Posted on by Fraser Cain

Mapping the Early Universe in 3 Dimensions

The invention of the CAT scan led to a revolution in medical diagnosis. Where X-rays give only a flat two-dimensional view of the human body, a CAT scan provides a more revealing three-dimensional view. To do this, CAT scans take many virtual “slices” electronically and assemble them into a 3D picture.

Now a new technique that resembles CAT scans, known as tomography, is poised to revolutionize the study of the young universe and the end of the cosmic “dark ages.” Reporting in the Nov. 11, 2004, issue of Nature, astrophysicists J. Stuart B. Wyithe (University of Melbourne) and Abraham Loeb (Harvard-Smithsonian Center for Astrophysics) have calculated the size of cosmic structures that will be measured when astronomers effectively take CAT scan-like images of the early universe. Those measurements will show how the universe evolved over its first billion years of existence.

“Until now, we’ve been limited to a single snapshot of the universe’s childhood-the cosmic microwave background,” says Loeb. “This new technique will let us view an entire album full of the universe’s baby photos. We can watch the universe grow up and mature.”

Slicing Space
The heart of the tomography technique described by Wyithe and Loeb is the study of 21-centimeter-wavelength radiation from neutral hydrogen atoms. In our own galaxy, this radiation has helped astronomers to map the Milky Way’s spherical halo. To map the distant young universe, astronomers must detect 21-cm radiation that has been redshifted: stretched to longer wavelengths (and lower frequencies) by the expansion of space itself.

Redshift is directly correlated to distance. The farther a cloud of hydrogen is from the Earth, the more its radiation is redshifted. Therefore, by looking at a specific frequency, astronomers can photograph a “slice” of the universe at a specific distance. By stepping through many frequencies, they can photograph many slices and build up a three-dimensional picture of the universe.

“Tomography is a complicated process, which is one reason why it hasn’t been done before at very high redshifts,” says Wyithe. “But it’s also very promising because it’s one of the few techniques that will let us study the first billion years of the universe’s history.”

A Soap Bubble Universe
The first billion years are critical because that is when the first stars began to shine and the first galaxies began to form in compact clusters. Those stars burned hotly, emitting huge amounts of ultraviolet light that ionized nearby hydrogen atoms, splitting electrons from protons and clearing away the fog of neutral gas that filled the early universe.

Young galaxy clusters soon were surrounded by bubbles of ionized gas much like soap bubbles floating in a tub of water. As more ultraviolet light flooded space, the bubbles grew larger and gradually merged together. Eventually, about a billion years after the Big Bang, the entire visible universe was ionized.

To study the early universe when the bubbles were small and the gas mostly neutral, astronomers must take slices through space as if slicing a block of swiss cheese. Loeb says that just as with cheese, “if our slices of the universe are too narrow, we’ll keep hitting the same bubbles. The view will never change.”

To get truly useful measurements, astronomers must take larger slices that hit different bubbles. Each slice must be wider than the width of a typical bubble. Wyithe and Loeb calculate that the largest individual bubbles reached sizes of about 30 million light-years across in the early universe (equivalent to more than 200 million light-years in the expanded universe of today). Those crucial predictions will guide the design of radio instruments to conduct tomographical studies.

Astronomers soon will test Wyithe and Loeb’s predictions using an array of antennas tuned to operate at the 100-200 megahertz frequencies of redshifted 21-cm hydrogen. Mapping the sky at these frequencies is extremely difficult because of manmade interference (TV and FM radio) and the effects of the earth’s ionosphere on low-frequency radio waves. However, new low-cost electronics and computer technologies will make extensive mapping possible before the end of the decade.

“Stuart and Avi’s calculations are beautiful because once we have built our arrays, the predictions will be straightforward to test as we take our first glimpses of the early universe,” says Smithsonian radio astronomer Lincoln Greenhill (CfA).

Greenhill is working to create those first glimpses through a proposal to equip the National Science Foundation’s Very Large Array with the necessary receivers and electronics, funded by the Smithsonian. “With luck, we will create the first images of the shells of hot material around several of the youngest quasars in the universe,” says Greenhill.

Wyithe and Loeb’s results also will help guide the design and development of next-generation radio observatories being built from the ground up, such as the European LOFAR project and an array proposed by a US-Australian collaboration for construction in the radio-quiet outback of Western Australia.

Original Source: Harvard CfA News Release

Posted on by Fraser Cain

Density Waves in Saturn’s Rings

A University of Colorado at Boulder-built instrument riding on the Cassini-Huygens spacecraft is being used to distinguish objects in Saturn’s rings smaller than a football field, making them twice as sharp as any previous ring observations.

Joshua Colwell of CU-Boulder’s Laboratory for Atmospheric and Space Physics said the observations were made with the Ultraviolet Imaging Spectrograph, or UVIS, when Cassini was about 4.2 million miles, or 6.75 million kilometers, from Saturn in July. Saturn orbits the Sun roughly 1 billion miles from Earth.

Colwell and his colleagues used a technique known as stellar occultation to image the ring particles, pointing the instrument through the rings toward a star, Xi Ceti. The fluctuations of starlight passing through the rings provide information on the structure and dynamics of the particles within them, said Colwell, a UVIS science team member.

He likened the Saturn system to a mammoth phonograph record, with the planet in the middle and the rings stretching outward more than 40,000 miles, or 64,000 kilometers. The size of the ring particles varies from dust specks to mountains, with most ranging between marbles and boulders, he said.

The Cassini observations show dramatic variations in the number of ring particles over very short distances, Colwell said. The particles in individual ringlets are bunched closely together, with the amount of material dropping abruptly at the ringlet edge.

“What we see with the new observations is that some of the ring edges are very sharp,” said Colwell. The sharp edges of small ringlets are especially evident in the C ring and in the so-called Cassini Division on either side of the bright B ring, Saturn’s largest ring.

