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  • richardmitnick 4:39 pm on June 23, 2017 Permalink | Reply
    Tags: , ESA eLISA, , ,   

    From Goddard: “ESA to Develop Gravitational Wave Space Mission with NASA Support” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    June 22, 2017
    Francis Reddy
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    ESA (the European Space Agency) has selected the Laser Interferometer Space Antenna (LISA) for its third large-class mission in the agency’s Cosmic Vision science program. The three-spacecraft constellation is designed to study gravitational waves in space and is a concept long studied by both ESA and NASA.

    ESA’s Science Program Committee announced the selection at a meeting on June 20. The mission will now be designed, budgeted and proposed for adoption before construction begins. LISA is expected to launch in 2034. NASA will be a partner with ESA in the design, development, operations and data analysis of the mission.

    ESA/eLISA the future of gravitational wave research

    Gravitational radiation was predicted a century ago by Albert Einstein’s general theory of relativity. Massive accelerating objects such as merging black holes produce waves of energy that ripple through the fabric of space and time. Indirect proof of the existence of these waves came in 1978, when subtle changes observed in the motion of a pair of orbiting neutron stars showed energy was leaving the system in an amount matching predictions of energy carried away by gravitational waves.

    In September 2015, these waves were first directly detected by the National Science Foundation’s ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO).


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    The signal arose from the merger of two stellar-mass black holes located some 1.3 billion light-years away. Similar signals from other black hole mergers have since been detected.

    Seismic, thermal and other noise sources limit LIGO to higher-frequency gravitational waves around 100 cycles per second (hertz). But finding signals from more powerful events, such as mergers of supermassive black holes in colliding galaxies, requires the ability to detect frequencies much lower than 1 hertz, a sensitivity level only possible from space.

    LISA consists of three spacecraft separated by 1.6 million miles (2.5 million kilometers) in a triangular formation that follows Earth in its orbit around the sun. Each spacecraft carries test masses that are shielded in such a way that the only force they respond to is gravity. Lasers measure the distances to test masses in all three spacecraft. Tiny changes in the lengths of each two-spacecraft arm signals the passage of gravitational waves through the formation.

    For example, LISA will be sensitive to gravitational waves produced by mergers of supermassive black holes, each with millions or more times the mass of the sun. It will also be able to detect gravitational waves emanating from binary systems containing neutron stars or black holes, causing their orbits to shrink. And LISA may detect a background of gravitational waves produced during the universe’s earliest moments.

    For decades, NASA has worked to develop many technologies needed for LISA, including measurement, micropropulsion and control systems, as well as support for the development of data analysis techniques.

    For instance, the GRACE Follow-On mission, a U.S. and German collaboration to replace the aging GRACE satellites scheduled for launch late this year, will carry a laser measuring system that inherits some of the technologies originally developed for LISA.

    NASA/DLR Grace

    The mission’s Laser Ranging Interferometer will track distance changes between the two satellites with unprecedented precision, providing the first demonstration of the technology in space.

    In 2016, ESA’s LISA Pathfinder successfully demonstrated key technologies needed to build LISA.

    ESA/LISA Pathfinder

    Each of LISA’s three spacecraft must gently fly around its test masses without disturbing them, a process called drag-free flight. In its first two months of operations, LISA Pathfinder demonstrated this process with a precision some five times better than its mission requirements and later reached the sensitivity needed for the full multi-spacecraft observatory. U.S. researchers collaborated on aspects of LISA Pathfinder for years, and the mission carries a NASA-supplied experiment called the ST7 Disturbance Reduction System, which is managed by NASA’s Jet Propulsion Laboratory in Pasadena, California.

    For more information about the LISA project, visit:

    https://lisa.nasa.gov

    See the full article here.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

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  • richardmitnick 2:43 pm on June 20, 2017 Permalink | Reply
    Tags: , , , , , ESA eLISA, ESA Gravitational Wave Mission Selected. Planet Hunting Mission Moves Forward, , , ESA/Plato, ,   

    From ESA: “Gravitational Wave Mission Selected. Planet Hunting Mission Moves Forward” 

    ESA Space For Europe Banner

    European Space Agency

    1
    Merging black holes. No image credit

    20 June 2017
    ESA Media Relations Office

    Tel: + 33 1 53 69 72 99

    Email: media@esa.int

    The LISA trio of satellites to detect gravitational waves from space has been selected as the third large-class mission in ESA’s Science programme, while the Plato exoplanet hunter moves into development.

    ESA/eLISA the future of gravitational wave research

    These important milestones were decided upon during a meeting of ESA’s Science Programme Committee today, and ensure the continuation of ESA’s Cosmic Vision plan through the next two decades.

    The ‘gravitational universe’ was identified in 2013 as the theme for the third large-class mission, L3, searching for ripples in the fabric of spacetime created by celestial objects with very strong gravity, such as pairs of merging black holes.

    Predicted a century ago by Albert Einstein’s general theory of relativity, gravitational waves remained elusive until the first direct detection by the ground-based Laser Interferometer Gravitational-Wave Observatory in September 2015. That signal was triggered by the merging of two black holes some 1.3 billion light-years away. Since then, two more events have been detected.

    Furthermore, ESA’s LISA Pathfinder mission has also now demonstrated key technologies needed to detect gravitational waves from space.

    ESA/LISA Pathfinder

    This includes free-falling test masses linked by laser and isolated from all external and internal forces except gravity, a requirement to measure any possible distortion caused by a passing gravitational wave.

