If a scientific team working at the National Institute of Standards and Technology (NIST) is right, we may be able to find extraterrestrial life even before it leaves its home planet—by looking for left- (or right-) handed light.
The technique the team has developed* for detecting life elsewhere in the universe will not spot aliens directly. Rather, it could allow spaceborne instruments to see a telltale sign that life may have influenced a landscape: a preponderance of molecules that have a certain “chirality,” or handedness. A right-handed molecule has the same composition as its left-handed cousin, but their chemical behavior differs. Because many substances critical to life favor a particular handedness, Thom Germer and his colleagues think chirality might reveal life’s presence at great distances, and have built a device to detect it.
“You don’t want to limit yourself to looking for specific materials like oxygen that Earth creatures use, because that makes assumptions about what life is,” says Germer, a physicist at NIST. “But amino acids, sugars, DNA—each of these substances is either right- or left-handed in every living thing.”
Many molecules not associated with life exhibit handedness as well. But when organisms reproduce, their offspring possess chiral molecules that have the same handedness as those in their parents’ bodies. As life spreads, the team theorizes, the landscape will eventually have a large amount of molecules that favor one handedness.
“If the surface had just a collection of random chiral molecules, half would go left, half right,” Germer says. “But life’s self-assembly means they all would go one way. It’s hard to imagine a planet’s surface exhibiting handedness without the presence of self assembly, which is an essential component of life.”
Because chiral molecules reflect light in a way that indicates their handedness, the research team built a device to shine light on plant leaves and bacteria, and then detect the polarized reflections from the organisms’ chlorophyll from a short distance away. The device detected chirality from both sources.
The team intends to improve its detector so it can look at pond surfaces and then landscape-sized regions on Earth. Provided the team continues to get good results, Germer says, they will propose that it be built into a large telescope or mounted on a space probe.
“We need to be sure we get a signal from our own planet before we can look at others,” he says. “But what’s neat about the concept is that it is sensitive to something that comes from the process behind organic self-assembly, but not necessarily life as we know it.”
Funding for this research was provided by the Space Telescope Science Institute and the European Space Agency.
* W.B. Sparks, J. Hough, T.A. Germer, F. Chen, S. DasSarma, P. DasSarma, F.T. Robb, N. Manset, L. Kolokolova, N. Reid, F.D. Macchetto and W. Martin. Detection of circular polarization in light scattered from photosynthetic microbes. Proceedings of the National Academy of Sciences, April 20, 2009.
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Lightest exoplanet yet discovered
Well-known exoplanet researcher Michel Mayor today announced the discovery of the lightest exoplanet found so far. The planet, “e”, in the famous system Gliese 581, is only about twice the mass of our Earth. The team also refined the orbit of the planet Gliese 581 d, first discovered in 2007, placing it well within the habitable zone, where liquid water oceans could exist. These amazing discoveries are the outcome of more than four years of observations using the most successful low-mass-exoplanet hunter in the world, the HARPS spectrograph attached to the 3.6-metre ESO telescope at La Silla, Chile.
“The holy grail of current exoplanet research is the detection of a rocky, Earth-like planet in the ‘habitable zone’ — a region around the host star with the right conditions for water to be liquid on a planet’s surface”, says Michel Mayor from the Geneva Observatory, who led the European team to this stunning breakthrough.
Planet Gliese 581 e orbits its host star – located only 20.5 light-years away in the constellation Libra (“the Scales”) — in just 3.15 days. “With only 1.9 Earth-masses, it is the least massive exoplanet ever detected and is, very likely, a rocky planet”, says co-author Xavier Bonfils from Grenoble Observatory.
Being so close to its host star, the planet is not in the habitable zone. But another planet in this system appears to be. From previous observations — also obtained with the HARPS spectrograph at ESO’s La Silla Observatory and announced two years ago — this star was known to harbour a system with a Neptune-sized planet (ESO 30/05) and two super-Earths (ESO 22/07). With the discovery of Gliese 581 e, the planetary system now has four known planets, with masses of about 1.9 (planet e), 16 (planet b), 5 (planet c), and 7 Earth-masses (planet d). The planet furthest out, Gliese 581 d, orbits its host star in 66.8 days. “Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star,” says team member Stephane Udry. The new observations have revealed that this planet is in the habitable zone, where liquid water could exist. “‘d’ could even be covered by a large and deep ocean — it is the first serious 'water world' candidate,” continued Udry.