The Cassini observations with UVIS show that the distance between the presence and absence of orbiting material at some ring edges can be as little as 160 feet, or 50 meters, about the length of a typical commercial jetliner, he said.

The sharp edges illustrate the dynamics that constrain the ring processes against their natural tendency to spread into nearby, empty space, said Colwell. “Nature abhors a vacuum, so it is likely gravity from a nearby small moon and ongoing meteoroid collisions confine the particles in the ring.”

Colwell presented his findings at the 36th annual Division of Planetary Sciences Meeting held in Louisville, Ky., Nov. 8 to Nov 12.

The stellar occultation process using UVIS also shows very high-resolution views of several density waves visible in the rings, including a previously unstudied one, he said. Density waves are ripple-like features in the rings caused by the influence of Saturn’s moons — in this case, the small moon, Janus.

“Small moons near Saturn’s rings stir the ring particles with their gravitational pull,” Colwell said. At certain locations in the rings, known as resonances, the orbit of a particular moon matches up with the orbit of certain ring particles in a way that enhances the stirring process, he said.

The density waves, which resemble a tightly wound spiral much like the groove in a phonograph record, slowly propagate away from the resonance toward the perturbing moon, he said. “This can create a wave in the ring that looks like a ripple in a pond,” said Colwell.

“The shapes of these wave peaks and troughs help scientists understand whether the ring particles are hard and bouncy, like a golf ball, or soft and less bouncy, like a snowball,” Colwell said. He noted that a density wave analysis by scientists involved in NASA’s Voyager 2 mission that visited Saturn in 1981 were used to determine the mass and thickness of the planet’s rings.

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 Science Mission Directorate in Washington, D.C.

CU-Boulder Professor Larry Esposito of LASP is the principal investigator for the $12.5 million UVIS instrument, designed and built for JPL at CU-Boulder.

Original Source: CU Boulder News Release

Posted on by Fraser Cain

Icy Objects Could Be Smaller Than Previously Thought

Image credit: NASA/JPL
Pluto’s status as our solar system’s ninth planet may be safe if a recently discovered Kuiper Belt Object is a typical “KBO” and not just an oddball.

Astronomers have new evidence that KBOs (Kuiper Belt Objects) are smaller than previously thought.

KBOs – icy cousins to asteroids and the source of some comets – are the leftover building blocks of the outer planets. Astronomers using the world’s most powerful telescopes have discovered about 1,000 of these objects orbiting beyond Neptune since discovering the first one in 1992. These discoveries fueled debate on whether Pluto is a planet or a large (1,400-mile diameter) closer-in KBO.

Researchers estimate that the total mass of the Kuiper Belt is about a tenth of Earth’s mass. Most theorize that there are more than 10,000 KBOs with diameters greater than 100 kilometers (62 miles), compared to 200 asteroids known to be that large in the main asteroid belt between Mars and Jupiter.

“People were finding all these KBOs that were huge – literally half the size of Pluto or larger,” University of Arizona astronomer John Stansberry said. “But those supposed sizes were based on assumptions that KBOs have very low albedos, similar to comets.”

Albedo is a measure of how much light an object reflects. The more light an object reflects, the higher its albedo. Actual data on Kuiper Belt Object albedos have been hard to come by because the objects are so distant, dim and cold. Many astronomers have assumed that KBO albedos – like comet albedos – are around four percent and have used that number to calculate KBO diameters.

However, in early results from their Spitzer Space Telescope survey of 30 Kuiper Belt Objects, Stansberry and colleagues found that a distant KBO designated 2002 AW197 reflects 18 percent of its incident light and is about 700 kilometers (435 miles) in diameter. That’s considerably smaller and more reflective than expected, Stansberry said.

“2002 AW197 is believed to be one of the largest KBOs thus far discovered,” he said. “These results indicate that this object is larger than all but one main-belt asteroid (Ceres), about half the size of Pluto’s moon, Charon, and about 30 percent as large and a tenth as massive as Pluto.”

Stansberry and his colleagues took the data with Spitzer’s Multiband Imaging Photometer (MIPS) on April 13, 2004. George Rieke’s team at the University of Arizona developed and built the extremely heat-sensitive MIPS. It detects heat from very cold objects by taking images at far-infrared wavelengths.

In this case, MIPS detected heat from a Kuiper Belt Object with a surface temperature of around minus 370 degrees Fahrenheit at an astonishing distance of 4.4 billion miles (7 billion kilometers), or one-and-a-half times farther away frm the sun than Pluto.

Without MIPS, astronomers operating under the assumption that 2002 AW197 reflects four percent of its incident light would calculate that it is 1500 kilometers (932 miles) in diameter, or two-thirds as large as Pluto, Stansberry said.

“We’re finally starting to get data on the basic physical parameters of KBOs,” Stansberry said. “That will help us determine what their compositions are, how they evolve, how massive they are, what their real size distributions and dynamics are and how Pluto fits into the whole picture,” he said.

Such data will also offer insight on how comets are processed on their successive journeys around the sun, he added.

“It’s not surprising that comets are darker than KBOs,” Stansberry said.”When something in the Kuiper Belt chips off a piece of a Kuiper Belt Object, presumably that piece would have a higher albedo on its first swing through the inner solar system. But it doesn’t take long before it loses its high albedo surface and builds up a lot of very dark materials, at least in its outermost surface.”

Others with Stansberry in this Spitzer study are Dale Cruikshank and Josh Emery of NASA Ames Research Center, Yan Fernandez of the University of Hawaii, George Rieke of the University of Arizona and Michael Werner of NASA’s Jet Propulsion Laboratory.

Stansberry said the team will finish collecting their KBO data with Spitzer soon.

“We’ll know a lot more about how big and bright these things are by this time next year,” he said.

Stansberry is presenting the research today at the 86th annual meeting of the American Astronomical Society Division of Planetary Science in Louisville, Ky.