    The distortion affects the fabric of spacetime on the minuscule scale of a few millionths of a millionth of a metre over a distance of a million kilometres and so must be measured extremely precisely.

    LISA Pathfinder will conclude its pioneering mission at the end of this month, and LISA, the Laser Interferometer Space Antenna, also an international collaboration, will now enter a more detailed phase of study. Three craft, separated by 2.5 million km in a triangular formation, will follow Earth in its orbit around the Sun.

    Following selection, the mission design and costing can be completed. Then it will be proposed for ‘adoption’ before construction begins. Launch is expected in 2034.

    Planet-hunter adopted

    In the same meeting Plato – Planetary Transits and Oscillations of stars – has now been adopted in the Science Programme, following its selection in February 2014.

    ESA/PLATO

    This means it can move from a blueprint into construction. In the coming months industry will be asked to make bids to supply the spacecraft platform.

    Following its launch in 2026, Plato will monitor thousands of bright stars over a large area of the sky, searching for tiny, regular dips in brightness as their planets cross in front of them, temporarily blocking out a small fraction of the starlight.

    The mission will have a particular emphasis on discovering and characterising Earth-sized planets and super-Earths orbiting Sun-like stars in the habitable zone – the distance from the star where liquid surface water could exist.

    It will also investigate seismic activity in some of the host stars, and determine their masses, sizes and ages, helping to understand the entire exoplanet system.

    Plato will operate from the ‘L2’ virtual point in space 1.5 million km beyond Earth as seen from the Sun.

    LaGrange Points map. NASA

    Missions of opportunity

    3
    Proba-3. No image credit.

    The Science Programme Committee also agreed on participation in ESA’s Proba-3 technology mission, a pair of satellites that will fly in formation just 150 m apart, with one acting as a blocking disc in front of the Sun, allowing the other to observe the Sun’s faint outer atmosphere in more detail than ever before.

    ESA will also participate in Japan’s X-ray Astronomy Recovery Mission (XARM), designed to recover the science of the Hitomi satellite that was lost shortly after launch last year.

    JAXA/Hitomi telescope lost

    4
    LAXA/NASA XARM future satellite

    See the full article here .

    Please help promote STEM in your local schools.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 9:40 am on May 16, 2017 Permalink | Reply
    Tags: , , , , , , ESA eLISA, Hunting for ECOs: Gravitational Wave 'Smoking Guns'   

    From astrobites: “Hunting for ECOs: Gravitational Wave ‘Smoking Guns'” 

    Astrobites bloc

    Astrobites

    May 16, 2017
    Lisa Drummond

    Title: Gravitational-wave signatures of exotic compact objects and of quantum corrections at the horizon scale
    Authors: Vitor Cardoso, Seth Hopper, Caio F. B. Macedo, Carlos Palenzuela, Paolo Pani
    First Author’s Institution: Universidade de Lisboa
    1
    Status: Physical Review D, open access

    An exotic compact object (ECO) consists of matter that is not electrons, neutrons, protons or muons. There have been numerous “exotic” astronomical objects proposed (for example, quark stars, boson stars and preon stars) but none of these hypothetical stars have been detected. Up until recently, detecting objects that do not radiate electromagnetically has been challenging for astronomers and only accomplished indirectly. With the advent of the emerging field of gravitational wave astronomy, we have the ability to directly detect ECOs (if they exist) – we just need to know the gravitational wave “smoking gun” to look for!


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    But why study ECOs at all, given we don’t know if they exist? Even as purely hypothetical objects, they are useful as tractable toy models for testing consequences of general relativity. In addition, they could play a role in solving some of the biggest mysteries in the Universe – boson stars, for example, have been considered as potential dark matter candidates (see here). And if they do exist, we need to be able to know how to distinguish their gravitational wave signals from those of objects that have already been observed.

    This brings us to today’s astrobite. Firstly, the authors simulate bouncing a wave packet off the gravitational potential of several different models of ECOs and observe that, qualitatively, ultra-compact objects have a universal signature in their response. Secondly, the authors investigate the complementary problem of boson stars colliding. Boson stars are chosen because they are ECOs whose formation can potentially occur in dynamical scenarios and they are relatively simple to treat numerically.

    Echoes of ECOs

    2
    Figure 1: The spacetime around very massive objects like stars and black holes is distorted due to their gravitational field. If the same amount of mass is packed into a smaller region of space, there will be a more significant effect on the gravitational field and consequently a more distorted region of space time surrounding them. Image source: https://medium.com/starts-with-a-bang/astroquizzical-how-does-gravity-escape-from-a-black-hole-5ef156bf048d

    Figure 1 compares the distortion of spacetime due to the gravitational fields of the Sun, a neutron star and a black hole; what we see is that if the same mass is packed into a more compact region, the surrounding gravitational forces are more extreme. In some sense, ECOs are halfway between conventional compact objects that are made of matter (such as neutron stars) and black holes (where all the mass has been compacted into a singular point through gravitational collapse). ECOs are not point-like, but have the potential to be compact enough to exhibit some black-hole-like properties. For example, ECOs can have photon spheres, which only exist around ultra-compact objects.

    A photon sphere is a region of space around an object (typically a black hole, but potentially also ECOs) where photons travel in orbits (see Figure 2).

    3
    igure 2: Arrows depict possible orbits of photons around a black hole. The dotted circle is the photon sphere. Image source: http://www.realclearscience.com/blog/2015/07/can_light_orbit_massive_objects.html

    It is typically unstable for a black hole and small perturbations will push the photon out of orbit. However, ECOs do not have event horizons, which are boundaries around a black hole beyond which light cannot escape.

