Friday, 7 August 2015
Tuesday, 4 August 2015
today`s discussion :Is sex education is need in schools? If yes then how to implement it ? discuss its merits +- etc possibilities also... in comments..
Posted by We Are Future Kalam on Tuesday, August 4, 2015
Friday, 31 July 2015
Origins of Stars and Planets
When studying the origins of stars and planets, researchers at the Jet Propulsion Laboratory (JPL) use telescopes and advanced models to study the formation and death of stars, the physical and chemical processes in the spinning clouds of gas and dust where these stars are born, and the direct detection of planets around other stars. JPL collaborates with many groups that use telescopes to look for these conditions in the universe.
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| Simulated image of a nearby planetary system, as would be taken using an advanced coronagraph demonstrated at JPL. From Trauger and Traub, Nature 446 771 (2007). |
Planetary systems form from clouds of gas and dust orbiting the youngest stars. Studying this process requires making measurements with high spatial resolution and high contrast. Researchers in the origins of stars and planets research area use the Hubble, Spitzer, Herschel and Keck telescopes to study circumstellar matter and extrasolar planets. They are also leading the development of future telescope technologies that will open up the field for further study. Scientists in the space and astrophysical plasmas research area use computer modeling to translate the observational data into information about the processes that lead to forming stars and planets. Their models model the gas flows around young stars, the molecular reactions in the flows, the evolution of the solid material within and the emission of the radiation reaching our detectors.
This work comprises:
- Development of high contrast imaging technologies and future space telescope mission concepts, toward the goal of directly imaging planets around other stars. Laboratory coronagraphs have achieved contrasts exceeding billion-to-one in JPL space-simulating testbeds.
- High contrast imaging and interferometry experiments carried out at the Palomar and Keck observatories and at the Center for High Angular Resolution Astronomy (CHARA) array.
- Studies of planet formation in the circumstellar disks of young stars using ground and space observatories and computer modeling. Imaging with Hubble, in combination with Spitzer and Herschel measurements and detailed modeling, is leading to new insights into the disks' structure, composition and evolution.
- Numerical modeling to predict the planet formation signatures that will be detectable with future telescopes such as SOFIA and JWST.
- Characterization of the composition and structure of exoplanet atmospheres using infrared spectroscopy of transiting hot Jupiters.
- Studies of outflows from young stars and dying stars.
Selected Research Projects
Scientists in the origins of stars and planets research area work on a broad range of cutting-edge research projects, which include:
The Herschel Space Observatory
The European Space Agency (ESA)'s Herschel Space Observatory was launched on May 14, 2009, and with a primary mirror 3.5 m across, is the largest, most powerful infrared telescope ever flown in space. NASA and JPL's contributions to this groundbreaking observatory were comprised of two instruments: The Spectral and Photometric Imaging Receiver (SPIRE) and the Heterodyne Instrument for the Far Infrared (HIFI). SPIRE used "spider web bolometers," which are 40 times more sensitive than previous composite bolometers. SPIRE was developed at JPL by Dr. James Bock, SPIRE's Co-Investigator. Also onboard Herschel is the Heterodyne Instrument for the Far Infrared (HIFI) instrument. HIFI sensed radiation along six wavelength bands. NASA provided the mixers and local oscillator chains for the two highest bands, five and six; other local oscillator components for bands one through four; and power amplifiers. All instruments were cooled to -271ºC inside a cryostat filled with liquid superfluid helium. The mission finally exhausted its coolant on April 29, 2013.
The European Space Agency (ESA)'s Herschel Space Observatory was launched on May 14, 2009, and with a primary mirror 3.5 m across, is the largest, most powerful infrared telescope ever flown in space. NASA and JPL's contributions to this groundbreaking observatory were comprised of two instruments: The Spectral and Photometric Imaging Receiver (SPIRE) and the Heterodyne Instrument for the Far Infrared (HIFI). SPIRE used "spider web bolometers," which are 40 times more sensitive than previous composite bolometers. SPIRE was developed at JPL by Dr. James Bock, SPIRE's Co-Investigator. Also onboard Herschel is the Heterodyne Instrument for the Far Infrared (HIFI) instrument. HIFI sensed radiation along six wavelength bands. NASA provided the mixers and local oscillator chains for the two highest bands, five and six; other local oscillator components for bands one through four; and power amplifiers. All instruments were cooled to -271ºC inside a cryostat filled with liquid superfluid helium. The mission finally exhausted its coolant on April 29, 2013.
