Astronomers Peer Into Our Universe’s Dark Age

Image credit: NASA
Astronomers who want to study the early universe face a fundamental problem. How do you observe what existed during the “dark ages,” before the first stars formed to light it up? Theorists Abraham Loeb and Matias Zaldarriaga (Harvard-Smithsonian Center for Astrophysics) have found a solution. They calculated that astronomers can detect the first atoms in the early universe by looking for the shadows they cast.

To see the shadows, an observer must study the cosmic microwave background (CMB) – radiation left over from the era of recombination. When the universe was about 370,000 years old, it cooled enough for electrons and protons to unite, recombining into neutral hydrogen atoms and allowing the relic CMB radiation from the Big Bang to travel almost unimpeded across the cosmos for the past 13 billion years.

Over time, some of the CMB photons encountered clumps of hydrogen gas and were absorbed. By looking for regions with fewer photons – regions that are shadowed by hydrogen – astronomers can determine the distribution of matter in the very early universe.

“There is an enormous amount of information imprinted on the microwave sky that could teach us about the initial conditions of the universe with exquisite precision,” said Loeb.

Inflation and Dark Matter
To absorb CMB photons, the hydrogen temperature (specifically its excitation temperature) must be lower than the temperature of the CMB radiation – conditions that existed only when the universe was between 20 and 100 million years old (age of Universe: 13.7 billion years). Coincidentally, this is also well before the formation of any stars or galaxies, opening a unique window into the so-called “dark ages.”

Studying CMB shadows also allows astronomers to observe much smaller structures than was possible previously using instruments like the Wilkinson Microwave Anisotropy Probe (WMAP) satellite. The shadow technique can detect hydrogen clumps as small as 30,000 light-years across in the present-day universe, or the equivalent of only 300 light-years across in the primordial universe. (The scale has grown larger as the universe expanded.) Such resolution is a factor of 1000 times better than the resolution of WMAP.

“This method offers a window into the physics of the very early universe, namely the epoch of inflation during which fluctuations in the distribution of matter are believed to have been produced. Moreover, we could determine whether neutrinos or some unknown type of particle contribute substantially to the amount of ‘dark matter’ in the universe. These questions – what happened during the epoch of inflation and what is dark matter – are key problems in modern cosmology whose answers will yield fundamental insights into the nature of the universe,” said Loeb.

An Observational Challenge
Hydrogen atoms absorb CMB photons at a specific wavelength of 21 centimeters (8 inches). The expansion of the universe stretches the wavelength in a phenomenon called redshifting (because a longer wavelength is redder). Therefore, to observe 21-cm absorption from the early universe, astronomers must look at longer wavelengths of 6 to 21 meters (20 to 70 feet), in the radio portion of the electromagnetic spectrum.

Observing CMB shadows at radio wavelengths will be difficult due to interference by foreground sky sources. To gather accurate data, astronomers will have to use the next generation of radio telescopes, such as the Low Frequency Array (LOFAR) and the Square Kilometer Array (SKA). Although the observations will be a challenge, the potential payoff is great.

“There’s a gold mine of information out there waiting to be extracted. While its full detection may be experimentally challenging, it’s rewarding to know that it exists and that we can attempt to measure it in the near future,” said Loeb.

This research will be published in an upcoming issue of Physical Review Letters, and currently is available online at http://arxiv.org/abs/astro-ph/0312134.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Original Source: Harvard CfA News Release

Probing for Dark Matter Underground

Image credit: Fermilab
With the first data from their underground observatory in Northern Minnesota, scientists of the Cryogenic Dark Matter Search have peered with greater sensitivity than ever before into the suspected realm of the WIMPS. The sighting of Weakly Interacting Massive Particles could solve the double mystery of dark matter on the cosmic scale and of supersymmetry on the subatomic scale.

