X-43A is Ready for Testing

Image credit: NASA
NASA has set Saturday, March 27, for the flight of its experimental X-43A research vehicle. The unpiloted 12-foot-long vehicle, part aircraft and part spacecraft, will be dropped from the wing of a B-52 aircraft, boosted to nearly 100,000 feet by a booster rocket and released over the Pacific Ocean to briefly fly under its own power at seven times the speed of sound, almost 5,000 mph.

The flight is part of the Hyper-X program, a research effort designed to demonstrate alternate propulsion technologies for access to space and high-speed flight within the atmosphere. It will provide unique “first time” free flight data on hypersonic air-breathing engine technologies that have large potential pay-offs.

Hyper-X is inherently a high-risk program. No vehicle has ever flown at hypersonic speeds powered by an air-breathing scramjet engine. In addition, the rocket boost and subsequent separation from the rocket to get to the scramjet test condition have complex elements that must work properly for the mission to be successful.

The $250 million program began with conceptual design and scramjet engine wind tunnel work in 1996. In a scramjet (supersonic-combustion ramjet), the flow of air through the engine remains supersonic, or greater than the speed of sound, for optimum engine efficiency and vehicle speed. There are few or no moving parts, but achieving proper ignition and combustion in a matter of milliseconds proved to be an engineering challenge of the highest order. After a series of successful wind tunnel tests, however, NASA is ready to prove that air-breathing scramjets work in flight.

This will mark the first time a non-rocket, air-breathing scramjet engine has powered a vehicle in flight at hypersonic speeds, defined as speeds above Mach 5 or five times the speed of sound.

Researchers believe these technologies may someday offer more airplane-like operations and other benefits compared to traditional rocket systems. Rockets provide limited throttle control and must carry heavy tanks filled with liquid oxygen, necessary for combustion of fuel. An air-breathing engine, like that on the X-43A, scoops oxygen from the air as it flies. The weight savings could be used to increase payload capacity, increase range or reduce vehicle size for the same payload.

The X-43A will fly in the Naval Air Warfare Center Weapons Division Sea Range over the Pacific Ocean off the coast of southern California.

After booster burnout, the 2,800-pound, wedge-shaped research vehicle will separate and fly on its own to perform a preprogrammed set of tasks. After an approximate ten second test firing of the engine, the X-43A will glide through the atmosphere conducting a series of aerodynamic maneuvers for up to six minutes on its way to splashdown.

This will be the second flight in the X-43A project. On June 2, 2001, the first X-43A vehicle was lost moments after release from the wing of the B-52. Following booster ignition, the combined booster and X-43A vehicle deviated from its flight path and was deliberately destroyed. Investigation into the mishap showed that there was no single contributing factor, but the root cause of the problem was identified as the control system of the booster.

For this flight, the B-52 will carry the booster with the attached X-43A to at least 40,000 feet before its release, versus the 24,000 feet of the first attempt. The booster will carry the X-43A research vehicle to approximately the same test conditions — altitude and speed — as planned for the first flight.

NASA’s Langley Research Center, Hampton, Va., and Dryden Flight Research Center, Edwards, Calif., jointly conduct the Hyper-X program.

A video clip, images and additional information about the project are available on the Internet at:

http://www.nasa.gov/missions/research/x43-main.html

NASA Television will carry the flight and the post-flight news briefing live. NASA TV is available on AMC 9, TRANSPONDER 9C, 85 degrees west longitude, vertical polarization with a frequency of 3880 MHz and audio of 6.8 MHz.

Original Source: NASA News Release

Opportunity is Parked at the Shore of an Ancient Martian Sea

Image credit: NASA/JPL
NASA’s Opportunity rover has demonstrated some rocks on Mars probably formed as deposits at the bottom of a body of gently flowing saltwater.

“We think Opportunity is parked on what was once the shoreline of a salty sea on Mars,” said Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the science payload on Opportunity and its twin Mars Exploration Rover, Spirit.

Clues gathered so far do not tell how long or how long ago liquid water covered the area. To gather more evidence, the rover’s controllers plan to send Opportunity out across a plain toward a thicker exposure of rocks in the wall of a crater.

NASA’s Associate Administrator for Space Science Dr. Ed Weiler said, “This dramatic confirmation of standing water in Mars’ history builds on a progression of discoveries about that most Earthlike of alien planets. This result gives us impetus to expand our ambitious program of exploring Mars to learn whether microbes have ever lived there and, ultimately, whether we can.”