    When you hit a bell, it vibrates; the surface of the bell oscillates between different configurations until the vibration is damped and the ringing stops. Similarly if you “hit” a black hole by bouncing another mass off of it, it “rings” until it is stationary again (see Figure 3). A black hole is a cosmic bell that will “ring” by oscillating in shape between a elongated sphere and a flattened sphere. The damping of the ringing by the emission of gravitational waves is called ringdown. Orbits of a photon around a black hole spacetime can be understood in terms of an “effective potential” whose peaks (troughs) are locations of unstable (stable) photon spheres. There is a close correspondence between this potential and the potential felt by the vibrations of the black hole (discussed in detail here).

    4
    Figure 3: After a perturbation, the black hole “rings” by changing shape, oscillating between an elongated and flattened spheroid. It produces gravitational waves during this “ringdown” phase until it is stationary once more. Image source: http://slideplayer.com/slide/4179737/

    To study the ringdown signal, the authors simulate bouncing a wave packet off both a black hole and an ECO. The initial ringdown of the ECO is identical to the black hole [Physical Review Letters]. This initial signal corresponds to the “ringing” of the photon sphere and is rapidly damped. Crucially, ECOs have a stellar surface rather than an event horizon, meaning they can also have an inner photon sphere that is stable. The main burst of radiation can then reflect off the potential barrier at the inner photon sphere (the potential barrier shape is given in Figure 4) rather than getting absorbed at the event horizon.

    5
    Figure 4: Qualitative features of the potential felt by perturbations of a black hole (top) and ECOs (bottom). The wormhole (middle) is another exotic object which we do not discuss in this bite. The maximum and minimum of the potential correspond to the locations of the unstable outer photon sphere and the stable inner photon sphere respectively. Figure 1 in paper.

    Consquently, after the initial ringdown signal, there are “echoes” from the inner photon sphere. In summary, the signal gets “trapped” in the cavity between the outer and inner photon spheres and leaks out after a time delay \Delta t . Therefore, the characteristic signature of an ultra-compact object without an event horizon is a series of distorted echoes following well after the initial ringdown signal has died away. This is exactly the effect we see in Figure 5.

    6
    Figure 5: Gravitational waveform for the infall of a test particle into a black hole (dotted black line) and an ECO (red line). The initial ringdown caused by the ringing of the outer photon sphere are present for both the black hole and ECO signal. The pulse then travels inward and is either absorbed by the event horizon (in the black hole case) or bounces off the inner photon sphere in the ECO case, leading to subsequent echoes in the signal. Figure 3 in paper.

    Colliding Boson Stars

    Now, we are ready to tackle the next topic of the paper: colliding boson stars. This scenario is complementary to the echo signatures found in the ringdown of ECOs; here the purpose is to investigate gravitational waves produced by fairly viable ECOs (boson stars) rather than more contrived objects such as wormholes or gravastars.

    8
    A model of ‘folded’ space-time illustrates how a wormhole bridge might form with at least two mouths that are connected to a single throat or tube.
    Credit: edobric | Shutterstock

    7
    https://futurism.com/the-gravastar-an-alternative-to-black-holes/

    The authors answer the question of whether boson stars can mimic black holes in different scenarios.

    Boson stars are in general much less compact than black holes and therefore only very finely-tuned boson stars will actually have a photon sphere, so the echo effects discussed in the previous section are only marginally relevant here. Nonetheless, boson star collisions exhibit distinctive and sometimes quite exotic behaviour that is qualitatively different to black hole collisions with the same masses. In certain cases, the two stars actually annihilate during the merger, while in other scenarios there is a repulsive force between the stars so they bounce back and forth until they lose all their kinetic energy and settle back into a binary.

    The phenomena discussed in this paper are quite exotic. However, it is important to remember that gravitational wave astronomy gives us, more than ever before, the opportunity for exciting and unexpected discoveries which challenge known physics – and we need to be proactive in looking for them!

    See the full article here .

    Please help promote STEM in your local schools.

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    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 8:50 am on April 4, 2017 Permalink | Reply
    Tags: , , , , ESA eLISA,   

    From astrobites: “Observing across the gravitational wave spectrum” 

    Astrobites bloc

    Astrobites

    Apr 4, 2017
    Maria Charisi

    Title: The promise of multi-band gravitational wave astronomy after GW150914
    Author: Alberto Sesana
    First author’s institution: University of Birmingham, UK
    1
    Status: Published in Physical Review Letters (2016) [open access]

    A hundred years ago, Einstein published a new theory of gravity, the General Theory of Relativity. Massive objects, like the Sun, curve the geometry of the spacetime around them. The curvature of the spacetime then dictates the motion of other objects around them, e.g., the orbit of the Earth around the Sun. The theory predicts that when massive objects, like black holes (BHs) accelerate, they perturb the spacetime and produce gravitational waves, tiny ripples in spacetime that propagate outwards with the speed of light.

    However, it wasn’t until only a year ago that this prediction was directly confirmed. On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves (GWs) from two colliding black holes (also see Abbott et al. 2016 for the discovery paper).

    2
    Figure 1: The gravitational waveform as seen by the LIGO detector in Hanford, WA (red) and in Livingston, LA (blue). The illustration on the top shows the stages of the binary merger that correspond to the different parts of the waveform.



