Tag: forms (page 2 of 13)

7 Reasons You Need More Magnesium

Margie King, GuestMagnesium is the fourth most abundant mineral in your body.  But few people fully appreciate this miraculous mineral. The human genome project reveals that 3,751 human proteins have binding sites for magnesium.[i]  And so far we know this one essential mineral activates over 350 biochemical processes in the body to keep things flowing.Here are just seven good reasons to get more magnesium today. 1. Prevent Migraines. According to University of Vermo [...]

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US Government Admits Americans Have Been Overdosed on Fluoride

Dr. MercolaThe US government has finally admitted they’ve overdosed Americans on fluoride and, for first time since 1962, are lowering its recommended level of fluoride in drinking water.1,2,3About 40 percent of American teens have dental fluorosis,4 a condition referring to changes in the appearance of tooth enamel—from chalky-looking lines and splotches to dark staining and pitting—caused by long-term ingestion of fluoride during the time teeth are forming.In some areas, fluoro [...]

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The Class-Domination Theory of Power

by G. William DomhoffNOTE: WhoRulesAmerica.net is largely based on my book,Who Rules America?, first published in 1967 and now in its7th edition. This on-line document is presented as a summary of some of the main ideas in that book.Who has predominant power in the United States? The short answer, from 1776 to the present, is: Those who have the money -- or more specifically, who own income-producing land and businesses -- have the power. George Washington was one of the biggest landowner [...]

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‘Hats Off’ To HATS-6b: Discovery of ‘puffy’ new planet brings scientists closer to finding new life in outer space

An artist's impression of the planet HATS-6b, orbiting the star, HATS-6. (Supplied: ANU) Excerpt from abc.net.au A "puffy" new planet orbiting a small, cool star has been discovered 500 light years away from Earth, by a team of scientists c...

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Here’s How To Avoid One Of The Most Common Life Regrets

Excerpt from huffingtonpost.comKarl Pillemer, a Ph.D. gerontologist at Cornell University, has spent the last several years interviewing hundreds of older Americans to systematically collect their practical wisdom.His first book, 30 Lessons for Livin...

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Guiding Our Search for Life on Other Earths


The James Webb Telescope


Excerpt from space.com

A telescope will soon allow astronomers to probe the atmosphere of Earthlike exoplanets for signs of life. To prepare, astronomer Lisa Kaltenegger and her team are modeling the atmospheric fingerprints for hundreds of potential alien worlds. Here's how:
The James Webb Space Telescope, set to launch in 2018, will usher a new era in our search for life beyond Earth. With its 6.5-meter mirror, the long-awaited successor to Hubble will be large enough to detect potential biosignatures in the atmosphere of Earthlike planets orbiting nearby stars.
And we may soon find a treasure-trove of such worlds. The forthcoming exoplanet hunter TESS (Transiting Exoplanet Survey Satellite), set to launch in 2017, will scout the entire sky for planetary systems close to ours. (The current Kepler mission focuses on more distant stars, between 600 and 3,000 light-years from Earth.) 

Astronomer Lisa Kaltenegger




While TESS will allow for the brief detection of new planets, the larger James Webb will follow up on select candidates and provide clues about their atmospheric composition. But the work will be difficult and require a lot of telescope time.
"We're expecting to find thousands of new planets with TESS, so we'll need to select our best targets for follow-up study with the Webb telescope," says Lisa Kaltenegger, an astronomer at Cornell University and co-investigator on the TESS team.
To prepare, Kaltenegger and her team at Cornell's Institute for Pale Blue Dots are building a database of atmospheric fingerprints for hundreds of potential alien worlds. The models will then be used as "ID cards" to guide the study of exoplanet atmospheres with the Webb and other future large telescopes.
Kaltenegger described her approach in a talk for the NASA Astrobiology Institute's Director Seminar Series last December.
"For the first time in human history, we have the technology to find and characterize other worlds," she says. "And there's a lot to learn."