“Bedding patterns in some finely layered rocks indicate the sand-sized grains of sediment that eventually bonded together were shaped into ripples by water at least five centimeters (two inches) deep, possibly much deeper, and flowing at a speed of 10 to 50 centimeters (four to 20 inches) per second,” said Dr. John Grotzinger, rover science-team member from the Massachusetts Institute of Technology, Cambridge, Mass.

In telltale patterns, called crossbedding and festooning, some layers within a rock lie at angles to the main layers. Festooned layers have smile-shaped curves produced by shifting of the loose sediments’ rippled shapes under a current of water.

“Ripples that formed in wind look different than ripples formed in water,” Grotzinger said. “Some patterns seen in the outcrop that Opportunity has been examining might have resulted from wind, but others are reliable evidence of water flow,” he said.

According to Grotzinger, the environment at the time the rocks were forming could have been a salt flat, or playa, sometimes covered by shallow water and sometimes dry. Such environments on Earth, either at the edge of oceans or in desert basins, can have currents of water that produce the type of ripples seen in the Mars rocks.

A second line of evidence, findings of chlorine and bromine in the rocks, also suggests this type of environment. Rover scientists presented some of that news three weeks ago as evidence the rocks had at least soaked in mineral-rich water, possibly underground water, after they formed. Increased assurance of the bromine findings strengthens the case rock-
forming particles precipitated from surface water as salt concentrations climbed past saturation while water was evaporating.

Dr. James Garvin, lead scientist for Mars and lunar exploration at NASA Headquarters, Washington, said, “Many features on the surface of Mars that orbiting spacecraft have revealed to us in the past three decades look like signs of liquid water, but we have never before had this definitive class of evidence from the martian rocks themselves. We planned the Mars Exploration Rover Project to look for evidence like this, and it is succeeding better than we had any right to hope. Someday we must collect these rocks and bring them back to terrestrial laboratories to read their records for clues to the biological potential of Mars.”

Squyres said, “The particular type of rock Opportunity is finding, with evaporite sediments from standing water, offers excellent capability for preserving evidence of any biochemical or biological material that may have been in the water.”

Engineers at NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif., expect Opportunity and Spirit to operate several months longer than the initial rover’s three-month prime missions on Mars. To analyze hints of crossbedding, mission controllers programmed Opportunity to move its robotic arm more than 200 times in one day, taking 152 microscope pictures of layering in a rock called “Last Chance.”

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for NASA’s Office of Space Science, Washington. For images and information about the project on the Internet, visit:

http://www.nasa.gov

http://marsrovers.jpl.nasa.gov

http://athena.cornell.edu

Original Source: NASA News Release

Shuttle Components Were Installed Backwards

Technicians working on the space shuttles discovered last week that some gears in the braking mechanism had been installed backwards, in some cases, nearly two decades ago. They had never been inspected since. Fortunately, the reversed gears were in one of the least stressful positions of the assembly; had it been installed in a high-stress position, it could have failed when the shuttle landed – probably leading to its destruction. New parts will be installed before the shuttle returns to flight next March.

New Proposal to Search for Dark Matter

Image credit: Hubble
WIMPs speeding at 670,000 mph on a “highway” in space may be raining onto Earth ? a phenomenon that might prove the existence of “dark matter” that makes up most our galaxy and one-fourth of the universe, says a study co-authored by a University of Utah physicist.

Many researchers have long suspected that dark matter may be made of WIMPS or Weakly Interacting Massive Particles, which are theorized subatomic particles. More than 20 groups of physicists worldwide are building or have built devices to detect them.

Scientists who run a WIMP detector named DAMA (Dark Matter) in Italy claimed in 1998 that the underground device sensed WIMPs reaching Earth from an unseen halo of dark matter surrounding our Milky Way galaxy. The claim was doubted by scientists who run other WIMP detectors, which are designed differently than DAMA and have not found WIMPs.

The new study ? published in the March 19 issue of the journal Physical Review Letters ? advises how the DAMA scientists might prove their claim.

“We?re suggesting a way to check if what DAMA claimed to have seen are really WIMPs,” says study co-author Paolo Gondolo, an assistant professor of physics at the University of Utah. “This is about finding out what 90 percent of our galaxy is made of.”

