Eco Paints
Conventional lead based paint emits harmful chemicals into the air, such as pesticides, herbicides and toxins, which are referred to as volatile organic compounds (VOC). Eco paints, on the other hand, contain fewer or no toxins at all, in which case they’re labelled as being VOC free. Eco paints are odourless and popular types are milk, plant, water or soy based, rather than lead.
Green Roofs:
There are two distinct types of green roofs: intensive and extensive.
Intensive green roofs are essentially elevated parks. They can sustain shrubs, trees, walkways and benches with their complex structural support, irrigation, drainage and root protection layers. The foot or more of growing medium needed for an intensive green roof creates a load of 80-150 pounds (36-68 kilograms) per square foot.
Extensive green roofs are relatively light at 15-50 pounds (7-23 kilograms) per square foot. They support native ground cover that requires little maintenance. Extensive green roofs usually exist for their environmental benefits and dont function as accessible rooftop gardens.
Benefits:
Protect the roof membrane from harsh weather and ultraviolet radiation, allowing them to last twice as long traditional roofs.
Have a fairly stable surface temperature, remaining at air temperature or cooler while traditional rooftops can soar up to 90º F (32º C) above air temperature.
The extra growing medium and vegetation insulates the building from intense temperatures and minimizes heat gain. According to a Canadian study, even a six-inch extensive green roof can reduce summer energy demands by 75 percent.
Thank you for taking the time to learn more about renewable energy - Knowledge Is Power! For more information go to www.endeavorscorp.com or write to us at info@endeavorscorp.com if you have questions or want to get involved. Have a green day!
Sources: Institute BE, WBDG, DTH, Eco Designer, How Stuff Works, How Stuff Works, Inhabitat, Baubilt, Building Science, Wikipedia, One Project Closer, Magnolia Lane, Colors 4 Your Home, Our Green Home
Rose of Galaxies
"Rose" of Galaxies (4/20/11)
Arp 273 – click for 987×1000 image
More: here, here, here, here, here, here, here
Read More..
The newly released Hubble image shows a large spiral galaxy, known as UGC 1810, with a disk that is distorted into a rose-like shape by the gravitational tidal pull of the companion galaxy below it, known as UGC 1813. A swath of blue jewel-like points across the top is the combined light from clusters of intensely bright and hot young blue stars. These massive stars glow fiercely in ultraviolet light.
The smaller, nearly edge-on companion shows distinct signs of intense star formation at its nucleus, perhaps triggered by the encounter with the companion galaxy.
Arp 273 – click for 987×1000 image
More: here, here, here, here, here, here, here
Thursday, November 20, 2014
Dwarf galaxies start making sense
Cosmology has, for a decade, had its "standard model", which largely explains most of the cosmological phenomena that astronomers are able to observe. Except for a relatively small number of things that dont seem to make sense in the model. Prominent among the latter are dwarf galaxies – by one definition, galaxies having less than 10% of the total mass of the Milky Way.
The standard model of cosmology is known officially as the Λ-cold-dark-matter model – ΛCDM. (This theory has no particular relation to the Standard Model of particle physics.) Cold dark matter (CDM) refers to the hypothesis that a large part of the detectable mass content of the universe consists of particles that are not accounted for by the Standard Model of particle physics. The dark matter is said to be "cold", because it appears to consist mostly of "non-relativistic" particles, meaning particles moving at speeds not close to the speed of light. That excludes, for example, neutrinos.
As weird as the idea of dark matter might seem, there is abundant evidence for it, which cant easily be better explained in other possible ways. (Although, many other possibilities have been proposed.) I havent written a lot about this recently, since the evidence for CDM just keeps piling up, but heres one important study. Dark matter is "observed" indirectly through its gravitational effects on ordinary visible matter. For instance, the motions of stars in the Milky Way have recently been analyzed closely enough to show that the dark matter in which the Milky Way is embedded has the shape of a squashed beach ball. (See here, here, here.)
Λ is the conventional symbol used for the "cosmological constant", which is a concept from Einsteins general theory of relativity. It is supposed to account for the observed phenomenon of "dark energy". This too is controversial, but there is much evidence for it, from a variety of different studies that are not all based on the same kinds of observations. I last wrote at length on the evidence here.
I need to write a lot more about recent evidence for dark energy, but Ill be very brief about it here. There is very recent evidence involving the motion of galaxies quite near our own (see here). Other than that, the evidence for dark energy is based on observations of distant Type Ia supernovae (about which theres a lot of recent news), "weak lensing" (see here), and "baryon acoustic oscillations" (a large topic).