The CDMS II result, described in a paper submitted to Physical Review Letters, shows with 90 percent certainty that the interaction rate of a WIMP with mass 60 GeV must be less than 4 x 10-43 cm2 or about one interaction every 25 days per kilogram of germanium, the material in the experiment’s detector. This result tells researchers more than they have ever known before about WIMPS, if they exist. The measurements from the CDMS II detectors are at least four times more sensitive than the best previous measurement offered by the EDELWEISS experiment, an underground European experiment near Grenoble, France.

“Think of this improved sensitivity like a new telescope with twice the diameter and thus four times the light collection of any that came before it,” said CDMS II cospokesperson Blas Cabrera of Stanford University. “We are now able to look for a signal that is just one-fourth as bright as any we have seen before. Over the next few years, we expect to improve our sensitivity by a factor of 20 or more.”

The results are being presented at the April Meeting of the American Physical Society on May 3 and 4 in Denver by Harry Nelson and graduate student Joel Sanders, both of the University of California-Santa Barbara, and by Gensheng Wang and Sharmila Kamat of Case Western Reserve University.

“We know that neither our Standard Model of particle physics nor our model of the cosmos is complete,” said CDMS II spokesperson Bernard Sadoulet of the University of California at Berkeley. “This particular missing piece seems to fit both puzzles. We are seeing the same shape from two different directions.”

WIMPs, which carry no charge, are a study in contradictions. While physicists expect them to have about 100 times the mass of protons, their ghostly nature allows them to slip through ordinary matter leaving barely a trace. The term “weakly interacting” refers not to the amount of energy deposited when they interact with normal matter, but rather to the fact that they interact extremely infrequently. In fact, as many as a hundred billion WIMPs may have streamed through your body as you read these first few sentences.

With 48 scientists from 13 institutions, plus another 28 engineering, technical and administrative staffers, CDMS II operates with funding from the Office of Science of the U.S. Department of Energy, from the Astronomy and Physics Divisions of the National Science Foundation and from member institutions. The DOE’s Fermi National Accelerator Laboratory provides the project management for CDMS II.

“The nature of dark matter is fundamental to our understanding of the formation and evolution of the universe,” said Dr. Raymond L. Orbach, Director of DOE’s Office of Science. “This experiment could not have succeeded without the active collaboration of the DOE’s Office of Science and the National Science Foundation.”

Michael Turner, Assistant Director for Math and Physical Sciences at NSF, described identifying the constituent of the dark matter as one of the great challenges in both astrophysics and particle physics.

“Dark matter holds together all structures in the universe-including our own Milky Way-and we still do not know what the dark matter is made of,” Turner said. “The working hypothesis is that it is a new form of matter-which, if correct will shed light on the inner workings of the elementary forces and particles. In pursuing the solution to this important puzzle, CDMS is now at the head of the pack, with another factor of 20 in sensitivity still to come.”

Dark matter in the universe is detected through its gravitational effects on all cosmic scales, from the growth of structure in the early universe to the stability of galaxies today. Cosmological data from many sources confirm that this unseen dark matter totals more than seven times the amount of ordinary visible matter forming the stars, planets and other objects in the universe.

“Something out there formed the galaxies and holds them together today, and it neither emits nor absorbs light,” said Cabrera. “The mass of the stars in a galaxy is only 10 percent of the mass of the entire galaxy, so the stars are like Christmas tree lights decorating the living room of a large dark house.”

Physicists also believe WIMPs could be the as-yet unobserved subatomic particles called neutralinos. These would be evidence for the theory of supersymmetry, introducing intriguing new physics beyond today’s Standard Model of fundamental particles and forces.

Supersymmetry predicts that every known particle has a supersymmetric partner with complementary properties, although none of these partners has yet been observed. However, many models of supersymmetry predict that the lightest supersymmetric particle, called the neutralino, has a mass about 100 times that of the proton.

“Theorists came up with all of these so-called ‘supersymmetric partners’ of the known particles to explain problems on the tiniest distance scales,” said Dan Akerib of Case Western Reserve University. “In one of those fascinating connections of the very large and the very small, the lightest of these superpartners could be the missing piece of the puzzle for explaining what we observe on the very largest distance scales.”