Herschel will continue communicating with its ground stations for some time now that the helium is exhausted, during which a range of technical tests will be performed. In May, 2013 it was propelled into its long-term stable parking orbit around the Sun.
Herschel was crucial in helping researchers study and understand:
- Birth of stars
- How galaxies formed and evolved in the early universe, and the nature of enormously powerful galactic energy sources
- The formation, evolution, and interrelationship of stars and the interstellar medium in the Milky Way and other galaxies
- Chemistry in our galaxy
- Molecular chemistry in the atmospheres of Mars and our solar system's comets and giant planets, and the nature of comet-like objects in the Kuiper belt beyond Neptune.
With its unique ability to detect light in the full 60-670 micron range, Herschel was successful in gathering information that has previously been unavailable.
The Exoplanet Exploration Program
Exoplanetary science is among the fastest evolving fields of today's astronomical research. Ground-based planet-hunting surveys alongside dedicated space missions (such as Kepler and CoRoT) are delivering an ever-increasing number of exoplanets.
Exoplanetary science is among the fastest evolving fields of today's astronomical research. Ground-based planet-hunting surveys alongside dedicated space missions (such as Kepler and CoRoT) are delivering an ever-increasing number of exoplanets.
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| Spectrum of transiting extrasolar planet, made with the Spitzer Space Telescope. From Swain et al., Astrophysical Journal 674 482 (2008). |
In January 2013, the NASA Astrophysics Division initiated the formation of two Science and Technology Definition Teams (STDTs) to study probe-scale (cost less than $1B) mission concepts for the direct detection of extrasolar planets orbiting nearby stars. One will study a concept based on a telescope with an internal coronagraph to generate the ultra-high contrast images needed for planet detection. A second study will use a pair of spacecraft flying in formation - a telescope and an external occulter (starshade). The STDTs are supported by a Design Team staffed by the Exoplanet Exploration Program. Final Reports from the studies will be due by January 2015.
The Hubble Space Telescope
Among its many discoveries, the Hubble Space Telescope has revealed the age of the universe to be about 13 to 14 billion years, much more accurate than the old range of anywhere from 10 to 20 billion years. Hubble played a key role in the discovery of dark energy, a mysterious force that causes the expansion of the universe to accelerate.
Among its many discoveries, the Hubble Space Telescope has revealed the age of the universe to be about 13 to 14 billion years, much more accurate than the old range of anywhere from 10 to 20 billion years. Hubble played a key role in the discovery of dark energy, a mysterious force that causes the expansion of the universe to accelerate.
Hubble has revealed galaxies in all stages of evolution, as well as protoplanetary disks, clumps of gas and dust around young stars that likely function as birthing grounds for new planets. It discovered that gamma-ray bursts — strange, incredibly powerful explosions of energy — occur in far-distant galaxies when massive stars collapse. And these are only a handful of its many contributions to astronomy.
The Hubble Space Telescope's science instruments -- its cameras, spectrographs, and fine guidance sensors -- work either together or individually to bring us stunning images from the farthest reaches of space.
One of these instruments, the Wide Field/Planetary Camera, was installed on the Hubble telescope when it was first launched into Earth orbit on a space shuttle on April 24, 1990. Scientists soon discovered, however, that a tiny error in the curvature of the space telescope's main mirror made it impossible to focus images sharply. Fortunately, JPL engineers determined that by changing the optics of the camera instrument, the telescope's problem could be overcome. The Wide Field and Planetary Camera 2 was installed on the Hubble telescope by astronauts on December 2, 1993. This brought Hubble's vision to perfect focus, and over the next few years the space telescope has relayed phenomenal pictures and made possible a variety of discoveries. The James Webb Space Telescope (JWST) could add to Hubble's discoveries, when it launches in 2018. JWST is a large, infrared-optimized space telescope that will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. JWST could peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. Webb's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.