Gondolo and colleagues say that in addition to the WIMPs pouring into our Milky Way galaxy from the surrounding halo, a dark matter “highway” of WIMPS may be raining onto our solar system after flying out of Sagittarius, a dwarf galaxy that slowly is being gobbled up and torn apart by gravity from the Milky Way.

The combination of the Milky Way WIMPS and those from the Sagittarius dwarf galaxy should produce a distinct pattern in the Italian data that “would be a smoking gun for WIMP detection,” the new study says.

Gondolo conducted the research with physicist Katherine Freese and graduate student Matthew Lewis of the University of Michigan, and astronomer Heidi Jo Newberg of Rensselaer Polytechnic Institute in Troy, N.Y.

The Dark Side of the Universe
Scientists realized a few decades ago that the motions of galaxies within the universe could not be explained by the gravitational pull of visible galaxies, stars and gases. For a long time, scientists said that 10 percent of the universe was visible matter and 90 percent was unseen dark matter filling the voids among stars and galaxies.

In recent years, however, astronomers determined that the universe and its galaxies were flying apart at an accelerating rate, a phenomenon consistent with the existence of an anti-gravitational force known as “dark energy.”

Gondolo says scientists now believe the universe is about 5 percent visible matter, 25 percent dark matter and 70 percent dark energy.

Unlike dark matter, which is subject to gravity, dark energy is not pulled into our galaxy, so the Milky Way is about 10 percent matter and 90 percent dark matter, Gondolo says.

The spinning motion of the flattened, spiral disk-shaped Milky Way is too fast to be explained merely by the gravity of its visible stars and gases, so scientists believe it is surrounded by a much larger “halo” ? actually a flattened sphere ? that contains some stars but mostly unseen dark matter.

Over the years, numerous theories were proposed as to the nature of the dark matter: from dim brown dwarf stars that never ignited to the whimsically named MACHOs (Massive Compact Halo Objects) and subatomic WIMPs.

Gondolo says WIMPs and other subatomic particles called axions now are considered the most likely candidates to be dark matter.

The DAMA detector, located at Italy?s Gran Sasso National Laboratory, is run by an international collaboration of physicists led by the University of Rome. The DAMA group announced in 1998 that it found evidence for WIMPS.

Because DAMA is underground, overlying rock filters out particles created when cosmic rays hit Earth?s atmosphere and produce showers of smaller particles. WIMPs are “weakly interacting” particles, so they pass through Earth. But they can hit sodium iodide crystals inside DAMA, causing flashes of light and making sodium or iodine ions recoil.

If WIMPs do exist, they flow toward our solar system from the halo around our galaxy. As the Earth orbits around the sun, it sometimes moves “upstream” against the flow of oncoming WIMPs, and sometimes moves with the flow. The DAMA scientists believe this explains the up-and-down pattern in the number of particles detected by DAMA, and supports the assertion those particles are WIMPs.

Other physicists, however, remain unconvinced. Their detectors, which use germanium as a sensor instead of sodium iodide, should be equally sensitive, but have not “seen” WIMPs. They argue the annual fluctuation in the number of particles detected by DAMA may be caused by seasonal changes in the atmosphere, the DAMA detector or DAMA?s environment, so that the particles have not been proven to be WIMPs.

The New Study: A Solution from Sagittarius?
The visible Milky Way is vast, about 100,000 light years across, or about 588 million billion miles (588 times 10 to the 15th power). For eons, the Milky Way has been absorbing and tearing apart the Sagittarius dwarf galaxy, which is one-tenth the Milky Way?s diameter.

Newberg and other astronomers recently discovered two arc-shaped “tails” or streams of stars flowing from Sagittarius. The streams are believed to also contain WIMPs ? if they exist. Our solar system sits in one of these streams, which Gondolo and Freese describe as a possible “dark matter ?highway? raining down upon the solar system.”

In the new study, Gondolo and colleagues suggest how the combination of WIMPs from the Milky Way?s halo and from the Sagittarius stream would register on the DAMA detector:

— The dates of the maximum and minimum number of WIMPs detected by DAMA would shift when dark matter from Sagittarius is considered. That is because the Sagittarius WIMPs hit Earth from a different angle than Milky Way halo WIMPS, changing the dates when the most and the fewest WIMPs hit Earth and thus DAMA. Gondolo says the peak should be May 25 instead of June 2 if Sagittarius WIMPs and halo WIMPs both hit Earth. DAMA found the maximum was
May 21, plus or minus 22 days.

