medium and large. Relatively small black holes holding the mass of a few suns are common, while supermassive black holes millions to billions of solar masses are thought to lurk at the heart of nearly every galaxy. One more massive than four million suns, for example, is thought to hide in the center of the Milky Way.

    However, middle-weight black holes had eluded astronomers for years. Scientists recently discovered an intermediate-mass black hole, called HLX-1 (Hyper-Luminous X-ray source 1), approximately 290 million light-years from Earth, which appears to be about 20,000 solar masses in size.

    Medium-size black holes are thought to be the building blocks of supermassive black holes, so understanding more about them can shed light on how these monsters and the galaxies that surround them evolved.

    Fastest-spinning Black Hole
    Credit: NASA / NASA / CXC / M.Weiss

    Black holes can whirl the fabric of space around themselves at extraordinary speeds. One black hole called GRS 1915+105, in the constellation Aquila (The Eagle) about 35,000 light-years from Earth, is spinning more than 950 times per second.

    An item placed on the edge of the black hole’s event horizon — the edge past which nothing can escape — would spin around it at a speed of more than 333 million mph (536 million kph), or about half the speed of light.

    Tabletop Black Holes
    Credit: Chris Kuklewicz

    Black holes are thankfully quite far away from Earth, but this distance makes it difficult to gather clues that could help solve the many mysteries that surround them. However, researchers are now recreating the enigmatic properties of black holes on tabletops.

    For instance, black holes possess gravitational pulls so powerful that nothing, including light, can escape after falling past a border known as the event horizon. Scientists have created an artificial event horizon in the lab using fiber optics. They have also recreated the so-called Hawking radiation thought to escape from black holes.

    See the full article here.

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  • richardmitnick 10:58 am on March 15, 2015 Permalink | Reply
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    From Space.com: “New Horizons: Exploring Pluto and Beyond” 

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    January 27, 2015
    Elizabeth Howell

    NASA New Horizons spacecraft II
    NASA/New Horizons spacecraft

    New Horizons is a NASA spacecraft on its way to the dwarf planet Pluto. It scooted by Jupiter in 2007, and will pass by Pluto in July 2015 before possibly heading farther into the Kuiper Belt — a massive zone of icy bodies beyond Neptune.

    Known objects in the Kuiper belt beyond the orbit of Neptune (scale in AU; epoch as of January 2015).

    Investigators with the Hubble Space Telescope have identified a few targets for the spacecraft after it zooms by Pluto and its moons, but the mission extension depends on how well New Horizons is performing at that time and if it can receive approval in NASA’s budget.

    NASA Hubble Telescope
    NASA/ESA HUbble

    When the spacecraft reaches Pluto, it will be only the fifth one to head so far away from Earth (the other ones being Pioneer 10 and Pioneer 11, and Voyager 1 and Voyager 2, which are either in the outer solar system or in the case of Voyager 1, interstellar space.)

    NASA Pioneer 10
    Pioneer 10

    NASA Pioneer 11
    Pioneer 11

    NASA Voyager 1
    Voyager 1

    NASA Voyager 2
    Voyager 2

    Pluto’s distance — about 3 billion miles (5 billion kilometers) from Earth — presented power challenges for New Horizon’s designers, since the sun’s rays are too weak to generate power. There will also be long communications delays for those staying in touch with the 1,054-pound spacecraft; at Pluto, it will take 4.5 hours for a one-way message to get there from Earth.

    Further, our understanding of the Pluto system keeps changing. The planet was discovered in 1930 by astronomer Clyde Tombaugh at the Lowell Observatory.

    Lowell Observatory
    Lowell Observatory

    Since then, we’ve discovered new moons — which can also be seen as dangerous obstacles for a spacecraft, if not accounted for. And in 2006 — shortly after New Horizons launched — astronomers voted to demote Pluto from its planetary status. New Horizons carries some of Tombaugh’s ashes.

    Design challenges for long missions

    Spacecraft typically have a set design lifetime, similar to warranties on electronics or cars. Over time, solar particles, cosmic rays and other phenomena can degrade the surface of the spacecraft or mess up the electronics. This makes long missions such as New Horizons especially challenging.

    “You’ve got to remember that it takes 9.5 years to even get to where we want to take the mission,” said Glen Fountain, the New Horizons mission project manager from Johns Hopkins University Applied Physics Laboratory, in a 2006 interview with NASA.

    “So we need a highly reliable system,” he said. “So, we have built into the electronics nearly two of everything. We are redundant. We have two guidance control processors, computers. We have two command and data handling processors. We have two solid-state recorders. Even if there is a failure, you can switch from one to the other.”

    Another question, Fountain acknowledged, was how to handle power when the sun is too weak to provide solar power. New Horizons carries nuclear power (more precisely, a radioisotope thermoelectric generator) on board to solve this problem.

    Mission Control kept the spacecraft in deep hibernation after a quick pass by Jupiter in February 2007. New Horizons underwent periodic wakeups until a last emerging from hibernation for good in December 2014, which will last through the “Pluto encounter” of 2015.

    NASA did a detailed systems check of the spacecraft once a year to make sure it’s working properly and to, if necessary, make adjustments to its path to Pluto. The spacecraft also ferried a basic signal back to Earth once a week.

    Zipping by Jupiter

    New Horizons launched Jan. 19, 2006, on an Atlas V rocket from Cape Canaveral Air Force Station in Florida. A power outage and high winds delayed two previous launch attempts, but New Horizons made it safely into space on the third try.

    The spacecraft’s first destination was Jupiter, in February and March 2007. New Horizons passed by less than 1.4 million miles (2.4 million km) of the solar system’s largest planet, making it the first spacecraft to swing by since the Galileo probe finished its mission at Jupiter in 2003.

    NASA Galileo

    Among New Horizons’ first pictures were some of Io, Jupiter’s volcanic moon. The spacecraft captured the clearest pictures ever of the Tvashtar volcano on Io, showing volcanic fallout that was bigger than the state of Texas.

    Additionally, the spacecraft flew through a stream of charged particles swirling behind Jupiter. It found large bubbles of charged particles, or plasma, and also revealed variations in the stream.

    At the time, astronomers said the observations could help with understanding the environment around “hot Jupiter” planets found at other stars.

    Plans for Pluto

    One of the principal aims of New Horizons is to figure out the origins of Pluto and its companion Charon, a moon that is more than half Pluto’s size. At the time, Pluto and Charon were considered a double planet (although the definition of Pluto changed, as will be explained below.)

    NASA believed Charon formed when Pluto hit another big object long ago, creating debris that circled around Pluto and eventually formed Charon. It’s a similar theory to how Earth’s moon formed, so the scientists hoped to understand the creation of our moon better by looking at Charon’s origins.

    Scientists are also eager to learn about the visual differences between Charon and Pluto. From Hubble observations, researchers deduced Pluto is far more reflective than Charon, and that Pluto has an atmosphere while Charon does not.

    NASA further speculated that Pluto might even have volcanic activity, because the Voyager 2 spacecraft spotted possible volcanoes (to researchers’ surprise) on Triton, a moon of Neptune that is of a similar size and composition.