Detecting life from space  

In its 1990 flyby of Earth, the Galileo spacecraft took a spectrum of sunlight filtered through our planet's atmosphere. In a 1993 paper in the journal Nature, astronomer Carl Sagan analyzed that data and found a large amount of oxygen together with methane — a telltale sign of life on Earth. These observations established a control experiment for the search of extraterrestrial life by modern spacecraft.
"The spectrum of a planet is like a chemical fingerprint," Kaltenegger says. "This gives us the key to explore alien worlds light years away."
Current telescopes have picked up the spectra of giant, Jupiter-like exoplanets. But the telescopes are not large enough to do so for smaller, Earth-like worlds. The James Webb telescope will be our first shot at studying the atmospheres of these potentially habitable worlds.
Some forthcoming ground-based telescopes — including the Giant Magellan Telescope (GMT), planned for completion in 2020, and the European Extremely Large Telescope (E-ELT), scheduled for first light in 2024 — may also be able to contribute to that task. [The Largest Telescopes on Earth: How They Compare]
And with the expected discovery by TESS of thousands of nearby exoplanets, the James Webb and other large telescopes will have plenty of potential targets to study. Another forthcoming planet hunter, the Planetary Transits and Oscillations of stars (PLATO), a planned European Space Agency mission scheduled for launch around 2022-2024, will contribute even more candidates.
However, observation time for follow-up studies will be costly and limited.
"It will take hundreds of hours of observation to see atmospheric signatures with the Webb telescope," Kaltenegger says. "So we'll have to pick our targets carefully."

Giant Magellan Telescope
Set to see its first light in 2021, The Giant Magellan Telescope will be the world’s largest telescope.

Getting a head start

To guide that process, Kaltenegger and her team are putting together a database of atmospheric fingerprints of potential alien worlds. "The models are tools that can teach us how to observe and help us prioritize targets," she says.
To start, they have modeled the chemical fingerprint of Earth over geological time. Our planet's atmosphere has evolved over time, with different life forms producing and consuming various gases. These models may give astronomers some insight into a planet's evolutionary stage.
Other models take into consideration the effects of a host of factors on the chemical signatures — including water, clouds, atmospheric thickness, geological cycles, brightness of the parent star, and even the presence of different extremophiles.
"It's important to do this wide range of modeling right now," Kaltenegger said, "so we're not too startled if we detect something unexpected. A wide parameter space can allow us to figure out if we might have a combination of these environments."
She added: "It can also help us refine our modeling as fast as possible, and decide if more measurements are needed while the telescope is still in space. It's basically a stepping-stone, so we don't have to wait until we get our first measurements to understand what we are seeing. Still, we'll likely find things we never thought about in the first place."
 

A new research center

The spectral database is one of the main projects undertaken at the Institute for Pale Blue Dots, a new interdisciplinary research center founded in 2014 by Kaltenegger. The official inauguration will be held on May 9, 2015.
"The crux of the institute is the characterization of rocky, Earth-like planets in the habitable zone of nearby stars," Kaltenergger said. "It's a very interdisciplinary effort with people from astronomy, geology, atmospheric modeling, and hopefully biology."
She added: "One of the goal is to better understand what makes a planet a life-friendly habitat, and how we can detect that from light years away. We're on the verge of discovering other pale blue dots. And with Sagan's legacy, Cornell University is a really great home for an institute like that."

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Our sun is five billion years younger than most other stars in our galaxy






Excerpt from stgist.com



The sun, or the nearest star from Earth, was formed around 5 billion years after the Milky Way galaxy’s peak production of stars, a new research published in the Astrophysical Journal. 

Using multiple ground based, and space telescopes, including the Magellan Telescopes located at Las Campanas Observatory in South America, a new study was able to confirm that the closest star from us, the Sun, was formed after the so-called stellar “baby boom” of the Milky Way galaxy.

It’s like traveling back in time. Researchers from Texas A&M University in College Station, headed by astronomer Casey Papovich, were able to see the undepicted past of our own galaxy by observing similar regions located billions of light years away from us.

The “baby boom” happened around 10 billion years ago, the new study published in Astrophysical Journal revealed. At that time, the Milky Way galaxy was producing 30 times more stars than today. If so, then our solar system’s 4.6 billion years old Sun was formed more than 5 billion years after the production peak.