The CDMS II team practices “underground astronomy,” with particle detectors located nearly a half-mile below the earth’s surface in a former iron mine in Soudan, Minnesota. The 2,341 feet of the earth’s crust shields out cosmic rays and the background particles they produce. The detectors are made of germanium and silicon, semiconductor crystals with similar properties. The detectors are chilled to within one-tenth of a degree of absolute zero, so cold that molecular motion becomes negligible. The detectors simultaneously measure the charge and vibration produced by particle interactions within the crystals. WIMPS will signal their presence by releasing less charge than other particles for the same amount of vibration.

“Our detectors act like a telescope equipped with filters that allow astronomers to distinguish one color of light from another,” said CDMS II project manager Dan Bauer of Fermilab. “Only, in our case, we are trying to filter out conventional particles in favor of dark matter WIMPS.”

Physicist Earl Peterson of the University Minnesota oversees the Soudan Underground Laboratory, also home to Fermilab’s long-baseline neutrino experiment, the Main Injector Neutrino Oscillation Search.

“I’m excited about the significant new result from CDMS II, and I congratulate the collaboration,” Peterson said. “I’m pleased that the facilities of the Soudan Laboratory contributed to the success of CDMS II. And I’m especially pleased that the work of Fermilab and the University of Minnesota in expanding the Soudan Laboratory has resulted in superb new physics.”

As CDSMII searches for WIMPs over the next few years, either the dark matter of our universe will be discovered, or a large range of supersymmetric models will be excluded from possibility. Either way, the CDMS II experiment will play a major role in advancing our understanding of particle physics and of the cosmos.

The CDMS II collaborating institutions include Brown University, Case Western Reserve University, Fermi National Accelerator Laboratory, Lawrence Berkeley National Laboratory, the National Institutes of Standards and Technology, Princeton University, Santa Clara University, Stanford University, the University of California-Berkeley, the University of California-Santa Barbara, the University of Colorado at Denver, the University of Florida, and the University of Minnesota.

Fermilab is a DOE Office of Science national laboratory operated under contract by Universities Research Association, Inc.

Original Source: Fermilab News Release

Sea Launch Sends DIRECTV Satellite to Orbit

Image credit: Boeing
Sea Launch Company today successfully delivered the DIRECTV 7S broadcast satellite to orbit from its ocean-based platform on the Equator, marking ten consecutive successes for this highly reliable system. Early data indicate the spacecraft is in excellent condition.

The Sea Launch Zenit-3SL rocket lifted off at 5:42 am PDT (12:42 GMT) from the Odyssey Launch Platform, positioned at 154 degrees West Longitude, precisely on schedule. All systems performed nominally throughout the flight. The Block DM-SL upper stage inserted the 5,483 kg (12,063 lb.) DIRECTV 7S satellite into geosynchronous transfer orbit, on its way to a final orbital position at 119 degrees West Longitude. A ground station in Weilheim, Germany, acquired the spacecraft?s first signal, shortly after spacecraft separation, as planned.

Immediately following the mission, Jim Maser, president and general manager of Sea Launch, said, “In a 29-minute flight with a single-burn of our upper stage, Sea Launch has once again broken its own record by successfully deploying the heaviest commercial satellite in history. This achievement further solidifies Sea Launch?s position as the preeminent heavy lift commercial launch service in the industry.”

“I want to congratulate DIRECTV on today?s exciting mission. We are so proud to be able to provide another launch for DIRECTV and we look forward to building upon a long and mutually beneficial relationship as you continue to expand your direct-to-home business. I also want to congratulate the entire Sea Launch team and thank each member of the team for their enormous contribution to today?s flawless mission.”

DIRECTV 7S, the second spot beam satellite in the DIRECTV fleet, will use highly focused spot beam technology to provide DIRECTV with the capacity to deliver local channels to 41 additional markets, expanding local channel coverage to a total of 106 markets. Built by Space Systems/Loral (SS/L) at their state-of-the-art manufacturing facility in Palo Alto, Calif., the 1300-series spacecraft is one of several high capacity direct-to-home (DTH) broadcast satellites SS/L has produced for DIRECTV, the leading U.S. digital television provider. This is Sea Launch’s second mission for DIRECTV and third for Loral. The first DIRECTV launch was on October 9, 1999, when Sea Launch successfully placed DIRECTV 1R into orbit. The most recent launch for Loral was Telstar 14/Estrela do Sul 1 on January 10, 2004.