    New Horizons crossed Neptune’s orbit in August 2014, and in September, the spacecraft team released pictures that the machine took of a small moon called Hydra that summer. The goal was not only to take the pictures, but to do a simulated “satellite search” — it’s possible there are other moons of Pluto that are just waiting to be discovered, when the spacecraft gets closer.

    The spacecraft emerged from hibernation again in December 2014, representing the first of a series of milestones as New Horizons approaches Pluto. “Technically, this was routine, since the wake-up was a procedure that we’d done many times before,” said Glen Fountain, New Horizons project manager at the Johns Hopkins Applied Physics Laboratory, in a statement. “Symbolically, however, this is a big deal. It means the start of our pre-encounter operations.”

    Pluto’s planetary status changes

    Ten years can be a long time in planetary science, and that is particularly true of Pluto. Since New Horizons left our planet in 2006, we’ve discovered another moon nearby Pluto. Planners have made course corrections to keep the spacecraft away from Pluto’s moons.

    Further, Pluto was demoted from its position as the ninth planet in our solar system. In August 2006, members of the International Astronomical Union (IAU) — the global body that governs astronomy names and other matters — met in a general assembly to decide on the definition of a planet.

    This vote was called in response to the recent discoveries of large bodies in the Kuiper Belt, an area beyond Neptune believed to contain trillions of objects.

    On Aug. 24, 2006, IAU representatives determined three features all planets must possess:

    They must orbit the sun (and not another body, as a moon orbits a planet).
    They must have enough mass to form a round shape.
    They must be large enough to clean out bits of rock and other matter in the area around their orbits.

    Pluto didn’t meet all the classifications, and was reclassified as a dwarf planet.

    The decision drew fire from Alan Stern, the principal investigator of the New Horizons mission. “I’m embarrassed for astronomy. Less than 5 percent of the world’s astronomers voted,” he said in a 2006 interview with Space.com. “This definition stinks, for technical reasons.”

    The decision is still controversial, years later. Little is known about Pluto because it is so far away from Earth, but we have been able to increase our understanding of it by peering at the planet with the Hubble Space Telescope and other observatories. More fuel may be added to the debate as NASA’s Dawn spacecraft gets close-up to Ceres this year, one of the largest members of our solar system’s asteroid belt.

    NASA Dawn Spacescraft

    An overhead view of the New Horizons spacecraft’s path across Uranus’ orbit.
    Credit: NASA, JHU/APL


    It is expected that New Horizon’s arrival at Pluto will give us more data about its surface, its moons and its environment, which can better refine our knowledge of the dwarf planet and its system.

    Over the northern hemisphere summer of 2014, investigators used the Hubble Space Telescope to see if there were any Kuiper Belt objects within reach of New Horizons after it concludes its Pluto mission. Scientists identified three candidates, with each of them at least 1 billion miles (1.6 billion kilometers) beyond the dwarf planet.

    The team plans to make a pitch to NASA for extended operations in 2016, to take a closer look at one of these worlds. Meanwhile, even after the mission ends, a group of scientists, artists, engineers and more are proposing placing a sort of message from Earth on the free hard drive space on the New Horizons spacecraft.

    “When New Horizons gets past Pluto, [and] has done all its data and is going on the slow boat to the heliopause [the boundary between the solar system and interstellar space], then it might be possible to just reprogram about 100 megabytes of its memory and upload a new sights and sounds of Earth that are not created by a small group of scientists but, in fact, are globally crowdsourced,” said Jill Tarter, who is the co-founder of the SETI (Search for Extraterrestrial Intelligence) Institute, in 2013.

    See the full article here.

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  • richardmitnick 3:27 am on March 12, 2015 Permalink | Reply
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    From Space.com: “Eagle Nebula (M16): Hubble Images & Pillars of Creation” 2012 

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    July 02, 2012
    Nola Taylor Redd

    This classic image of the Pillars of Creation inside of the Eagle Nebula reveals a stellar nursery where new stars may be hatched.
    Credit: NASA, ESA, STScI, J. Hester and P. Scowen (Arizona State University)

    NASA Hubble Telescope

    In 1995, the world was astounded by the beautiful Hubble Space Telescope images of the Eagle Nebula a cloud of interstellar gas and dust 7,000 light-years from Earth. Let’s take a look at this intriguing region.

    What is the Eagle Nebula?

    Overview of some famous sights in the Eagle Nebula
    HST 24 August 2008

    Also known as M16, the Eagle Nebula is a 5.5 million-year-old cloud of molecular hydrogen gas and dust stretching approximately 70 light years by 55 light years. Inside the nebula, gravity pulls clouds of gas together to collapse inward. If enough gas is present, nuclear fusion is ignited in the center, and the compact cloud becomes a shining star. The Eagle Nebula is thought to have several star-forming regions within it.

    The gas and dust that ultimately collapsed into the sun four billion years ago likely resided in a structure similar to the Eagle Nebula.

    A tower of cold gas and dust rises from the Eagle Nebula.
    Credit: NASA, ESA, and The Hubble Heritage Team STScI/AURA)

    Where is the Eagle Nebula?

    The Eagle Nebula lies 6,500 light-years away in the inner spiral arm of the Milky Way next to our own, the Sagittarius or Sagittarius-Carina Arm. When viewing the sky, the stellar nursery is found within the constellation of Serpens, the Serpent.

    The nebula is viewable with the low-powered telescopes readily available to amateur astronomers, or with a pair of binoculars. With such equipment, observers can see approximately twenty stars clearly, surrounded by gas, dust, and the light of other, dimmer stars. In good conditions, the three pillars may also be seen.

    What are the Pillars of Creation?

    One of the best-known pictures of the Eagle Nebula is the Hubble Space Telescope image taken in 1995, highlighting the “Pillars of Creation.” The three columns contain the materials for building new stars, and stretch four light-years out into space. Newborn stars outside of the famous Hubble image are responsible for sculpting the pillars, using ultraviolet light to burn away some of the gas within the clouds.


    In 2010, images of the pillars taken by NASA’s Chandra X-ray Observatory peered inside the pillars to reveal only a handful of x-ray sources. Because new stars are supposed to be a hot bed of x-ray activity, scientists speculated that the star-forming days of the pillars were coming to an end. [VIDEO: Inside the Pillars of Creation]

    Similarly, research from 2007 suggested that a stellar supernova six thousand years ago could have already blown the pillars out of formation and into space. Because light takes time to travel, it may be another thousand years before we can see their demise.

    Chandra’s X-ray Observatory reveals x-ray images in the Eagle Nebula, although few are visible within the Pillars of Creation
    Credit: X-ray: NASA/CXC/U.Colorado/Linsky et al.; Optical: NASA/ESA/STScI/ASU/J.Hester & P.Scowen

    NASA Chandra Telescope

    What are EGGs?

    Evaporating gaseous globules, or EGGs, are dense pockets of gas that lie at the top of the columns. Some EGGs appear as tiny bumps in the surface, while others have been completely uncovered or cut off completely from the pillars.

    Although some EGGs will collapse down into new stars, others lack sufficient gas to create a new stellar candidate.

    The EGGs are about a hundred times the Earth’s distance to the sun, so the solar system would fit comfortably inside most of them. They last ten thousand to twenty thousand years.