The gentle pull of an exoplanet as it orbits the host star introduces a tiny wobble in the star’s motion — only about 7 km/hour, corresponding to brisk walking speed — that can just be detected on Earth with today’s most sophisticated technology. Low-mass red dwarf stars such as Gliese 581 are potentially fruitful hunting grounds for low-mass exoplanets in the habitable zone. Such cool stars are relatively faint and their habitable zones lie close in, where the gravitational tug of any orbiting planet found there would be stronger, making the telltale wobble more pronounced. Even so, detecting these tiny signals is still a challenge, and the discovery of Gliese 581 e and the refinement of Gliese 581 d’s orbit were only possible due to HARPS’s unique precision and stability.
“It is amazing to see how far we have come since we discovered the first exoplanet around a normal star in 1995 — the one around 51 Pegasi,” says Mayor. “The mass of Gliese 581 e is 80 times less than that of 51 Pegasi b. This is tremendous progress in just 14 years.”
The astronomers are confident that they can still do better.
“With similar observing conditions an Earth-like planet located in the middle of the habitable zone of a red dwarf star could be detectable,” says Bonfils. “The hunt continues.”
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ESO, the European Southern Observatory, will hold a press conference on Tuesday morning to announce "a major and truly unique discovery in the field of exoplanets, made possible with ESO telescopes."
With solar system exploration progressing at pace, some scientists are considering missions to often overlooked worlds. One of these is Ceres, the smallest known dwarf planet which lies within the asteroid belt. Investigations have shown that it is an excellent target for exploration and may even have astrobiological significance.
Ceres Polar Lander
Joël Poncy is in charge of interplanetary advanced projects within the Observation and Science Directorate of Thales Alenia Space, a European company that works on satellite systems and other orbital infrastructures. This organization has been involved in many scientific missions, including the Huygens probe, CoRoT, ExoMars, Mars Express and Venus Express. Poncy and his team, in association with Olivier Grasset and Gabriel Tobie from LPG-Nantes, now have turned their eyes to Ceres.
Preliminary plans for a Ceres Polar Lander are currently being drawn up. The idea is to build a low-cost mission using reliable existing technology to complement other larger missions, while benefiting from NASA’s Dawn mission results. Assuming launch by a Soyuz rocket, the spacecraft would take around four years to reach Ceres. It would then enter orbit before attempting a landing.
Poncy elaborates, “the lander would separate from the carrier, brake, land close to the target site while automatically avoiding boulders and permanent shadows. We would then operate a Phoenix-like analysis of the surrounding soil and release a mini-rover to explore further. Astrobiological experiments similar to ExoMars can be envisaged.”
NASA's Kepler mission has taken its first images of the star-rich sky where it will soon begin hunting for planets like Earth.
The new "first light" images show the mission's target patch of sky, a vast starry field in the Cygnus-Lyra region of our Milky Way galaxy. One image shows millions of stars in Kepler's full field of view, while two others zoom in on portions of the larger region. The images can be seen online at:
http://www.nasa.gov/mission_pages/kepler/multimedia/20090416.html
"Kepler's first glimpse of the sky is awe-inspiring," said Lia LaPiana, Kepler's program executive at NASA Headquarters in Washington. "To be able to see millions of stars in a single snapshot is simply breathtaking."
One new image from Kepler shows its entire field of view -- a 100-square-degree portion of the sky, equivalent to two side-by-side dips of the Big Dipper. The regions contain an estimated 14 millions stars, more than 100,000 of which were selected as ideal candidates for planet hunting.
Two other views focus on just one-thousandth of the full field of view. In one image, a cluster of stars located about 13,000 light-years from Earth, called NGC 6791, can be seen in the lower left corner. The other image zooms in on a region containing a star, called Tres-2, with a known Jupiter-like planet orbiting every 2.5 days.