Sun’s late formation allowed the solar system we know today to produce planets with heavier elements. Scientists say elements heavier than hydrogen and helium became more abundant in “late to the game systems”, and the death of massive stars that were formed before the Sun had provided materials needed to form planets, including Earth and its complex life forms.

Scientists scanned through a collection of more than 24,000 galaxies, and took at least 2,000 snapshots of galaxies that closely resemble our own. The census has provided the most complete picture yet of how spiral galaxies similar to Milky Way form in the universe.

According to Mr. Papovich, the lead author of the study who also serves as an associate professor in the Department of Physics and Astronomy at A&M University in Texas, they know where to find traces by analyzing how galaxies like our own were formed.

Papovich said his team has provided a data that clearly show the rapid phase of growth around 9 to 10 billion years ago, or at least more than 5 billion years after our Sun formed. They also found the connection between the size of the galaxy, and the formation of stars.

Surprisingly, the robust collection of distant galaxies confirmed that stars formed inside the Milky Way, instead of forming in other smaller baby galaxies that later merged to join the system.

In separate studies, scientists were able to confirm that our own solar system is wetter than thought. Beyond Earth, celestial objects like Jupiter’s Galilean moons Europa and Ganymede, Saturn’s Enceladus, and even the dwarf planet Ceres in the asteroid belt, are hosting fluid slightly similar to Earth’s — and it is highly possible that the Sun’s late formation allowed this setup to exist.

Papovich who worked alongside Texas A&M postdoctoral researchers Vithal Tilvi and Ryan Quadri, were joined by at least two dozen astronomers from other countries. The research is published April 9th entitled “ZFOURGE/CANDELS: ON THE EVOLUTION OF M* GALAXY PROGENITORS FROM z = 3 TO 0.5*.” The research was funded by NASA

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Huge Alien Planet Bathes in the Light of Four Suns



30 Ari with its newly discovered companion stars
Karen Teramura

Excerpt from nbcnews.com


Astronomers have spotted a fourth star in a planetary system called 30 Ari, bringing the number of known planet-harboring quadruple-sun systems to two. 

"Star systems come in myriad forms. There can be single stars, binary stars, triple stars, even quintuple star systems," study lead author Lewis Roberts, of NASA's Jet Propulsion Laboratory, said in a statement. "It's amazing the way nature puts these things together." 

30 Ari lies 136 light-years from the sun in the constellation Aries. Astronomers discovered a giant planet in the system in 2009; the world is about 10 times more massive than Jupiter and orbits its primary star every 335 days. There's also a pair of stars that lie approximately 1,670 astronomical units away. (One AU is the distance between Earth and the sun — about 93 million miles, or 150 million kilometers).

The newfound star circles its companion once every 80 years, at a distance of just 22 AU, but it does not appear to affect the exoplanet's orbit despite such proximity. This is a surprising result that will require further observations to understand, researchers said. 

To a hypothetical observer cruising through the giant planet's atmosphere, the sky would appear to host one small sun and two bright stars visible in daylight. With a large enough telescope, one of the bright stars could be resolved into a binary pair. 

The discovery marks just the second time a planet has been identified in a four-star system. The first four-star planet, PH1b or Kepler-64b, was spotted in 2012 by citizen scientists using publicly available data from NASA's Kepler mission. 

Planets with multiple suns have become less of a novelty in recent years, as astronomers have found a number of real worlds that resemble Tatooine, Luke Skywalker's home planet in the Star Wars films. 

The research was published online this month in the Astronomical Journal.

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VLA photos 18 years apart show dramatic difference in young stellar system

Excerpt from bulletinstandard.com  A pair of pictures of a young star, produced 18 years apart, has revealed a dramatic distinction that is giving astronomers with a exclusive, "real-time" appear at how enormous stars create in the e...