    Discovery of the Eagle Nebula

    When Swiss astronomer Philippe Loys de Chéseaux discovered the Eagle Nebula in the mid-eighteenth century, he only described the cluster of stars surrounding it. Charles Messier independently rediscovered it in 1764 as part of his catalog, dubbing it M16.

    The first image of the nebula appears to have been made by American astronomer Edward Barnard, in 1895.

    See the full article here.

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  • richardmitnick 7:29 am on March 10, 2015 Permalink | Reply
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    From Space.com- “Oort Cloud: The Outer Solar System’s Icy Shell” 2012 

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    July 02, 2012
    Nola Taylor Redd


    A giant shell of icy bodies known as the Oort Cloud encircles the solar system. When its inhabitants interact with passing stars, molecular clouds, and gravity from the galaxy, they may find themselves spiraling inward toward the sun, or cast completely out of the solar system into distant regions of space. Although this shell was first proposed in 1950, its extreme distance makes it challenging for scientists to identify objects within it.

    Identifying the Oort Cloud

    Within a few million years the light from bright stars will have boiled away this molecular cloud of gas and dust. The cloud has broken off from the Carina Nebula. Newly formed stars are visible nearby, their images reddened by blue light being preferentially scattered by the pervasive dust. This image spans about two light-years and was taken by the Hubble Space Telescope in 1999.

    NASA Hubble Telescope

    Detail of Carina Nebula taken by the VLT telescope Credit: ESO

    ESO VLT Interferometer

    In 1950, Dutch astronomer Jan Oort suggested that some of the comets entering the solar system come from a cloud of icy bodies that may lie as far as 100,000 times Earth’s distance from the sun, a distance of up to 93 trillion miles (150 trillion kilometers).

    Two types of comets travel through the solar system. Those with short periods, on the order of a few hundred years, stem from the Kuiper Belt, a pancake of icy particles near the orbit of Pluto. Longer period comets, with orbits of thousands of years, come from the more distant Oort Cloud.

    Known objects in the Kuiper belt beyond the orbit of Neptune (scale in AU; epoch as of January 2015). Source: Minor Planet Center, http://www.cfeps.ne

    The two regions vary primarily in terms of distance and location. The Kuiper Belt orbits in approximately the same plane as the planets, ranging from 30 to 50 times as far from the Sun as Earth. But the Oort Cloud is a shell that surrounds the entire solar system, and is a hundred times as distant.

    Comets from the Oort Cloud can travel as far as three light-years from the sun. The farther they go, the weaker the sun’s gravitational hold grows. Passing stars and clouds of molecular gas can easily change the orbit of these comets, stripping them from our star or casting them back toward it. The path of the comets is constantly shifting, depending on what factors influence it.

    Oort Cloud inhabitants

    The estimated two trillion objects in the Oort Cloud are primarily composed of ices such as ammonia, methane, and water. Formed in the beginning of the solar system, they remain pristine chunks of its early life, allowing comets to provide insight into the environment in which the early Earth evolved. While gravity drew other bits of dust and ice together into larger celestial bodies, the residents of the Oort Cloud weren’t as fortunate. Gravity from the other planets—primarily gas giants such as Jupiter—kicked them into the outer solar system, where they remain.

    The population of the Oort Cloud is in a constant state of flux. Not only are some of its residents permanently booted out of the system through interactions with passing neighbors, the sun may also capture the inhabitants from the shells surrounding other stars. Some of the bodies plunging toward the sun may have been kidnapped early in the sun’s evolution, when it was part of a more closely-packed cluster of stars.

    When the comet Hyakutake passed within 9 million miles (15 million kilometers) of Earth in 1996, it was completing a journey of about 17,000 years from the distant reaches of the Oort Cloud. Hale-Bopp was another long-period comet that traveled in from the Oort Cloud. Visible for nearly a year and a half, it passed within 122 million miles (197 million kilometers) of the Earth. Both of these Oort Cloud objects had their orbits drastically changed as a result of their pass through the solar system. Halley’s Comet is also believed to have originally come from the Oort Cloud, although it is now a Kuiper Belt object.


    The comet Hale-Bopp captured the attention of millions when it traveled in from the Oort Cloud to pass near the Earth before returning to its distant home. Credit: J. C. Casado

    Scientists have identified four other objects that they believe are part of this distant group. The largest of the four, Sedna, thought to be three-quarters the size of Pluto, lies 8 billion miles (13 billion kilometers) from Earth and orbits the sun approximately every 10,500 years. The other three objects are known as 2006 SQ372, 2008 KV42, and 2000 CR105, and range between 30 to 155 miles (50 to 250 km) in size.

    See the full article here.

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  • richardmitnick 7:33 pm on March 3, 2015 Permalink | Reply
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    From Space.com: “The Father of SETI: Q&A with Astronomer Frank Drake” 

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    February 26, 2015
    Leonard David

    Arecibo Observatory

    Detecting signals from intelligent aliens is a lifelong quest of noted astronomer Frank Drake. He conducted the first modern search for extraterrestrial intelligence (SETI) experiment in 1960. More than five decades later, the hunt remains front-and-center for the scientist.

    Frank Drake

    Drake also devised a thought experiment in 1961 to identify specific factors believed to play a role in the development of civilizations in our galaxy. This experiment took the form of an equation that researchers have used to estimate the possible number of alien civilizations — the famous Drake Equation.

    The Drake equation is:

    N = R*. fp. ne. fl. fi. fc. L


    N = the number of civilizations in our galaxy with which radio-communication might be possible (i.e. which are on our current past light cone);


    R* = the average rate of star formation in our galaxy
    fp = the fraction of those stars that have planets
    ne = the average number of planets that can potentially support life per star that has planets
    fl = the fraction of planets that could support life that actually develop life at some point
    fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
    fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
    L = the length of time for which such civilizations release detectable signals into space

    Drake constructed the “Arecibo Message” of 1974 — the first interstellar message transmitted via radio waves from Earth for the benefit of any extraterrestrial civilization that may be listening.

    The message consists of seven parts that encode the following (from the top down):[4]

    The numbers one (1) to ten (10)
    The atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up deoxyribonucleic acid (DNA)
    The formulas for the sugars and bases in the nucleotides of DNA
    The number of nucleotides in DNA, and a graphic of the double helix structure of DNA
    A graphic figure of a human, the dimension (physical height) of an average man, and the human population of Earth
    A graphic of the Solar System indicating which of the planets the message is coming from
    A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish

    This is the message with color added to highlight its separate parts. The actual binary transmission carried no color information.

    Space.com caught up with Drake to discuss the current state of SETI during an exclusive interview at the NASA Innovative Advanced Concepts (NIAC) 2015 symposium, which was held here from Jan. 27 to Jan. 29.

    Drake serves on the NASA NIAC External Council and is chairman emeritus of the SETI Institute in Mountain View, Calif. and director of the Carl Sagan Center for the Study of Life in the Universe.

    Space.com: What’s your view today concerning the status of SETI?

    Frank Drake: The situation with SETI is not good. The enterprise is falling apart for lack of funding. While NASA talks about “Are we alone?” as a number one question, they are putting zero money into searching for intelligent life. There’s a big disconnect there.

    We’re on the precipice. The other thing is that there are actually negative events on the horizon that are being considered.

    Space.com: And those are?

