The chances of space shuttle Discovery launching on the STS-133 mission in 2010 could be in jeopardy. Cracked foam on the shuttle’s external tank was removed early Wednesday morning and underneath engineers found a structural crack on the tank itself. The serpentine crack is about 22 cm (9 inches) long and is located on a structural rib or “stringer.” Cracks like this have appeared on other tanks and were fixed at the production facility in New Orleans. But this type of repair has never been attempted at the launch pad. Continue reading “Structural Crack Found on Shuttle Tank”
As the get older, Sun-like stars become red giants. 30-50 percent of these red giants exhibit a strange variability in their brightness that has so far eluded explanation. Image Credit: ESO/S. Steinhofel
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While science education often focuses on teaching the scientific method (or at least tries to), the real process of science is often far less linear. Theories tie together so many points of data, that making singular predictions that confirm or refute a proposition is often challenging. Such is the case for stellar evolution. The understanding is woven together from so many independent pieces, that the process is more of a roaring sea than a directed river.
Realizing this, I’ve been keen on instances in which necessary predictions are observationally confirmed later. A new study, led by Mariela Vieytes from the University of Buenos Aires and accepted in an upcoming publication of Astronomy & Astrophysics, does just that by demonstrating one of the necessary conditions for predictions of post main sequence evolution. Specifically, astronomers need to establish that stars undergo significant amounts of mass loss (~0.1-0.3 M☉) during their red giant branch evolution. This requirement was set forth as part of the expected behavior necessary to explain: “i) the very existence of the horizontal branch (HB) and its morphology, ii) the pulsational properties of RR Lyrae stars, iii) the absence of asymptotic giant branch (AGB) stars brighter than the red giant branch (RGB) tip, and the chemistry and characteristics in the AGB, post-AGB and planetary nebula evolutionary phases, iv) the mass of white dwarf (WD) stars.”
Astronomers expected to find confirmation of this mass loss by detecting gas congregating in the cores of globular clusters after being shed by stars evolving along the RGB. Yet searches for this gas came up mostly empty. Eventually astronomers realized that gas would be stripped relatively quickly as globular clusters plunged through the galactic plane. But this left them with the need to confirm the prediction in some other manner.
One way to do this is to look at the stars themselves. If they show velocities in their photospheres greater than the escape velocity, they will lose mass. Just how much higher will determine the amount of mass lost. By analyzing the Doppler shift of specific absorption lines of several stars in the cluster ω Centauri, the team was able to match the amount of mass being lost to predictions from evolutionary models. From this, the team concluded that their target stars were losing between the rates of mass loss are estimated as a few 10-9 and 10-10 M☉ yr-1. This is in general agreement with the predictions set forth by evolutionary models.
The International Space Station shows up in this image taken by the University of Hertfordshire's All-Sky Camera located at Niton, Isle of Wight. Credit: Dr. Lucy Rogers/University of Hertfordshire
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I know I always smile when I see the International Space Station in the night sky, but here the sky itself appears happy, with the ISS crossing the field of view of the Niton All-Sky camera. With a long exposure, a “star trail” forms as the space station moves across the sky. 🙂
The camera is located on the Isle of Wight and operated through the University of Hertfordshire. Check out the camera’s website — there a some great “unusual” images” which include meteors, atmospheric phenomena and even wildlife making an appearance.
Screenshot of news footage of what has been dubbed the 'mystery missle.'
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What took place in the skies above California’s coastline Monday, Nov. 8? That is still being hotly debated by experts and laymen alike. What appears to be a missile firing some 35 miles off the coast of California, near the Island of Catalina appears in a KCBS news chopper footage. The Pentagon has stated that it does not know what is displayed in the images. But instead of mystery, intrigue and government coverup, there is likely a more ordinary explanation: it was an optical illusion.
The Boeing Co. every so often will deploy aircraft from San Nicolas Island. These flights are part of an anti-missile laser testing program. However, the company has announced that it had nothing in the air on Monday. According to the Orange County Register, a very similar contrail was noted off of California Coast just one year earlier.
One possible explanation for the mysterious ‘plume’ is that it was the test firing of a new commercial space rocket – there has not been any confirmation of this.
While experts at Globalsecurity.org say that more than likely what is being viewed in the video is an aircraft and its contrail approaching the camera. That matches up with what scientists that have come forward have stated – that this is nothing more than the contrail made from a jetliner. In short, this whole sensation may have been caused over an optical illusion. One caused by a large aircraft, the sunset and the odd angle that the helicopter that collected the footage was shooting from.