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| Star-forming region in Carina. Credit: NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI). |
Spitzer Telescope
The Spitzer Space Telescope (formerly SIRTF, the Space Infrared Telescope Facility) was launched into space by a Delta rocket from Cape Canaveral, Florida on August 25, 2003. During its mission, Spitzer will obtain images and spectra by detecting the infrared energy, or heat, radiated by objects in space between wavelengths of 3 and 180 microns (1 micron is one-millionth of a meter). Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground.
The Spitzer Space Telescope (formerly SIRTF, the Space Infrared Telescope Facility) was launched into space by a Delta rocket from Cape Canaveral, Florida on August 25, 2003. During its mission, Spitzer will obtain images and spectra by detecting the infrared energy, or heat, radiated by objects in space between wavelengths of 3 and 180 microns (1 micron is one-millionth of a meter). Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground.
Consisting of a 0.85-meter telescope and three cryogenically-cooled science instruments, Spitzer is the largest infrared telescope ever launched into space. Infrared reveals information about the cooler objects in space, such as smaller stars which are too dim to be detected by their visible light, extrasolar planets, and giant molecular clouds. Also, many molecules in space, including organic molecules, have their unique signatures in the infrared.
Because infrared is primarily heat radiation, the telescope must be cooled to near absolute zero (-459 degrees Fahrenheit or -273 degrees Celsius) so that it can observe infrared signals from space without interference from the telescope's own heat. Also, the telescope must be protected from the heat of the Sun and the infrared radiation put out by the Earth. To do this, Spitzer carries a solar shield and will be launched into an Earth-trailing solar orbit. This unique orbit places Spitzer far enough away from the Earth to allow the telescope to cool rapidly without having to carry large amounts of cryogen (coolant).
Contacts
Structure and Evolution of Normal & Active Galaxies
Galactic structure and evolution involve analyses of whole galaxies as self-contained systems of dark matter, stars, and gas that evolve over billions of years. The history of a galaxy is shaped by its internal metabolic processes (star formation and death, gravitational interactions among all its components, and sometimes by an active black hole engine at its core) as well as by interactions with other galaxies, its environment, and the universe itself. Understanding how galaxies, especially the Milky Way, formed and evolved is key to understanding an ancient part of humankind's own origins.
Typically a hundred thousand light years across with the mass of a few hundred billion suns, each galaxy is home to most of the universe's many basic building blocks: interstellar gas and dust, stars and planets, neutron stars and black holes, and, often at the galaxy's center, an active supermassive black hole engine that may outshine the combined light from all its stars. These are the abundant but mysterious dark matter that dominate a galaxy's mass.
On a “small” scale, galaxy evolution is influenced by the death of old stars, which expel newly-created elements forged in their central furnaces, as well as the formation of new stars from enriched interstellar gas. This keeps the stellar population replenished over eons of time. A galaxy's shape is determined by how the stars and gas move within the gravitational field of the galaxy's (mostly dark) matter, and the rate at which it forms stars is determined by how much interstellar gas it has.
Occasionally, two galaxies collide and merge, leading initially to a rapid increase in the rate of star formation and a rapid funneling of gas fuel to the supermassive black hole engine in the center. This active galactic nucleus (or AGN) sometimes shines so brightly that all we can see on Earth is a quasar at its center. In fact, the radiation pressure and powerful jets generated by the AGN can drive out all the gas accreted in the merger, thereby shutting off the supply of gas that fueled star formation and nuclear activity in the first place.
On a very large scale, galaxies appear to have formed out of the expanding universe shortly after the Big Bang. So the study of galaxy evolution requires understanding not only star formation and supermassive black holes, but also cosmology -- the birth and evolution of the universe itself.
Featured Projects
NuSTAR
The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing hard X-ray telescope in orbit, allowing true imaging in this largely unknown region of the spectrum. Currently, it is conducting a census of black holes on all scales, mapping newly-created radioactive material in nebulae from recently-exploded stars, and exploring jets of plasma ejected at nearly the speed of light from the most powerful AGN in order to understand what powers these giant engines.