    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    From the waveform shown in Figure 1, we can infer that the binary that produced GW150914 initially consisted of two black holes with masses about 36 and 29 times the mass of the sun, which merged to form a new black hole of 52 solar masses, releasing the remaining 3 solar masses in gravitational radiation. The masses of the black holes were surprisingly high, compared to most astronomers’ expectations (from observations of other BH systems in the galaxy, we expected binaries with BHs of about 10 solar masses), challenging our understanding of binary formation.

    This paper points out that massive binaries, like GW150914, produce strong gravitational radiation at earlier stages of their evolution, e.g., years before the merger, when the binary is at larger separations, orbiting at lower frequencies. They found that the low-frequency GWs could be detectable by the Laser Interferometer Space Antenna (LISA). LISA will be a space-based GW observatory sensitive in the milli-Hertz frequencies, which cannot be detected from the ground.

    3
    Figure 2: The gravitational wave amplitude for a distribution of binaries with masses similar to GW150914. Each line represents the final years of the evolution of each binary. The purple and orange line show the sensitivity of LISA and LIGO, respectively.

    ESA/eLISA

    If we could detect binary black holes long before they merge, we could learn a lot more about the merger and the sources themselves. First, the binary evolves in the LISA band for several years, as opposed to a few seconds in the LIGO band. This will allow us to constrain the parameters of the binary (e.g., the BH masses, distance, etc) to very high precision. Additionally, we will be able to predict the exact time of the merger within seconds and the location of the merger within about a square degree in the sky (for comparison GW150914 was localized within 100 deg^2). This huge improvement in localization, combined with the ability to predict the exact time of the merger, will greatly facilitate the searches for electromagnetic counterparts, i.e. electromagnetic radiation produced during the merger. The detection of light associated with GWs (or even the lack of counterparts to deep limits) will help us understand the environments, in which BH mergers occur. Last but not least, since LISA is still in the design phase, studies like this will inform the decisions on the technical characteristics of the instrument.

    This feat of science and engineering, decades in the making, opened a new window to observe the universe and signifies the beginning of a new exciting era in modern astronomy!

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    What do we do?

    Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
    Why read Astrobites?

    Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.
    Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

     
  • richardmitnick 4:05 pm on February 18, 2017 Permalink | Reply
    Tags: , ESA eLISA   

    From BBC: “Gravity probe exceeds performance goals” 

    BBC
    BBC

    2.18.17
    Jonathan Amos

    ESA/LISA Pathfinder
    ESA/LISA Pathfinder

    The long-planned LISA space mission to detect gravitational waves looks as though it will be green lit shortly.

    Scientists working on a demonstration of its key measurement technologies say they have just beaten the sensitivity performance that will be required.

    The European Space Agency (Esa), which will operate the billion-euro mission, is now expected to “select” the project, perhaps as early as June.

    The LISA venture intends to emulate the success of ground-based detectors.

    LIGO bloc new
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    These have already witnessed the warping of space-time that occurs when black holes 10-20 times the mass of the Sun collide about a billion light-years from Earth.

    LISA, however, aims to detect the coming together of truly gargantuan black holes, millions of times the mass of the Sun, all the way out to the edge of the observable Universe.

    Researchers will use this information to trace the evolution of the cosmos, from its earliest structures to the complex web of galaxies we see around us today.

    The performance success of the measurement demonstration was announced here in Boston at the annual meeting of the American Association for the Advancement of Science (AAAS).

    It occurred on Esa’s LISA “Pathfinder” (LPF) spacecraft that has been flying for just over a year.

    This probe is trialling parts of the laser interferometer that will eventually be used to detect passing gravitational waves.

    When Pathfinder’s instrumentation was set running it was hoped it would get within a factor of 10 of the sensitivity that would ultimately be needed by the LISA mission, proper.

    In the event, LPF not only matched this mark, but went on to exceed it after 12 months of experimentation.

    “You can do the full science of LISA just based on what LPF has got. And that’s thrilling; it really is beyond our dreams,” Prof Stefano Vitale, Pathfinder’s principal investigator, told BBC News.

    2
    LIGO

    Gravitational waves are a prediction of the Theory of General Relativity
    It took decades to develop the technology to directly detect them
    They are ripples in the fabric of space and time produced by violent events
    Accelerating masses will produce waves that propagate at the speed of light
    Detectable sources ought to include merging black holes and neutron stars
    LIGO fires lasers into long, L-shaped tunnels; the waves disturb the light
    Detecting the waves opens up the Universe to completely new investigations

    The first detection of gravitational waves at the US LIGO laboratories in late 2015 has been described as one of the most important physics breakthroughs in decades.

    Being able to sense the subtle warping of space-time that occurs as a result of cataclysmic events offers a completely new way to study the Universe, one that does not depend on traditional telescope technology.

    Rather than trying to see the light from far-off events, scientists would instead “listen” to the vibrations these events produce in the very fabric of the cosmos.

    LIGO achieved its success by discerning the tiny perturbations in laser light that was bounced between super-still mirrors suspended in kilometres’ long, vacuum tunnels.

    LISA would do something very similar, except its lasers would bounce between free-floating gold-platinum blocks carried on three identical spacecraft separated by 2.5 million km.