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Citizen Scientists Find Green Blobs in Hubble Galaxy Shots





Excerpt from wired.com

In 2007, A Dutch schoolteacher named Hanny var Arkel discovered a weird green glob of gas in space. Sifting through pictures of galaxies online, as part of the citizen science project Galaxy Zoo, she saw a cloud, seemingly glowing, sitting next to a galaxy. Intrigued, astronomers set out to find more of these objects, dubbed Hanny’s Voorwerp (“Hanny’s object” in Dutch). Now, again with the help of citizen scientists, they’ve found 19 more of them, using the Hubble space telescope to snap the eight haunting pictures in the gallery above.



Since var Arkel found the first of these objects, hundreds more volunteers have swarmed to help identify parts of the universe in the Galaxy Zoo gallery. To find this new set, a couple hundred volunteers went through nearly 16,000 pictures online (seven people went through all of them), clicking yes/no/maybe as to whether they saw a weird green blob. Astronomers followed up on the galaxies they identified using ground-based telescopes, and confirmed 19 new galaxies surrounded by green gas.



What causes these wispy tendrils of gas to glow? Lurking at the center of each of these galaxies is a supermassive black hole, millions to billions times as massive as the sun, with gravity so strong that even light can’t escape them. As nearby gas and dust swirls into the black hole, like water circling a drain, that material heats up, producing lots of radiation—including powerful ultraviolet. Beaming out from the galaxy, that ultraviolet radiation strikes nearby clouds of gas, left over from past collisions between galaxies. And it makes the clouds glow an eerie green. “A lot of these bizarre forms we’re seeing in the images arise because these galaxies either interacted with a companion or show evidence they merged with a smaller galaxy,” says William Keel, an astronomer at the University of Alabama, Tuscaloosa.



The eight in this gallery, captured with Hubble, are especially weird. That’s because the quasar, the black-hole engine that’s supposed to be churning out the ultraviolet radiation, is dim—too dim, in fact, to be illuminating the green gas. Apparently, the once-bright quasar has faded. But because that UV light takes hundreds of thousands of years to travel, it can continue to illuminate the gas long after its light source has died away.  


Hubble finds phantom objects close to dead quasars

That glowing gas can tell astronomers a lot about the quasar that brought it to light. “What I’m so excited about is the fact that we can use them to do archaeology,” says Gabriela Canalizo, an astronomer at the University of California, Riverside, who wasn’t part of the new research. Because the streaks of gas are so vast, stretching up to tens of thousands of light years, the way they glow reveals the history of the radiation coming from the quasar. As the quasar fades, so will the gas’s glow, with the regions of gas closer to the quasar dimming first. By analyzing how the glow dwindles with distance from the quasar, astronomers can determine how fast the quasar is fading. “This was something we’ve never been able to do,” Canalizo says.

Measuring how fast the quasar fades allows astronomers to figure out exactly what’s causing it to turn off in the first place. “What makes them dim is running out of material to eat,” Canalizo says. That could happen if the quasar is generating enough radiation to blow away all the gas and dust surrounding the black hole—the same gas and dust that feeds it. Without a steady diet, the quasar is powerless to produce radiation. Only if more gas happens to make its way toward the black hole can the quasar turn on again. The glowing gas can provide details of this process, and if other mechanisms are at play.

With more powerful telescopes, astronomers will likely find many more. Hanny’s Verwoort, it turns out, may not be that weird after all.

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Why the U.S. Gave Up on the Moon

Moon nearside



Excerpt from spacenews.com


Recently, several space advocacy groups joined forces to form the Alliance for Space Development. Their published objectives include a mention of obvious near-term goals such as supporting the commercial crew program, transitioning from use of the International Space Station to future private space stations and finding ways to reduce the cost of access to space.  What is notably missing from these objectives and those of many other space agencies, companies and advocacy groups is any mention of building a permanent settlement on the moon. It’s as if the lunar surface has become our crazy uncle that we all acknowledge exists but we’d prefer not to mention (or visit).  What made the next logical step in mankind’s progression beyond the bounds of Earth such a taboo subject?  If, as the Alliance for Space Development suggests, our nation wishes to move toward a path of permanent space settlements, the most logical step is our own planet’s satellite.

