Space Archives
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Index
  1. Hubble views volatile moon...04/21/99
  2. Telescopes that can see the invisible universe...04/20/99
  3. 3 planets found around distant star...04/16/99
  4. Scientists find evidence of complete solar system...04/15/99
  5. Hubble finds most distant galaxy...04/15/99
  6. A New Class of Black Holes?...04/13/99
  7. Antimatter and fusion take center stage at propulsion workshop...04/13/99
  8. Astronomers Spot Remnants of 'Hypernovas'...04/13/99
  9. "Mother Ship" will take on a whole new meaning...04/07/99
  10. Surveyor scouts prime sites for Mars landings...03/30/99
  11. Hubble surveys 6 spiral galaxies...03/23/99
  12. Moonlight and Earthshine...03/18/99
  13. NASA to fix Hubble Telescope...03/15/99
  14. Saturn's Mysterious Moon...03/11/99
  15. NASA to fix Hubble trouble...03/11/99
  16. Finding the 'smoking gun' before it fires...03/10/99
  17. NASA tries to save spinning craft...03/08/99
  18. NASA announces completion of 'space plane' launch port...03/07/99
  19. Satellite launched to study stars...03/05/99
  20. Bringing Mars into the Iron Age...03/03/99
  21. Future telescope could shatter solar high-resolution barrier...03/02/99
  22. New rocket prototype unveiled...03/02/99
  23. Once in a Blue Moon...02/27/99
  24. Chandra will target the age of the Universe...02/22/99
  25. Researchers find clues to life`s origin in interstellar clouds...02/19/99
  26. Much ado about Pluto...02/17/99
  27. Evidence for great volcanism on Mars...02/17/99
  28. Group: NASA headed for crisis...02/06/99
  29. NASA rearranges flights because of telescope, Russian trouble...02/06/99
  30. Astronomers focus on young star, dust ring...02/06/99
  31. SOHO satellite brought back to life...02/05/99
  32. It's official: no 'demotion' for planet Pluto...02/04/99
  33. NASA planning plane bound for Mars02/02/99
  34. NASA Space Science News...02/02/99
  35. NASA Reports on recent Gamma Ray Blast...01/29/99
  36. Pluto may be stripped of planetary status...01/21/99
  37. Saturn-bound Cassini develops problem...01/15/99
  38. Astronomers expand estimate of galaxies in the universe...1/8/99
  39. Solar storm blew away part of the Earth's upper atmosphere...1/7/99
  40. Exciting New Hubble Space Telescope Images...1/6/99
  41. A Gas Bar "Feeding" An Active Galactic Nucleus...1/6/99
  42. NASA rockets to Mars with Polar Lander...1/4/99

Space Index


Hubble views volatile moon...04/21/99

(CNN) -- The Space Telescope Institute released stunning images Thursday of Jupiter's moon Io sweeping across the face of the giant planet, along with a closeup of the satellite spewing volcanic "snow."

The pictures of the planetary duo were released to commemorate the ninth anniversary of the Hubble telescope's launch on April 24, 1990. All of these images were taken with the Wide Field and Planetary Camera 2.

Three overlapping snapshots show in crisp detail Io passing above Jupiter's turbulent clouds. over a 1.8-hour time span. Io is roughly the size of Earth's moon but 2,000 times farther away.

In two of the images, Io appears to be skimming Jupiter's cloud tops, but it's actually 310,000 miles (500,000 km) away. Io races around Jupiter in 1.8 days, whereas the moon circles Earth every 28 days.

The conspicuous black spot on Jupiter is Io's shadow and is about the size of the moon itself (2,262 miles, or 3,640 km across).

The colors do not correspond closely to what the human eye would see because ultraviolet light is invisible.

In the close-up ultraviolet picture of Io, the mound rising from Io's surface is actually an eruption from Pillan, a volcano that had previously been dormant.

"Other observations have inferred sulfur dioxide 'snow' in Io's plumes, but this image offers direct observational evidence for sulfur dioxide 'snow' in an Io plume," said John R. Spencer of Lowell Observatory in Flagstaff, Arizona.

Scientists will get a closer look at Io later this year during a pair of close flybys to be performed by NASA's Galileo spacecraft, which has been orbiting Jupiter and its moons for nearly 3 1/2 years.

The first Galileo flyby is scheduled for October 10 at an altitude of 379 miles (610 km), and the other will take place November 25, when the spacecraft passes only 186 miles (300 km) above Io's fiery surface.

If the spacecraft survives this daring journey into the intense Jovian radiation environment near Io, it will send back images with dramatically higher resolution than any obtained before, according to mission scientists.