— The “smoking gun” that would prove WIMPS exist is more complicated to explain. When particles hit sodium iodide in DAMA, the ions recoil in proportion to the mass and speed of the incoming particle. Gondolo says WIMPs from the Milky Way halo move at speeds of zero to 600 kilometers per second (1.34 million mph), with an average speed of 220 kilometers per second (about 492,000 mph). WIMPs in the Sagittarius stream or highway all move at 300 kilometers per second (about 671,000 mph). When the recoil energies of the two kinds of WIMPs are combined and plotted on a graph, there should be a steep “step” or drop in the number of collisions with higher recoil energies, reflecting the fact that Sagittarius WIMPs do not exceed 671,000 mph.

If DAMA scientists find that “step” in their data, it should be the smoking gun to prove dark matter exists in the form of WIMPs, Gondolo says.

“This would be a corroboration of their result,” he adds. “As way to check if they really have seen WIMPs, they could look for the specific signature of WIMPs in the Sagittarius stream.”

Scientists at DAMA are aware of the new study and are rechecking their data to determine if it contains the evidence that could prove the detector found WIMPs. The process could take months, and it will take a few years for newer detectors to confirm the finding, Gondolo says.

He and his colleagues suspect other detectors have not found WIMPs because the particles may be lighter and smaller than expected, so germanium does not recoil much when hit by an incoming WIMP, while DAMA?s ions have measurable recoil.

Gondolo says he studies dark matter because “I want to know what the universe is made of. I was unsatisfied when I learned most of the universe is not made of atoms.”

Original Source: University of Utah News Release

Supernova Explodes Inside a Nebula

Image credit: LBL
By measuring polarized light from an unusual exploding star, an international team of astrophysicists and astronomers has worked out the first detailed picture of a Type Ia supernova and the distinctive star system in which it exploded.

Using the European Southern Observatory’s Very Large Telescope in Chile, the researchers determined that supernova 2002ic exploded inside a flat, dense, clumpy disk of dust and gas, previously blown away from a companion star. Their work suggests that this and some other precursors of Type Ia supernovae resemble the objects known as protoplanetary nebulae, well known in our own Milky Way galaxy.

Lifan Wang of Lawrence Berkeley National Laboratory, Dietrich Baade of the European Southern Observatory (ESO), Peter H?flich and J. Craig Wheeler of the University of Texas at Austin, Koji Kawabata of the National Astronomical Observatory of Japan, and Ken’ichi Nomoto of the University of Tokyo report their findings in the 20 March 2004 issue of Astrophysical Journal Letters.

Casting supernovae to type
Supernovae are labeled according to the elements visible in their spectra: Type I spectra lack hydrogen lines, while Type II spectra have these lines. What makes SN 2002ic unusual is that its spectrum otherwise resembles a typical Type Ia supernova but exhibits a strong hydrogen emission line.

Type II and some other supernovae occur when the cores of very massive stars collapse and explode, leaving behind extremely dense neutron stars or even black holes. Type Ia supernovae, however, explode by a very different mechanism.

“A Type Ia supernova is a metallic fireball,” explains Berkeley Lab’s Wang, a pioneer in the field of supernova spectropolarimetry. “A Type Ia has no hydrogen or helium but lots of iron, plus radioactive nickel, cobalt, and titanium, a little silicon, and a bit of carbon and oxygen. So one of its progenitors must be an old star that has evolved to leave behind a carbon-oxygen white dwarf. But carbon and oxygen, as nuclear fuels, do not burn easily. How can a white dwarf explode?”

The most widely accepted Type Ia models assume that the white dwarf — roughly the size of Earth but packing most of the mass of the sun — accretes matter from an orbiting companion until it reaches 1.4 solar masses, known as the Chandrasekhar limit. The now superdense white dwarf ignites in a mighty thermonuclear explosion, leaving behind nothing but stardust.

Other schemes include the merger of two white dwarfs or even a lone white dwarf that re-accretes the matter shed by its younger self. Despite three decades of searching, however, until the discovery and subsequent spectropolarimetric studies of SN 2002ic, there was no firm evidence for any model.

In November of 2002, Michael Wood-Vasey and his colleagues in the Department of Energy’s Nearby Supernova Factory based at Berkeley Lab reported the discovery of SN 2002ic, shortly after its explosion was detected almost a billion light-years away in an anonymous galaxy in the constellation Pisces.