More information about this and other new results from the Spitzer Space Telescope is on the Web at http://www.spitzer.caltech.edu/Media/index.shtml The Spitzer Space Telescope is managed for NASA by the Jet Propulsion Laboratory in Pasadena, Calif.

Original Source: University of Arizona News Release

Posted on by Fraser Cain

Launch Date Set for Solar Sail

The Cosmos 1 team announced today that the world?s first solar sail spacecraft will be set for launch on March 1, 2005 from a submerged submarine in the Barents Sea. Cosmos 1 ? a project of The Planetary Society ? is sponsored by Cosmos Studios.

?With the spacecraft now built and undergoing its final checkout, we are ready to set our launch date,? said Louis Friedman, Executive Director of The Planetary Society and Project Director of Cosmos 1. ?The precedent-setting development of the first solar sail spacecraft has had its ups and downs like a roller coaster ride, but now the real excitement begins.?

Cosmos 1?s mission goal is to perform the first controlled solar sail flight as the spacecraft is propelled by photons from sunlight. The Cosmos 1 launch period will extend from March 1 to April 7, 2005. The actual launch date will be determined by the Russian Navy, which directs the launch on the Volna rocket ? a rocket taken from the operational intercontinental ballistic missile inventory.

?This whole venture is audacious and risky,? noted Bruce Murray, who co-founded The Planetary Society with Carl Sagan and Louis Friedman. ?It is a testament to the inspiring nature of space exploration and to the desire of people everywhere to be part of the adventure of great projects.?

Sagan, Murray and Friedman founded The Planetary Society in 1980 to advance the exploration of other worlds and to seek other life. Launching a spacecraft to test an innovative and untried flight technology helps to fulfill the bold mission they envisioned for the organization. Sagan remained the President of The Planetary Society until his death in December, 1996.

Cosmos 1 will rocket into space on a submarine-launched ballistic missile, the Volna, from beneath the surface of the Barents Sea. A network of Russian, American and Czech ground stations will track and receive data from the spacecraft.

International cooperation is just one of the novel aspects of this privately funded mission. It is the first space mission conducted by a popular space interest organization, the first sponsored by a media company, and the first to test flight using only sunlight pressure. Sailing by light pressure is the only technology known that might carry out practical interstellar flight.

?Starting the countdown clock for the launch of Cosmos 1 on Carl?s birthday could not be more appropriate? said Ann Druyan, Cosmos 1 Program Director and Carl Sagan?s professional collaborator and widow. ?We have converted the delivery system for a weapon of mass destruction into a means for pioneering a way to set sail for the stars,? she added. ?That?s Carl Sagan 101, a perfect embodiment of his life and vision.?

Druyan?s science-based media company, Cosmos Studios, has provided most of the funding for this project.

Several solar sail spacecraft have been proposed over the last few years, but none except Cosmos 1 has been built. NASA, and the European, Japanese and Russian space agencies all have solar sail research and development programs. Deployment tests have been conducted by the space agencies and more are being planned.

The Planetary Society, without government funds, but with support of Cosmos Studios and Society members, put together an international team of space professionals to attempt this first actual solar sail flight. The Space Research Institute (IKI) in Moscow oversaw the creation of the flight electronics and mission control software while NPO Lavochkin, one of Russia?s largest aerospace companies, built the spacecraft. American consultants have provided additional components, including an on-board camera built by Malin Space Science Systems.

Solar sailing is done not with wind, but with reflected light pressure – its push on giant sails can continuously change orbital energy and spacecraft velocity. Once injected into Earth?s orbit, the sail will be deployed by inflatable tubes, which pull out the sail material and make the structure rigid. The 600-square-meter sail of Cosmos 1 will have eight blades, configured like a giant windmill. The blades can be turned like helicopter blades to reflect sunlight in different directions, and the sail can ?tack? as orbital velocity is increased. Each blade measures 15 meters in length and is made from 5-micron-thin aluminized, reinforced mylar ? about 1/4 the thickness of a trash bag.

Once Cosmos 1 is deployed in orbit, the solar sail will be visible to the naked eye throughout much of the world, its silvery sails shining as a bright pinpoint of light traveling across the night sky.

You can visit the following sites for comprehensive background materials on Cosmos 1, including the progress of the countdown to launch: http://planetary.org/solarsail and http://solarsail.org.

Original Source: Planetary Society News Release

Posted on by Fraser Cain

X-Ray Portrait of Proxima Centauri

Chandra and XMM-Newton observations of the red dwarf star Proxima Centauri have shown that its surface is in a state of turmoil. Flares, or explosive outbursts, occur almost continually. This behavior can be traced to Proxima Centauri’s low mass, about a tenth that of the Sun. In the cores of low mass stars, nuclear fusion reactions that convert hydrogen to helium proceed very slowly, and create a turbulent, convective motion throughout their interiors. This motion stores up magnetic energy which is often released explosively in the star’s upper atmosphere where it produces flares in X-rays and other forms of light.

The same process produces X-rays on the Sun, but the magnetic energy is released in a less explosive manner through heating loops of gas, with occasional flares. The difference is due to the size of the convection zone, which in a more massive star such as the Sun, is smaller and closer to its surface.

Red dwarfs are the most common type of star. They have masses between about 8% and 50% of the mass of the Sun. Though they are much dimmer than the Sun, they will shine for much longer – trillions of years in the case of Proxima Centauri, compared to the estimated 10 billion-year lifetime of the Sun.

X-rays from Proxima Centauri are consistent with a point-like source. The extended X-ray glow is an instrumental effect. The nature of the two dots above the image is unknown – they could be background sources.

Original Source: Chandra News Release

Posted on by Fraser Cain

A Solar System’s Icy Building Blocks

Two new results from NASA’s Spitzer Space Telescope released today are helping astronomers better understand how stars form out of thick clouds of gas and dust, and how the molecules in those clouds ultimately become planets.