Moreover, local radar did not pick up any fast-moving objects during the time of the ‘launch.’ In fact, in most of the footage the ‘missile’ or ‘rocket’ appears to barely move. For those that regularly follow launches only a single snippet of the video appears to show the fiery exhaust of a rocket – but this could also be the glint of sunlight off of metal.
According to the American Aerospace Defense Command, “there is no indication of any threat to our nation.” Neither NASA nor the U.S. Missile Defense Agency were quite as forthcoming, as these organizations did not immediately release information regarding the incident. Both the U.S. Air Force and Navy have stated that they were not responsible for whatever caused the vapor trail.
This is not the first time plane contrails have been mistaken for rocket launches. See the website Contrail Science for more information and to see similar previous events.
For those of you working on your Comet Hunter’s certificates – or for those who just love these travelers from the Oort Cloud – there’s a new partner in the morning sky. Say hello to C/2010 V1 Ikeya Murakami! If you’re familiar with how a comet looks and already know the steps, then let the easiness lure you out. However, if you’ve never danced with a comet before, then come inside and we’ll teach you the steps…
Our first teacher is John Chumack of Galactic Images who sent us the lead picture for this article. Not all comets jump right out of the sky at you, and some require you wait for just the precise moment in time to catch it. As John says, “I had a very short window to grab it. I could not take more shots due to Dawn rising fast! But I did get very nice details… and it is sporting a little red tail, and a great bow shock!” As you can read, even just a few moments are worth it and the clue here is that Comet Ikeya Murakami isn’t in the easiest of places for most observers. How about if we find out exactly where to look?
Follow the green brick road! This morning comet Ikeya Murakami would have been a same field object with Saturn and it’s headed toward Venus. How easy can it get? Simply aim your binoculars at Saturn and slowly follow the trajectory towards Venus. By November 30 Ikeya Murakami will be about 2 degrees north of the stunningly bright planet and also a same field object in most binoculars.
So, what would the comet be like to watch for awhile? First off, remember that what you will see in binoculars and a small telescope will resemble a small, unresolved globular cluster. It will be a faint fuzzy with a faint tail. More aperture will help, but the approaching Sun is the real culprit here. Comet C/2010 V1 Ikeya Murakami won’t be terribly bright, but you might catch other interesting things while you watch, too. Just ask the one and only Joe Brimacombe!
If you don’t catch C/2010 V1 Ikeya Murakami on the first try – don’t be disappointed… And try again! (the “Aqua” Man would.) But don’t wait too long because the Moon is going to be along soon, making morning skies even brighter. If you do catch it, be sure to share your impressions with us…
Cuz’ there ain’t nothin’ like a little dance before dawn.
From end to end, the newly discovered gamma-ray bubbles extend 50,000 light-years, or roughly half of the Milky Way's diameter, as shown in this illustration. Credit: NASA
NASA’s Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.
“What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center,” said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. “We don’t fully understand their nature or origin.”
The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. A paper about the findings has been accepted for publication in The Astrophysical Journal.
Finkbeiner and Harvard graduate students Meng Su and Tracy Slatyer discovered the bubbles by processing publicly available data from Fermi’s Large Area Telescope (LAT). The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are the highest-energy form of light.
Other astronomers studying gamma rays hadn’t detected the bubbles partly because of a fog of gamma rays that appears throughout the sky. The fog happens when particles moving near the speed of light interact with light and interstellar gas in the Milky Way. The LAT team constantly refines models to uncover new gamma-ray sources obscured by this so-called diffuse emission. By using various estimates of the fog, Finkbeiner and his colleagues were able to isolate it from the LAT data and unveil the giant bubbles.
Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure’s shape and emissions suggest it was formed as a result of a large and relatively rapid energy release — the source of which remains a mystery.
One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way’s black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way’s center several million years ago.
“In other galaxies, we see that starbursts can drive enormous gas outflows,” said David Spergel, a scientist at Princeton University in New Jersey. “Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics.”
Hints of the bubbles appear in earlier spacecraft data. X-ray observations from the German-led Roentgen Satellite suggested subtle evidence for bubble edges close to the galactic center, or in the same orientation as the Milky Way. NASA’s Wilkinson Microwave Anisotropy Probe detected an excess of radio signals at the position of the gamma-ray bubbles.
The Fermi LAT team also revealed Tuesday the instrument’s best picture of the gamma-ray sky, the result of two years of data collection.
“Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, we see the extreme universe in progressively greater detail,” said Julie McEnery, Fermi project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
NASA’s Fermi is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.