    Drake: There are two instruments, really the powerful ones for answering the “are we alone” question … the Arecibo telescope[above] and the Green Bank Telescope [GBT].


    They are the world’s two largest radio telescopes, and both of them are in jeopardy. There are movements afoot to close them down … dismantle them. They are both under the National Science Foundation and they are desperate to cut down the amount of money they are putting into them. And their choice is to just shut them down or to find some arrangement where somebody else steps in and provides funding.

    So this is the worst moment for SETI. And if they really pull the rug out from under the Green Bank Telescope and Arecibo … it’s suicide.

    Space.com: What happens if they close those down?

    Drake: We’re all then sitting in our living rooms and watching science fiction movies.

    Space.com: How about the international scene?

    Drake: The international scene has gone down too because all the relevant countries are cash-strapped also.

    There is a major effort in China, a 500-meter [1,640 feet] aperture spherical radio telescope. The entire reflector is under computer control with actuators. They change the shape of the reflector depending on what direction they are trying to look. The technology is very complicated and challenging. The Russians tried it and it never worked right. But … there are serious resources there.

    Space.com: Why isn’t SETI lively and bouncing along fine given all the detections?

    Drake: You would think. All those planetary detections are the greatest motivator to do SETI that we ever had. But it hasn’t had any impact, at least yet.

    Space.com: How do you reconcile the fact that exoplanet discoveries are on the upswing, yet mum’s the word from ET?

    Drake: People say that all the time … saying that you’ve been searching for years and now you’ve searched thousands of stars and found nothing. Why don’t you just give up … isn’t that the sensible thing?

    There’s a good answer to all that. Use the well-know equation and put in the parameters as we know them. A reasonable lifetime of civilizations is like 10,000 years, which is actually much more than we can justify with our own experience. It works out one in every 10 million stars will have a detectable signal. That’s the actual number. That means, to have a good chance to succeed, you have to look at a million stars at least — and not for 10 minutes — for at least days because the signal may vary in intensity. We haven’t come close to doing that. We just haven’t searched enough.

    Space.com: What are we learning about habitable zones?

    Drake: Actually the case is very much stronger for a huge abundance of life. The story seems to be that almost every star has a planetary system … and also the definition of “habitable zone” has expanded. In our system, it used to be that only Mars and Earth were potentially habitable. Now we’ve got an ocean on Europa … Titan.

    The habitable zone goes out. A habitable zone is not governed just by how far you are from the star, but what your atmosphere is. If you’ve got a lot of atmosphere, you’ve got a greenhouse effect. And that means the planet can be much farther out and be habitable.

    “Radio waving” to extraterrestrials. Outward bound broadcasting from Earth has announced humanity’s technological status to other starfolk, if they are out there listening.
    Credit: Abstruse Goose

    Space.com: What is your view on the debate regarding active SETI — purposely broadcasting signals to extraterrestrials?

    Drake: There is controversy. I’m very against sending, by the way. I think it’s crazy because we’re sending all the time. We have a huge leak rate. It has been going on for years. There is benefit in eavesdropping, and you would have learned everything you can learn through successful SETI searches. There’s all kinds of reasons why sending makes no sense.

    Frank Drake, center, with his colleagues, Optical SETI (OSETI) Principal Investigator Shelley Wright and Rem Stone with the 40-inch Nickel telescope at Lick Observatory in California. Outfitted with the OSETI instrument, the silver rectangular instrument package protrudes from the bottom of the telescope, plus computers, etc.
    Credit: Laurie Hatch Photography

    That reminds me of something else. We have learned, in fact, that gravitational lensing works. If they [aliens] use their star as a gravitational lens, they get this free, gigantic, super-Arecibo free of charge. They are not only picking up our radio signals, but they have been seeing the bonfires of the ancient Egyptians. They can probably tell us more about ourselves than we know … they’ve been watching all these years.

    Space.com: Can you discuss the new optical SETI efforts that you are involved with? You want to search for very brief bursts of optical light possibly sent our way by an extraterrestrial civilization to indicate their presence to us.

    Drake: It’s alive and well. We’ve gotten a couple of people who are actually giving major gifts. There’s no funding problem. There is a new instrument that has been built, and it’s going to be installed at the Lick Observatory [in California] in early March.

    The whole thing is designed to look for laser flashes. The assumption is — and this is where it gets to be tenuous — the extraterrestrials are doing us a favor. It does depend on extraterrestrials helping you by targeting you. These stellar beams are so narrow that you’ve got to know the geometry of the solar system that you’re pointing it at. They want to communicate. They have to be intent on an intentional signal specifically aimed at us. That’s a big order. So there are required actions on the part of the extraterrestrials for this to work. The big plus is that it’s cheap and relatively easy to do.

    See the full article here.

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  • richardmitnick 9:07 pm on February 9, 2015 Permalink | Reply
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    From Space.com: “How We Found the Most Distant Quasar (Yet) Known” 

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    February 09, 2015
    Daniel Mortlock, Imperial College London

    False-color image of the field around the quasar ULAS J1120+0641 (the faint yellow source indicated by the cross hairs). Only its color distinguishes the quasar from the other sources, mostly ordinary stars in Earth’s Milky Way galaxy. Credit: The United Kingdom Infrared Telescope [UKIRT]

    UKIRT interior

    Just before midnight on Sept. 3, 2010, an astronomical database went live on the Web. The Eighth Data Release of the — take a breath now — United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) wasn’t particularly noteworthy in computing terms, but it was of considerable scientific significance: It contained new data on hundreds of millions of astronomical objects, many of them never previously seen.

    The vast majority of these objects were ordinary sunlike stars in Earth’s own Milky Way galaxy, but there was about a 10 percent chance that hidden somewhere in the terabytes of data was a single object more distant than any known. My job was to find it.

    Catching a quasar

    I was in an international team led by my Imperial College colleague Steve Warren, and the particular type of object we were looking for was a quasar. This is the glowing accretion disk of gas that can form around a supermassive black hole at the center of an otherwise ordinary galaxy. The material being pulled into the black hole gets compressed and heated to the point that it easily outshines all the stars in the host galaxy. In many cases, that host galaxy is so faint it is not detected, leaving only the quasar visible.

    The main reason for putting so much effort into finding distant quasars , in particular, is that they are by far the brightest, and hence most revealing, astronomical objects in the early universe. Back in 2010, the most distant quasar known appeared to astronomers as it was when the universe was 900 million years old, just 7 percent of its current age of 13.9 billion years. (The finite speed of light means that larger physical distances translate to greater distances in time, or look-back times.)

    It is remarkable that a disk of glowing gas about the size of our solar system can be seen billions of light years away, but the comparatively small size of quasars also means they appear star-like when viewed from Earth, just unresolved points of light in the night sky. This is one reason that quasars can be so hard to find: In any astronomical image taken through a single-wavelength filter, they are indistinguishable from ordinary stars, which massively outnumber them.

    The secret to finding quasars is looking for their distinctive colors . The most distant quasars are very red in color, being almost invisible at optical wavelengths while appearing bright in the near-infrared. (This is due to a combination of the cosmological expansion — which Doppler-shifts all light to longer wavelengths — and absorption by neutral — i.e., un-ionized — hydrogen atoms present in the early universe.) In contrast, stars like the sun mainly emit optical light, although cooler brown dwarfs (essentially “failed” stars in which hydrogen fusion never got going) are almost as red as the target quasars. So, quasar searches are typically done by comparing images of the same part of the sky taken with different wavelength filters.