In spite of all this evidence, ΛCDM isnt without its problems. As already suggested, one set of problems involves dwarf galaxies. There are at least two (somewhat related) parts to this problem. The larger part of the problem is simply that not enough very small dwarf galaxies (masses less than a percent of the Milky Ways) have been detected. This is often known as the "missing satellite problem".
Dwarf galaxies, being very small, are also intrinsically dim, and thus difficult to observe at all unless theyre very nearby. However, only about 11 dwarf galaxies are known to be satellites of the Milky Way – and such satellites should be the easiest of dwarf galaxies to detect. This is a serious problem, since simluations of expected galaxies sizes based on the way that dark matter should be expected to clump together predict as many as 500 dwarf satellites of the Milky Way.
The other problem is known as the cuspy halo problem. "Halo" refers to the cloud of cold dark matter in which all visible galaxies are expected to be embedded. Simulations indicate that the dark matter should be concentrated in the center of the halo instead of being evenly distributed throughout. This is intuitively reasonable – after all, most of the ordinary matter in our solar system is concentrated right in the middle, in the Sun itself.
This problem exists somewhat even for large galaxies like the Milky Way, but it is much more severe for dwarf galaxies. In fact, it seems as though the smaller the galaxy is, the greater the tendency for the dark matter (as indicated by orbital motion of stars within the galaxy) to be distributed fairly smoothly, with little or no density cusp in the center.
Related to this is a recent finding (see here) that smaller galaxies seem to have a smaller proportion of ordinary baryonic matter to dark matter than does the universe as a whole. And, in fact, the smaller the galaxy, the smaller the proportion of ordinary matter. In the universe as a whole, there is much evidence, based on detected abundances of light elements and observations of the cosmic microwave background, that there should be about 5 times as much mass in the form of dark matter as there is of ordinary matter. One might expect this proportion to be about the same in galaxies. Yet instead, in the smallest galaxies, astronomers can detect less than 1% as much ordinary matter (in the form of visible stars) as one would expect to find.
This would suggest that an important reason we cant detect very many small galaxies is that they simply have too few stars and are too dim to see. But it still doesnt explain why this should be the case.
In fact, I wrote 2½ years ago about a study that reported finding many small galaxies consisting of 99% or more of dark matter (here). The authors of the study even speculated that the reason such galaxies were mostly composed of dark matter was that "the fierce ultraviolet radiation given off by the first stars, which formed just a few hundred million years after the Big Bang, may have blown all of the hydrogen gas out of the dwarf galaxies forming at that time." And they added, "The loss of gas prevented the galaxies from creating new stars, leaving them very faint, or in many cases completely dark. When this effect is included in theoretical models, the numbers of expected and observed dwarf galaxies agree."
Kind of makes sense, doesnt it? In fact, even for galaxies that began to form later, a large number of supernovae early in the life of a galaxy might be enough to blow away most of the hydrogen from which additional stars could form. And indeed, a recent much more detailed simulation of galaxy formation supports precisely this idea.
Why is it that previous simulations had not caught this? The reason is very simple: detailed simulations of galaxy formation and evolution are exceedingly demanding of computer resources. In order to make such simulations even possible – up until now – astrophysicists considered only the effect of gravitational collapse of a mixture of ordinary and dark matter. The effects resulting from star formation and subsequent supernovae were omitted entirely.
Duh.
Actually, this simplification is pretty understandable. The simulation that is the subject of the research under discussion here, that did take into account stellar formation processes, consumed an almost incredible amount of computing time. According to one report, "The simulation was carried out using about 250 processors running for about two months." Thats more than 40 processor-years.
And thats just for one simulation, involving a single set of initial conditions.
Heres the abstract:
Bulgeless dwarf galaxies and dark matter cores from supernova-driven outflows
Basically what the simulation has to do is to incorporate a level of granularity that reflects the size of a typical star-forming region: "Baryonic processes are included, as gas cooling, heating from the cosmic ultraviolet field, star formation and supernova-driven gas heating. The resolution is such that dense gas clumps as small as 105 M⊙ are resolved, similar to real star-forming regions."
It certainly wasnt possible to do a simulation where the granularity was on the order of the size of a single star – that could take 105 times as long. Yet the results are very reasonable. The simulation produced a galaxy that closely resembles dwarf galaxies actually observed. In particular, the simulated galaxy has no "cusp" of dark matter density at the center, and no central bulge of visible stars in the center either.