Through a cooperative arrangement with Boeing Launch Services (BLS), Sea Launch signed an agreement with Arianespace in November 2003 to launch DIRECTV 7S. This arrangement allowed Arianespace to negotiate a seamless transfer of the satellite to Sea Launch, and for DIRECTV to secure a guaranteed launch slot for this important mission. The launch services alliance utilizes launch systems from three leading service providers – Arianespace, Boeing Launch Services and Mitsubishi Heavy Industries – to provide customers with on-time launches and total mission assurance.

Original Source: Boeing News Release

Send Me Your Venus Photos

With Venus reaching its brightest point, I’m going to set you all a little challenge: take some photos. Grab your digital camera (with or without a telescope) and snap a picture. Since Venus is just a really bright star in the sky, I’d like to see some context in the picture. Maybe show some of your local horizon, or a nice sunset – let’s see Venus from where you live. Send in your pictures and I’ll publish a bunch. Tell me your name, location, and anything interesting you did to capture your image (or an interesting story about how you organized your family to get outdoors).

Get outside, enjoy the sky!

Fraser Cain
Publisher
Universe Today

New Explaination for Cosmic Rays

Image credit: Hubble
University of California scientists working at Los Alamos National Laboratory have proposed a new theory to explain the movement of vast energy fields in giant radio galaxies (GRGs). The theory could be the basis for a whole new understanding of the ways in which cosmic rays — and their signature radio waves — propagate and travel through intergalactic space.

In a paper published this month in The Astrophysical Journal Letters, the scientists explain how magnetic field reconnection may be responsible for the acceleration of relativistic electrons within large intergalactic volumes. That is, the movement of charged particles in space that are originally energized by massive black holes.

“If our understanding of this process is correct,” says Los Alamos astrophysicist Philipp Kronberg, “it could be a paradigm shift in current thinking about the nature of GRGs and cosmic rays.”

Researchers still do not fully understand why magnetic field reconnection occurs, but this much is known: a deeper understanding of the mechanism could have important applications here on Earth, such as the creation of a system of magnetic confinement for fusion energy reactors.

If the Los Alamos scientists’ theory is correct, the discovery also has wide-ranging astrophysical consequences. It implies that magnetic field reconnection or some other highly efficient field-to-particle energy conversion process could be a principal source of all extragalactic radio sources, and possibly also the mysterious “Ultra High Energy Cosmic Ray particles”.

Giant radio galaxies are vast celestial objects that emit a continuum of radio wavelengths detectable with radio telescopes like those at the Very Large Array in Socorro, N.M. Using comprehensive data on seven of the largest radio galaxies in the Universe gathered over the past two decades, the researchers were able to study cosmic ray energy fields that are expelled from the GRGs centers — which are almost certain to contain supermassive black holes — outward as much as a few millions of light years into intergalactic space (1 light year = 5,900,000,000,000 miles).

What the Los Alamos researchers concluded was that the high energy content of these giant radio galaxies, their large ordered magnetic field structures, the absence of strong large-scale shocks and very low internal gas densities point to a direct and efficient conversion of the magnetic field to particle energy in a process that astrophysicists call magnetic field reconnection. Magnetic field reconnection is a process where the lines of a magnetic field connect and vanish, converting the field’s energy into particle energy. Reconnection is considered a key process in the sun’s corona for the production of solar flares and in fusion experiment devices called tokamaks. It also occurs in the interaction between the solar wind and the Earth’s magnetic field and is considered a principal cause of magnetospheric storms.