    If the UKIDSS data had been perfect, it might have been possible to identify any record-breaking quasars immediately. But all real astronomical data is noisy: The measured colors of the sources in the UKIDSS catalogue (and all other data sets) don’t quite match their true values.

    As a result, in a plot of measured brightness ratios from different filters, stars and brown dwarfs overlap with distant quasars . The traditional approach of identifying all objects with colors like the target objects, which had worked in previous searches at lower distances, would have been hopelessly inefficient with UKIDSS.

    That could easily have been a potentially fatal problem for the project, as there were far too many objects to study more closely through re-observation. What was needed was some way to prioritize the best candidates only on the basis of the data at hand.

    This sort of problem — how best to make use of limited astronomical data — is the subject of the emerging field of astrostatistics (which, the complaints of Microsoft Word 2011 notwithstanding, is spelled without a hyphen).

    Astrostatistics sort the Big Data

    The solution we came up with was to use the statistical technique of Bayesian model comparison to assess each candidate, in turn, by considering which of two hypotheses was more consistent with the data: that a given object is a (cool) star or that the object is a (distant) quasar.

    An additional vital ingredient in the method is Bayes’ theorem, a fundamental mathematical result published posthumously by the Presbyterian minister Thomas Bayes (1701-1761). The theorem demands the inclusion of prior information, rather than just the data at hand. This is often cited as a reason not to use Bayesian methods, because it can often seem that there is no other, prior useful information available. But in our case we actively needed to use the (prior) fact that stars outnumber quasars by many thousands to one. The odds of any object chosen randomly from the UKIDSS database being a distant quasar were correspondingly low, and so most apparently promising candidates would correctly be discarded.

    Measured colors (essentially the ratio of how bright objects appear in different wavelength filters) for objects detected in the United Kingdom Infrared Telescope Infrared Deep Sky Survey that passed researchers’ initial selection criteria (shown by the dashed lines). Even though the sources are broadly consistent with being distant quasars, the vast majority are actually either stars or brown dwarfs in the Milky Way galaxy (the predicted properties of which are shown as the blue curve). The five distant quasars (ULAS J1120+0641 and ULAS J1148+0702, along with the three already known) are indicated in blue, with error bars to illustrate the limited precision of the measurements. The predicted quasar properties are shown as the blue curve, with labels showing how these colors change with look-back time. Credit: Daniel Mortlock

    Another appealing aspect of the Bayesian approach is that it automatically encodes many of the criteria that we had been applying intuitively (and qualitatively) when we had first started the search. Fainter objects had been rejected because the color estimates were less precise; now they were objectively ranked in descending order by the fact that a star, when that faint, could end up having the measured colors of a quasar. We had regarded ambiguous objects with measured colors halfway between the two populations with limited enthusiasm; now they were rejected for being so much more likely to have been “scattered” from the dominant stellar population.

    The result of applying the Bayesian ranking scheme to the UKIDSS data was that an input list of tens of thousands of apparently good candidates was reduced to fewer than 50 objects. Three of those already had been identified as very distant (but not quite record-breaking) quasars by the earlier Sloan Digital Sky Survey (SDSS), an important validation of our approach. Quick follow-up observations to confirm the UKIDSS measurements of the remainder allowed us to discard all but two of the other candidates; we sent the coordinates of the two survivors to the Gemini North Telescope for more precise spectroscopic measurements (in which the light is separated into different wavelengths).

    Gemini North telescope
    Gemini North Interior
    Gemini North

    Ancient quasar revealed

    The first of the two objects, with the perhaps uninspiring name of ULAS J1120+0641, was observed on the night of Nov. 27, 2010, and it was immediately revealed it to be easily the most distant quasar known, bettering the previous record holder by a full hundred million years.

    We had found what we were looking for — and the short time between the initial data release and the confirmation was important, as there were other research groups with access to the same data attempting the same search. (The second object, ULAS J1148+0702, was also confirmed as a quasar, but was in the same distance range as the slightly closer quasars found earlier by SDSS.) In the time since its discovery, the quasar ULAS J1120+0641 has been observed using telescopes all around the planet, and the Hubble Space Telescope in orbit.

    Scientists are still unraveling this quasar’s secrets to this day. Aside from revealing what conditions were like 800 million years after the Big Bang, ULAS J1120+0641 is also the home of the earliest supermassive black hole found to date, a monster with two billion times the mass of the sun that had, in contradiction with most standard theories of black hole formation, somehow coalesced in the cosmologically short time available. And none of this would have been possible without a piece of mathematics done by an 18th century Presbyterian priest.

    See the full article here.

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  • richardmitnick 9:01 am on February 8, 2015 Permalink | Reply
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    From Space.com: “How Would the World Change If We Found Alien Life?” 

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    February 06, 2015
    Elizabeth Howell

    If contact with extraterrestrial life is made through radio telescopes, a decipherment process may have to take place to understand the message.
    Credit: NASA

    In 1938, Orson Welles narrated a radio broadcast of “War of the Worlds” as a series of simulated radio bulletins of what was happening in real time as Martians arrived on our home planet. The broadcast is widely remembered for creating public panic, although to what extent is hotly debated today.

    Still, the incident serves as an illustration of what could happen when the first life beyond Earth is discovered. While scientists might be excited by the prospect, introducing the public, politicians and interest groups to the idea could take some time.

    How extraterrestrial life would change our world view is a research interest of Steven Dick, who just completed a term as the Baruch S. Blumberg NASA/Library of Congress Chair of Astrobiology. The chair is jointly sponsored by the NASA Astrobiology Program and the John W. Kluge Center, at the Library of Congress.

    Dick is a former astronomer and historian at the United States Naval Observatory, a past chief historian for NASA, and has published several books concerning the discovery of life beyond Earth. To Dick, even the discovery of microbes would be a profound shift for science.

    “If we found microbes, it would have an effect on science, especially biology, by universalizing biology,” he said. “We only have one case of biology on Earth. It’s all related. It’s all DNA-based. If we found an independent example on Mars or Europa, we have a chance of forming a universal biology.”

    Dick points out that even the possibilities of extraterrestrial fossils could change our viewpoints, such as the ongoing discussion of ALH84001, a Martian meteorite found in Antarctica that erupted into public consciousness in 1996 after a Science article said structures inside of it could be linked to biological activity. The conclusion, which is still debated today, led to congressional hearings.

    Photo of the martian meteorite ALH84001. Dull, dark fusion crust covers about 80% of the sample

    “I’ve done a book about discovery in astronomy, and it’s an extended process,” Dick pointed out. “It’s not like you point your telescope and say, ‘Oh, I made a discovery.’ It’s always an extended process: You have to detect something, you have to interpret it, and it takes a long time to understand it. As for extraterrestrial life, the Mars rock showed it could take an extended period of years to understand it.”

    Mayan decipherments

    In his year at the Library of Congress, Dick spent time searching for historical examples (as well as historical analogies) of how humanity might deal with first contact with an extraterrestrial civilization. History shows that contact with new cultures can go in vastly different directions.