The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing hard X-ray telescope in orbit, allowing true imaging in this largely unknown region of the spectrum. Currently, it is conducting a census of black holes on all scales, mapping newly-created radioactive material in nebulae from recently-exploded stars, and exploring jets of plasma ejected at nearly the speed of light from the most powerful AGN in order to understand what powers these giant engines.
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| NuSTAR (magenta) plus an optical image of the spiral galaxy IC 342, shows two very active black hole systems – too powerful to be stellar-mass black holes, but not powerful enough to be AGN. These may be candidates for the elusive “intermediate mass” black holes often predicted, but not yet confirmed to exist. Image Credit: NASA. |
WISE
The Wide-field Infrared Survey Explorer (WISE) is a near- and mid-infrared (3.5 - 23 μm wavelength) space telescope launched by NASA in late 2009. It has found the most luminous galaxies in the universe (called hot dust obscured galaxies or “hot DOGs”), discovered 30,000 new dark solar system bodies (some very near the earth), determined the history of star formation in normal galaxies, and will be providing an infrared catalog for the even more powerful James Webb Space Telescope (JWST). Having lost all of its solid hydrogen cryogen in September 2010, WISE is now turned off, but analysis and archiving of the massive amounts of returned data is ongoing.
The Wide-field Infrared Survey Explorer (WISE) is a near- and mid-infrared (3.5 - 23 μm wavelength) space telescope launched by NASA in late 2009. It has found the most luminous galaxies in the universe (called hot dust obscured galaxies or “hot DOGs”), discovered 30,000 new dark solar system bodies (some very near the earth), determined the history of star formation in normal galaxies, and will be providing an infrared catalog for the even more powerful James Webb Space Telescope (JWST). Having lost all of its solid hydrogen cryogen in September 2010, WISE is now turned off, but analysis and archiving of the massive amounts of returned data is ongoing.
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| The two extremes of the WISE universe, and so much more in between. Top left: A top-down view of the Solar System, showing all the minor planets observed by WISE’s NEOWISE project (main belt asteroids [black dots]; known near-earth objects [green] and comets [blue]; WISE-discovered NEOS [red] and comets [yellow]). Top right: The current view of how many “killer” asteroids have been found so far (almost all of those larger than 1 km in size), half of those larger than 0.5 km, etc.). Bottom: The entire WISE infrared sky, showing the Milky Way along with the positions of “hot DOGs” – the most luminous galaxies in the universe (magenta dots). Between these two extremes WISE has studied almost everything else: the coolest brown dwarf stars, newly-forming stars, and normal and active galaxies. Image Credit: NASA. |
Current Projects
CLASH
The Cluster Lensing And Supernova Survey with Hubble (CLASH) is an innovative survey to place new constraints on the fundamental components of the cosmos using Hubble Space Telescope observations of distant clusters of galaxies.
The Cluster Lensing And Supernova Survey with Hubble (CLASH) is an innovative survey to place new constraints on the fundamental components of the cosmos using Hubble Space Telescope observations of distant clusters of galaxies.
Deep Space Network Ground Radio Telescopes
While the main job of NASA’s Deep Space Network (DSN) is to track distant spacecraft like Voyager, Cassini, and Spitzer, these communication antennas also can be used as ground radio telescopes either as single dishes or as some of the most powerful elements in world-wide Very Long Baseline Interferometry (VLBI) arrays, which also may include a space radio telescope as well (Space VLBI). JPL has built a new observing system for this network called the DSN Transient Observatory (DTO). Its goal is to detect radio transients (short [10 millisecond] but very powerful bursts of radio radiation) in the distant cosmos.
While the main job of NASA’s Deep Space Network (DSN) is to track distant spacecraft like Voyager, Cassini, and Spitzer, these communication antennas also can be used as ground radio telescopes either as single dishes or as some of the most powerful elements in world-wide Very Long Baseline Interferometry (VLBI) arrays, which also may include a space radio telescope as well (Space VLBI). JPL has built a new observing system for this network called the DSN Transient Observatory (DTO). Its goal is to detect radio transients (short [10 millisecond] but very powerful bursts of radio radiation) in the distant cosmos.