In August of 2003, Mario Hamuy from the Carnegie Observatories and his colleagues reported that the source of the copious hydrogen-rich gas in SN 2002ic was most likely a so-called Asymptotic Giant Branch (AGB) star, a star in the final phases of its life, with three to eight times the mass of the sun — just the sort of star that, after it has blown away its outer layers of hydrogen, helium, and dust, leaves behind a white dwarf.

Moreover, this seemingly self-contradictory supernova — a Type Ia with hydrogen — was in fact similar to other hydrogen-rich supernovae previously designated Type IIn. This in turn suggested that, while Type Ia supernovae are indeed remarkably similar, there may be wide differences among their progenitors.

Because Type Ia supernovae are so similar and so bright — as bright or brighter than whole galaxies — they have become the most important astronomical standard candles for measuring cosmic distances and the expansion of the universe. Early in 1998, after analyzing dozens of observations of distant Type Ia supernovae, members of the Department of Energy’s Supernova Cosmology Project based at Berkeley Lab, along with their rivals in the High-Z Supernova Search Team based in Australia, announced the astonishing discovery that the expansion of the universe is accelerating.

Cosmologists subsequently determined that over two-thirds of the universe consists of a mysterious something dubbed “dark energy,” which stretches space and drives the accelerating expansion. But learning more about dark energy will depend on careful study of many more distant Type Ia supernovae, including a better knowledge of what kind of star systems trigger them.

Picturing structure with spectropolarimetry
The spectropolarimetry of SN 2002ic has provided the most detailed picture of a Type Ia system yet. Polarimetry measures the orientation of light waves; for example, Polaroid sunglasses “measure” horizontal polarization when they block some of the light reflected from flat surfaces. In an object like a cloud of dust or a stellar explosion, however, light is not reflected from surfaces but scattered from particles or from electrons.

If the dust cloud or explosion is spherical and uniformly smooth, all orientations are equally represented and the net polarization is zero. But if the object is not spherical — shaped like a disk or a cigar, for example — more light will oscillate in some directions than in others.

Even for quite noticeable asymmetries, net polarization rarely exceeds one percent. Thus it was a challenge for the ESO spectropolarimetry instrument to measure faint SN 2002ic, even using the powerful Very Large Telescope. It took several hours of observation on four different nights to acquire the necessary high-quality polarimetry and spectroscopy data.

The team’s observations came nearly a year after SN 2002ic was first detected. The supernova had grown much fainter, yet its prominent hydrogen emission line was six times brighter. With spectroscopy the astronomers confirmed the observation of Hamuy and his associates, that ejecta expanding outward from the explosion at high velocity had run into surrounding thick, hydrogen-rich matter.

Only the new polarimetric studies, however, could reveal that most of this matter was shaped as a thin disk. The polarization was likely due to the interaction of high-speed ejecta from the explosion with the dust particles and electrons in the slower-moving surrounding matter. Because of the way the hydrogen line had brightened long after the supernova was first observed, the astronomers deduced that the disk included dense clumps and had been in place well before the white dwarf exploded.

“These startling results suggest that the progenitor of SN 2002ic was remarkably similar to objects that are familiar to astronomers in our own Milky Way, namely protoplanetary nebulae,” says Wang. Many of these nebulae are the remnants of the blown-away outer shells of Asymptotic Giant Branch stars. Such stars, if rotating rapidly, throw off thin, irregular disks.

A matter of timing
For a white dwarf to collect enough material to reach the Chandrasekhar limit takes a million years or so. By contrast, an AGB star loses copious amounts of matter relatively quickly; the protoplanetary-nebula phase is transitory, lasting only a few hundreds or thousands of years before the blown-off matter dissipates. “It’s a small window,” says Wang, not a long enough time for the leftover core (itself a white dwarf) to re-accrete enough material to explode.

Thus it’s more likely that a white dwarf companion in the SN 2002ic system was already busily collecting matter long before the nebula formed. Because the protoplanetary phase lasts only a few hundred years, and assuming a Type Ia supernova typically takes a million years to evolve, only about a thousandth of all Type Ia supernovae are expected to resemble SN 2002ic. Fewer still will exhibit its specific spectral and polarimetric features, although “it would be extremely interesting to search for other Type Ia supernovae with circumstellar matter,” Wang says.