    Hernan Cortes’ treatment of the Aztecs is often cited as an example of how wrong first contact can go. But there were other efforts that were a little more mutually beneficial, although the outcomes were never perfect. Fur traders in Canada in the 1800s worked closely with Native Americans, for example, and the Chinese treasure fleet of the 15th Century successfully brought its home culture far beyond its borders, perhaps even to East Africa.

    Even when both sides were trying hard to make communication work, there were barriers, noted Dick.

    “The Jesuits had contact with Native Americans,” he pointed out. “Certain concepts were difficult, like when they tried to get across the ideas of the soul and immortality.”

    Indirect contact by way of radio communications through the Search for Extraterrestrial Intelligence (SETI), also illustrates the challenges of transmitting information across cultures. There is historical precedence for this, such as when Greek knowledge passed west through Arab translators in the 12th Century. This shows that it is possible for ideas to be revived, even from dead cultures, he said.

    Allen Telescope Array
    SETI’s Institute’s Allen Telescope Array

    SETI@home screensaver
    SETI@home project

    Arecibo Observatory
    Arecibo Observatory. used by SETI@home

    “There will be a decipherment process. It might be more like the Mayan decipherments,” Dick said.

    The ethics of contact

    As Dick came to a greater understanding about the potential cultural impact of extraterrestrial intelligence, he invited other scholars to present their findings along with him. Dick chaired a two-day NASA/Library of Congress Astrobiology Symposium called “Preparing for Discovery,” which was intended to address the impact of finding any kind of life beyond Earth, whether microbial or some kind of intelligent, multicellular life form.

    The symposium participants discussed how to move beyond human-centered views of defining life, how to understand the philosophical and theological problems a discovery would bring, and how to help the public understand the implications of a discovery.

    “There is also the question of what I call astro-ethics,” Dick said. “How do you treat alien life? How do you treat it differently, ranging from microbes to intelligence? So we had a philosopher at our symposium talking about the moral status of non-human organisms, talking in relation to animals on Earth and what their status is in relation to us.”

    Dick plans to collect the lectures in a book for publication next year, but he also spent his time at the library gathering materials for a second book about how discovering life beyond Earth will revolutionize our thinking.

    “It’s very farsighted for NASA to fund a position like this,” Dick added. “They have all their programs in astrobiology, they fund the scientists, but here they fund somebody to think about what the implications might be. It’s a good idea to do this, to foresee what might happen before it occurs.”

    It’s also quite possible that the language we receive across these indirect communications would be foreign to us. Even though mathematics is often cited as a universal language, Dick said there are actually two schools of thought. One theory is that there is, indeed, one kind of mathematics that is based on a Platonic idea, and the other theory is that mathematics is a construction of the culture that you are in.

    See the full article here.

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  • richardmitnick 10:38 am on February 5, 2015 Permalink | Reply
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    From Space.com: “Mystery of the Universe’s Gamma-Ray Glow Solved” 

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    February 05, 2015
    Calla Cofield

    Five years of data from the Fermi Gamma-ray Space Telescope paint a picture of the universe in gamma-rays. Scientists with Fermi think the flux of gamma-rays can be explained by known sources.
    Credit: gamma ray sky, gamma ray universe, fermi telescope, blazars, radio galaxies, gamma ray emitters, gamma ray sources, milky way gamma rays

    The steady glow of high-energy gamma-ray light that spreads across the cosmos has puzzled astronomers for decades. One team of researchers thinks it has the best explanation yet for the source of this strange emission.

    After observing the universe with NASA’s Fermi Gamma-ray Space Telescope for six years, scientists with the mission say the majority of the gamma-ray glow they have seen can be explained by objects already known to science. If there are any as-yet unknown sources out there, their contribution to the glow would be very small, scientists say.

    NASA Fermi Telescope

    “We have a very plausible story. We’re not 100 percent confident that this is the final answer, but it really constrains what other exotic possibilities could be out there,” said Keith Bechtol, a postdoctoral researcher at the University of Chicago and a member of the Fermi collaboration who worked on the analysis.

    Galactic Haze Seen by Planck and Galactic ‘Bubbles’ Seen by Fermi
    Credit: ESA/Planck Collaboration (microwave); NASA/DOE/Fermi LAT/D. Finkbeiner et al. (gamma rays)
    This all-sky image shows the distribution of the galactic haze seen by ESA’s Planck mission at microwave frequencies superimposed over the high-energy sky, as seen by NASA’s Fermi Gamma-ray Space Telescope. Image released February 13, 2012.

    ESA Planck

    W44 Supernova Remnant
    Credit: NASA/DOE/Fermi LAT Collaboration, ROSAT, JPL-Caltech, and NRAO/AUI
    Fermi’s LAT mapped GeV-gamma-ray emission (magenta) from the W44 supernova remnant. The features clearly align with filaments detectable in other wavelengths. This composite merges X-rays (blue) from the Germany-led ROSAT mission, infrared (red) from NASA’s Spitzer Space Telescope, and radio (orange) from the NRAO’s Very Large Array near Socorro, N.M.

    NASA ROSAT satellite

    NASA Spitzer Telescope


    Fermi: a gamma-ray gumshoe

    NASA’s Fermi Gamma-ray Space Telescope snaps pictures of the entire observable universe — from end to end — in gamma-rays, which are some of the highest-energy photons in nature.

    While that wide view of the universe is useful, it can make it a challenge to pinpoint the exact sources of these gamma-rays. Instead, Fermi sees a diffuse glow coming from the universe. This glow is technically known as the extragalactic gamma ray background, or the EGB. Previous gamma-ray telescopes have also seen this light that fills the background of the cosmos.

    “We’ve known about this gamma-ray background since the late 1960s,” Bechtol said. “It’s a very-long-standing mystery, and each generation of gamma-ray telescopes has given us a little more information.”

    With help from other telescopes, the Fermi telescope can identify where some of this high-energy background light is coming from. There are very energetic galaxies called blazars, for example, that give off a high flux of gamma-rays. The Energetic Gamma Ray Experiment Telescope (EGRET), which preceded Fermi, broke records by detecting some 300 gamma-ray sources. So far, the Fermi telescope has identified more than 3,000 sources.

    NASA Energetic Gamma Ray Telescope

    But 3,000 is only a drop in the ocean of gamma-ray sources in the entire universe, scientists say.

    “We think every galaxy is producing gamma-rays at some level,” Bechtol said. “The vast majority are too faint to be seen individually and instead their collective emission is blurred together.” (Many galaxies radiate high levels of optical light, and can be seen by telescopes like the Hubble. But their gamma-ray emission is too faint to be detected.)

    “It’s frustrating not to know the answer, but the fact that there’s a mystery — I think that’s what attracted a lot of us to this problem,” Bechtol said. “At least for me, I like being on the edge of that discovery space where there’s still blank parts on the map.”

    Cracking the mystery

    The Fermi telescope can’t see most of the objects that radiate gamma-ray light, so the scientists have to try to estimate how many gamma-ray objects are out there.

    In an analysis first made public in September 2014, members of the Fermi collaboration took the known sources of gamma-rays and added them together with models that predicted the frequency and location of unseen sources. The scientists calculated how much gamma-ray light both the detected and modeled sources would produce together.