    4
    A cutaway impression of the laser interferometer system inside Lisa Pathfinder. ESA.

    Lisa Pathfinder’s payload is a laser interferometer, which measures the behaviour of two free-falling blocks made from a platinum-gold alloy
    Placed 38cm apart, these “test masses” are inside cages that are very precisely engineered to insulate them against all disturbing forces
    When this super-quiet environment is maintained, the falling blocks will follow a “straight line” that is defined only by gravity
    It is under these conditions that a passing gravitational wave would be noticed by ever so slightly changing the separation of the blocks
    Lisa Pathfinder has demonstrated sub-femtometre sensitivity, but the satellite cannot itself make a detection of the ripples
    To do this, a space-borne observatory would need to reproduce the same performance with blocks positioned 2.5 million km apart

    In both cases, the demand is to characterise fantastically small accelerations in the measurement apparatus as it squeezed and stretched by the passing gravitational waves.

    For LISA the projected standard is to characterise movements down below the femto-g level – a millionth of a billionth of the acceleration a falling apple experiences at Earth’s surface; and to do that over periods of minutes to hours.

    LISA Pathfinder has just succeeded in achieving sub-femto sensitivity over timescales of half a day. Getting stability at the lowest frequencies is very important.

    “The lower the frequency to which you go, the bigger are the bodies that generate gravitational waves; the more intense are the gravitational waves; and the more far away are the bodies. So, the lower the frequencies, the deeper into the Universe you go,” explained Prof Vitale, who is affiliated to Italian the Institute for Nuclear Physics and University of Trento.

    To be clear, LPF cannot itself detect gravitational waves because the “arm length” of the system has been shrunk down from 2.5 million km to just 38 cm – to be able to fit inside a single demonstration spacecraft – but it augurs well for the full system.

    ESA/eLISA
    ESA/eLISA

    Esa recently issued a call for proposals to fly a gravitational science mission in 2034. The BBC understands the agency received only one submission – from the LISA Consortium.

    This is unusual. Normally such calls attract a number of submissions from several groups all with different ideas for a mission. But in this instance, it is maybe not so surprising given that the LISA concept has been investigated for more than two decades.

    Prof Karsten Danzmann, co-PI on LPF and the lead proposer of LISA, hopes a way can be found to fly his consortium’s three-spacecraft detection system earlier than 2034, perhaps as early as 2029. But that requires sufficient money being available.

    “The launch date is only programatically dominated, not technically,” Prof Danzmann told BBC News.

    “And with all the interest in gravitational waves building up right now, ways will be found to fly almost simultaneously with Athena (Europe’s next-generation X-ray telescope slated to launch in 2028).

    ESA Athena spacecraft
    ESA/Athena spacecraft

    “This would make perfect sense because we can tell the X-ray guys where to look, because we get the alert of any bright (black hole) merger immediately, and then we can tell them, ‘look in the next hour and you’ll see an X-ray flash’.”

    “That would be tremendously exciting to do multi-messenger astronomy with LISA and Athena at the same time.”

    LISA could be selected as a confirmed project at Esa’s Science Programme Committee in June. There would then be a technical review followed by parallel industrial studies to assess the best, most cost-effective way to construct the mission.

    Agreement will also be sought with the Americans to bring them onboard. They are likely to contribute about $300-400m of the overall cost in the form of components, such as the lasers that will be fired between LISA’s trio of spacecraft.

    The LPF demonstration experiments are due to end in May, or June at the latest.

    See the full article here .

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  • richardmitnick 8:33 am on October 26, 2016 Permalink | Reply
    Tags: , , , , , ESA eLISA, , Next step towards a gravitational-wave observatory in space   

    From ESA: “Next step towards a gravitational-wave observatory in space” 

    ESA Space For Europe Banner

    European Space Agency

    25 October 2016

    1
    Merging black holes. No image credit.

    Today, ESA has invited European scientists to propose concepts for the third large mission in its science programme, to study the gravitational Universe.

    A spaceborne observatory of gravitational waves – ripples in the fabric of spacetime created by accelerating massive objects – was identified in 2013 as the goal for the third large mission (L3) in ESA’s Cosmic Vision plan.

    A Gravitational Observatory Advisory Team was appointed in 2014, composed of independent experts. The team completed its final report earlier this year, further recommending ESA to pursue the mission having verified the feasibility of a multisatellite design with free-falling test masses linked over millions of kilometres by lasers.

    Now, following the first detection of the elusive waves with ground-based experiments and the successful performance of ESA’s LISA Pathfinder mission, which demonstrated some of the key technologies needed to detect gravitational waves from space, the agency is inviting the scientific community to submit proposals for the first space mission to observe gravitational waves.

    ESA/LISA Pathfinder
    ESA/LISA Pathfinder

    ESA/eLISA
    ESA/eLISA

    Gravitational waves promise to open a new window for astronomy, revealing powerful phenomena across the Universe that are not accessible via observations of cosmic light,” says Alvaro Gimenez, ESA’s Director of Science.

    Predicted a century ago by Albert Einstein’s general theory of relativity, gravitational waves remained elusive until the first direct detection by the ground-based Laser Interferometer Gravitational-Wave Observatory and Virgo collaborations, made in September 2015 and announced earlier this year.

    LIGO bloc new
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    The signal originated from the coalescence of two black holes, each with some 30 times the mass of the Sun and about 1.3 billion light-years away. A second detection was made in December 2015 and announced in June, and revealed gravitational waves from another black hole merger, this time involving smaller objects with masses around 7 and 14 solar masses.

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project
    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    1
    LISA Pathfinder performance. No image credit.

    Meanwhile, the LISA Pathfinder mission was launched in December 2015 and started its scientific operations in March this year, testing some of the key technologies that can be used to build a space observatory of gravitational waves.

    Data collected during its first two months showed that it is indeed possible to eliminate external disturbances on test masses placed in freefall at the level of precision required to measure passing gravitational waves disturbing their motion.