"It's thrilling to see this treasure trove of stars," said William Borucki, science principal investigator for Kepler at NASA's Ames Research Center at Moffett Field, Calif. "We expect to find hundreds of planets circling those stars, and for the first time, we can look for Earth-size planets in the habitable zones around other stars like the sun."
Kepler will spend the next three-and-a-half years searching more than 100,000 pre-selected stars for signs of planets. It is expected to find a variety of worlds, from large, gaseous ones, to rocky ones as small as Earth. The mission is the first with the ability to find planets like ours -- small, rocky planets orbiting sun-like stars in the habitable zone, where temperatures are right for possible lakes and oceans of water.
To find the planets, Kepler will stare at one large expanse of sky for the duration of its lifetime, looking for periodic dips in starlight that occur as planets circle in front of their stars and partially block the light. Its 95-megapixel camera, the largest ever launched into space, can detect tiny changes in a star's brightness of only 20 parts per million. Images from the camera are intentionally blurred to minimize the number of bright stars that saturate the detectors. While some of the slightly saturated stars are candidates for planet searches, heavily saturated stars are not.
"Everything about Kepler has been optimized to find Earth-size planets," said James Fanson, Kepler's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Our images are road maps that will allow us, in a few years, to point to a star and say a world like ours is there."
Scientists and engineers will spend the next few weeks calibrating Kepler's science instrument, the photometer, and adjusting the telescope's alignment to achieve the best focus. Once these steps are complete, the planet hunt will begin.
"We've spent years designing this mission, so actually being able to see through its eyes is tremendously exciting," said Eric Bachtell, the lead Kepler systems engineer at Ball Aerospace & Technology Corp. in Boulder, Colo. Bachtell has been working on the design, development and testing of Kepler for nine years.
Kepler is a NASA Discovery mission. Ames is responsible for the ground system development, mission operations and science data analysis. JPL manages the Kepler mission development. Ball Aerospace & Technologies Corp. is responsible for developing the Kepler flight system and supporting mission operations.
For images, animations and more information about the Kepler mission, visit:
NASA's twin STEREO probes are entering a mysterious region of space to look for remains of an ancient planet which once orbited the Sun not far from Earth. If they find anything, it could solve a major puzzle--the origin of the Moon.
"The name of the planet is Theia," says Mike Kaiser, STEREO project scientist at the Goddard Space Flight Center. "It's a hypothetical world. We've never actually seen it, but some researchers believe it existed 4.5 billion years ago—and that it collided with Earth to form the Moon."
The "Theia hypothesis" is a brainchild of Princeton theorists Edward Belbruno and Richard Gott. It starts with the popular Great Impact theory of the Moon's origin. Many astronomers hold that in the formative years of the solar system, a Mars-sized protoplanet crashed into Earth. Debris from the collision, a mixture of material from both bodies, spun out into Earth orbit and coalesced into the Moon. This scenario explains many aspects of lunar geology including the size of the Moon's core and the density and isotopic composition of moon rocks.
It's a good theory, but it leaves one awkward question unanswered: Where did the enormous protoplanet come from?
Sun-Earth Lagrange points are regions of space where the pull of the Sun and Earth combine to form a "gravitational well." The flotsam of space tends to gather there much as water gathers at the bottom of a well on Earth. 18th-century mathematician Josef Lagrange proved that there are five such wells in the Sun-Earth system: L1, L2, L3, L4 and L5 located as shown in the diagram below.
When the solar system was young, Lagrange points were populated mainly by planetesimals, the asteroid-sized building blocks of planets. Belbruno and Gott suggest that in one of the Lagrange points, L4 or L5, the planetesimals assembled themselves into Theia, nicknamed after the mythological Greek Titan who gave birth to the Moon goddess Selene.
"Their computer models show that Theia could have grown large enough to produce the Moon if it formed in the L4 or L5 regions, where the balance of forces allowed enough material to accumulate," says Kaiser. "Later, Theia would have been nudged out of L4 or L5 by the increasing gravity of other developing planets like Venus and sent on a collision course with Earth."