    This calculated output of gamma rays matches closely with the actual gamma ray-background that Fermi observes — the entire EGB.

    The final estimate shows that roughly 50 percent of the gamma-ray background comes from extremely energetic galaxies known as blazars. Ten to 30 percent of the gamma ray background emanates from star-forming galaxies like the Milky Way, which can collectively contain many smaller gamma-ray sources, like supernovas. Another 20 percent is from radio galaxies, which are blazars, but are pointed away from the Earth, and thus cannot be seen as easily by Fermi.

    “There could definitely be new gamma-ray sources out there,” Bechtol said. “It’s just that their total contribution would have to be relatively small.”

    It’s also possible that dark matter — the mysterious material that makes up 80 percent of all the matter in the universe — is producing gamma-rays, and the Fermi results may help scientists figure out what kind of particle (or particles) make up dark matter.

    Two large uncertainties remain in Fermi’s estimation. First, it is difficult to measure the gamma-ray glow of the universe to begin with, and Bechtol said he and his collaborators put a lot of time into improving that measurement.

    Second, the scientists are making estimates about objects they cannot directly observe, most of which are located beyond the Milky Way galaxy (or extragalactic).

    “When [scientists] first discovered the gamma-ray background, it was largely a mystery as to what created it,” Bechtol said. “And now it seems like everything is fitting together very well. Right now, the simplest explanation involving known astrophysical sources seems to be doing just fine.”

    The Fermi Large Area Telescope has spotted highly energetic ejections of gamma-rays throughout the universe. Scientists with Fermi believe known gamma-ray sources can account for the overall gamma-ray flux in the universe, but they say there is still room for surprises.
    Credit: NASA/DOE/Fermi LAT Collaboration

    Light from back in time

    Fermi’s success at decoding the gamma-ray background had depended largely on its increased sensitivity to gamma-rays and its detection of more gamma-ray sources than previous telescopes. In addition, Fermi scientists have worked to gain a better understanding of how gamma-ray emissions have changed throughout the history of the universe. This is valuable because when Fermi looks at sources of gamma-rays, it is actually looking into the past.

    Light travels at a finite speed — the light from the sun takes 8 minutes to reach Earth, which means humans actually see the sun as it was 8 minutes ago. By the same logic, objects that are billions of light-years away from Earth are seen by Fermi as they were billions of years ago.

    “We’re literally measuring the light output over the history of the universe, and for me, that’s what makes this exciting,” Bechtol said. “We’re seeing all different time periods in the universe at the same time. All of the light from all those different periods is added together to form the gamma ray background.”

    Having a historical perspective makes a big difference for Fermi because the cosmic output of gamma-rays has likely been different at various times throughout the last 13 billion years. For example, the universe has seen periods when the population of blazars exploded and other times when the population growth slowed down. They also need to understand precisely how far away those blazars are, in order to accurately measure how long ago these bright sources burned.

    The Fermi scientists have solved a long-standing puzzle, but Bechtol said there are still other mysteries in the gamma-ray universe. There are other gamma-ray telescopes that can detect even higher-energy gamma-rays than Fermi, and it’s possible that in those energy ranges, there are sources of gamma-rays that scientists don’t know about yet.

    “We think this [result] is converging on the final answer, but history has shown us that, sometimes, there’s more to the story,” Bechtol said. “I certainly think that, as we start to look at higher energies […], there will start to be some surprises.”

    See the full article here.

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  • richardmitnick 5:02 pm on February 2, 2015 Permalink | Reply
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    From Space.com: “Does Humanity’s Destiny Lie in Interstellar Space Travel? (Op-Ed)” 

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    January 27, 2015
    Donald Goldsmith

    An artist’s interpretation of utilizing a wormhole to travel through space, Thorne kick-started a serious discussion among scientists about whether or wormhole travel is possible. Credit: NASA

    Imagine a time when humans, having spent decades exploring the solar system through landings on Venus and Mars; passages by the largest asteroids; close-up surveys of Jupiter and its giant moons; repeated loops through Saturn’s system of rings and satellites; detailed photography of Uranus, Neptune and Pluto; and even landing on a comet, finally create a coherent plan to travel through interstellar space to reach the nearest stars and their planets.

    That time has almost arrived. Once NASA’s Dawn spacecraft arrives at the asteroid Ceres in March of this year , and the space agency’s New Horizons spacecraft flies by Pluto in July, humans will have completed the solar system exploration described above. They will have done so, of course, by creating complex and highly capable spacecraft that not only secure high-resolution images of the objects they encounter, but also roll across planetary surfaces to measure local conditions in a dozen different ways, including spectroscopic and chemical analysis of the composition and history of each object.

    NASA Dawn Spacescraft

    NASA New Horizons spacecraft
    NASA/New Horizons

    Will humans ever replace robotic explorers?

    To many of us, the success of our automated spacecraft heralds the long-awaited moments when humans finally land on Mars, Ganymede (Jupiter’s largest moon) or Titan (Saturn’s largest moon), eventually to establish self-sustaining colonies that might provide a continuing opportunity to maintain our existence if our home planet were to become uninhabitable. The interplay between our logical wishes to deepen our knowledge of the solar system and our gut-level desires for personal encounters with new situations — always present though not always acknowledged — has governed humans’ ever-shifting plans to explore our nearby cosmic environment for half a century.

    Just about everyone welcomes new information about the solar system, but what many really — really — want is for humanity to plant its boots on new soil, as Earth-bound explorers have done for many centuries. Lonely humans in space speak directly to our emotions, but pioneering spacecraft far less so. (Even an apparent exception, such as the hero of the movie “WALL-E,” connects with us through its seeming humanity, a fact that won’t surprise anyone who reflects for a moment on how storytelling works.)

    Some facts remain evident: Human exploration of space is dangerous and expensive, requiring the provision of food and water, recycling of wastes, significant amounts of energy to run those systems, protection against harsh radiation and a return journey (or not, depending on volunteers’ propensities). In comparison, automated spacecraft have only modest energy requirements, and can last for decades or more. As time passes, this comparison progressively favors machines, since they (thanks to humans!) become ever more competent, while our bodies evolve at a much slower pace.

    As the brilliant physicist Freeman Dyson explains in the new podcast available at RawScience.tv, “Instruments have gotten enormously … humans are really out of it. If you want to go to space, that’s for fun, not for science … This is not understood by the people in charge [of planning for future exploration missions].”

    To be sure, when we dream of the far future, we can easily envision (thanks, in part, to many science-fiction stories and films) beings that combine today’s human bodies with advanced technology to produce a human-machine hybrid far more capable of long journeys and survival in strange situations than individuals are today.

    Humanity’s destiny in space

    Dyson’s argument in favor of machines counts for little among those who insist — who know — that our destiny lies in the presence of humans, not our mechanistic surrogates, in space. For many of us, this knowledge runs more deeply than argument can reach. A glance at the history of the United States’ space program reminds us of the many times, during the 40-plus years since the last lunar landing, that NASA has attempted to produce a reasonable plan to send humans beyond low-Earth orbit — only to have the expense of such projects, combined with the lack of a clear focus for astronaut activity, lead to their abandonment. Because the manned lunar program basically served as a counterpunch to Soviet efforts in space, once NASA and the United States achieved their initial goal of landing on the moon, they proved unable of following a coherent plan for future space exploration by humans.