The research determined that the measurement of the total energy content of at least one of these giant radio galaxies — which is believed to have at its center a black hole with a mass equal to 100 million times that of our sun — was 10 61 ergs. Ergs are a measure of energy where one erg is the amount of energy needed to lift one gram of weight a distance of one centimeter. This energy level of 10 61 ergs is several times more than the thermonuclear energy that could be released by all the stars in a galaxy, offering substantial proof to the researchers that the source of the measured energy could not be typical solar fusion or even supernovae.

In addition to the high energy content, the large, orderly structure of the magnetic field and the absence of strong large-scale shocks — like those that might be present from a supernova explosion — led the scientists to believe that the process of magnetic field reconnection is at work.

In addition to Kronberg, the theory is the result of work by Los Alamos scientists Stirling Colgate, Hui Li and Quentin Dufton. The research was funded by Los Alamos Laboratory-Directed Research and Development (LDRD) funding. LDRD funds basic and applied research and development focusing on creative concepts selected at the discretion of the Laboratory Director.

Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy and works in partnership with NNSA’s Sandia and Lawrence Livermore national laboratories to support NNSA in its mission.

Los Alamos enhances global security by ensuring safety and confidence in the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction and improving the environmental and nuclear materials legacy of the cold war. Los Alamos’ capabilities assist the nation in addressing energy, environment, infrastructure and biological security problems.

Original Source: Los Alamos National Laboratory News Release

Book Review: Strange Matters

The frontiers of space and time are where the physicists and cosmologist are positioned in their search for an understanding of our surroundings. These theoreticians and experimenters are looking for smaller and smaller particles in our space and at the same time are considering the possibility of more than one universe. For them, time may or may not have begun with the start of the universe. It is a relative dimension, and it may even consist of more than one dimension. As equipment gets more advanced, whether stronger atom smashers or more powerful telescopes, these experts obtain more and more clues about existence and often more and more questions.

In our surroundings stranger and stranger ideas are contemplated. There may be planets without central stars. Our universe may start growing with hyperinflation, slow down growth and then speed up again. Patterns of galaxies look like they grow on bubbles. While great attractors have matter streaming into them. Dark matter and negative energy may be more important than visible matter and known energy in keeping our universe together. The universe could be expanding and continue to do so forever, in steady state, or it could be contracting where a big crunch brings the universe back to that which existed before the big bang. There may be other universes alongside or intertwined with our own, or there may be multiple copies of our universe. Theoreticians are looking at their equations and current observations and trying to make reason of it all. Experimenters, of course, would cherish the idea of travelling about the galaxies so as to equally provide for an understanding. However, for now, being stuck on a planet forces them to make the most of whatever is at hand.

Theoreticians rely, for the most part, on mathematics. Math is a standardized means of expressing relationships between entities. Because of its formality, a mathematical equation will often provide more than just the one answer needed and theoreticians will pronounce new elements or conditions based on these alternate answers. Though these can appear, at first, to be nonsensical, experimenters might then establish proof of the validity of these answers. This method of mathematical ‘prediscovery’ has lead to such exotic concepts as strange matter, dark energy, negative pressure and fractional electric charges. And the theoreticians and experimenters are an essential combination in advancing our understanding.

However, even with the steady advances being made, there still remains their greatest challenge, to combine gravitational force with electromagnetism. Physicists are looking hard for this unifying theory and, though many pronouncements are made, there is still no proof for any particular one. Super symmetry or string theory is a strong candidate. By vibrating at different frequencies or notes, a string could mimic any elementary particle. Recent theories have overcome earlier anomalies in the conservation laws and actually provide tens to hundreds of possibilities. These are now considered to be equivalent candidates as each can fold into the other due to the concept of topology. Experimenters, however, will be challenged as the largest of these strings are believed to be on the order of 10-31 cm. Needless to say they aren’t able to do this, at least yet.

And this is one of the curiosities that Tom raises. Is the universe set in a specific way, for a specific reason, or is it the mathematics that defines the state of the universe? This is termed by the cosmologists as the anthropic principal. That is, people are needed to define that in which they exist so perhaps, without people, this universe wouldn’t exist or at least it wouldn’t the way we know it. Further, mathematics is a human construct. So how is it continually able to predict knowledge? And how is it we can say something exists even though we can’t detect it with any of our five senses? Still, with all the good that has come from curiosity it is fortuitous that people are curious.