“Since its launch in June 2008, Fermi repeatedly has proven itself to be a frontier facility, giving us new insights ranging from the nature of space-time to the first observations of a gamma-ray nova,” said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. “These latest discoveries continue to demonstrate Fermi’s outstanding performance.”
This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Source: NOAA)
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The body of evidence for climate change is strong and convincing, and multiple lines of evidence show the changes are caused largely by human activities. The consensus among scientists about the reality of the phenomenon is also convincing.
But from the nature of public discussions on the subject today – at least in the US – that consensus might not be apparent. And somehow the discussion has become a “debate,” which is often divided down political party lines.
“We have to make it clear that the ice sheets are not Republicans or Democrats – they don’t have a political agenda as they disappear,” said Michael Mann, a physicist at Pennsylvania State University, who has been at the recent forefront of climate research. “Certain facts cannot be denied. We have to find a way to steer the conversation to a good faith debate about what we can do about the problem, not this bad faith debate about the reality of it.”
Why has the public discourse become so polarizing and why is there a fair amount of legislators and the public who now think that climate change is an elaborate hoax?
Michael Mann, Professor Director, Earth System Science Center, Pennsylvania State University. Credit: PSU
Mann referred specifically to an infamous memo sent out by GOP political consultant Frank Luntz in 2002 to President George Bush, “which basically said that if the public comes to understand the reality of this problem they will demand policy action to deal with it,” Mann said, “and so you need to manufacture doubt and controversy and uncertainty and cultivate a set of scientists who can act for advocates essentially for fossil fuel industry. And that is what is happened.”
And the science became politicized. “If you can politicize something in today’s political environment,” Mann continued, “you can immediately get half the population on your side. Unfortunately the forces of anti-science — those who deny the science — have been very effective in politicizing the framing.”
Line plot of global mean land-ocean temperature index, 1880 to present, with the base period 1951-1980. The dotted black line is the annual mean and the solid red line is the five-year mean. The green bars show uncertainty estimates. Credit: NASA
But thousands of scientists from almost 200 countries around the world agreed on the most recent Intergovernmental Panel on Climate Change (IPCC) report which said most of the observed increases in global average temperatures is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. Additionally, the US National Academy of Sciences, the National Academies of all the G-8 nations, the American Association for the Advancement of Science and several other scientific bodies have all issued equivalent statements of consensus of the reality of human-caused climate change.
“Certain facts cannot be denied because you don’t like the implications,” Mann said.
Mann is probably best known for known for his “hockey stick” reconstruction of past climate, (Nature, 1998) which shows the world is warmer now than it has been for at least 1000 years. The “hockey stick” has been attacked by climate change deniers, and while new research has better defined the data, it has not been disproven, nor is it the only line of evidence for global warming.
“The hockey stick is not ‘the’ pillar of evidence for the reality of climate change,” Mann said. “There are multiple pillars that include just the basic understanding of chemistry and physics. But it is one of the more visually compelling pieces of evidence for warming.”
The 'hockey stick' chart from the Intergovernmental Panel on Climate Change Third Assessment Report in 2001.
Mann conceded that various other studies and reconstructions of past climate data don’t agree entirely and that there are uncertainties of how much warming will continue because the predictions are based on models, which attempt to predict the future.
“There are legitimate uncertainties, but unfortunately the public discourse is so far removed from where the scientific discourse and controversies actually are, “Mann said. “There is not an uncertainty of the reality of climate change, that sea levels are going to rise, that arctic sea ice will be gone in a few decades or a whole lot of other areas, but we do have an uncertainty in our ability to project regional climate change.”
Mann said scientists don’t completely understand the El Nino and La Nina affects, how cloud feedback will influence the warming and other modeling issues.
However, Mann said, the science has improved over the past few years, and still, there is enough evidence for not just a hockey stick, but an entire hockey league.
“Every reconstruction reveals that the warming is indeed anomalous in a very long term context. Global temperatures are running the highest they have ever run. The twelve month running averages are warmer than they have ever been in documented history. There is no cooling of the globe and no decline to hide,” Mann said referring to the “Climategate” emails that were stolen from East Anglia climate research center and leaked just a few weeks before the Copenhagen climate summit in late 2009.
“Hackers stole thousands of emails –private correspondences between scientists,” said Mann, “and their words were cherry picked, taken out of context and distorted to make it sound like scientists were engaged in some sort of hoax.”
‘Hide the decline’ actually meant the scientists were going to remove unreliable tree-ring data, not cover up any decline in temperatures.