And so the simulation adequately accounts for properties of real dwarf galaxies, which no previous simulation has done. The intense outflowing "winds" from supernovae that result from the heaviest initially-formed stars sweep all ordinary baryonic matter out of the central region. These winds are simply high-energy photons, which interact only with ordinary matter, not dark matter. However, the ordinary matter does interact gravitationally with the dark matter, which also then gets pulled away from the center.
The simulation does not directly settle the question of why so few very small dwarf galaxies are observed. Presumably, many small dwarfs actually do form. They just have so little ordinary matter that is able to coalesce into stars that the galaxies are too dim to detect at any great distance. This is in accord with other studies that show that the smallest galaxies have only a very small proportion of visible ordinary matter.
Further reading:
Supernova winds blow galaxies into shape (1/13/10)
Supernovae put dark matter in the right place (1/13/10)
New research resolves conflict in theory of how galaxies form (1/13/10)
Astrophysicists unwind Cold Dark Matter Catastrophe conundrum (1/14/10)
Puzzling Dwarf Galaxies Finally Make Sense (1/13/10)
Galaxy formation: Gone with the wind? (1/13/10)
Read More..
The standard model of cosmology is known officially as the Λ-cold-dark-matter model – ΛCDM. (This theory has no particular relation to the Standard Model of particle physics.) Cold dark matter (CDM) refers to the hypothesis that a large part of the detectable mass content of the universe consists of particles that are not accounted for by the Standard Model of particle physics. The dark matter is said to be "cold", because it appears to consist mostly of "non-relativistic" particles, meaning particles moving at speeds not close to the speed of light. That excludes, for example, neutrinos.
As weird as the idea of dark matter might seem, there is abundant evidence for it, which cant easily be better explained in other possible ways. (Although, many other possibilities have been proposed.) I havent written a lot about this recently, since the evidence for CDM just keeps piling up, but heres one important study. Dark matter is "observed" indirectly through its gravitational effects on ordinary visible matter. For instance, the motions of stars in the Milky Way have recently been analyzed closely enough to show that the dark matter in which the Milky Way is embedded has the shape of a squashed beach ball. (See here, here, here.)
Λ is the conventional symbol used for the "cosmological constant", which is a concept from Einsteins general theory of relativity. It is supposed to account for the observed phenomenon of "dark energy". This too is controversial, but there is much evidence for it, from a variety of different studies that are not all based on the same kinds of observations. I last wrote at length on the evidence here.
I need to write a lot more about recent evidence for dark energy, but Ill be very brief about it here. There is very recent evidence involving the motion of galaxies quite near our own (see here). Other than that, the evidence for dark energy is based on observations of distant Type Ia supernovae (about which theres a lot of recent news), "weak lensing" (see here), and "baryon acoustic oscillations" (a large topic).
In spite of all this evidence, ΛCDM isnt without its problems. As already suggested, one set of problems involves dwarf galaxies. There are at least two (somewhat related) parts to this problem. The larger part of the problem is simply that not enough very small dwarf galaxies (masses less than a percent of the Milky Ways) have been detected. This is often known as the "missing satellite problem".
Dwarf galaxies, being very small, are also intrinsically dim, and thus difficult to observe at all unless theyre very nearby. However, only about 11 dwarf galaxies are known to be satellites of the Milky Way – and such satellites should be the easiest of dwarf galaxies to detect. This is a serious problem, since simluations of expected galaxies sizes based on the way that dark matter should be expected to clump together predict as many as 500 dwarf satellites of the Milky Way.
The other problem is known as the cuspy halo problem. "Halo" refers to the cloud of cold dark matter in which all visible galaxies are expected to be embedded. Simulations indicate that the dark matter should be concentrated in the center of the halo instead of being evenly distributed throughout. This is intuitively reasonable – after all, most of the ordinary matter in our solar system is concentrated right in the middle, in the Sun itself.
This problem exists somewhat even for large galaxies like the Milky Way, but it is much more severe for dwarf galaxies. In fact, it seems as though the smaller the galaxy is, the greater the tendency for the dark matter (as indicated by orbital motion of stars within the galaxy) to be distributed fairly smoothly, with little or no density cusp in the center.
Related to this is a recent finding (see here) that smaller galaxies seem to have a smaller proportion of ordinary baryonic matter to dark matter than does the universe as a whole. And, in fact, the smaller the galaxy, the smaller the proportion of ordinary matter. In the universe as a whole, there is much evidence, based on detected abundances of light elements and observations of the cosmic microwave background, that there should be about 5 times as much mass in the form of dark matter as there is of ordinary matter. One might expect this proportion to be about the same in galaxies. Yet instead, in the smallest galaxies, astronomers can detect less than 1% as much ordinary matter (in the form of visible stars) as one would expect to find.