Herschel
Named after Sir Frederick William Herschel, the Herschel telescope is a far-infrared and submillimeter (57 micrometers to 0.67 millimeters wavelength) telescope launched by ESA in early 2009. It has revealed new information about the earliest, most distant stars and galaxies, as well as those closer to home. Having lost all of its liquid helium cryogen in April 2013, Herschel is now turned off, but analysis and archiving of the massive amounts of data that it returned is ongoing.
Named after Sir Frederick William Herschel, the Herschel telescope is a far-infrared and submillimeter (57 micrometers to 0.67 millimeters wavelength) telescope launched by ESA in early 2009. It has revealed new information about the earliest, most distant stars and galaxies, as well as those closer to home. Having lost all of its liquid helium cryogen in April 2013, Herschel is now turned off, but analysis and archiving of the massive amounts of data that it returned is ongoing.
JWST/MIRI
The James Webb Space Telescope (JWST) could be the premier observatory in the next decade, following in Hubble's footsteps but working primarily in the red to mid-infrared region (0.6 - 27 microns wavelength). The Mid InfraRed Instrument (MIRI) works in a wavelength range similar to WISE (5 - 27 microns) and will take advantage of JWST's large 6.5 meter mirror. It can study every phase in the history of the Milky Way and other galaxies, from the first galaxies formed after the Big Bang, to those forming stars to the present day.
The James Webb Space Telescope (JWST) could be the premier observatory in the next decade, following in Hubble's footsteps but working primarily in the red to mid-infrared region (0.6 - 27 microns wavelength). The Mid InfraRed Instrument (MIRI) works in a wavelength range similar to WISE (5 - 27 microns) and will take advantage of JWST's large 6.5 meter mirror. It can study every phase in the history of the Milky Way and other galaxies, from the first galaxies formed after the Big Bang, to those forming stars to the present day.
Long Wavelength Array (LWA-OVRO)
JPL and Caltech, in collaboration with UNM are building a large low frequency radio telescope array at the Owens Valley Radio Observatory. This facility is designed for transient radio source searches and technology development for future larger arrays to detect highly red-shifted neutral hydrogen from the cosmic Dark Ages.
JPL and Caltech, in collaboration with UNM are building a large low frequency radio telescope array at the Owens Valley Radio Observatory. This facility is designed for transient radio source searches and technology development for future larger arrays to detect highly red-shifted neutral hydrogen from the cosmic Dark Ages.
NITARP
The NASA/IPAC Teacher Archive Research Program (NITARP) gets high school and college teachers involved in authentic astronomical research. The program places small groups of educators with a professional astronomer who will serve as a mentor on an original research project using data from NASA missions. The educators then incorporate the experience into their classrooms and share their new knowledge with students and other teachers. To date, the research projects have involved a broad range of astronomy from star formation, to evolved stars, to active galactic nuclei. The program has resulted in five articles successfully published in the Astrophysical Journal.
The NASA/IPAC Teacher Archive Research Program (NITARP) gets high school and college teachers involved in authentic astronomical research. The program places small groups of educators with a professional astronomer who will serve as a mentor on an original research project using data from NASA missions. The educators then incorporate the experience into their classrooms and share their new knowledge with students and other teachers. To date, the research projects have involved a broad range of astronomy from star formation, to evolved stars, to active galactic nuclei. The program has resulted in five articles successfully published in the Astrophysical Journal.
Spitzer Space Telescope
In addition to studying the origin of stars and planets, the Spitzer infrared observatory also is used to study galaxies at distances so great that we are seeing them as they existed billions of years ago. All light from these galaxies is stretched by the expansion of the universe to about twice its normal wavelength. (For example, the emission line of oxygen with a wavelength of 0.501 μm and the H| | line at 0.656 μm are shifted to 1.0 and 1.3 microns. So, whereas local galaxies can be studied at optical wavelengths, it is better to study "high redshift" galaxies in the infrared. Spitzer has lost all of its cryogenic coolant, but the observatory is still being operated as a “warm” mission (only cooled to the temperature of cold space).