If this idea is correct, Theia itself is long gone, but some of the ancient planetesimals that failed to join Theia may still be lingering at L4 or L5.
"The STEREO probes are entering these regions of space now," says Kaiser. "This puts us in a good position to search for Theia's asteroid-sized leftovers."
Just call them "Theiasteroids."
Astronomers have looked for Theiasteroids before using telescopes on Earth, and found nothing, but their results only rule out kilometer-sized objects. By actually entering L4 and L5, STEREO will be able to hunt for much smaller bodies at relatively close range.
"The search actually began last month when both spacecraft rolled 180 degrees so that they could take a series of 2-hour exposures of the general L4/L5 areas. In the first sets of images, amateur astronomers found some known asteroids and new comet Itagaki was imaged just a couple of days after the announcement of its discovery. No Theiasteroids however."
Hunting for Theiasteroids is not STEREO's primary mission, he points out. "STEREO is a solar observatory. The two probes are flanking the sun on opposite sides to gain a 3D view of solar activity. We just happen to be passing through the L4 and L5 Lagrange points en route. This is purely bonus science."
"We might not see anything," he continues, "but if we discover lots of asteroids around L4 or L5, it could lead to a mission to analyze the composition of these asteroids in detail. If that mission discovers the asteroids have the same composition as the Earth and Moon, it will support Belbruno and Gott's version of the giant impact theory."
The search will continue for many months to come. Lagrange points are not infinitesimal points in space; they are broad regions 50 million kilometers wide. The STEREO probes are only in the outskirts now. Closest approach to the bottoms of the gravitational wells comes in Sept-Oct. 2009. "We have a lot of observing ahead of us," notes Kaiser.
Readers, you may be able to help. The STEREO team is inviting the public to participate in the search by scrutinizing photos as they come in from the spacecraft. If you see a dot of light moving with respect to the stars, you may have found a Theiasteroid. Links to the data and further instructions may be found at sungrazer.nrl.navy.mil.
Let the hunt begin!
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Artist's impression of the five-Earth mass planet, Gliese 581 c, found in the habitable zone around the red dwarf Gliese 581. Credit: European Southern Observatory
Source and Credit: Astrobiology Magazine (NASA)
Summary (Apr 09, 2009): Not astrobiologists' first choice, red dwarf stars have now gained acceptance as potential hosts for habitable planets. They may not be great to live by in the first couple billion years, but they eventually settle down into relatively pleasant stars.
Roughly three quarters of the stars in the galaxy are red dwarfs. Planet searches have typically passed over these tiny faint stars because they were thought to be unfriendly to potential life forms. However, this prejudice has softened. Preliminary results from a dedicated research program have shown that planets around red dwarfs could be habitable if they can maintain a magnetic field for a few billion years.
Red dwarfs - also called M dwarfs - are between 7 and 60 percent as massive as our sun. Their lower mass means they don’t burn as hot or as brightly, emitting less than 5 percent as much light as the sun. However, they have strong magnetic activity, which makes them relatively bright in X-rays and UV radiation and causes them to flare frequently.
To understand the environment around these common stars, the "Living with a Red Dwarf" program was started three years ago. It is piecing together observational data to provide a profile of how red dwarfs vary in brightness and magnetic activity as they age.
"This is the information that you would want to know to model the suitability for life on a nearby planet," says Ed Guinan of Villanova University, a scientist working with the program.
As habitability goes, red dwarfs were thought to be the bad roommates of the cosmos.
Because they are so faint, the habitable zone — the distance from a star where liquid water can exist — is in many cases closer than the orbital distance between Mercury and our sun. When a planet orbits a star this closely, the gravitational pull of the star may cause the planet to become tidally locked with the same side always facing the star (similar to the Moon's fixed gaze on the Earth).
The habitable zone (HZ) around a red (dM), orange (dK) and yellow (dG) dwarf star. The dotted pink circle is orbit which would have our Earth's temperature. Credit: Living with a Red Dwarf program.
Engineers have successfully ejected the dust cover from NASA's Kepler telescope, a spaceborne mission soon to begin searching for worlds like Earth.