This would suggest that an important reason we cant detect very many small galaxies is that they simply have too few stars and are too dim to see. But it still doesnt explain why this should be the case.
In fact, I wrote 2½ years ago about a study that reported finding many small galaxies consisting of 99% or more of dark matter (here). The authors of the study even speculated that the reason such galaxies were mostly composed of dark matter was that "the fierce ultraviolet radiation given off by the first stars, which formed just a few hundred million years after the Big Bang, may have blown all of the hydrogen gas out of the dwarf galaxies forming at that time." And they added, "The loss of gas prevented the galaxies from creating new stars, leaving them very faint, or in many cases completely dark. When this effect is included in theoretical models, the numbers of expected and observed dwarf galaxies agree."
Kind of makes sense, doesnt it? In fact, even for galaxies that began to form later, a large number of supernovae early in the life of a galaxy might be enough to blow away most of the hydrogen from which additional stars could form. And indeed, a recent much more detailed simulation of galaxy formation supports precisely this idea.
Why is it that previous simulations had not caught this? The reason is very simple: detailed simulations of galaxy formation and evolution are exceedingly demanding of computer resources. In order to make such simulations even possible – up until now – astrophysicists considered only the effect of gravitational collapse of a mixture of ordinary and dark matter. The effects resulting from star formation and subsequent supernovae were omitted entirely.
Duh.
Actually, this simplification is pretty understandable. The simulation that is the subject of the research under discussion here, that did take into account stellar formation processes, consumed an almost incredible amount of computing time. According to one report, "The simulation was carried out using about 250 processors running for about two months." Thats more than 40 processor-years.
And thats just for one simulation, involving a single set of initial conditions.
Heres the abstract:
Bulgeless dwarf galaxies and dark matter cores from supernova-driven outflows
For almost two decades the properties of ‘dwarf’ galaxies have challenged the cold dark matter (CDM) model of galaxy formation. Most observed dwarf galaxies consist of a rotating stellar disk embedded in a massive dark-matter halo with a near-constant-density core. Models based on the dominance of CDM, however, invariably form galaxies with dense spheroidal stellar bulges and steep central dark-matter profiles, because low-angular-momentum baryons and dark matter sink to the centres of galaxies through accretion and repeated mergers. Processes that decrease the central density of CDM halos have been identified, but have not yet reconciled theory with observations of present-day dwarfs. This failure is potentially catastrophic for the CDM model, possibly requiring a different dark-matter particle candidate. Here we report hydrodynamical simulations (in a framework assuming the presence of CDM and a cosmological constant) in which the inhomogeneous interstellar medium is resolved. Strong outflows from supernovae remove low-angular-momentum gas, which inhibits the formation of bulges and decreases the dark-matter density to less than half of what it would otherwise be within the central kiloparsec. The analogues of dwarf galaxies—bulgeless and with shallow central dark-matter profiles—arise naturally in these simulations.
Basically what the simulation has to do is to incorporate a level of granularity that reflects the size of a typical star-forming region: "Baryonic processes are included, as gas cooling, heating from the cosmic ultraviolet field, star formation and supernova-driven gas heating. The resolution is such that dense gas clumps as small as 105 M⊙ are resolved, similar to real star-forming regions."
It certainly wasnt possible to do a simulation where the granularity was on the order of the size of a single star – that could take 105 times as long. Yet the results are very reasonable. The simulation produced a galaxy that closely resembles dwarf galaxies actually observed. In particular, the simulated galaxy has no "cusp" of dark matter density at the center, and no central bulge of visible stars in the center either.
And so the simulation adequately accounts for properties of real dwarf galaxies, which no previous simulation has done. The intense outflowing "winds" from supernovae that result from the heaviest initially-formed stars sweep all ordinary baryonic matter out of the central region. These winds are simply high-energy photons, which interact only with ordinary matter, not dark matter. However, the ordinary matter does interact gravitationally with the dark matter, which also then gets pulled away from the center.
The simulation does not directly settle the question of why so few very small dwarf galaxies are observed. Presumably, many small dwarfs actually do form. They just have so little ordinary matter that is able to coalesce into stars that the galaxies are too dim to detect at any great distance. This is in accord with other studies that show that the smallest galaxies have only a very small proportion of visible ordinary matter.