In addition to studying the origin of stars and planets, the Spitzer infrared observatory also is used to study galaxies at distances so great that we are seeing them as they existed billions of years ago. All light from these galaxies is stretched by the expansion of the universe to about twice its normal wavelength. (For example, the emission line of oxygen with a wavelength of 0.501 μm and the H| | line at 0.656 μm are shifted to 1.0 and 1.3 microns. So, whereas local galaxies can be studied at optical wavelengths, it is better to study "high redshift" galaxies in the infrared. Spitzer has lost all of its cryogenic coolant, but the observatory is still being operated as a “warm” mission (only cooled to the temperature of cold space).
Theoretical Investigations
The behavior of normal and active galaxies also can be studied with JPL’s supercomputers and other forms of theoretical calculation. Indeed, it is with such studies, and detailed comparison with observations, that the greatest understanding of these objects is achieved. Similar to weather prediction or airplane aerodynamic studies on the earth, these astrophysical simulations build galaxy or black hole systems inside a supercomputer’s memory and use the laws of physics to determine how the system evolves. Sometimes the simulation follows the flow of cosmic fluid or the interaction of hundreds of thousands of star and dark matter “particles.”
The behavior of normal and active galaxies also can be studied with JPL’s supercomputers and other forms of theoretical calculation. Indeed, it is with such studies, and detailed comparison with observations, that the greatest understanding of these objects is achieved. Similar to weather prediction or airplane aerodynamic studies on the earth, these astrophysical simulations build galaxy or black hole systems inside a supercomputer’s memory and use the laws of physics to determine how the system evolves. Sometimes the simulation follows the flow of cosmic fluid or the interaction of hundreds of thousands of star and dark matter “particles.”
Future Projects
Cosmic Dawn
JPL is developing several experiment concepts for observing the Dark Age – the period preceding the Epoch of Reionization (EOR), which refers to the period in the history of the universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources. These sources may have been stars, galaxies, quasars, or some combination of the above. Experiment concepts include ground-based, lunar orbiting, and lunar surface instruments, with eventual observations and intensity mapping in both low frequency neutral hydrogen and high frequency CO.
JPL is developing several experiment concepts for observing the Dark Age – the period preceding the Epoch of Reionization (EOR), which refers to the period in the history of the universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources. These sources may have been stars, galaxies, quasars, or some combination of the above. Experiment concepts include ground-based, lunar orbiting, and lunar surface instruments, with eventual observations and intensity mapping in both low frequency neutral hydrogen and high frequency CO.
NANOGrav
JPL is participating in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a collaboration aiming to detect and study the gravitational waves from supermassive black hole binaries. Such binaries are predicted to be the late-stage remnants of mergers of galaxies. The technique ensures precise pulsar timing by utilizing the world's largest radio telescopes, eventually possibly including radio antennas in NASA's Deep Space Network (DSN).
JPL is participating in the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a collaboration aiming to detect and study the gravitational waves from supermassive black hole binaries. Such binaries are predicted to be the late-stage remnants of mergers of galaxies. The technique ensures precise pulsar timing by utilizing the world's largest radio telescopes, eventually possibly including radio antennas in NASA's Deep Space Network (DSN).
OMEGA
The Observatory for Multi-Epoch Gravitational lens Astrophysics (OMEGA) is an Explorer scale mission concept that aims to decipher the nature of the dark matter that makes up 25% of the mass of the universe. It will do so by using gravitational lensing observations of distant Active Galactic Nuclei (far behind nearby galaxies and clusters of galaxies) to map the granularity and distribution of dark structures in the nearby objects. This will reveal the physical properties of the dark matter particle(s).
The Observatory for Multi-Epoch Gravitational lens Astrophysics (OMEGA) is an Explorer scale mission concept that aims to decipher the nature of the dark matter that makes up 25% of the mass of the universe. It will do so by using gravitational lensing observations of distant Active Galactic Nuclei (far behind nearby galaxies and clusters of galaxies) to map the granularity and distribution of dark structures in the nearby objects. This will reveal the physical properties of the dark matter particle(s).
The project scientists for Spitzer, Herschel, WISE, NuSTAR, JWST/MIRI, and the principal investigator on OMEGA all work at JPL.
Contacts
Thursday, 30 July 2015
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