Two discoveries — the detection of an oddly dim object inside what was thought to be an empty cloud, and the discovery of icy planetary building blocks in a system believed to resemble our own solar system in its infancy — were presented today at the first Spitzer science conference in Pasadena, Calif. Since Spitzer science observations began less than one year ago, the infrared capabilities of the space observatory have unveiled hundreds of space objects too dim, cool or distant to be seen with other telescopes.

In one discovery, astronomers have detected a faint, star-like object in the least expected of places — a “starless core.” Named for their apparent lack of stars, starless cores are dense knots of gas and dust that should eventually form individual newborn stars. Using Spitzer’s infrared eyes, a team of astronomers led by Dr. Neal Evans of the University of Texas at Austin probed dozens of these dusty cores to gain insight into conditions that are needed for stars to form.

Starless cores are fascinating to study because they tell us what conditions exist in the instants before a star forms. Understanding this environment is key to improving our theories of star formation, said Evans.

But when they looked into one core, called L1014, they found a surprise — a warm glow coming from a star-like object. The object defies all models of star formation; it is fainter than would be expected for a young star. Astronomers theorize that the mystery object is one of three possibilities: the youngest “failed star,” or brown dwarf ever detected; a newborn star caught in a very early stage of development; or something else entirely.

This object might represent a different way of forming stars or brown dwarfs. Objects like this are so dim that previous studies would have missed them. It might be like a stealth version of star formation, Evans said. The new object is located 600 light-years away in the constellation Cygnus.

In another discovery, Spitzer’s infrared eyes have peered into the place where planets are born — the center of a dusty disc surrounding an infant star — and spied the icy ingredients of planets and comets. This is the first definitive detection of ices in planet-forming discs.

This disc resembles closely how we imagine our own solar system looked when it was only a few hundred thousand years old. It has the right size, and the central star is small and probably stable enough to support a water-rich planetary system for billions of years into the future, said Dr. Klaus Pontoppidan of Leiden Observatory in the Netherlands, who led the team that made this discovery.

Previously, astronomers had seen ices, or ice-coated dust particles, in the large cocoons of gas and dust that envelop young stars. But they were not able to distinguish these ices from those in the inner planet-forming portion of a star’s disc. Using Spitzer’s ultra- sensitive infrared vision and a clever trick, Pontoppidan and his colleagues were able to overcome this challenge.

Their trick was to view a young star and its dusty disc at “dawn.” Discs can be viewed from a variety of angles, ranging from the side or edge-on, where the discs appear as dark bars, to face-on, where the discs become washed out by the light of the central star. They found that if they observed a disc at a 20-degree angle, at a position where the star peeks out like our Sun at dawn, they could see the ices.

“We hit the sweet spot,” said Pontoppidan. “Our models predicted that the search for ices in discs is a problem of finding an object with just the right viewing angle, and Spitzer confirmed that model.”

In this system, astronomers found ammonium ions as well as components of water and carbon dioxide ice.

The Spitzer science conference, “The Spitzer Space Telescope: New Views of the Cosmos,” is being held at the Sheraton Pasadena hotel.

JPL manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington, D.C. Science operations are conducted at the Spitzer Science Center, Pasadena, Calif. JPL is a division of Caltech. For more information about Spitzer visit www.spitzer.caltech.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

What Will Huygens Land In?

The prospect of the Huygens probe landing on a hard, soft or liquid surface when it lands on Titan next January still remain following further analysis of data taken during the Cassini mother ship’s closest encounter with Saturn’s largest moon during its fly-by on 26th October.

Commenting on the latest data results and implications for the Huygens probe Mark Leese of the Open University, Programme Manager for Science Surface Package [SSP] instruments that will unravel the mysteries of Titan said:

“It’s interesting that all of the possible landing scenarios that we envisaged – a hard crunch onto ice, a softer squelch into solid organics or a splash-down on a liquid hydrocarbon lake – still seem to exist on Titan.”

Leese added, “A first look at the measurements of Titan’s atmosphere during the fly-by suggest that the “Atmosphere Model” we developed and used to design the Huygens probe is valid and all looks good for the probe release on Christmas day and descent to the surface on 14th January 2005.”

Further analysis of Titan’s upper atmosphere, the thermosphere, has revealed a strange brew as Dr Ingo Mueller-Wodarg of Imperial College London explained,” Our instrument, the Ion Neutral Mass Spectrometer (INMS), made in-situ measurements of atmospheric gases in Titan’s upper atmosphere and found a potent cocktail of nitrogen and methane, stirred up with signatures of hydrogen and other hydrocarbons. We are now working on a ‘Weather Report’ for the Huygens landing in January”.

Commenting on the surface characteristics of Titan Professor John Zarnecki of the Open University, lead scientist for the Huygens SSP said: “The recent results from the fly-by have started to show us a very diverse and complicated surface. Titan is geologically active but hasn’t yet given up all of its secrets. Combining the visible images with infrared and RADAR data from this and future fly-bys should help to clarify the picture – but the arrival of the Huygens probe in January will perhaps be the key to unlock these mysteries.”

Professor Carl Murray, of the Imaging Science System [ISS] team from Queen Mary, University of London also commented on the surface features: “The images of the Huygens’ landing site returned by the cameras show a diverse range of features. We see bright and dark areas roughly aligned in an east-west direction. These are similar to wind streaks seen on Mars and may indicate that material on Titan has been deposited by the effects of wind blowing across the landscape. All indications suggest that we are in for a real treat in January when the Huygens probe reaches Titan’s surface and returns the first in situ data from this alien world.”

UK scientists and technologists are amongst an international team continuing to analyse the latest data received from the NASA/ESA/ASI Cassini Huygens mission after the spacecraft made its close fly-by of Titan last week. The data has provided a wealth of information about Saturn’s largest moon, which will not only assist the European Space Agency’s Huygens team in advance of the probe landing on Titan in January 2005 but will also increase our understanding of the relationship between Titan and its parent planet Saturn.