Governato, F., Brook, C., Mayer, L., Brooks, A., Rhee, G., Wadsley, J., Jonsson, P., Willman, B., Stinson, G., Quinn, T., & Madau, P. (2010). Bulgeless dwarf galaxies and dark matter cores from supernova-driven outflows Nature, 463 (7278), 203-206 DOI: 10.1038/nature08640 |
Further reading:
Supernova winds blow galaxies into shape (1/13/10)
Supernovae put dark matter in the right place (1/13/10)
New research resolves conflict in theory of how galaxies form (1/13/10)
Astrophysicists unwind Cold Dark Matter Catastrophe conundrum (1/14/10)
Puzzling Dwarf Galaxies Finally Make Sense (1/13/10)
Galaxy formation: Gone with the wind? (1/13/10)
Monday, November 17, 2014
Satellite Catches a Galaxy Ablaze With Starbirth
NASA's Swift Satellite Catches a Galaxy Ablaze With Starbirth (2/26/08)
M33 – click for 1440× 900 image
More: here, here, here
Read More..
The Triangulum Galaxy is also called M33 for being the 33rd object in Charles Messier’s sky catalog. It is located about 2.9 million light-years from Earth in the constellation Triangulum. It is a member of our Local Group, the small cluster of galaxies that includes our Milky Way Galaxy and the Andromeda Galaxy (M31). Despite sharing our Milky Way’s spiral shape, M33 has only about one-tenth the mass. M33’s visible disk is about 50,000 light-years across, half the diameter of our galaxy.
Swift’s Ultraviolet/Optical Telescope (UVOT) took the images through three separate ultraviolet filters from December 23, 2007 to January 4, 2008. The mosaic showcases UVOT’s high spatial resolution. Individual star clusters and star-forming gas clouds are clearly resolved, even in the crowded nucleus of the galaxy. The image also includes Milky Way foreground stars and much more distant galaxies shining through M33.
M33 – click for 1440× 900 image
More: here, here, here
Saturday, November 15, 2014
Beyond Einstein
Heres the second article in a series Im going to do on NASAs advanced astrophysics and cosmology science program, which theyve called "Beyond Einstein". The first in the series is here. It provides background on the Bush administrations lamentable intentions to delay indefinitely or even abandon most of the more advanced of NASAs pure science programs, including Beyond Einstein.
My purpose in writing about this is to stimulate interest in the program among that part of the U. S. public that pays attention to basic science, especially advanced studies of the universe at large. Because, you see, as a result of last weeks elections, the character of the U. S. Congress is going to change significantly next year. Theres reason to hope priorities can change. When NASAs science budgets are discussed in future years, we can advocate that Congress reinstate funds for the missions that make up the Beyond Einstein program.
The main purpose of this post is to present background information on the program. But of course, a few words need to be said first about what the Beyond Einstein program is. Fortunately, NASAs home page of the project does a really great job of providing both an overview and detailed background information. See especially the science page, the mission descriptions, and additional resources.
In a nutshell, the various missions together and separately will investigate four of the most mysterious phenomena that we know of in the universe: black holes, gravitational waves, dark energy, and cosmic inflation. These phenomena are grounded in Einsteins general theory of relativity. Yet theres a great deal we dont understand about each one – hence the name "Beyond Einstein".
This graphic from the project site sums it up (click for full-size image):
If you go to this page, youll be able to click on individual parts of the graphic for more information. The items at the far left are space missions that have already been launched (except for GLAST, whose launch is scheduled for late 2007) or ground-based facilities (LIGO) that are currently working on different parts of the puzzle. Immediately to the right of those are two missions (LISA and Constellation-X) that are well-along in planning – but not yet approved and funded. They (as well as everything else to their right) are missions that were ditched, at least for the present, in NASAs 2007 budget.
LISA will use interferometry techniques, as does LIGO, to search for gravitational waves. But because the separation of the three observation points will be millions of kilometers, instead of a few thousand in LIGO, it will be vastly more sensitive. LISA should be able to detect gravitational waves resulting from supernovae or black hole collisions.
Constellation-X is to consist of four X-ray telescopes on a single spacecraft. It is a successor to previous space-based X-ray observatories, such as Chandra. Constellation-X will be able to study phenomena that are energetic in the X-ray part of the spectrum, such as physics in the vicinity of black holes and very hot gas found in large galaxy clusters.