Mann said the real crime was the illegal theft of private correspondence, in addition to the moral crime of intentionally distorting what scientists believe and think.
Mann took his audience to task by saying, “I’d like to say the mainstream media recognized the manufactured controversy for what is was, but they didn’t, entirely.” He also admitted that scientists have not done all they could in the past to make the science clear and their words convincing.
But looking at the current political climate, Mann asked for journalists’ help in the future.
“No doubt we are in for a period of months or even years where climate science is likely to be subject to the sort of politically motivated inquisition that we haven’t seen, frankly, since the 1950’s,” he said. “It is necessary and important for the scientific community to do the best it I can to defend itself from this oncoming attack, and frankly, we are entirely reliant on the willingness of the mainstream media to serve in its role as the critical and independent arbiter and not just report the two sides of the so-called debate, but to actually establish what is fact and what is fiction. The scientists will not be successful against the attack that is coming unless the media is serving its role.”
Mann ended his talk with a picture of his daughter enthralled by a polar bear at a zoo. “I don’t want to have to tell my daughter that polar bears became extinct because we failed to counter a well funded effort to distract the public,” he said.
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Note: For any reader who thinks they need to leave a comment to debate the climate change science, before posting, please take a look at the following information:
Many spiral galaxies are known to harbor bars. Not the sort in which liquor is served as a social lubricant, but rather, the kind in which gas is served to the central regions of a galaxy. But just as recent studies have identified alcohol as one of the most risky drugs, a new study using results from the Galaxy Zoo 2 project have indicated galactic bars may be associated with dead galaxies as well.
The Galaxy Zoo 2 project is the continuation of the original Galaxy Zoo. Whereas the original project asked participants to categorize galaxies into Hubble Classifications, the continuation adds the additional layer of prompting users to provide further classification including whether or not the nearly quarter of a million galaxies showed the presence of a bar. While relying on only quickly trained volunteers may seem like a risky venture, the percentage of galaxies reported to have bars (about 30%) was in good agreement with previous studies using more rigorous methods.
The new study, led by Karen Masters of the Institute of Cosmology and Gravitation at the University of Portsmouth, analyzed the presence or lack of bars in relation to other variables, such as “colour, luminosity, and estimates of the bulge size, or prominence.” When looking to see if the percent of galaxies with bars evolved over the redshifts observed, the team found no evidence that this had changed in the sample (the GZ2 project contains galaxies to a lookback time of ~6 billion years).
When comparing the fraction with bars to the overall color of the galaxy, the team saw strong trends. In blue galaxies (which have more ongoing star formation) only about 20% of galaxies contained bars. Meanwhile, red galaxies (which contain more older stars) had as many as 50% of their members hosting bars. Even more striking, when the sample was further broken down into grouping by overall galaxy brightness, the team found that dimmer red galaxies were even more likely to harbor bars, peaking at ~70%!
Before considering the possible implications, the team stopped to consider whether or not there was some inherent biasing in the selection based on color. Perhaps bars just stood out more in red galaxies and the ongoing star formation in blue galaxies managed to hide their presence? The team referenced previous studies that determined visual identification for the presence of bars was not hindered in the wavelengths presented and only dipped in the ultraviolet regime which was not presented. Thus, the conclusion was deemed safe.
While the findings don’t establish a causal relationship, the connection is still apparent: If a galaxy has a bar, it is more likely to lack ongoing star formation. This discovery could help astronomers understand how bars form in the first place. Given both structure, such as bars and spiral arms, and star formation are associated with galactic interactions, the expectation would be that we should observe more bars in galaxies in which interactions have caused them to form as well as triggering star formation. As such, this study helps to constrain modes of bar formation. Another possible connection is the ability of bars to assist in movement of gas, potentially shuttling and shielding it from being accessible for formation. As Masters states, “It’s not yet clear whether the bars are some side effect of an external process that turns spiral galaxies red, or if they alone can cause this transformation. We should get closer to answering that question with more work on the Galaxy Zoo dataset.”
An artist illustration of the Cassini spacecraft. Credit: NASA/JPL
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NASA announced that the Cassini spacecraft in orbit around Saturn will have its suite of scientific cameras offline until at least Nov. 24. Cassini is currently in safe mode due to a malfunction in the spacecraft’s computer. This shut down all non-essential systems to prevent any further damage happening to the spacecraft. This means that all scientific efforts on the mission have been suspended until the problem can be resolved.