Professor Michele Dougherty from Imperial College is lead scientist on the Cassini Magnetometer, which is studying the interaction between the plasma in Saturn’s magnetosphere and the atmosphere and ionosphere of Titan. “We have been able to model the Magnetometer data very well from the Titan flyby. There does not seem to be an internal magnetic field at Titan from the observations we obtained during this flyby, but we will have a much better idea about this when we have a further flyby in December which is on a very similar trajectory. All we can say at this point is that if there is a magnetic field generated in the interior of Titan, then it is very small”

Dr Andrew Coates from University College London’s Mullard Space Science Laboratory, a Co-Investigator on the Cassini Electron Spectrometer team, said: “We received some remarkable new information about Titan’s plasma environment within the context of Saturn’s fascinating magnetosphere. Unexpectedly, it looks like we can directly use features of the electron results to understand what Titan’s upper atmosphere is made of, supplementing the ion measurements from companion sensors on other instruments. Our electron results contain tell-tale fingerprints of photoelectrons and Auger electrons which we will use for this. Also, the total picture shows how important electrons, raining down on Titan’s upper atmosphere, are in helping the feeble sunlight drive the complex chemistry in Titan’s upper atmosphere.”

Nick Shave, Space Business Manager at UK IT company LogicaCMG said “The amazing imagery and radar results recently received from Cassini of Titan’s surface is providing important early information and creating real excitement in the industrial community. UK industry’s critical contributions to Cassini-Huygens via the LogicaCMG Huygens flight software and other systems, such as the parachutes by Martin Baker, will enable even more spectacular science that could help unlock some of the secrets of life on Earth.”

UK scientists are playing significant roles in the Cassini Huygens mission with involvement in 6 of the 12 instruments onboard the Cassini orbiter and 2 of the 6 instruments on the Huygens probe. The UK has the lead role in the magnetometer instrument on Cassini (Imperial College) and the Surface Science Package on Huygens (Open University).

UK industry had developed many of the key systems for the Huygens probe, including the flight software (LogicaCMG) and parachutes (Martin Baker). These mission critical systems need to perform reliably in some of the most challenging and remote environments ever attempted by a man made object.

Original Source: PPARC News Release

Posted on by Fraser Cain

Black Holes or Galaxies, Which Came First?

Astronomers using the National Science Foundation’s Very Large Array (VLA) radio telescope to study the most distant known quasar have found a tantalizing clue that may answer a longstanding cosmic chicken-and-egg question: which came first, supermassive black holes or giant galaxies?

For years, astronomers have noted a direct relationship between the mass of a galaxy’s central, supermassive black hole and the total mass of the “bulge” of stars at its core. The more massive the black hole, the more massive the bulge. Scientists have speculated extensively about whether the black hole or the stellar bulge formed first. Recently, some theories have suggested that the two may form simultaneously.

However, the new VLA observations of a quasar and its host galaxy seen as they were when the Universe was less than a billion years old indicate that the young galaxy has a supermassive black hole but no massive bulge of stars.

“We found a large amount of gas in this young galaxy, and, when we add the mass of this gas to that of the black hole, they add up to nearly the total mass of the entire system. The dynamics of the galaxy imply that there isn’t much mass left to make up the size of stellar bulge predicted by current models,” said Chris Carilli, of the National Radio Astronomy Observatory (NRAO), in Socorro, NM.

The scientists studied a quasar dubbed J1148+5251, that, at more than 12.8 billion light-years, is the most distant quasar yet found. Discovered in 2003 by the Sloan Digital Sky Survey, J1148+5251 is a young galaxy with a bright quasar core seen as it was when the Universe was only 870 million years old. The Universe now is 13.7 billion years old.

Aiming the VLA at J1148+4241 for about 60 hours, the researchers were able to determine the amount of molecular gas in the system. In addition, they were able to measure the motions of that gas, and thus estimate the total mass of the galactic system. Earlier studies of the system had produced estimates that the black hole was 1 to 5 billion times the mass of our Sun.

The new VLA observations indicate that there are about 10 billion solar masses of molecular gas in the system, and that the system’s total mass is 40-50 billion solar masses. The gas and black hole combined thus account for 11-15 billion solar masses out of that total.

“The accepted ratio indicates that a black hole of this mass should be surrounded by a stellar bulge of several trillion solar masses. Our dynamical measurement shows there’s not much mass left over, excluding the black hole and the gas, to form a stellar bulge. This provides evidence that the black hole forms before the stellar bulge,” said Fabian Walter, of the Max Planck Institute for Radioastronomy in Heidelberg, Germany, who was a Jansky Postdoctoral Fellow at NRAO in Socorro when the observations were made.

“One example certainly doesn’t make the case, but in this object we we apparently have an example of a black hole without much of a stellar bulge. Now we need to make detailed studies of more such objects in the far-distant, early Universe,” Carilli said. “With the vastly improved sensitivity of the Expanded VLA and the Atacama Large Millimeter Array (ALMA), which will come on line in a few years, we will have the tools we need to resolve this question definitively,” Carilli added.

“Studies like this are the key to understanding how galaxies first formed,” Walter said.

Walter and Carilli worked with Frank Bertoldi and Karl Menten of the Max Planck Institute in Bonn; Pierre Cox of the Institute of Space Astrophysics of the University of Paris-South; Fred K.Y. Lo of the NRAO in Charlottesville, VA; Xiahui Fan of the University of Arizona’s Steward Observatory; and Michael Strauss of Princeton University, on the project. Their research results are being published in the Astrophysical Journal Letters.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Original Source: NRAO News Release

Posted on by Fraser Cain

Soyuz 2 Test Successful

The maiden flight of a Soyuz 2-1a launch vehicle took place on Monday 8 November 2004 from the Plesetsk Cosmodrome in Russia at 21:30 Moscow time (19:30 Paris). Starsem, Arianespace and their Russian partners report that the mission was accomplished successfully.