The missions in the center of the chart are less far along in planning. Of the three, the dark energy probe appears to be farthest along. In fact, there are actually three possible designs in competition. In August, NASA authorized a comparative analysis of the three designs in order to identify the "best". Each of them will measure the effects of dark energy over the history of the universe by locating and studying 1000 or more Type 1a supernovae. They differ in the additional kinds of measurements they can make. However, the status of this mission (as well as the others discussed here) has recently been thrown into further uncertainty, as well explain in a minute.
The purpose of the inflation probe is to gather stronger evidence for the process of inflation that appears to have occurred beginning a mere 10-35 seconds after the big bang. (As discussed here and here, back in March NASA announced that an analysis of WMAP data in fact gave preliminary evidence for inflation.) In addition, the probe will seek data that can discriminate among the many possible models which can describe inflation. There are different ways that the probe can study the problem, including a more detailed analysis of polarization in the cosmic microwave background, and a study of the evolution of large-scale structure in the universe.
The black hole finder, as the name implies, will be designed to locate and study black holes (both stellar-mass supernova remnants and supermassive black holes) in order to learn more about how they form and grow. As such, it will build upon work done by Constellation-X.
As for the two "vision missions", its really too early for scientists and engineers to define them in any detail. Much will depend on phenomena that are better understood from the results of earlier missions, and most likely phenomena we dont even know of yet. Understandably, these missions (and certainly others like them) are decades in the future.
And this brings us to the latest news. It should be clear enough that there are plenty of overlaps and interdependencies among the various missions. The capabilities of later missions will depend critically on what we learn from earlier ones. After all, until 1997, no one seriously suspected that dark energy even existed. (And some experts still doubt its existence.)
Because of this, as well as because of the severe present constraints on NASAs science budget, The National Research Council (NRC) of the National Academies has formed a committee – at the request of NASA and the U. S. Department of Energy – to conduct an assessment of the Beyond Einstein program. The first meeting of the committee was held last week (November 6-8). The agenda is here. Further information on the committee, including its membership and staff, is here.
This is the committees task statement:
As of right now, I havent seen any accounts of what happened at the meeting last week. If anyone out there has some actual information about the meeting, or has seen reports of it, please let me know.
What I do know is that some people are pretty worried that the real purpose of this committee is to narrow down the Beyond Einstein program to just one mission, or possibly two, because of NASAs budget problems. This might entail not merely postponing other missions, but essentially killing them altogether. The problem is that, if some level of misson activity cannot be funded on an ongoing basis, then many researchers and their institutions will have to find other things to do, and it could be very difficult to bring teams back together when, or if, funding becomes available. See two posts here and here, from Steinn Sigurðsson for examples of the kind of speculation going around.
Oh yes, there is one other thing. Along with the announcement on October 31 (before the NRC committee meeting), that a final service mission will be flown for the Hubble Space Telescope, there were strong hints that other astronomy missions are on hold. The report on this printed in Science: Hubble Gets a Green Light, With Other Missions on Hold is available only to subscribers, but says at the end:
Make of that what you will, but it certainly doesnt sound too good.
On the other hand, it certainly looks like the task of the NRC committee is to select at least one of the Beyond Einstein missions. Further, NASA is going ahead with other new astronomy projects. In addition to GLAST (launches late 2007), on October 13 there was an announcement that the Wide-field Infrared Survey Explorer will be launched in 2009 to do infrared sky maps, which would capture both nearby planetary systems undergoing formation as well as very distant galaxies – news report, further information.
So heres the bottom line I see for now: The NRC committee will take a year or so to ponder the situation. They may pick one project to go forward with initially. (Betting seems to be on the dark energy probe, because of the involvement of the Department of Energy.) Other missions in the advanced planning stage (LISA and Constellation-X) may wind up on hold, or one may be slotted as well.
The important point: there is plenty of time to make the argument before the appropriate Congressional committees that the NASA science budget should be increased enough so that the Beyond Einstein program can go forward, without having to sacrifice planning that has already been done and disrupting teams that are already in place.
Fortunately, as a result of last weeks elections, Congress will have new people in charge who should be inclined to place a higher value on basic science than those they are replacing.
Update 1 (11/13/06): According to a comment by Steinn, LISA and Con-X have been "approved", but only minimally funded.
Update 2 (11/14/06): Now Steinn says funding was cut off. In any case, theyre going noplace fast at this point.
----------------------------
Additional information:
----------------------------
Tags: astrophysics, cosmology, Beyond Einstein, black holes, dark energy, cosmic inflation, gravitational waves, NASA
Read More..