Nevertheless, says Dietrich Baade, principal investigator of the polarimetry project that used the VLT, “it’s the assumption that all Type Ia supernovae are basically the same that permits the observations of SN 2002ic to be explained.”

Binary systems with different orbital characteristics and different kinds of companions at different stages of stellar evolution can still give rise to similar explosions, through the accretion model. Notes Baade, “The seemingly peculiar case of SN 2002ic provides strong evidence that these objects are in fact very much alike, as the stunning similarity of their light curves suggests.”

By showing the distribution of the gas and dust, spectropolarimetry has demonstrated why Type Ia supernovae are so much alike even though the masses, ages, evolutionary states, and orbits of their precursor systems may differ so widely.

The Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our website at http://www.lbl.gov.

Original Source: Berkeley Lab News Release

Opportunity’s Out of the Crater

Image credit: NASA/JPL
The Mars Exploration Rover Opportunity’s landing site is now viewable in panorama as the rover exited the crater which scientists consider one of the investigative landmarks on the red planet.

This image mosaic, compiled from navigation and panoramic camera images during the 33rd, 35th, and 36th sols on Mars, shows a panoramic view of the crater where the rover had been exploring since its dramatic arrival in late January 2004.

The crater, now informally referred to as “Eagle Crater,” is approximately 22 meters (72 feet) in diameter. Opportunity’s lander is visible in the center of the image. Track marks reveal the rover’s progress. The rover cameras recorded this view as Opportunity climbed close to the crater rim as part of a soil survey campaign.

After a slightly slippery start yestersol, Opportunity made it out of “Eagle Crater”on sol 57, which ends at 8:45 p.m. PST on March 22. The drive along the crater’s inner slope that was initiated on the last sol continued this sol until Opportunity exited its landing-site crater.

The rover tried driving uphill out of its landing-site crater during its 56th sol, ending at 10:05 p.m. March 21, PST, but slippage prevented success.

The rover remained healthy, and it later completed a turn to the right and a short drive along the crater’s inner slope.

Controllers sent it on a different route for exiting the crater and images from the navigation camera confirmed that the rover is now about 9 meters (about 29.5 feet) outside of the crater.

The rover also conducted remote sensing observations between naps this sol. After completing the drive out of the crater, the navigation camera imaged Opportunity’s brand new view of the plains of Meridiani Planum.

Opportunity flipped more meters on its odometer during the latest drives along the current soil survey campaign, surpassing the total drive distance of 1997’s Sojourner rover.

During the martian night, rover planners will awaken Opportunity to take miniature thermal emission spectrometer observations of the ground and the atmosphere.

Original Source: Astrobiology Magazine

Five Years of Universe Today

In case you weren’t counting, today marks the fifth anniversary of Universe Today. That’s right, I started this space web rag on March 22, 1999 as a hobby; an excuse for me to learn more about web publishing and online marketing. Little did I realize I’d still be working on it five years later. 🙂 I never dreamed I’d have more than a few hundred subscribers, but there are now 21,000 of you signed up to get the email edition.

Since I began Universe Today, I’ve moved servers seven times, had two children, lost two hard drives, published 805 newsletters, worked at three different jobs, and served up about 200 million “hits”. There have been a few dry spells, too, when I didn’t have the time or enthusiasm to work on the website – the last year’s been a blast though. If you want to take a look back at the history of the website, here’s a handy link through the Wayback Machine. I know, I know, it started out pretty ugly.

So, I just wanted to take a moment and thank everyone for your enthusiastic support, engaging conversation in the forum, and gentle feedback at my tpyos. I’d also like to thank my sponsors (especially Countdown Creations, who’s been a big contributor right from the beginning).

Here’s to many, many more years.

Fraser Cain
Publisher
Universe Today

A New Look at McNeil’s Nebula

Image credit: Gemini
A timely discovery by American amateur astronomer Jay McNeil, followed immediately by observations at the Gemini Observatory, has provided a rare glimpse into the slow, yet violent birth of a star about 1,500 light-years away. The resulting findings reveal some of the strongest stellar winds ever detected around an embryonic Sun-like star.

McNeil?s find was completely serendipitous. He was surveying the sky in January from his backyard in rural Kentucky and taking electronic images through his 3-inch (8-centimeter) telescope. When he examined his work, he noticed a small glowing smudge of light in the constellation of Orion that wasn?t there before. ?I knew this part of the sky very well and I couldn?t believe what I was seeing,? said McNeil. Astronomers were alerted almost immediately, via the Internet, and quickly realized that he had come across something special.