    While ground-based detectors are sensitive to gravitational waves with frequencies of around 100 Hz – or a hundred oscillation cycles per second – an observatory in space will be able to detect lower-frequency waves, from 1 Hz down to 0.1 mHz. Gravitational waves with different frequencies carry information about different events in the cosmos, much like astronomical observations in visible light are sensitive to stars in the main stages of their lives while X-ray observations can reveal the early phases of stellar life or the remnants of their demise.

    In particular, low-frequency gravitational waves are linked to even more exotic cosmic objects than their higher-frequency counterparts: supermassive black holes, with masses of millions to billions of times that of the Sun, that sit at the centre of massive galaxies. The waves are released when two such black holes are coalescing during a merger of galaxies, or when a smaller compact object, like a neutron star or a stellar-mass black hole, spirals towards a supermassive black hole.

    Observing the oscillations in the fabric of spacetime produced by these powerful events will provide an opportunity to study how galaxies have formed and evolved over the lifetime of the Universe, and to test Einstein’s general relativity in its strong regime.

    Concepts for ESA’s L3 mission will have to address the exploration of the Universe with low-frequency gravitational waves, complementing the observations performed on the ground to fully exploit the new field of gravitational astronomy. The planned launch date for the mission is 2034.

    Lessons learned from LISA Pathfinder will be crucial to developing this mission, but much new technology will also be needed to extend the single-satellite design to multiple satellites. For example, lasers much more powerful than those used on LISA Pathfinder, as well as highly stable telescopes, will be necessary to link the freely falling masses over millions of kilometres.

    Large missions in ESA’s Science Programme are ESA-led, but also allow for international collaboration. The first large-class mission is Juice, the JUpiter ICy moons Explorer, planned for launch in 2022, and the second is Athena, the Advanced Telescope for High-ENergy Astrophysics, an X-ray observatory to investigate the hot and energetic Universe, with a planned launch date in 2028.

    esa-juice-spacecraft
    ESA/Juice spacecraft

    ESA/Athena spacecraft
    ESA/Athena spacecraft

    Letters of intent for ESA’s new gravitational-wave space observatory must be submitted by 15 November, and the deadline for the full proposal is 16 January 2017. The selection is expected to take place in the first half of 2017, with a preliminary internal study phase planned for later in the year.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

    ESA50 Logo large

     
  • richardmitnick 6:32 am on July 2, 2016 Permalink | Reply
    Tags: , , , , ESA eLISA,   

    From Durham U: “Seeds of supermassive black holes could be revealed by gravitational waves” 

    Durham U bloc

    Durham University

    27 June 2016
    No writer credit found

    Gravitational waves captured by space-based detectors could help identify the origins of supermassive black holes, according to new computer simulations of the Universe.

    Scientists led by Durham University’s Institute for Computational Cosmology ran the huge cosmological simulations that can be used to predict the rate at which gravitational waves caused by collisions between the monster black holes might be detected.

    The amplitude and frequency of these waves could reveal the initial mass of the seeds from which the first black holes grew since they were formed 13 billion years ago and provide further clues about what caused them and where they formed, the researchers said.

    RAS National Astronomy Meeting

    The research is being presented at the Royal Astronomical Society’s National Astronomy Meeting in Nottingham, UK. It was funded by the Science and Technology Facilities Council, the European Research Council and the Belgian Interuniversity Attraction Poles Programme.

    The study combined simulations from the EAGLE project – which aims to create a realistic simulation of the known Universe inside a computer – with a model to calculate gravitational wave signals.

    2
    The EAGLE simulation is one of the largest cosmological hydrodynamical simulations ever, using nearly 7 billion particles to model the physics. It took more than one and a half months of computer time on 4000 compute cores of the DiRAC-2 supercomputer in Durham. It was performed with a heavily modified version of the public GADGET-2 simulation code.

    EAGLE is a project of the Virgo Consortium for cosmological supercomputer simulations.

    VIRGO Collaboration bloc

    Two detections of gravitational waves caused by collisions between supermassive black holes should be possible each year using space-based instruments such as the Evolved Laser Interferometer Space Antenna (eLISA) detector that is due to launch in 2034, the researchers said.

    ESA/eLISA
    ESA/eLISA

    In February the international LIGO and Virgo collaborations announced that they had detected gravitational waves for the first time using ground-based instruments and in June reported a second detection.

    Supermassive black holes

    As eLISA will be in space – and will be at least 250,000 times larger than detectors on Earth – it should be able to detect the much lower frequency gravitational waves caused by collisions between supermassive black holes that are up to a million times the mass of our sun.

    Current theories suggest that the seeds of these black holes were the result of either the growth and collapse of the first generation of stars in the Universe; collisions between stars in dense stellar clusters; or the direct collapse of extremely massive stars in the early Universe.

    As each of these theories predicts different initial masses for the seeds of supermassive black hole seeds, the collisions would produce different gravitational wave signals.

    This means that the potential detections by eLISA could help pinpoint the mechanism that helped create supermassive black holes and when in the history of the Universe they formed.

    Gravitational waves

    Lead author Jaime Salcido, PhD student in Durham University’s Institute for Computational Cosmology, said: “Understanding more about gravitational waves means that we can study the Universe in an entirely different way.

    “These waves are caused by massive collisions between objects with a mass far greater than our sun.

    “By combining the detection of gravitational waves with simulations we could ultimately work out when and how the first seeds of supermassive black holes formed.”