My purpose in writing about this is to stimulate interest in the program among that part of the U. S. public that pays attention to basic science, especially advanced studies of the universe at large. Because, you see, as a result of last weeks elections, the character of the U. S. Congress is going to change significantly next year. Theres reason to hope priorities can change. When NASAs science budgets are discussed in future years, we can advocate that Congress reinstate funds for the missions that make up the Beyond Einstein program.
The main purpose of this post is to present background information on the program. But of course, a few words need to be said first about what the Beyond Einstein program is. Fortunately, NASAs home page of the project does a really great job of providing both an overview and detailed background information. See especially the science page, the mission descriptions, and additional resources.
In a nutshell, the various missions together and separately will investigate four of the most mysterious phenomena that we know of in the universe: black holes, gravitational waves, dark energy, and cosmic inflation. These phenomena are grounded in Einsteins general theory of relativity. Yet theres a great deal we dont understand about each one – hence the name "Beyond Einstein".
This graphic from the project site sums it up (click for full-size image):
If you go to this page, youll be able to click on individual parts of the graphic for more information. The items at the far left are space missions that have already been launched (except for GLAST, whose launch is scheduled for late 2007) or ground-based facilities (LIGO) that are currently working on different parts of the puzzle. Immediately to the right of those are two missions (LISA and Constellation-X) that are well-along in planning – but not yet approved and funded. They (as well as everything else to their right) are missions that were ditched, at least for the present, in NASAs 2007 budget.
LISA will use interferometry techniques, as does LIGO, to search for gravitational waves. But because the separation of the three observation points will be millions of kilometers, instead of a few thousand in LIGO, it will be vastly more sensitive. LISA should be able to detect gravitational waves resulting from supernovae or black hole collisions.
Constellation-X is to consist of four X-ray telescopes on a single spacecraft. It is a successor to previous space-based X-ray observatories, such as Chandra. Constellation-X will be able to study phenomena that are energetic in the X-ray part of the spectrum, such as physics in the vicinity of black holes and very hot gas found in large galaxy clusters.
The missions in the center of the chart are less far along in planning. Of the three, the dark energy probe appears to be farthest along. In fact, there are actually three possible designs in competition. In August, NASA authorized a comparative analysis of the three designs in order to identify the "best". Each of them will measure the effects of dark energy over the history of the universe by locating and studying 1000 or more Type 1a supernovae. They differ in the additional kinds of measurements they can make. However, the status of this mission (as well as the others discussed here) has recently been thrown into further uncertainty, as well explain in a minute.
The purpose of the inflation probe is to gather stronger evidence for the process of inflation that appears to have occurred beginning a mere 10-35 seconds after the big bang. (As discussed here and here, back in March NASA announced that an analysis of WMAP data in fact gave preliminary evidence for inflation.) In addition, the probe will seek data that can discriminate among the many possible models which can describe inflation. There are different ways that the probe can study the problem, including a more detailed analysis of polarization in the cosmic microwave background, and a study of the evolution of large-scale structure in the universe.
The black hole finder, as the name implies, will be designed to locate and study black holes (both stellar-mass supernova remnants and supermassive black holes) in order to learn more about how they form and grow. As such, it will build upon work done by Constellation-X.
As for the two "vision missions", its really too early for scientists and engineers to define them in any detail. Much will depend on phenomena that are better understood from the results of earlier missions, and most likely phenomena we dont even know of yet. Understandably, these missions (and certainly others like them) are decades in the future.
And this brings us to the latest news. It should be clear enough that there are plenty of overlaps and interdependencies among the various missions. The capabilities of later missions will depend critically on what we learn from earlier ones. After all, until 1997, no one seriously suspected that dark energy even existed. (And some experts still doubt its existence.)
Because of this, as well as because of the severe present constraints on NASAs science budget, The National Research Council (NRC) of the National Academies has formed a committee – at the request of NASA and the U. S. Department of Energy – to conduct an assessment of the Beyond Einstein program. The first meeting of the committee was held last week (November 6-8). The agenda is here. Further information on the committee, including its membership and staff, is here.
This is the committees task statement:
1. Assess the five proposed Beyond Einstein missions (Constellation-X, Laser Interferometer Space Antenna, Joint Dark Energy Mission, Inflation Probe, and Black Hole Finder probe) and recommend which of these five should be developed and launched first, using a funding wedge that is expected to begin in FY 2009. The criteria for these assessments include:
a. Potential scientific impact within the context of other existing and planned space-based and ground-based missions; and
b. Realism of preliminary technology and management plans, and cost estimates.