This launch marks a major step forward in the Soyuz evolution programme as this modernised version of the launcher implements a digital control system providing additional mission flexibility and enabling control of the launch vehicle with a larger fairing.

The next step will be the introduction of the Soyuz 2-1b. This launcher version will have a more powerful third-stage engine to significantly increase the overall launch vehicle performance and provide additional payload mass capability. The inaugural flight of the Soyuz 2-1b is presently scheduled for mid-2006 from Baikonur.

Both new versions of the Soyuz launcher will be adapted in view of their exploitation by Arianespace from the Europe?s spaceport in French Guiana. This will be made possible through the ?Soyuz at CSG? ESA programme, which encompasses the development of a Soyuz launch complex on the territory of Sinnamary and participation in the Soyuz 2-1b development.

The Soyuz at CSG programme is a key building block in the implementation of strategic cooperation between ESA and the Russian Space Agency, which falls under the general framework of the Agreement between the Government of the Russian Federation and ESA on Cooperation and Partnership in the Exploration and Use of Outer Space for Peaceful Purposes, signed in Paris on 11 February 2003.

ESA?s decision to open the CSG for the exploitation of the Soyuz ST launcher from Europe?s Spaceport in French Guiana is a major step forward in reinforcing the range of accessible missions that can be performed from the Spaceport. The versatile and flexible medium-class Soyuz ST launch vehicle, together with the heavy-lift Ariane 5 and the Vega small launcher will provide Arianespace with a family of launchers enabling it to cost-effectively perform the full spectrum of commercial and institutional missions from French Guiana.

The inaugural flight of a Soyuz ST from French Guiana is scheduled for 2007.

?We share the excitement of Starsem, Arianespace and their Russian partners for the successful launch of the new Soyuz 2-1a model and we will continue to strive to accomplish what we have started: to bring Soyuz to the European spaceport as soon as possible to enhance Europe?s launch capabilities? says Jean-Pierre Haigner?, ESA?s Soyuz at CSG Programme Manager.

Original Source: ESA News Release

Posted on by Fraser Cain

What’s Up This Week – Nov 8 – 14, 2004

Image credit: Hubble
Monday, November 8 – Saturn turns retrograde on this date and today will be the closest approach of asteroid 4433 Goldstone to Earth at a respectable distance of 1.358 AU – or just 149,597,871 km. While asteroids of this nature are being closely monitored, they aren’t really observable to the majority of the amateur astro community. In case you’ve ever wondered just what it would be like to follow an asteroid, why not try your hand at locating and tracking one one of the brightest and easiest for beginners? Vesta!

Asteroid Vesta is considered to be a minor planet since its approximate diameter is 525 km (326 miles) wide, making it slightly smaller in size than the state of Arizona. Vesta was discovered on March 29, 1807 by Heinrich Olbers and it was the fourth such “minor planet” to be identified. Olbers discovery was fairly easy because Vesta is the only asteroid bright enough at times to be seen unaided from Earth. Why? Orbiting the Sun every 3.6 years and rotating on its axis in 5.24 hours, Vesta has an albedo (or surface reflectivity) of 42%. Although it is about 220 million miles away, pumpkin-shaped Vesta is the brightest asteroid in our solar system because it has a unique geological surface. Spectroscopic studies show it to be basaltic, which means lava once flowed on the surface. (Very interesting since most asteroids were once though to be rocky fragments left-over from our forming solar system!)

Studies by the Hubble telescope confirmed this, as well as a large meteoric impact crater which exposed Vesta’s olivine mantle. Debris from Vesta’s collision then set sail away from the parent asteroid. Some of them remained within the asteroid belt near Vesta to become asteroids themselves with the same spectral pyroxene signature, but some escaped through the “Kirkwood Gap” created by Jupiter’s gravitational pull and allowed these small fragments to be put into an orbit that would eventually bring them “down to Earth”. Did one make it? Of course! In 1960 a piece of Vesta fell to Earth and was recovered in Austrailia. Thanks to Vesta’s unique properties, the meteorite was definitely classified as once being a part of our third largest asteroid.

Now, that we’ve learned about Vesta, let’s talk about what we can see from our own backyards. As you can discern from the image, even the Hubble Space Telescope doesn’t give incredible views of this bright asteroid. What we will be able to see in our telescopes and binoculars will closely resemble a roughly magnitude 7 “star”, and it is for that reason that I strongly encourage you to visit Heaven’s Above, follow the instructions and print yourself a detailed map of the area. When you locate the proper stars and the asteroid’s probable location, mark physically on the map Vesta’s position. Keeping the same map, return to the area a night or two later and see how Vesta has moved since your original mark. Since Vesta will stay located in the constellation of Aquarius all month, your observations need not be on a particular night, but once you learn how to observe an asteroid and watch it move – you’ll be back for more!

Tuesday, November 9 – Remember last week when Jupiter and Venus did a spectacular morning dance in the sky? Well, the excitement hasn’t ended yet for now the Moon has joined the show. Before local dawn, Jupiter will be 1 degree to the lower right of the crescent Moon. For most of us, this beautiful “sky scenery” would be pleasure enough, but for those living in eastern Canada and the north-eastern United States, something just a bit more exciting is about to happen – the Moon is going to occult Jupiter during the daylight hours! Timing for such events is very critical and varies widely by location. To ensure success, please visit the International Occultation Timing Association (IOTA) for precise times in your area.

Asteroid 2000 JE5 will be performing a very near Earth fly-by today as it passes only 0.131 AU away. While that is less than the distance between Earth and the Sun, it is still 19,597,338 km or 12,177,221 miles away!

Thanks to dark skies, early tonight would be a great opportunity to use telescopes or large binoculars to study one of the finest of deep space objects, the “Ring” nebula. Located in the quickly westering constellation of Lyra and roughly halfway between bright stars Sheilak (Beta Lyrae) and Sulfat (Gamma Lyrae) this wonderful planetary nebula can be seen in small binoculars and comes to life with a telescope. But before we view the “Ring”, let’s learn a little more about the M57 and the two stars we’ll use to find it.