    Co- author Professor Richard Bower, of Durham University’s Institute for Computational Cosmology, added: “Black holes are fundamental to galaxy formation and are thought to sit at the centre of most galaxies, including our very own Milky Way.

    “Discovering how they came to be where they are is one of the unsolved problems of cosmology and astronomy.

    “Our research has shown how space based detectors will provide new insights into the nature of supermassive black holes.”

    Detecting gravitational waves in space

    Gravitational waves were first predicted 100 years ago by Albert Einstein as part of his Theory of General Relativity.

    The waves are concentric ripples caused by violent events in the Universe that squeeze and stretch the fabric of space time but most are so weak they cannot be detected.

    LIGO detected gravitational waves using ground-based instruments, called interferometers, that use laser beams to pick up subtle disturbances caused by the waves.

    LSC LIGO Scientific Collaboration
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    eLISA will work in a similar way, detecting the small changes in distances between three satellites that will orbit the sun in a triangular pattern connected by beams from lasers in each satellite.

    In June it was reported that the LISA Pathfinder, the forerunner to eLISA, had successfully demonstrated the technology that opens the door to the development of a large space observatory capable of detecting gravitational waves in space.

    ESA/LISA Pathfinder
    ESA/LISA Pathfinder

    • Durham’s researchers will show how they use supercomputer simulations to test how galactic ingredients and violent events combine to shape the life history of galaxies when they exhibit at the Royal Society Summer Science Exhibition in London from 4 to 10 July, 2016.

    1
    Seeds of black holes could be revealed by gravitational waves detected in space. No image credit.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Durham U campus

    Durham University is distinctive – a residential collegiate university with long traditions and modern values. We seek the highest distinction in research and scholarship and are committed to excellence in all aspects of education and transmission of knowledge. Our research and scholarship affect every continent. We are proud to be an international scholarly community which reflects the ambitions of cultures from around the world. We promote individual participation, providing a rounded education in which students, staff and alumni gain both the academic and the personal skills required to flourish.

     
  • richardmitnick 4:19 pm on June 28, 2016 Permalink | Reply
    Tags: , , , , , ESA eLISA,   

    From Durham U: “Seeds of supermassive black holes could be revealed by gravitational waves 

    Durham U bloc

    Durham University

    27 June 2016
    No writer credit found


    Access mp4 video here .

    Gravitational waves captured by space-based detectors could help identify the origins of supermassive black holes, according to new computer simulations of the Universe.

    Scientists led by Durham University’s Institute for Computational Cosmology ran the huge cosmological simulations that can be used to predict the rate at which gravitational waves caused by collisions between the monster black holes might be detected.

    The amplitude and frequency of these waves could reveal the initial mass of the seeds from which the first black holes grew since they were formed 13 billion years ago and provide further clues about what caused them and where they formed, the researchers said.

    RAS National Astronomy Meeting

    The research is being presented today (Monday, June 27, 2016) at the Royal Astronomical Society’s National Astronomy Meeting in Nottingham, UK. It was funded by the Science and Technology Facilities Council, the European Research Council and the Belgian Interuniversity Attraction Poles Programme.

    The study combined simulations from the EAGLE project – which aims to create a realistic simulation of the known Universe inside a computer – with a model to calculate gravitational wave signals.

    Two detections of gravitational waves caused by collisions between supermassive black holes should be possible each year using space-based instruments such as the Evolved Laser Interferometer Space Antenna (eLISA) detector that is due to launch in 2034, the researchers said.

    ESA/eLISA
    ESA/eLISA

    In February the international LIGO and Virgo collaborations announced that they had detected gravitational waves for the first time using ground-based instruments and in June reported a second detection.

    LSC LIGO Scientific Collaboration
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation
    Caltech/MIT Advanced aLigo Hanford, WA, USA installation

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Supermassive black holes

    As eLISA will be in space – and will be at least 250,000 times larger than detectors on Earth – it should be able to detect the much lower frequency gravitational waves caused by collisions between supermassive black holes that are up to a million times the mass of our sun.

    Current theories suggest that the seeds of these black holes were the result of either the growth and collapse of the first generation of stars in the Universe; collisions between stars in dense stellar clusters; or the direct collapse of extremely massive stars in the early Universe.

    As each of these theories predicts different initial masses for the seeds of supermassive black hole seeds, the collisions would produce different gravitational wave signals.

    This means that the potential detections by eLISA could help pinpoint the mechanism that helped create supermassive black holes and when in the history of the Universe they formed.

    Gravitational waves

    Lead author Jaime Salcido, PhD student in Durham University’s Institute for Computational Cosmology, said: “Understanding more about gravitational waves means that we can study the Universe in an entirely different way.

    “These waves are caused by massive collisions between objects with a mass far greater than our sun.

    “By combining the detection of gravitational waves with simulations we could ultimately work out when and how the first seeds of supermassive black holes formed.”

    Co- author Professor Richard Bower, of Durham University’s Institute for Computational Cosmology, added: “Black holes are fundamental to galaxy formation and are thought to sit at the centre of most galaxies, including our very own Milky Way.

    “Discovering how they came to be where they are is one of the unsolved problems of cosmology and astronomy.

    “Our research has shown how space based detectors will provide new insights into the nature of supermassive black holes.”

    Detecting gravitational waves in space

    Gravitational waves were first predicted 100 years ago by Albert Einstein as part of his Theory of General Relativity.

    The waves are concentric ripples caused by violent events in the Universe that squeeze and stretch the fabric of space time but most are so weak they cannot be detected.