"The cover released and flew away exactly as we designed it to do," said Kepler Project Manager James Fanson of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This is a critical step toward answering a question that has come down to us across 100 generations of human history -- are there other planets like Earth, or are we alone in the galaxy?"
Kepler, which launched on March 6 from Cape Canaveral, Fla., will spend three-and-a-half years staring at more than 100,000 stars in our Milky Way galaxy for signs of Earth-size planets. Some of the planets are expected to orbit in a star's "habitable zone," a warm region where water could pool on the surface. The mission's science instrument, called a photometer, contains the largest camera ever flown in space -- its 42 charge-coupled devices (CCDs) will detect slight dips in starlight, which occur when planets passing in front of their stars partially block the light from Kepler's view.
The telescope's oval-shaped dust cover, measuring 1.7 meters by 1.3 meters (67 inches by 52 inches), protected the photometer from contamination before and after launch. The dust cover also blocked stray light from entering the telescope during launch -- light that could have damaged its sensitive detectors. In addition, the cover was important for calibrating the photometer. Images taken in the dark helped characterize noise coming from the instrument's electronics, and this noise will later be removed from the actual science data.
"Now the photometer can see the stars and will soon start the task of detecting the planets," said Kepler's Science Principal Investigator William Borucki at NASA's Ames Research Center, Moffett Field, Calif. "We have thoroughly measured the background noise so that our photometer can detect minute changes in a star's brightness caused by planets."
At 7:13 p.m. PDT on April 7, engineers at Kepler's mission operations center at the Laboratory for Atmospheric and Space Physics, Boulder, Colo., sent commands to pass an electrical current through a "burn wire" to break the wire and release a latch holding the cover closed. The spring-loaded cover swung open on a fly-away hinge, before drifting away from the spacecraft. The cover is now in its own orbit around the sun, similar to Kepler's sun-centric orbit. See an animation of the event at http://www.nasa.gov/mission_pages/kepler/multimedia/videos/cover.html .
With the cover off, starlight is entering the photometer and being imaged onto its focal plane. Engineers will continue calibrating the instrument using images of stars for another several weeks, after which science observations will begin.
Kepler is a NASA Discovery mission. NASA's Ames Research Center Ames is the home organization of the science principal investigator, and is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Kepler mission development. Ball Aerospace & Technologies Corp., Boulder, Colo., is responsible for developing the Kepler flight system and supporting mission operations.
For more information about the Kepler mission, visit http://www.nasa.gov/kepler .
Honda has developed the world’s first Brain Machine Interface (BMI) technology that uses electroencephalography (EEG) and near-infrared spectroscopy (NIRS) along with newly developed information extraction technology to enable control of a robot by human thought alone. It does not require any physical movement such as pressing buttons. This technology will be further developed for the application to human-friendly products in the future by integrating it with intelligent technologies and/or robotic technologies.
During the human thought process, slight electrical current and blood flow change occur in the brain. The most important factor in the development of the BMI technology is the accuracy of measuring and analyzing these changes. The newly developed BMI technology uses EEG, which measures changes in electrical potential on the scalp, and NIRS, which measures changes in cerebral blood flow, with a newly developed information extraction technology which enables statistical processing of the complex information from these two types of sensors. As a result, it became possible to distinguish brain activities with high precision without any physical motion, but just human thought alone.
The BMI technology announced uses a functional magnetic resonance imaging (fMRI) scanner to measure brain activities. The large size and powerful magnetic field generated by the fMRI scanner limited the locations and conditions where it can be used. As the newly developed measuring device uses EEG and NIRS sensors, it can be transported to and used in various locations.
In 19 years of observations, the Hubble Space Telescope has amassed a huge archive of data.
That archive may contain the telltale glow of undiscovered extrasolar planets, says David Lafrenière of the University of Toronto, Ontario, Canada. His team found the outermost of three massive planets known to orbit the young star HR 8799, which is 130 light-years away. The planetary trio was originally discovered in images taken with the Keck and Gemini North telescopes in 2007 and 2008. But using a new image processing technique that suppresses the glare of the parent star, Lafrenière found the telltale glow of the outermost planet in the system while studying Hubble archival data taken in 1998. The giant planet is young and hot, but still only 1/100,000th the brightness of its parent star (by comparison, cooler Jupiter is one-billionth the brightness of the sun).
Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has looked at over 200 other stars in coronagraphic mode, where the light of the star is largely blocked out, to search for the feeble glow of planets. Lafrenière plans to look for undiscovered planets in the NICMOS archive dataset and do follow-up observations with ground-based telescopes on any candidates that pop up. As an added bonus, NICMOS made a near-infrared measurement that suggests water vapor is in the atmosphere of the planet. This could not be easily achieved with ground-based telescopes, because water vapor in Earth's atmosphere absorbs some infrared wavelengths. Measuring the water absorption properties on this exoplanet will tell astronomers a great deal about the temperatures and pressures in the atmosphere, and about the prevalence of dust clouds. But don't go looking for beachfront property; the planet is 1,500 degrees Fahrenheit -- too hot even for water vapor clouds.
Read more:
Both a Spanish and a French astrophysicist have identified a band in the infrared range that serves to track the presence of organic material rich in oxygen and nitrogen in the interstellar dust grains. Should any telescope detect this band, the presence in space of aminoacids and other substances, which are the precursors to life, could be confirmed.
"We have proved in the laboratory that an organic material of prebiotic interest known as yellow stuff possesses a very characteristic absorption band that can be searched for in zones in space which have dust grains in order to try and identify similar substances", Guillermo Muñoz, a researcher at the Centre for Astrobiology (INTA-CSIC), points out to SINC.
The scientist explains that the dust grains observed in the interstellar clouds and around the young stars are usually "surrounded by tiny mantles of ice rich in water and other simple molecules, such as carbon monoxide (CO), methanol (CH3OH) or ammonia (NH3), upon which light and cosmic rays fall".
Muñoz and his French colleague Emmanuel Dartois, from the Institute of Space Astrophysics in Paris (France), have recreated these interstellar conditions in the laboratory by mixing various gases at a very low pressure and temperature (-263ºC), and then irradiating the interstellar ice which is formed with ultraviolet light. As a result yellow stuff is generated, a yellowish substance rich in carbon but with hydrogen, nitrogen and a lot of associated oxygen. This material is composed of numerous organic molecules, such as carboxylic acids, glycine and other aminoacids (molecules that are essential to the composition of proteins).
The yellow stuff absorption band is situated within the 3.4 micrometres of the mid-infrared spectrum and when represented on a graph its profile has two characteristic peaks. "This makes it possible to detect this band in planet-forming regions similar to our solar nebula and Solar System bodies", Muñoz points out.
"Moreover the synthesis of organic compounds by ice irradiation could be related to the presence of this substance in comets, such as the Halley comet, and could explain also the isotopic composition of the carbonaceous material detected in interplanetary dust and in types of meteorities rich in carbon which are known as carbonaceous chondrites", he adds.
Until now scientists have not observed the yellow stuff infrared band in interstellar space, and the same is true for Solar System bodies, but they do postulate that this could be due to the limitations in present techniques. In the case of carbonaceous chondrites and interplanetary dust, both contain carbon associated with heavy hydrogen isotopes (deuterium above all, 2H) and nitrogen (15N) characteristic of chemical reactions at very low temperatures, such as those generated in irradiated ice, but that type of meteoritic carbon is different to yellow stuff.
The prebiotic substances derived from the irradiation of ice lose their organic character and high hydrogen, nitrogen and oxygen content when heated at more than 300 ºC; this occurs in the proximities of the Sun. "That type of heated yellow stuff, which still maintains a high content of heavy isotopes, could be the sort that is found to form part of the carbonaceous chondrites and interplanetary dust", Muñoz points out to SINC.
The Rosetta space probe belonging to the European Space Agency will try to detect aminoacids and other molecules of prebiotic interest in the central core of the Comet 67P/Churyumov-Gerasimenko, when the probe arrives there in 2014.