Tom’s book is a wonderful tour de force of current thinking in physics and cosmology. It discusses much of the progress in scientific ideas, from early principles such as conservation of energy through to the wave/particle concept of light and beyond. Often Tom includes the results of personal interviews and this adds solid credence to the work. Also, though mathematics is often raised, the book has no equations. Albeit, a good understanding and interest of physics and physical principles will allow you to get the most out of this tour.

Though I do appreciate the ability of a journalist to capture the essence of a story, there are times this book reads like a collection of headlines rather than a continuous connected prose. The subject is the same throughout, i.e. physics and cosmology, but it is difficult to grasp what, if any, overall point is being made. The book would greatly benefit with the presentation of a reason for research and analysis in this area.

The physicists and cosmologists are indeed finding matter to be strange. Tom Siegfried in his book Strange Matters, Undiscovered Ideas at the Frontiers of Space and Time will bring the reader up to speed on who is doing what to provide a better understanding of our cosmos. Tom’s journalistic skills allow very complex topics to be easily read and understood by the uninitiated. Read this book and you will realize that, though perhaps strange, the ideas being contemplated at the forefront of space and time show humans to be a gifted species with great potential.

Read more reviews and descriptions from Amazon.com

Review by Mark Mortimer

Computer to Simulate Exploding Star

Image credit: University of Chicago
University scientists are preparing to run the most advanced supercomputer simulation of an exploding star ever attempted.

Tomasz Plewa, Senior Research Associate in the Center for Astrophysical Thermonuclear Flashes and Astronomy & Astrophysics, expects the simulation to reveal the mechanics of exploding stars, called supernovae, in unprecedented detail.

The simulation is made possible by the U.S. Department of Energy?s special allocation of an extraordinary 2.7 million hours of supercomputing time to the Flash Center, which typically uses less than 500,000 hours of supercomputer time annually.

?This is beyond imagination,? said Plewa, who submitted the Flash Center proposal on behalf of a research team at the University and Argonne National Laboratory.

The Flash Center project was one of three selected to receive supercomputer time allocations under a new competitive program announced last July by Secretary of Energy Spencer Abraham.

The other two winning proposals came from the Georgia Institute of Technology, which received 1.2 million processor hours, and the DOE?s Lawrence Berkeley National Laboratory, which received one million processor hours.

The supercomputer time will help the Flash Center more accurately simulate the explosion of a white dwarf star, one that has burned most or all of its nuclear fuel. These supernovae shine so brightly that astronomers use them to measure distance in the universe. Nevertheless, many details about what happens during a supernova remain unknown.

Simulating a supernova is computationally intensive because it involves vast scales of time and space. White dwarf stars gravitationally accumulate material from a companion star for millions of years, but ignite in less than a second. Simulations must also account for physical processes that occur on a scale that ranges from a few hundredths of an inch to the entire surface of the star, which is comparable in size to Earth.

Similar computational problems vex the DOE?s nuclear weapons Stockpile Stewardship and Management Program. In the wake of the Comprehensive Test Ban Treaty, which President Clinton signed in 1996, the reliability of the nation?s nuclear arsenal must now be tested via computer simulations rather than in the field.

?The questions ultimately are how is the nuclear arsenal aging with time, and is your code predicting that aging process correctly?? Plewa said.

Flash Center scientists verify the accuracy of their supernovae code by comparing the results of their simulations both to laboratory experiments and to telescopic observations. Spectral observations of supernovae, for example, provide a sort of bar code that reveals which chemical elements are produced in the explosions. Those observations currently conflict with simulations.

?You want to reconcile current simulations with observations regarding chemical composition and the production of elements,? Plewa said.

Scientists also wish to see more clearly the sequence of events that occurs immediately before a star goes supernova. It appears that a supernova begins in the core of a white dwarf star and expands toward the surface like an inflating balloon.