?It is extremely rare that we have an opportunity to study an important event like this, where a newly born star erupts and sheds light on its otherwise dark stellar nursery,? said Gemini astronomer Dr. Colin Aspin. Dr. Aspin and Dr. Bo Reipurth, (of the University of Hawaii?s Institute for Astronomy), published the first paper on this object, now known as McNeil?s Nebula. Their work, based on observations using the Frederick C. Gillett Gemini North Telescope on Mauna Kea, is in press for Astrophysical Journal Letters.

?McNeil?s Nebula is allowing us to add another important piece to the puzzle of the long, protracted birth of a star,? said Reipurth. ?It has been more than thirty years since anything similar has been seen, so for the first time, we have an opportunity to study such an event with modern instrumentation like that available at Gemini.?

Detailed images and spectra of the stellar newborn, taken using the Gemini Near-Infrared Imager and Multi-Object Spectrograph, demonstrate that the star has brightened considerably. It is blasting gas away from itself at speeds of more than 600 kilometers per second (over 2000 times faster than a typical commercial airplane). The observations indicate the eruption was triggered by complex interactions in a rotating disk of gas and dust around the star. For reasons that are still not fully understood, the inner part of the disk begins to heat up, causing the gases to glow. At the same time, some gas funnels along magnetic field lines onto the surface of the star, creating very bright hot spots and causing the star to grow. The eruption also cleared out some of the dust and gas surrounding the young star, allowing light to escape and illuminate a cone-shaped cavity carved out by previous eruptions into the gas.

The birth of a star takes several tens of thousands of years and these observations are but a brief snapshot of the process. Although this is very a rapid schedule on astronomical time scales, Reipurth explained that it?s impossibly slow compared to a human lifetime. ?We astronomers therefore have no choice but to compare various objects where each one is in a different state of development,? he said. ?This is very similar to the imaginary situation of an alien landing on Earth with only half an hour to understand the full life cycle of humans. By looking at people of various ages and using some logic, this alien could piece together our growth from infant to old age. This is how we are beginning to understand the birth and youth of stars. Rare events like the one McNeil discovered help to fill in the blanks in our understanding of stellar origins.?

This outburst may not be the first time the star has flared during its long tumultuous birth. Following McNeil?s discovery, an inspection of archival plates revealed that a similar event took place in 1966, when the star flared and faded again into its enshrouding gas. ?We know so little about these kind of eruptions that we cannot even say whether the star will continue to flare or will rapidly fade from view again,? said Aspin. ?We were extremely fortunate that Mr. McNeil discovered this when he did. In an event like this, the earlier we can observe it, the better our chances are of understanding what is going on.?

Fortunately for Aspin and Reipurth, McNeil discovered this in the early winter while the Orion region is still high in the night-time sky. It was also fortunate that McNeil was so familiar with this part of the sky that he noticed right away that something had changed. This combination of circumstances enabled the astronomers to prepare an observation run on Gemini very quickly. ?Our window for observing this object is closing rapidly but it will become visible again later this year,? said Aspin. ?By then this eruption could be over.?

A striking color image from Gemini reveals fine details in McNeil?s Nebula. The star and its bright disk shine like a lighthouse through the cavity of gas and dust. The Gemini image and an artist?s conception of how the escaping gas and hotspots on a young star might have caused this event can be found here.

The Gemini Observatory is an international collaboration that has built two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai`i (Gemini North) and the Gemini South telescope is located on Cerro Pach?n in central Chile (Gemini South), and hence provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in each partner country with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the UK Particle Physics and Astronomy Research Council (PPARC), the Canadian National Research Council (NRC), the Chilean Comisi?n Nacional de Investigaci?n Cientifica y Tecnol?gica (CONICYT), the Australian Research Council (ARC), the Argentinean Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) and the Brazilian Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq). The Observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

The Institute for Astronomy at the University of Hawaii conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Mauna Kea. Refer to http://www.ifa.hawaii.edu/ for more information about the Institute.

Original Source: Gemini Observatory News Release

Saturn With Cassini’s Blue Filter

Image credit: NASA/JPL
Bands and spots in Saturn’s atmosphere, including a dark band south of the equator with a scalloped border, are visible in this image from the Cassini-Huygens spacecraft.