Beta is a variable star that averages around 3.38 magnitude at its maximum, but drops to around 4.1 at minima. This typical lyrid-type eclipsing variable is relatively easy to observe even without optical aid because nearby Gamma remains a constant magnitude 3.25. For a few days, both stars will appear to be about the same brightness, but about every 13 days, Sheilak will fade out to about half the brightness of Sulafat! For those of you aiming a telescope towards Gamma, you will find that it is a optical double star with a 10th magnitude companion.

Roughly halfway between these two interesting stars (but a bit closer to Beta) is tonight’s object. The M57 is a classic example of a planetary nebula first discovered by French astronomer Antoine Darquier in 1779 and cataloged only days later by Charles Messier. At approximately 2300 light years away, the “Ring” is basically the ejecta of a dying star. Many theories exist about the structure of the nebula itself , but popular opinion is that we may be looking through the shell, much like looking down the barrel of a gun. Its interior star has reached white dwarf stages, slowly shedding its mass and complex waves of ultra-violet radiation which fluoresce the rarefied gases of the nebula expanding at the gentle rate of around 19 km (12 miles) per second. The nebula itself exhibits many different spectral qualities as seen in photography, but what does it really look like?

To binoculars, the M57 will appear almost stellar in size, but the small disk lacks the properties of starlight. To the average telescope, the “Ring” will appear much as you see here – a softly glowing torus with a gentle grey/green color. At low power it is spectacular because the accompanying stellar field is so rich. Larger telescopes can resolve the central star under excellent sky conditions along with variances in the structure of the ring itself. Reach for the “Ring” tonight… You’ll be glad you did!

(In loving memory of Carl Sagan who was born on November 9, 1934. You were an inspiration to us all…)

Wednesday, November 10 – The early morning show continues as Jupiter, Venus, the very thin crescent Moon and Mars all appear with 20 degree of each other just before local dawn. For observers in other parts of the world, today is your day to observe an occultation as the Moon moves across Venus! The “footprint” for this occultation will be for skywatchers in Australia, New Zealand and Southern Asia. As always, timing is everything, so please visit IOTA for precise times for your locations. Observers with sense of curiousity and a large telescope might like to know that Mars will also occult an 11.8 magnitude star. (The challenge will be seeing how long you can follow the progress.) Information on this event is slim, but if you want to know where and when – here’s your clue.

This evening we are once again going to study a single star and it will help you become acquainted with the constellation of Perseus. Its formal name is Beta Persii and it is the most famous of all eclipsing variable stars. Tonight, let’s identify Algol and learn all about the “Demon Star”.

Ancient history has given this star many names. Associated with the mythological figure, Perseus, Beta was considered to be the head of Medusa the Gorgon, and was known to the Hebrews as Rosh ha Satan or “Satan’s Head”. 17th century maps labeled Beta as Caput Larvae, or the “Spectre’s Head”, but it is from the Arabic culture that the star was formally named. They knew it as Al Ra’s al Ghul, or the “Demon’s Head”, and we know it as Algol. Because these medieval astronomers and astrologers associated Algol with danger and misfortune, we are led to believe that Beta’s strange visual variable properties were noted throughout history.

Italian astronomer Geminiano Montanari was the first to note that Algol occasionally “faded” and its methodical timing was cataloged by John Goodricke in 1782, who surmised that it was being partially eclipsed by a dark companion orbiting it. Thus was born the theory of the “eclipsing binary” and it was proved spectroscopically in 1889 by H.C. Vogel. At 93 light years away, Algol is the nearest eclipsing binary of its kind and is treasured by the amateur astronomer for it requires no special equipment to easily follow its stages. Normally Beta Persii holds a magnitude of 2.1, but approximately every three days it dims to magnitude 3.4 and gradually brightens again. The entire eclipse only lasts about 10 hours!

Although Algol is known to have two additional spectroscopic companions, the true beauty of watching this variable star is not telescopic – but visual. The constellation of Perseus is well placed this month for most observers and appears like a glittering chain of stars that lay between Cassiopeia and Andromeda. To help further assist you, re-locate last week’s study star, Gamma Andromedae (Almach) east of Algol. Almach’s visual brightness is about the same as Algol’s at maxima. Tonight at 16:55 UT, Algol will be at minima and will appear approximately the same brightness of Alpha Trianguli. Depending on what time zone you live in, it would be possible for you to see Algol return to full brightness once again at 02:55 UT on November 11! If you are clouded out, don’t worry. Agol reaches minima again on November 13 at 13:44 UT, November 16 at 10:33 UT, November 19 at 7:22 UT, November 22 at 4:11 UT, November 25 at 1:00 UT, November 27 at 21:49 UT and November 30 at 18:38 UT. Just remember that it only takes 10 hours to complete its eclipse and enjoy the “Demon”!

Thursday, November 11 – Southern hemisphere viewers? You asked for it and you got it. This morning the Moon will occult Mars for East Africa and Australia! It was a bit difficult for me to find precise timing information for you, but I did locate at list of cities and times that you might find useful. Best of luck!

Uranus becomes stationary today and Comet P/1996 R2 (Lagerkvist) will make its closest approach to Earth today at a distance of 1.793 AU. At around magnitude 17, this would be one serious observing challenge!

Tonight let us take the opportunity to visit with another planetary nebula seen from a different perspective – “The Dumbbell”. You will want to start fairly early, because as with Lyra, the constellation of Vulpecula is fast declining. The M27 is challenging with small binoculars, readily apparent in larger ones and superior in even small telescopes. By using previously visited stars Altair and Albireo, look for four stars that form the constellation of Sagitta between them. On a good night, the “Arrow” is easy to recognize. By looking at this constellation, get in mind the distance between the arrow’s point, Gamma, and the first of the three stars that make the arrow’s tailfeathers. Using this as your measure, return to Gamma and move the same distance due north, and let’s learn about the M27!