According to one theory, the flame front initially expands at a relatively ?slow? subsonic speed of 60 miles per second. Then, at some unknown point, the flame front detonates and accelerates to supersonic speeds. In the ultra-dense material of a white dwarf, supersonic speeds exceed 3,100 miles per second.

Another possibility: the initial subsonic wave fizzles when it reaches the outer part of the star, leading to a collapse of the white dwarf, the mixing of unburned nuclear fuel and then detonation.

?It will be very nice if in the simulations we could observe this transition to detonation,? Plewa said.

Flash Center scientists already are on the verge of recreating this moment in their simulations. The extra computer time from the DOE should push them across the threshold.

The center will increase the resolution of its simulations to one kilometer (six-tenths of a mile) for a whole-star simulation. Previously, the center could achieve a resolution of five kilometers (3.1 miles) for a whole-star simulation, or 2.5 kilometers (1.5 miles) for a simulation encompassing only one-eighth of a star.

The latter simulations fail to capture perturbations that may take place in other sections of the star, Plewa said. But they may soon become scientific relics.

?I hope by summer we?ll have all the simulations done and we?ll move on to analyze the data,? he said.

Original Source: University of Chicago News Release

Sea Launch Prepares for DIRECTV Launch

Image credit: Sea Launch
The Sea Launch team arrived at the launch site on the equator yesterday in preparation for the launch of the DIRECTV 7S broadcast satellite for DIRECTV Inc. on Tuesday, May 4, at 5:22am PDT (12:22:00 GMT), at the opening of a two-hour launch window. All systems are proceeding on schedule.

With launch site operations now underway, the marine crew has ballasted the Odyssey Launch Platform about 65 feet to ensure stability. The Sea Launch Commander (Assembly and Command Ship), will be stationed alongside the Odyssey, throughout the weekend, frequently connected by a link bridge that enables foot traffic between the two vessels.

The team will initiate a 72-hour launch countdown on Saturday, May 1. On the day before launch, the platform will be evacuated, with all personnel safely stationed on the ship, three miles from the platform, throughout launch operations. The rocket will be rolled out of its environmentally-protected hangar and automatically erected on the launch pad at L-27 hours.

Sea Launch?s Zenit-3SL vehicle will lift the 5,483 kg (12,063 lb.) DIRECTV 7S satellite to geosynchronous transfer orbit, on its way to a final orbital position at 119 degrees West Longitude. DIRECTV 7S, the second spot beam satellite in the DIRECTV fleet, will use highly focused spot beam technology to provide DIRECTV with the capacity to deliver local channels to 42 additional markets, expanding local channel coverage to a total of 106 markets. The satellite is also capable of operating from 101 degrees West Longitude, the primary orbital slot for DIRECTV. Built by Space Systems/Loral (SS/L) at their state-of-the-art manufacturing facility in Palo Alto, Calif., the 1300-series spacecraft is one of several high capacity direct-to-home (DTH) broadcast satellites SS/L has produced for DIRECTV, the leading U.S. digital television provider.

Sea Launch will carry a live satellite feed and streaming video of the entire mission, beginning at 5:00 am PDT (12:00:00 GMT). To downlink the broadcast, transponder coordinates are posted at: www.boeing.com/nosearch/sealaunch/broadcast.html
A simultaneous webcast will be posted at:
www.sea-launch.com/current_index_webcast.html

Sea Launch Company, LLC, headquartered in Long Beach, Calif., and marketed through Boeing Launch Services ( www.boeing.com/launch ), is the world?s most reliable commercial launch services provider. With the advantage of a launch site on the Equator, the proven Zenit-3SL rocket can lift a heavier spacecraft mass or provide longer life on orbit, yielding best value plus schedule assurance. Sea Launch offers the most direct and cost-effective route to geostationary orbit. For additional information, visit the Sea Launch website at: www.sea-launch.com

Original Source: Boeing News Release

Binary Pulsar System Confirmed

Image credit: NASA/JPL
The only known gravitationally bound pair of pulsars — extremely dense, spinning stars that beam radio waves — may be pirouetting around each other in an intricate dance.