The narrow-angle camera took the image in blue light on Feb. 29, 2004. The distance to Saturn was 59.9 million kilometers (37.2 million miles). The image scale is 359 kilometers (223 miles) per pixel.

Three of Saturn’s moons are seen in the image: Enceladus (499 kilometers, or 310 miles across) at left; Mimas (398 kilometers, or 247 miles across) left of Saturn’s south pole; and Rhea (1,528 kilometers, or 949 miles across) at lower right. The imaging team enhanced the brightness of the moons to aid visibility.

The BL1 broadband spectral filter (centered at 451 nanometers) allows Cassini to “see” light in a part of the spectrum visible as the color blue to human eyes. Scientist can combine images made with this filter with those taken with red and green filters to create full-color composites.

In this image, everything on the planet is a cloud, and the contrast between bright and dark features is determined by the different blue-light absorbing properties of the particles that comprise the clouds. White regions contain material reflecting in the blue; dark regions contain material absorbing in the blue. This reflecting/absorbing behavior is controlled by the composition of the cloud’s colored material, which is still a mystery — one which may be answered by Cassini. The differing concentrations of this material across the planet are responsible for its banded appearance in the visible region of the electromagnetic spectrum.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The imaging team is based at the Space Science Institute, Boulder, Colo.

For more information about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org .

Original Source: CICLOPS News Release

Does Io Look Like an Early Earth?

Image credit: NASA/JPL
Investigations into lava lakes on the surface of Io, the intensely volcanic moon that orbits Jupiter, may provide clues to what Earth looked like in its earliest phases, according to researchers at the University at Buffalo and NASA’s Jet Propulsion Laboratory.

“When I look at the data, it becomes startlingly suggestive to me that this may be a window onto the primitive history of Earth,” said Tracy K. P. Gregg, Ph.D., assistant professor of geology in the UB College of Arts and Sciences.

“When we look at Io, we may be seeing what Earth looked like when it was in its earliest stages, akin to what a newborn baby looks like in the first few seconds following birth,” she added.

Gregg and Rosaly M. Lopes, Ph.D., research scientist at JPL, gave a presentation about Io’s volcano, Loki, on Tuesday (March 16, 2004) at the Lunar and Planetary Science Conference in Houston.

Scientists have been interested in Loki, considered the most powerful volcano in the solar system, because of debate over whether or not it is an active lava lake, where molten lava is in constant contact with a large reservoir of magma stored in the planet’s crust.

Using models developed to investigate temperature changes on active lava lakes on Earth, Gregg and Lopes have concluded that Loki behaves quite differently from terrestrial lava lakes.

Gregg suggests that Loki and other lava lakes on Io might be more similar volcanologically to fast-spreading mid-ocean ridges on Earth, like the Southern East Pacific Rise.

According to Gregg, plate tectonics on Earth make these features long — as in thousands of kilometers — and narrow — as in less than 10 kilometers wide. Io, on the other hand, has no plate tectonics and a similar release of heat and magma would be circular, like Loki.

“These lava lakes could be an Ionian version of mid-ocean ridges,” functioning the way these ridges do on Earth, spilling huge amounts of lava on its surface, thus generating new crust, she said.

During the most intense periods of its eruption cycle, Gregg said, Loki churns out about 1,000 square meters of lava — about the size of a soccer field — per second.

“All planets start out hot and spend their ‘lifetimes’ trying to get cold,” explained Gregg.

This effort by planets to “chill,” she explained, is an attempt to attain a similar temperature to that of outer space, which is 4 Kelvin, or minus 269 degrees Celsius.

On Earth, she explained, the shifting of the planet’s tectonic plates, which focus the eruption of volcanoes at their boundaries, function to cool down the planet’s surface.

Io never developed plate tectonics because it is stuck in an incessant orbit between Jupiter and Europa, another of the Jovian planet’s moons.

“Io just never grew up,” she said, “since it’s continually being pushed around by Jupiter and Europa.”

But, she added, Earth only developed plate tectonics after it had been in existence for perhaps 200 to 500 million years.

Gregg and Lopes analyzed data obtained by the Galileo spacecraft, which orbited Jupiter for 14 years, finally disintegrating in Jupiter’s atmosphere last fall.

The University at Buffalo is a premier research-intensive public university, the largest and most comprehensive campus in the State University of New York.

Original Source: University at Buffalo News Release