2. Assess the Beyond Einstein missions sufficiently so that they can act as input for any future decisions by NASA or the next Astronomy and Astrophysics Decadal Survey on the ordering of the remaining missions. This second task element will assist NASA in its investment strategy for future technology development within the Beyond Einstein Program prior to the results of the Decadal Survey.
As of right now, I havent seen any accounts of what happened at the meeting last week. If anyone out there has some actual information about the meeting, or has seen reports of it, please let me know.
What I do know is that some people are pretty worried that the real purpose of this committee is to narrow down the Beyond Einstein program to just one mission, or possibly two, because of NASAs budget problems. This might entail not merely postponing other missions, but essentially killing them altogether. The problem is that, if some level of misson activity cannot be funded on an ongoing basis, then many researchers and their institutions will have to find other things to do, and it could be very difficult to bring teams back together when, or if, funding becomes available. See two posts here and here, from Steinn Sigurðsson for examples of the kind of speculation going around.
Oh yes, there is one other thing. Along with the announcement on October 31 (before the NRC committee meeting), that a final service mission will be flown for the Hubble Space Telescope, there were strong hints that other astronomy missions are on hold. The report on this printed in Science: Hubble Gets a Green Light, With Other Missions on Hold is available only to subscribers, but says at the end:
Griffins decision means that NASA will spend most of its astronomy budget on three major missions--the Hubble servicing flight, construction of the James Webb Space Telescope, and the Stratospheric Observatory for Infrared Astronomy (SOFIA). Technical troubles, schedule delays, and cost overruns plague the latter two. But Weiler [director of NASAs Goddard facility] says that the Webb is back on track after a rough couple of years, while SOFIA--which Griffin initially canceled only to revive in July--is slated to begin operations in 2009. Those large projects leave little room for smaller or future missions. For example, NASA halted work earlier this year on the extrasolar planet-seeking Space Interferometry Mission (SIM) in order to cover SOFIAs cost overruns. Those pressures worry some astronomers, who fear that the three missions will limit new efforts.
"Is the astronomy program with just [Webb], Hubble, and SOFIA a good astronomy program? You betcha," says Weiler. Although he acknowledges that there is a gap in smaller missions for the next few years, he notes that the cost of building the Webb will peak in 2008 and then decline over the next 5 years. "The big issue now is what to do with that wedge."
The four leading contenders appear to be the Joint Dark Energy Mission with the Energy Department, a mission called Constellation-X that features a bevy of x-ray telescopes, the Laser Interferometer Space Antenna to study black holes and the early universe, and SIM. NASA had intended to fund all in this decade and the next, but budget constraints likely will make for a competitive race.
Make of that what you will, but it certainly doesnt sound too good.
On the other hand, it certainly looks like the task of the NRC committee is to select at least one of the Beyond Einstein missions. Further, NASA is going ahead with other new astronomy projects. In addition to GLAST (launches late 2007), on October 13 there was an announcement that the Wide-field Infrared Survey Explorer will be launched in 2009 to do infrared sky maps, which would capture both nearby planetary systems undergoing formation as well as very distant galaxies – news report, further information.
So heres the bottom line I see for now: The NRC committee will take a year or so to ponder the situation. They may pick one project to go forward with initially. (Betting seems to be on the dark energy probe, because of the involvement of the Department of Energy.) Other missions in the advanced planning stage (LISA and Constellation-X) may wind up on hold, or one may be slotted as well.
The important point: there is plenty of time to make the argument before the appropriate Congressional committees that the NASA science budget should be increased enough so that the Beyond Einstein program can go forward, without having to sacrifice planning that has already been done and disrupting teams that are already in place.
Fortunately, as a result of last weeks elections, Congress will have new people in charge who should be inclined to place a higher value on basic science than those they are replacing.
Update 1 (11/13/06): According to a comment by Steinn, LISA and Con-X have been "approved", but only minimally funded.
Update 2 (11/14/06): Now Steinn says funding was cut off. In any case, theyre going noplace fast at this point.
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Additional information:
- Beyond Einstein: From the Big Bang to Black Holes
- This is a 110 page document you can download in PDF format, and its very much worth the effort. Its profusely illustrated (full color) and describes all of the missions and gives a good overview of the underlying science. Only problem is it was published in January 2003. But the additional science that has been learned in the last four years mostly confirms the premises of the program.
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Tags: astrophysics, cosmology, Beyond Einstein, black holes, dark energy, cosmic inflation, gravitational waves, NASA
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