    LIGO detected gravitational waves using ground-based instruments, called interferometers, that use laser beams to pick up subtle disturbances caused by the waves.

    eLISA will work in a similar way, detecting the small changes in distances between three satellites that will orbit the sun in a triangular pattern connected by beams from lasers in each satellite.

    In June it was reported that the LISA Pathfinder, the forerunner to eLISA, had successfully demonstrated the technology that opens the door to the development of a large space observatory capable of detecting gravitational waves in space.

    ESA/LISA Pathfinder
    ESA/LISA Pathfinder

    • Durham’s researchers will show how they use supercomputer simulations to test how galactic ingredients and violent events combine to shape the life history of galaxies when they exhibit at the Royal Society Summer Science Exhibition in London from 4 to 10 July, 2016.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Durham U campus

    Durham University is distinctive – a residential collegiate university with long traditions and modern values. We seek the highest distinction in research and scholarship and are committed to excellence in all aspects of education and transmission of knowledge. Our research and scholarship affect every continent. We are proud to be an international scholarly community which reflects the ambitions of cultures from around the world. We promote individual participation, providing a rounded education in which students, staff and alumni gain both the academic and the personal skills required to flourish.

     
    • Jona 1:41 am on July 10, 2016 Permalink | Reply

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      look. I’m definitely enjoying the information. I’m bookmarking and will be tweeting this to
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  • richardmitnick 10:28 am on June 12, 2016 Permalink | Reply
    Tags: , , ESA eLISA, ,   

    From Science Alert: “Scientists just successfully measured movement smaller than an atom in space” 

    ScienceAlert

    Science Alert

    10 JUN 2016
    JOSH HRALA

    1
    LISA Pathfinder. ESA

    Time to find more gravitational waves!

    Scientists working with the Laser Interferometer Space Antenna (LISA) Pathfinder – an experimental spacecraft designed to study gravity – have announced that they’ve been able to accurately measure tiny amounts of movement that are smaller than the width of an atom.

    While this news is remarkable on a technical level, the really exciting part is the successful measurement will likely lead to a better way for us to detect gravitational waves – ripples in the curvature of space-time that Einstein predicted in his general theory of relativity, and which were detected for the first time earlier this year.

    To pull off the feat, the team from the European Space Agency (ESA) parked the spacecraft 1.5 million kilometres (932,056 miles) away from Earth in a region of space that is halfway between us and the Sun. At this distance, the gravitational pull of both Earth and the Sun are cancelled out by one another, explains Tarek Bazley for Al Jazeera.

    This means that the objects onboard the craft – two 1.9-kilogram (4.1-pound) cubes of solid gold-platinum alloy – are actually in a free-fall through space, floating exactly 37.5 centimetres (14.8 inches) apart.

    Since the cubes are in free-fall, they technically shouldn’t move at all (outside of the speed they are already moving inside the craft, which is in orbit around the Sun). If they do, it’s likely because they were influenced by gravitational waves, which ripple out over the entire Universe, causing objects to wiggle ever so slightly.

    With this in mind, the researchers were able to verify that the craft is capable of measuring movements at the femtometre scale, which is one millionth of a billionth of a metre, explains Jesse Emspak for Smithsonian Magazine.

    While the Pathfinder on its own isn’t big enough to detect gravitational waves – for that, the objects measured must be super, super far apart, so the wave can hit both of them at slightly different times – it suggests that researchers can successfully use environments in space that are unaffected by the forces lingering directly outside its windows.

    “We wanted to see picometer scale motions,” the mission’s senior scientist Martin Hewitson told Smithsonian Magazine. “It’s more than 100 times better than [observations] on the ground.”

    When researchers from the Laser Interferometer Gravitational Wave Observatory (LIGO) detected gravitational waves earlier this year, they used lasers that were 1,118 kilometres (695 miles) apart. At this distance, reports Emspak, gravitational waves can be detected, but only ones that measure 100 to 1,000 Hz.

    Since the LISA Pathfinder was able to measure the movement so accurately, the team will soon embark on the next phase of the mission, with a device called the Evolved Laser Interferometer Space Antenna (eLISA).

    In this next stage, three separate spacecraft will orbit the Sun in the same sweet spot LISA is in. These crafts will link up to form an L shape, with each of them 999,402 kilometres (621,000 miles) apart.

    ESA/eLISA
    ESA/eLISA

    At such a great distance, the team should be able to accurately detect gravitational waves that are only 0.0001 to 1 Hz, a much more sensitive system than what LIGO had to work with.

    Using the same laser measuring techniques that were just validated inside the LISA Pathfinder, the team says they will be able to measure movements that are only a few trillionths of a metre.

    Understanding gravitational waves will give us a whole new view of how the Universe works. The fact that we can detect them at all is astonishing, and the successful measurement on board the LISA Pathfinder shows we’re already getting better at it.

    “When we open the gravitational wave window to the Universe we are seeing completely new objects, things that we have never been able to see before and never will be able to see using [the] electromagnetic spectrum,” LISA Pathfinder team member Paul McNamara told Al Jazeera. “We’re really on the cusp of observing the Universe in a whole new way.”

    “We now know gravitational waves are detectable – they exist,” is how the ESA’s Directorate of Science, Fabio Favata, put it. “[A]nd now, thanks to LISA Pathfinder, we know that we have sufficient sensitivity to observe them from space, and therefore a new window to the Universe has been opened.”

    While there is still a lot of work for researchers to do to get eLISA off the ground, it’s already exciting to think about the possible data it will eventually collect.

    The findings are published in Physical Review Letters.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
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