Lunar base conception
A 2006 NASA conception of a lunar base. Credit: NASA


A base on the lunar surface is a better place to study space settlement than a space station or Mars for many reasons. Unlike a space station, the base does not have to contend with aerodynamic drag, attitude control issues or contamination and impingement from its own thrusters. Unlike a space station, which exists in a total vacuum and resource void, a lunar base has access to at least some surface resources in the forms of minerals, albeit fewer than might be available on Mars.  Many people naturally want to go directly to Mars as our next step. Even SpaceX has publicly stated this as its ultimate goal, with SpaceX President Gwynne Shotwell noting that “we’re not moon people.” However, Mars makes sense only if we think the technology is ready to safely support humans on another surface for long periods of time. Furthermore, budget restrictions make an ambitious goal like going immediately to Mars an unlikely prospect. Why are we afraid to take the seemingly necessary baby steps of developing the technology for a long-term base on a surface that can be reached in mere days instead of months?  The tendency to want to skip a lunar settlement is not a new phenomenon. Even before the first landing on the moon, U.S. and NASA political leadership was contemplating the future of manned space, and few of the visions involved a lunar base. The early space program was driven by Cold War competition with Moscow, and the kinds of ideas that circulated at the time involved milestones that seemed novel such as reusable spaceplanes, nuclear-powered rockets, space stations and missions to Mars. 

When the United States was on the verge of a series of landings on the moon, building a permanent base just didn’t seem like much of a new giant leap. NASA's ConstellationNASA’s Constellation program, featuring the Orion manned capsule set atop the Ares 1 launch vehicle, was meant to send astronauts back to the moon. Credit: NASA  The idea of a lunar landing mission was not reintroduced seriously until the George W. Bush administration and the introduction of the Constellation program. This program came at a complex time for NASA: The space shuttle was recovering from the Columbia disaster, the space station was in the midst of construction and the United States found itself with large budget deficits. However, despite its budgetary and schedule problems, which are common in any serious aerospace development project from space programs to jumbo-jet development, it provided NASA with a vision and a goal that were reasonable and sensible as next steps toward a long-term future of exploration beyond Earth. 

Constellation was nevertheless canceled, and we have since returned to a most uncommon sense.  The decision to avoid any sort of lunar activity in current space policy may have been biased by the Obama administration’s desire to move as far away as possible from the policies of the previous administration. 

Regardless of the cause, discussion of returning to the moon is no longer on the table.  Without the moon, the only feasible mission that NASA could come up with that is within reach given the current technology and budget is the Asteroid Redirect Mission.  
Even planetary scientists have spoken out against the mission, finding that it will provide little scientific value. It will also provide limited engineering and technology value, if we assume that our long-term goal is to permanently settle space. The experience gained from this sort of flight has little applicability to planetary resource utilization, long-term life support or other technologies needed for settlement.  

If we are to have a program of manned space exploration, we must decide what the long-term goals of such a program should be, and we should align our actions with those goals. When resources such as funding are limited, space agencies and political leaders should not squander these limited resources on missions that make no sense. Instead, the limited funding should be used to continue toward our long-term goals, accepting a slower pace or slight scale-back in mission scope.  Establishing a permanent human settlement in space is a noble goal, one that will eventually redefine humanity. Like explorers before us, it is also not a goal that will be achieved in a short period of time. We would be wise to keep our eyes on that goal and the road needed to get us there. And the next likely stop on that road is a permanent home just above our heads, on the surface of the brightest light in the night sky.  