Although these seem like severe issues, mission managers are relatively sure that they will have no serious long-term effects on the overall mission. Cassini entered safe mode around 4 p.m. PDT (7 p.m. EDT) on Tuesday, Nov. 2. Managers want to review what took place onboard Cassini, correct what they can and ensure that this doesn’t happen again. Programmers have already ascertained that the likely cause of the problem was a faulty program code line that made its way back to Cassini.
Cassini captured this startling image of Saturn's moon Hyperion. Photo Credit: NASA/JPL
Ordinarily when faulty code is sent from Earth to Saturn, Cassini would reject any coding that is deemed ‘bad.’ However, this did not happen in this case, causing the problem. Controllers are not totally convinced that a solar fare didn’t corrupt the code on its way out to the gas giant.
“The spacecraft responded exactly as it should have, and I fully expect that we will get Cassini back up and running with no problems,” said Bob Mitchell, Cassini’s program manager at JPL. “Over the more than six years we have been at Saturn, this is only the second safing event. So considering the complexity of demands we have made on Cassini, the spacecraft has performed exceptionally well for us.”
Cassini launched from Cape Canaveral Air Force Station back in 1997 atop a Titan rocket. In the thirteen years since that time it has entered ‘safe’ mode a total of six times.
Cassini discovered that Saturn's moon Enceladus is 'jet-powered' in the form of geysers erupting from the moon's surface into space. Photo Credit: NASA/JPL
The largest loss for Cassini’s planners is this will cost them a flyby of Titan, one of Saturn’s moons and the only moon in the solar system with an appreciable atmosphere. All is not lost however, as there are still some 53 possible flybys of the moon currently scheduled. The mission is currently planned to last until 2017.
The Cassini-Huygens mission is a cooperative program managed between NASA, the European Space Agency (ESA) and the Italian Space Agency. JPL, a division of the California Institute of Technology (Caltech) manages the Cassini program for NASA’s Science Mission Directorate located in Washington, D.C.
A composite image shows a dark matter disk in red. From images in the Two Micron All Sky Survey. Credit: Credit: J. Read & O. Agertz.
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Although dark matter is inherently difficult to observe, an understanding of its properties (even if not its nature) allows astronomers to predict where its effects should be felt. The current understanding is that dark matter helped form the first galaxies by providing gravitational scaffolding in the early universe. These galaxies were small and collapsed to form the larger galaxies we see today. As galaxies grew large enough to shred incoming satellites and their dark matter, much of the dark matter should have been deposited in a flat structure in spiral galaxies which would allow such galaxies to form dark components similar to the disk and halo. However, a new study aimed at detecting the Milky Way’s dark disk have come up empty.
The study concentrated on detecting the dark matter by studying the luminous matter embedded in it in much the same way dark matter was originally discovered. By studying the kinematics of the matter, it would allow astronomers to determine the overall mass present that would dictate the movement. That observed mass could then be compared to the amount of mass predicted of both baryonic matter as well as the dark matter component.
The team, led by C. Moni Bidin used ~300 red giant stars in the Milky Way’s thick disk to map the mass distribution of the region. To eliminate any contamination from the thin disc component, the team limited their selections to stars over 2 kiloparsecs from the galactic midplane and velocities characteristic of such stars to avoid contamination from halo stars. Once stars were selected, the team analyzed the overall velocity of the stars as a function of distance from the galactic center which would give an understanding of the mass interior to their orbits.
Using estimations on the mass from the visible stars and the interstellar medium, the team compared this visible mass to the solution for mass from the observations of the kinematics to search for a discrepancy indicative of dark matter. When the comparison was made, the team discovered that, “[t]he agreement between the visible mass and our dynamical solution is striking, and there is no need to invoke any dark component.”
While this finding doesn’t rule out the presence of dark matter, it does place constraints on it distribution and, if confirmed in other galaxies, may challenge the understanding of how dark matter serves to form galaxies. If dark matter is still present, this study has demonstrated that it is more diffuse than previously recognized or perhaps the disc component is flatter than previously expected and limited to the thin disc. Further observations and modeling will undoubtedly be necessary.
Yet while the research may show a lack of our understanding of dark matter, the team also notes that it is even more devastating for dark matter’s largest rival. While dark matter may yet hide within the error bars in this study, the findings directly contradict the predictions of Modified Newtonian Dynamics (MOND). This hypothesis predicts the apparent gain of mass due to a scaling effect on gravity itself and would have required that the supposed mass at the scales observed be 60% higher than indicated by this study. Continue reading “Missing Milky Way Dark Matter”