Space Index


Telescopes that can see the invisible universe...04/20/99

(NASA) By studying the electromagnetic emissions of objects such as stars, galaxies, and black holes, astronomers hope to come to a better understanding of the universe. Although many astronomical puzzles can only be solved by comparing images of different wavelengths, telescopes are only designed to detect a particular portion of the electromagnetic spectrum. Astronomers therefore often use images from several different telescopes to study celestial phenomena. Shown below is the Milky Way Galaxy as seen by radio, infrared, optical, x-ray and gamma-ray telescopes.

Different types of telescopes usually don't take simultaneous readings. Space is a dynamic system, so an image taken at one time is not necessarily the precise equivalent of an image of the same phenomena taken at a later time. And often, there is barely enough time for one kind of telescope to observe extremely short-lived phenomena like gamma-ray bursts. By the time other telescopes point to the object, it has grown too faint to be detected.


Space Index


3 planets found around distant star...04/16/99

By Alan Boyle
MSNBC WASHINGTON —

Building on 11 years of observations, astronomers say three giant planets have been detected around a sunlike star 265 trillion miles away — representing the first planetary system that scientists think could be like our own.

THE TRIPLE DETECTION, announced Thursday by a team of seasoned planet-hunters, adds new glimmers of hope to the search for Earthlike planets and perhaps even extraterrestrial life. It firms up the argument that these worlds are indeed planets rather than brown dwarfs or captured stars. But it also poses new puzzles. “Today, with the discovery of the first planetary system beyond our own, we are witnessing the emergence of a new era in human exploration,” declared Geoffrey Marcy, an astronomer at San Francisco State University and one of the system’s discoverers.

Just as past cultures looked from their own lands across seas and skies, earthlings were now beginning “a reconnaissance, if you will, of planets around other stars,” he said. Marcy and his longtime colleague in the search for extrasolar planets, R. Paul Butler of the Anglo-Australian Observatory, detected the first planet around Upsilon Andromedae in 1996, using what has become a standard method: They tracked a pattern of Doppler shifts in the spectrum of light from the star, which hints at a wobble caused by the gravitational pull of the circling planet. About 20 distant worlds have been detected in this manner. In the case of Upsilon Andromedae, there was an extra wobble, even after the first planet’s gravitational pull was taken into effect.

Butler, Marcy and other researchers from San Francisco State, the Harvard-Smithsonian Center for Astrophysics and the High Altitude Observatory in Boulder, Col., determined that the extra wobble could only be explained by the presence of two additional planets. A computer simulation confirmed that the orbits could be stable. The researchers said they have submitted a paper on the subject to the Astrophysical Journal, drawing on observations made from the Lick Observatory in California and the Whipple Observatory in Arizona.

The Hubble Space Telescope have peered 13 billion years back into time, almost to the dawn of creation, to find the oldest, most distant object ever detected: a galaxy fizzing with new stars. The galaxy lies near the edge of the universe, 13 billion light-years from Earth, where its presence was detected by its faint ultraviolet light, which is invisible to conventional telescopes. Paradoxically, the oldest known galaxy, dubbed "Sharon" after the sister of one of its discoverers, appears young to us. That's because the deeper astronomers look into space, the further back in time they are looking. It takes so long for light traveling through space to reach Earth that astronomers scanning the edges of the universe are seeing objects as they were billions of years ago.


Space Index


Scientists find evidence of complete solar system...04/15/99

SAN FRANCISCO (AP) - The first evidence of the existence of another solar system somewhat like our own was reported today.

The discovery indicates that the Milky Way, which contains about 200 billion stars, probably has numerous planetary systems, San Francisco State University researchers said in announcing the find.

Astronomers knew one planet was circulating around Upsilon Andromedae, 44 light years from Earth. But after of studying 107 stars for 11 years at the Lick Observatory near San Jose, scientists said evidence of two additional planets has been spotted. The discovery would mean that for the first time, a true solar system - with multiple planets - had been located.

``It implies that planets can form more easily than we ever imagined, and that our Milky Way is teeming with planetary systems,'' said Debra Fischer, one of the researchers.

The planets were discovered using a method that measures their gravitational pull on their star, not by direct observation. Planets' gravity tugs on their stars, causing them to wobble slightly. By examining the star's ultraviolet light transmissions, astronomers can calculate back-and-forth shifts in the ultraviolet wavelengths. A larger wobble indicates the orbiting planet is large.

Astronomers from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and at the High-Altitude Observatory in Boulder, Colo., independently identified the two new planets.

The innermost of the three planets has at least 75 percent of the mass of Jupiter and is very close to its sun, orbiting once every 4.6 days. The middle planet is twice Jupiter's mass and orbits the star every 242 days from a location about as far as Venus from the sun. The outer planet has the mass of four Jupiters and orbits its star every 3 1/2 to 4 years. It is more than twice as far from its star as Earth is from the sun.