Paul Brower is an aerospace systems engineer on the operations team for the O3b Networks satellite fleet. He previously worked in mission control at NASA for 10 years.
Recently, several space advocacy groups joined forces to form the Alliance for Space Development. Their published objectives include a mention of obvious near-term goals such as supporting the commercial crew program, transitioning from use of the International Space Station to future private space stations and finding ways to reduce the cost of access to space.
What is notably missing from these objectives and those of many other space agencies, companies and advocacy groups is any mention of building a permanent settlement on the moon. It’s as if the lunar surface has become our crazy uncle that we all acknowledge exists but we’d prefer not to mention (or visit).
What made the next logical step in mankind’s progression beyond the bounds of Earth such a taboo subject?
If, as the Alliance for Space Development suggests, our nation wishes to move toward a path of permanent space settlements, the most logical step is our own planet’s satellite.
Lunar base conception
A 2006 NASA conception of a lunar base. Credit: NASA
A base on the lunar surface is a better place to study space settlement than a space station or Mars for many reasons. Unlike a space station, the base does not have to contend with aerodynamic drag, attitude control issues or contamination and impingement from its own thrusters. Unlike a space station, which exists in a total vacuum and resource void, a lunar base has access to at least some surface resources in the forms of minerals, albeit fewer than might be available on Mars.
Many people naturally want to go directly to Mars as our next step. Even SpaceX has publicly stated this as its ultimate goal, with SpaceX President Gwynne Shotwell noting that “we’re not moon people.” However, Mars makes sense only if we think the technology is ready to safely support humans on another surface for long periods of time. Furthermore, budget restrictions make an ambitious goal like going immediately to Mars an unlikely prospect. Why are we afraid to take the seemingly necessary baby steps of developing the technology for a long-term base on a surface that can be reached in mere days instead of months?
The tendency to want to skip a lunar settlement is not a new phenomenon. Even before the first landing on the moon, U.S. and NASA political leadership was contemplating the future of manned space, and few of the visions involved a lunar base. The early space program was driven by Cold War competition with Moscow, and the kinds of ideas that circulated at the time involved milestones that seemed novel such as reusable spaceplanes, nuclear-powered rockets, space stations and missions to Mars. When the United States was on the verge of a series of landings on the moon, building a permanent base just didn’t seem like much of a new giant leap.
NASA's Constellation
NASA’s Constellation program, featuring the Orion manned capsule set atop the Ares 1 launch vehicle, was meant to send astronauts back to the moon. Credit: NASA
The idea of a lunar landing mission was not reintroduced seriously until the George W. Bush administration and the introduction of the Constellation program. This program came at a complex time for NASA: The space shuttle was recovering from the Columbia disaster, the space station was in the midst of construction and the United States found itself with large budget deficits. However, despite its budgetary and schedule problems, which are common in any serious aerospace development project from space programs to jumbo-jet development, it provided NASA with a vision and a goal that were reasonable and sensible as next steps toward a long-term future of exploration beyond Earth.
Constellation was nevertheless canceled, and we have since returned to a most uncommon sense.
The decision to avoid any sort of lunar activity in current space policy may have been biased by the Obama administration’s desire to move as far away as possible from the policies of the previous administration. Regardless of the cause, discussion of returning to the moon is no longer on the table.
Without the moon, the only feasible mission that NASA could come up with that is within reach given the current technology and budget is the Asteroid Redirect Mission.
Even planetary scientists have spoken out against the mission, finding that it will provide little scientific value. It will also provide limited engineering and technology value, if we assume that our long-term goal is to permanently settle space. The experience gained from this sort of flight has little applicability to planetary resource utilization, long-term life support or other technologies needed for settlement.
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If we are to have a program of manned space exploration, we must decide what the long-term goals of such a program should be, and we should align our actions with those goals. When resources such as funding are limited, space agencies and political leaders should not squander these limited resources on missions that make no sense. Instead, the limited funding should be used to continue toward our long-term goals, accepting a slower pace or slight scale-back in mission scope.
Establishing a permanent human settlement in space is a noble goal, one that will eventually redefine humanity. Like explorers before us, it is also not a goal that will be achieved in a short period of time. We would be wise to keep our eyes on that goal and the road needed to get us there. And the next likely stop on that road is a permanent home just above our heads, on the surface of the brightest light in the night sky.

Paul Brower is an aerospace systems engineer on the operations team for the O3b Networks satellite fleet. He previously worked in mission control at NASA for 10 years.
- See more at: http://spacenews.com/op-ed-why-the-u-s-gave-up-on-the-moon/#sthash.czfTscvg.dpuf

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Top Secret Government Programs That Your Not Supposed To Know About

Originally Posted at in5d.com The following is the alleged result of the actions of one or more scientists creating a covert, unauthorized notebook documenting their involvement with an Above Top Secret government program. Government publications and information obtained by the use of public tax monies cannot be subject to copyright. This document is released into the public domain for all citizens of the United States of America. THE ‘MAJIC PROJECTS’ SIGMA is the project whic [...]

