Posted on by Fraser Cain

Getting Out of Endurance Might Not Be Easy

Operators of NASA’s Mars Exploration Rover Opportunity have determined that a proposed route eastward out of “Endurance Crater” is not passable, so the rover will backtrack to leave the crater by a southward route, perhaps by retracing its entry path.

“We’ve done a careful analysis of the ground in front of Opportunity and decided to turn around,” said Jim Erickson, rover project manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “To the right, the slope is too steep — more than 30 degrees. To the left, there are sandy areas we can’t be sure we could get across.”

Before turning around, Opportunity will spend a few days examining the rock layers in scarp about 10 meters (33 feet) high, dubbed “Burns Cliff.” From its location at the western foot of the cliff, the rover will use its panoramic camera and miniature thermal emission spectrometer to collect information from which scientists hope to determine whether some of the layers were deposited by wind, rather than by water. The rover will not reach an area about 15 meters (50 feet) farther east where two layers at different angles meet at the base of the cliff.

“We have pushed the vehicle right to the edge of its capabilities, and we’ve finally reached a spot where we may be able to answer questions we’ve been asking about this site for months,” said Dr. Steve Squyres, rover principal investigator at Cornell University, Ithaca, N.Y. “But after we’re done here, it’ll be time to turn around. Going any farther could cut off our line of retreat from the crater, and that’s not something anybody on the team wants to do.”

Opportunity entered the stadium-size crater on June 8 at a site called “Karatepe” along the crater’s southern rim. Inside the crater, it has found and examined multiple layers of rocks that show evidence of a wet environment in the area’s distant past.

Opportunity and its twin, Spirit, successfully completed their primary three-month missions on Mars in April. NASA has extended their missions twice, most recently on Oct. 1, because the rovers have remained in good condition to continue exploring Mars longer than anticipated.

Engineers have finished troubleshooting an indication of a problem with steering brakes on Spirit. The brakes are designed to keep the rover wheels from being bumped off course while driving. Spirit has intermittently sent information in recent weeks that the brakes on two wheels were not releasing properly when the rover received commands to set a new course. Testing and analysis indicate that the mechanism for detecting whether the brakes are released is probably sending a false indication. The rover team will disregard that signal and presume the brakes have actually released properly when commanded to do so. This anomaly has not been observed on the Opportunity rover.

“We’re going back to using the full steering capabilities of Spirit,” Erickson said.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA’s Science Mission Directorate, Washington, D.C. Additional information about the project is available from JPL at http://marsrovers.jpl.nasa.gov/ and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Hubble’s Accidental Asteroid Discovery

While analyzing NASA Hubble Space Telescope images of the Sagittarius dwarf irregular galaxy (SagDIG), an international team of astronomers led by Simone Marchi, Yazan Momany, and Luigi Bedin were surprised to see the trail of a faint asteroid that had drifted across the field of view during the exposures. The trail is seen as a series of 13 reddish arcs on the right in this August 2003 Advanced Camera for Surveys image.

As the Hubble telescope orbits around the Earth, and the Earth moves around the Sun, a nearby asteroid in our solar system will appear to move with respect to the vastly more distant background stars, due to an effect called parallax. It is somewhat similar to the effect you see from a moving car, in which trees by the side of the road appear to be moving much more rapidly than background objects at much larger distances. If the Hubble exposure were a continuous one, the asteroid trail would appear like a continuous wavy line. However, the exposure with Hubble’s camera was actually broken up into more than a dozen separate exposures. After each exposure, the camera’s shutter was closed while the image was transferred from the electronic detector into the camera’s computer memory; this accounts for the many interruptions in the asteroid’s trail.

Since the trajectory of the Hubble spacecraft around the Earth is known very accurately, it is possible to triangulate the distance to the asteroid in a manner similar to that used by terrestrial surveyors. It turns out to be a previously unknown asteroid, located 169 million miles from Earth at the time of observation. The distance places the new object, most likely, in the main asteroid belt, lying between the orbits of Mars and Jupiter. Based on the observed brightness of the asteroid, the astronomers estimate that it has a diameter of about 1.5 miles.

The brightest stars in the picture (easily distinguished by the spikes radiating from their images, produced by optical effects within the telescope), are foreground stars lying within our own Milky Way galaxy. Their distances from Earth are typically a few thousand light-years. The faint, bluish SagDIG stars lie at about 3.5 million light-years (1.1 Megaparsecs) from us. Lastly, background galaxies (reddish/brown extended objects with spiral arms and halos) are located even further beyond SagDIG at several tens of millions parsecs away. There is thus a vast range of distances among the objects visible in this photo, ranging from about 169 million miles for the asteroid, up to many quadrillions of miles for the faint, small galaxies.

The team reported their science findings about the asteroid in the October 2004 issue of New Astronomy.

Original Source: Hubble News Release

Posted on by Fraser Cain

Close View of Phobos

This image, taken by the High Resolution Stereo Camera (HRSC) on board ESA?s Mars Express spacecraft, is Europe?s highest-resolution picture so far of the Martian moon Phobos.

This HRSC image shows new detail that will keep planetary scientists busy for years, working to unravel the mysteries of this moon. The image shows the Mars-facing side of the moon, taken from a distance of less than 200 kilometres with a resolution of about seven metres per pixel during orbit 756.

Images of Phobos as shown here had already been taken at lower resolution in previous orbits (413, 649, 682, 715 and 748). In the coming months, these first pictures will be followed by a series of images taken in subsequent fly-bys.

The Mars Express spacecraft periodically passes near Phobos about one hour before it flies at an altitude of only 270 kilometres above the Martian surface, just above the atmosphere. Within minutes, the orbiting spacecraft turns from its attitude where it points at Mars to train its camera on this little world.

The HRSC provided an unprecedented near-simultaneous group of 10 different images of the surface, enabling the moon’s shape, topography, colour, ?regolith? light-scattering properties, and rotational and orbital states to be determined. The regolith is the small-grained material covering most non-icy planetary bodies, resulting from multiple impacts on the body?s surface.

These images have surpassed all previous images from other missions in continuous coverage of the illuminated surface, not blurred and at the highest resolution. The US Viking Orbiter obtained a few small areas sampled at an even higher resolution of a few metres per pixel, but these were not so sharp due to the close and fast fly-by.

The global ?groove? network is seen in sufficient detail to cover the Mars-facing surface continuously from near the equator up to the north pole with regular spacing between the grooves. It now may be possible to determine whether the grooves existed before the large cratering events, and exist deep within Phobos, or came after the cratering events and were superimposed on them.

Much more detail is seen inside the various-sized craters, showing some with marked albedo variations. Some craters have dark materials near the crater floors, some have regolith that slid down the crater walls, and some have very dark ejecta, possibly some of the darkest material in our Solar System.

This tiny moon is thought to be in a ?death spiral?, slowly orbiting toward the surface of Mars. Here, Phobos was found to be about five kilometres ahead of its predicted orbital position. This could be an indication of an increased orbital speed associated with its secular acceleration, causing the moon to spiral in toward Mars.

Eventually Phobos could be torn apart by Martian gravity and become a short-lived ring around Mars, or even impact on the surface. This orbit will be studied in more detail over the lifetime of the Mars Express.

Original Source: European Space Agency

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