“Pulsars are intriguing and puzzling objects. They pack as much mass as the Sun crammed into an object with a cross-sectional area about as large as Boston,” said Fredrick Jenet of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Jenet and Scott Ransom of McGill University, Montreal, Quebec, Canada, have developed a theoretical model to explain the behavior of this one-of-a-kind set of pulsars.

“The physics of radio pulsar emission has eluded researchers for more than three decades,” Jenet said. “This system may be the ‘Rosetta stone’ of radio pulsars, and this model is one step toward its translation.”

The research appears in the April 29 issue of the journal Nature. Jenet and Ransom studied the recently-discovered double pulsar system, in which two spinning pulsars orbit each other.

The discovery of the two-star system, officially named PSR J0737- 3039B, was announced in 2003 by a multinational team of researchers from Italy, Australia, the United Kingdom and the United States. Those researchers proposed that the duo contained one spinning pulsar and a neutron star. Later in 2003, scientists working at the Parkes Observatory in New South Wales, Australia, determined that both stars are actually pulsars. This discovery marked the first known example of a “binary,” or double, pulsar system. The stars are referred to as A and B.

Pulsars emit high-intensity radio radiation into a narrow beam. As the pulsar rotates, this beam moves in and out of our line of sight. Hence, we see periodic bursts of radio radiation. In this sense, a pulsar works like a lighthouse, in which the light may be on all the time, but it appears to blink on and off. Scientists were surprised to find that the B pulsar is on only at certain locations in its orbit. “It’s as though something is turning B on and off,” Jenet said.

According to Jenet and Ransom, this “something” is closely related to the radio emission beam emanating from the A pulsar. They believe that B becomes bright when it is illuminated by emission from A. Jenet and Ransom used Einstein’s Theory of General Relativity to predict the future evolution of this pulsar system. The theory implies that gravitational effects will change the emission pattern of A, which will then alter the exact orbital locations where B becomes bright.

The double pulsar system is located about 2,000 light years, or 10 million billion miles, from Earth. Jenet and Ransom based their research on observations made at the Green Bank Telescope in West Virginia.

Original Source: NASA/JPL News Release

Wallpaper: Bug Nebula

Image credit: Hubble
The Bug Nebula, NGC 6302, is one of the brightest and most extreme planetary nebulae known. At its centre lies a superhot dying star smothered in a blanket of ?hailstones?. A new Hubble image reveals fresh detail in the wings of this ?cosmic butterfly?.

This image of the Bug Nebula, taken with the NASA/ESA Hubble Space Telescope (HST), shows impressive walls of compressed gas. A torus (?doughnut?) shaped mass of dust surrounds the inner nebula (seen at the upper right).

At the heart of the turmoil is one of the hottest stars known. Despite an extremely high temperature of at least 250 000 degrees Celsius, the star itself has never been seen, as it shines most brightly in the ultraviolet and is hidden by the blanket of dust, making it hard to observe.

Chemically, the composition of the Bug Nebula also makes it one of the more interesting objects known. Earlier observations with the European Space Agency’s Infrared Space Observatory (ISO) have shown that the dusty torus contains hydrocarbons, carbonates such as calcite, as well as water ice and iron. The presence of carbonates is interesting. In the Solar System, their presence is taken as evidence for liquid water in the past, because carbonates form when carbon dioxide dissolves in liquid water and forms sediments. But its detection in nebulae such as the Bug Nebula, where no liquid water has existed, shows that other formation processes cannot be excluded.

Albert Zijlstra from UMIST in Manchester, UK, who leads a team of astronomers probing the secrets of this extreme object, says: ?What caught our interest in NGC 6302 was the mixture of minerals and crystalline ice – hailstones frozen onto small dust grains. Very few objects have such a mixed composition.?

The dense, dark dust torus around the central star contains the bulk of the measured dust mass and is something of a mystery to astronomers. They believe the nebula was expelled around 10 000 years ago, but do not understand how it formed or how long the dust torus can survive evaporation by the very hot central star.

Original Source: ESA News Release