    What do these ambitions tell us about the future of interstellar exploration? Even before we consider human versus automated journeys, we should note that any answers to this question begin with a number: 1 million. The stars nearest to the sun lie at distances approximately 1 million times the distance to Mars at its closest approach to Earth. This ratio implies that travel to the stars at speeds our best spacecraft are capable of will take hundreds of thousands of years, and this, in turn, implies that any interstellar exploration will require either a civilization that knows how to plan for the long haul, or the ability to make spacecraft that can travel much faster — perhaps 10,000 times more rapidly — than what we have now. (I’ll save the discussion of “wormholes” like those seen in the movies “Contact” and “Interstellar ” for later.)

    On the fast track, or slow and steady?

    Consider spacecraft that could carry astronauts through space at speeds approaching the speed of light, conferring two great advantages on the crew. Most obviously, the journey requires less time — only a few years to reach the nearest stars, and only a couple of decades to span the distances to the closest thousand stars. In addition, time slows down at near-light velocities — by a factor of 10, for example, for those who travel at 99.5 percent the speed of light. At that velocity, an astronaut who makes an interstellar journey covering 50 light years in each direction would age by only 10 years, but would return to an Earth where everyone has aged by 100 years. (Those who suspect that Einstein’s theory of relativity creates a “twin paradox” — that the traveler and those who stay behind should each see time slow down by a factor of 10 — can find an excellent explanation of the apparent paradox in David Mermin’s book “Space and Time in Special Relativity” (Waveland, 1989).)

    But how can we hope to move through space at close to the speed of light? More than 50 years ago, Dyson — who, even then, created intriguing and controversial ideas at the Institute for Advanced Study in Princeton, New Jersey — proposed that nuclear explosions could accelerate a spacecraft to ever-higher speeds. The “Project Orion” study, directed by Ted Taylor, though largely Dyson’s brainchild, envisioned that a series of nuclear explosions would strike a “pusher plate” attached to the rear of a spacecraft, eventually accelerating the spacecraft to any desired velocity.

    The concept remains theoretically feasible, though one can easily see that the expense would be enormous. As Dyson recalls in the RawScience podcast, by using the power of nuclear explosions, the Orion spacecraft could provide “both fast acceleration and fast travel, which nothing else could do … In principle, the idea was good,” Dyson said, but “it had one fatal flaw: The bombs are highly radioactive … As soon as you had the test-ban treaty … Orion was dead.”

    Even if we manage to accelerate a spacecraft to velocities close to the speed of light (10,000 times faster than our fastest space probes), any spacecraft moving at near-light velocities encounters a significant problem. The same special-relativity rules that allow a traveler to return to Earth much younger than her twin brother who stayed home also imply that collisions with space debris — even tiny dust particles — inevitably pose great dangers. [Photos: Step-by-Step Guide to NASA’s EFT-1 Orion Spacecraft Test Flight ]

    When the spacecraft encounters dust and pebbles, the objects’ near-light velocities, relative to the craft, enormously elevate their effective masses. An impactor’s increase in mass, together with the tremendous collision speeds, call for enormous amounts of shielding to protect anyone inside the spacecraft. Hence, any plans to travel through the Milky Way at near-light speeds must embrace not only a truly massive propulsion system, but also enough shielding to protect the humans inside the craft.

    Thinking in centuries

    Nevertheless, Dyson’s Orion concept remains, in many ways, the gold standard for visions of interstellar travel. In the recent podcast, Dyson noted that the name “Orion” has been passed on to NASA’s most recent spacecraft design not for an interstellar vehicle, but for a far more modest craft to take astronauts to other worlds in the solar system. Dyson also identified the most basic requirement for interstellar spaceflight: a society capable of long-term planning and execution. “If you want to have a program for moving out into the universe, you have to think in centuries, not in decades.”

    That necessity for a long-term vision poses a serious barrier to interstellar journeys in a society that has great difficulty planning for even the next five years.

    If we are prepared to think in centuries, as Dyson recommends, we should ask the key technological question: What prospects exist for interstellar space travel at comparatively low velocities? In the decades since this question first seriously arose, theorists have provided plenty of answers, which build on the success of our current interplanetary space probes. If you want to probe deeply into them, the coordinated websites of the Tau Zero Foundation and Centauri Dreams offer useful information on this topic. And if you want to examine a representative plan for interstellar travel, I recommend the PowerPoint presentation created by Steve Kilston, an astronomer who spent much of his career at Ball Aerospace (and with whom I have been friends since our undergraduate days). Kilston’s “Plausible Path to the Stars” envisions the creation — in approximately 500 years — of a cylindrical spaceship that will carry a million inhabitants, will rotate in order to simulate Earth’s gravity, will travel at 0.2 percent of the speed of light, and could reach the few dozen nearest stars in 10,000 years’ time.

    In other words, Kilston’s “Plausible Path,” like any other low-velocity journey, requires that generations upon generations of spacefarers pass their entire lives short of their goal. Today, this plan would attract few volunteers. But if human society came to feel sure of its long-term viability, so that our time horizon stretched beyond the current limits of (at most) our grandchildren’s lifetimes, the situation would become quite different. Perhaps the wisest aspect of Kilston’s plan lies in its final prelaunch phase: a 100-year cruise through the solar system to demonstrate the full feasibility of the spacecraft and the willingness of its crew to pass their lives in space.

    Thus, a practical, technologically reasonable plan to explore our cosmic environment rests simply upon achieving a society in which a 100-year journey, and a few thousand years of travel time, seem both logical and desirable. To see how far we now stand from this goal, we may merely compare a film based on Kilston’s “Plausible Path” with a movie like “Avatar” or “Interstellar.” In today’s world, almost no one is interested in moving from a situation in which months of spacecraft travel is far too long to one that tolerates multi-thousand-year journeys. Instead, we must hope for a better tomorrow.

    The wormhole option

    If we don’t want to wait, what about taking the “Interstellar” route and using a wormhole to pass near-instantaneously from here to there? Kip Thorne, a physicist at the California Institute of Technology who’s an expert on the subject — and whose screenplay inspired “Interstellar” — has written a book to accompany the film: “The Science of Interstellar” (W.W. Norton and Company, 2014). In the book, Thorne demonstrates that humans cannot rule out wormhole travel, but there is no guarantee that this method actually works, or that it could allow safe conduct through the voids of space.

    Physicists have recently suggested that the Milky Way could contain — or even be! — a giant wormhole. On the other hand, an argument against wormhole travel, or at least against its easy operation, lies in the fact that no creatures of a more advanced civilization appear to be popping out of wormholes in our solar system. A similar argument can be made against time travel, at least in the backward direction, since we have yet to encounter beings from the future who have decided to visit our present.

    To be frank, concepts of interstellar travel have progressed only modestly since Dyson envisioned the Orion project decades ago. Yes, layers of refinement have been added: “Slow” versus “fast” spaceflight has been debated and scored, experience has now given some indications of how well humans can survive long periods in space, and theoretical physics has provided some tantalizing possibilities that might make such journeys much easier than they now appear. But the big picture has not changed: First, we must figure out how to live successfully for the long term on Earth, and then we can go to the stars.

    See the full article here.

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