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This Alien Color Catalog May Help Us Spot Life on Other Planets






Excerpt from smithsonianmag.com


In the hunt for alien life, our first glimpse of extraterrestrials may be in the rainbow of colors seen coming from the surface of an exoplanet.

That's the deceptively simple idea behind a study led by Siddharth Hegde at the Max Planck Institute for Astronomy in Germany. Seen from light-years away, plants on Earth give our planet a distinctive hue in the near-infrared, a phenomenon called red edge. That's because the chlorophyll in plants absorbs most visible light waves but starts to become transparent to wavelengths on the redder end of the spectrum. An extraterrestrial looking at Earth through a telescope could match this reflected color with the presence of oxygen in our atmosphere and conclude there is life here.


exoplanets palette
Eight of the 137 microorganism samples used to measure biosignatures for the catalog of reflection signatures of Earth life forms. In each panel, the top is a regular photograph of the sample and the bottom is a micrograph, a version of the top image zoomed-in 400 times.



Plants, though, have only been around for 500 million years—a relative blip in our planet's 4.6-billion-year history. Microbes dominated the scene for some 2.5 billion years in the past, and some studies suggest they will rule the Earth again for much of its future. So Hegde and his team gathered 137 species of microorganisms that all have different pigments and that reflect light in specific ways. By building up a library of the microbes' reflectance spectra—the types of colors those microscopic critters reflect from a distance—scientists examining the light from habitable exoplanets can have a plethora of possible signals to search for, the team argues this week in the Proceedings of the National Academy of Sciences.

"No one had looked at the wide range of diverse life on Earth and asked how we could potentially spot such life on other planets, and include life from extreme environments on Earth that could be the 'norm' on other planets," Lisa Kaltenegger, a co-author on the study, says via email. "You can use it to model an Earth that is different and has different widespread biota and look how it would appear to our telescopes."

To make sure they got enough diversity, the researchers looked at temperate-dwelling microbes as well as creatures that live in extreme environments like deserts, mineral springs, hydrothermal vents or volcanically active areas.

While it might seem that alien life could take a huge variety of forms—for instance, something like the silicon-based Horta from Star Trek—it's possible to narrow things down if we restrict the search to life as we know it. First, any life-form that is carbon-based and uses water as a solvent isn't going to like the short wavelengths of light far in the ultraviolet, because this high-energy UV can damage organic molecules. At the other end of the spectrum, any molecule that alien plants (or their analogues) use to photosynthesize won't be picking up light that's too far into the infrared, because there's not enough energy at those longer wavelengths.

In addition, far-infrared light is hard to see through an Earth-like atmosphere because the gases block a lot of these waves, and whatever heat the planet emits will drown out any signal from surface life. That means the researchers restricted their library to the reflected colors we can see when looking at wavelengths in the visible part of the spectrum, the longest wavelength UV and short-wave infrared.

The library won't be much use if we can't see the planets' surfaces in the first place, and that's where the next generation of telescopes comes in, Kaltenegger says. The James Webb Space Telescope, scheduled for launch in 2018, should be able to see the spectra of relatively small exoplanet atmospheres and help scientists work out their chemical compositions, but it won't be able to see any reflected spectra from material at the surface. Luckily, there are other planned telescopes that should be able to do the job. The European Extremely Large Telescope, a 40-meter instrument in Chile, will be complete by 2022. And NASA's Wide Field Infrared Survey Telescope, which is funded and in its design stages, should be up and running by the mid-2020s.

Another issue is whether natural geologic or chemical processes could look like life and create a false signal. So far the pigments from life-forms look a lot different from those reflected by minerals, but the team hasn't examined all the possibilities either, says Kaltenegger. They hope to do more testing in the future as they build up the digital library, which is now online and free for anyone to explore at biosignatures.astro.cornell.edu.

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