The M27 was the first planetary nebula discovered by Charles Messier and cataloged on July 12, 1764. As we learned with the “Ring”, a planetary nebula is a star shedding its mass in a thin, cold field of hydrogen and helium gas illuminated by the energy of the star itself. It is the strong ultraviolet radiation that excites these rarefied gases to glow in the soft greenish-blue that our eyes can perceive in a spectral condition which can only exist in space – doubly ionized oxygen! The nebula lies about 1,000 light years away from us and is expanding at a rate of about 17 miles per second, meaning that it grows about one arc-second per century. If these figures are correct, it has taken about 50,000 years for the M57 to have reached it’s present size.

The Hubble Telescope reveals the M27 in all its glory. Instead of looking through the planetary’s shell as we did with the M57, we are looking at the entire structure itself. Larger telescopes will have no problem resolving out tenuous rifts, folds and concentrations in the lobes of the nebula, as well as embedded stars. The central star is also evident in larger telescopes and the outer shell named the Millikin 1976 is apparent in Earth based telescopes with an aperture of around 30″. But what about large binoculars and the average backyard telescope?

Don’t worry. The wonderful “dumbbell” shape first described by John Herschel is very there. The spectral qualities described above are easily seen in the most modest of instruments! The M27 is perhaps one of the finest of deep sky objects for the amateur, and tonight? It’s yours…

Friday, November 12 – This morning will mark the peak of the Southern Taurid meteor shower. The Earth will be entering the second “stream” of debris in the early morning hours. The Taurids have a predicted fall rate of 7 per hour, but thanks to their relatively slow speed (27 km or 17 miles per second) and a New Moon, they might produce spectacular results. Good luck!

Asteroid 33342 (1998 WT24) will make a near Earth fly-by as it passes on 0.097 AU away. Hey, wait a minute. That dry fact seems pretty close doesn’t it? Then let’s find out… 0.097 AU would be 14,511,006 km or 9,016,721 miles. That’s roughly 34 times further away than our Moon, yet less than half the distance to our nearest planet, Venus. In astronomical terms? That is close!

Tonight we continue with our planetary studies by finding another such nebula located within a deep-space object. The M15 is well positioned now in the constellation of Pegasus and we start by once again identifying the “Great Square”. Leading the constellation to the west of the square is bright star Epsilon Pegasi, or Enif. By focusing either small binoculars or your telescope on Epsilon, you will know if you have the correct star, for Enif appears gently red. From there, the M15 is an easy catch in binoculars about 4 degrees northwest (about one field of view) and will appear to modest powers (5X30) as a small, round fuzzy patch with a star caught on the edge. Now let’s use a telescope and learn about the M15 as we view it.

Discovered originally by Miraldi in 1746, the wonderfully compact globular cluster was rediscovered by Charles Messier in 1764. It is one of the richest of clusters with an intense, compact core region and ranks as the 12th brightest globular in the sky. Its thousands of stars are gathered in a huge ball spanning 120 light years across and approximately 40,000 light years from Earth, but the M15 has many surprises. It has well been known this particular globular cluster contains many variable stars and pulsars, as well as a planetary nebula. As a rich radio x-ray source, studies of the M15 revealed many neutron stars and made headlines when Chandra revealed the presence of a binary neutron star.

To the average telescope, is simply a beautiful compact globular cluster. Even small apertures will begin to resolve out individual stars. For those with larger telescopes, take the time to “power up” on the M15 and find the planetary amidst the awesome resolvability!

Saturday, November 13 – Double your pleasure, double your fun, as tonight we’ll view two star clusters instead of just one! It’s a Saturday night and what finer way to celebrate than to view one of the most impressive star clusters in our galaxy – the NGC869 and NGC884. This pair of rich galactic open clusters are a naked-eye object from a dark site, easily seen in the smallest of binoculars from urban locations and beyond compare when viewed with a telescope at lowest power.

The western-most of the pair is NGC869, also known as “h Perseii”. It contains at least 750 stars clustered in a brilliant mass spanning about 70 light years, and approximately 7,500 light years away from us. It’s eastern companion is NGC884, or “Chi Perseii”. The statistics are almost a match, but NGC884 only has about half as many stars – some being “super giants” over 50,000 times brighter than our own Sun! These twin clusters have only one major difference: NGC884 is approximately 10 million years old and the NGC869 is perhaps 5 million. The existance of these splendid clusters was cataloged as far back as 350 B.C. with both Ptolemy and Hipparchus noting their appearance – yet Messier never “discovered” them!

Be sure to check out Algol again tonight, it’s minima is at 13:34 UT. Mercury will also be occulted by the Moon today, but it is far to close to the Sun to observe.

Sunday, November 14 – Tonight the Moon is at perigee, or the closest in its elliptical orbit to Earth. The challenge this evening will be to spot the very slender two-day old crescent while it is at its closest – only 356,410 km (221,473 miles) away!

This would be extremely fitting as we observe the 35th anniversary of the Apollo 12 mission. At 11:20:00 a.m. EDT, from launch complex 34-A at Kennedy Space Center, Florida, the Apollo 12 left Earth on November 14, 1969 in the second manned space mission bound for the Moon.

For Southern Hemisphere observers, tonight would be a great opportunity to study the Small Magellanic Cloud. At 210,000 light years away, this near neighbor to the Milky Way will be apparent to the naked eye just north of Beta Toucanae. Easily viewed in binoculars and incredible in telescopes, the Small Magellanic Cloud is home to the rich globular cluster 47 Toucanae. As the second brightest globular cluster in the sky, 47 was once believed to be a star until the 1750’s when French astronomer Nicohlas Louis du Lacaille discovered its true nature.

Until next week? Keep looking up… I wish you clear skies and light speed!
~Tammy Plotner