No theory predicted that so many huge planets would form around a star, said astronomer Geoffrey Marcy, a member of the discovery team.

``I am mystified at how such a system of Jupiter-like planets might have been created,'' he said. ``This will shake up the theory of planet formation.''

Alex Wolszczan, an astronomy professor at Penn State University, called the discovery an ``important step'' toward understanding the cosmos.

``It has been anticipated and awaited by the scientific community. It's nice to see it's finally happened,'' he said. ``What I get right away from this particular discovery is that it emphasizes even more how different those systems are from our own.''


Space Index


A New Class of Black Holes?...04/13/99

From A NASA HQ Press Release The field of black holes, formerly dominated by heavyweights packing the gravitational punch of a billion Suns and lightweights just a few times heavier than our Sun, now has a new contender -- a just-discovered mysterious class of "middleweight" black holes, weighing in at 100 to 10,000 Suns.

Astronomers at NASA and Carnegie Mellon University have independently found evidence for the new type of black holes in spiral-shaped galaxies throughout the Universe. The newfound black holes, formed by an unknown process, are 100 to 10,000 times as massive as the Sun, yet each occupies less space than the Moon.

Right: M82 is a nearby galaxy now thought to harbor a middling-weight black hole in it's nucleus. It is a member of a group of galaxies dominated by itself, M81, and NGC 3077. M82 is thought by some to be limping away from a close encounter with M81. This galactic collision might have stirred up the inner stars and gas in M82, causing the unusual dark lanes of dust visible in the above photograph. More information

A black hole is a region of space where the force of gravity is so powerful that nothing, not even light, can escape its pull. Until now, scientists knew about two types of black holes: stellar and supermassive. Stellar black holes are the remains of dead stars several times heavier than the Sun, compressed to a diameter of a few miles or less. Supermassive black holes have mind-boggling masses of one million to one billion Suns and may have formed in the early universe from giant gas clouds or from the collapse of clusters of immense numbers of stars.

The astronomers identified the new class of black holes through X-ray light, the final cries of energy emitted from gas and particles spiraling into a black hole. The discovery will be announced today at the meeting of the High Energy Astrophysics Division of the American Astronomical Society in Charleston, SC.


Space Index


Antimatter and fusion take center stage at propulsion workshop...04/13/99

(NASA) It's one of the most attractive words in science fiction literature and nearly as good a topic at parties as black holes. It might also be the fuel that powers spaceships to the planets and perhaps the stars, even if it's just used as a sophisticated book of matches.

Right: Mars in 6 weeks? And back in a total of four months? That's the prediction of a design team working on antimatter rocket concepts at Pennsylvania State University. But first, you have to get the stuff - and store it. (PSU)

Antimatter and more "conventional" nuclear fusion occupied the final day of the 10th annual Advanced Propulsion Research Workshop held Tuesday-Thursday at the University of Alabama in Huntsville by NASA, Marshall, the Jet Propulsion Laboratory, and the American Institute of Aeronautics and Astronautics.

"Antimatter has tremendous energy density," said Dr. George Schmidt, chief of propulsion research and technology at NASA/Marshall. Matter-antimatter annihilation - the complete conversion of matter into energy - releases the most energy per unit mass of any known reaction in physics.

The popular belief is that an antimatter particle coming in contact with its matter counterpart yields energy. That's true for electrons and positrons (anti-electrons). They'll produce gamma rays at 511,000 electron volts.

But heavier particles like protons and anti-protons are somewhat messier, making gamma rays and leaving a spray of secondary particles that eventually decay into neutrinos and low-energy gamma rays.

And that is partly what Schmidt and others want in an antimatter engine. The gamma rays from a perfect reaction would escape immediately, unless the ship had thick shielding, and serve no purpose. But the charged debris from a proton/anti-proton annihilation can push a ship.

"We want to get as close as possible to the initial annihilation event," Schmidt explained. What's important is intercepting some of the pions and other charged particles that are produced and using the energy to produce thrust."


Space Index


Astronomers Spot Remnants of 'Hypernovas'...04/13/99

By Kenneth Chang

ABCNEWS.com One glowing cloud of gas and dust measures more than 850 light-years across. A second of these wispy nebulae is billowing outward at more than 100 miles per second. Both, spotted in the relatively nearby galaxy M101, could be ethereal remains of some of the universe’s most cataclysmic events.

Brighter Than an Exploding Star “These are possibly the most powerful explosions in our universe since the Big Bang,” says Q. Daniel Wang, an astrophysicist at Northwestern University in Illinois. Such explosions, dubbed “hypernovas,” would be even more powerful versions of supernovas, the brilliant last-gasp bursts of massive dying stars. Still just a hypothetical notion, hypernovas may throw out 100 times more energy than a run-of-the-mill supernova, and are a popular explanation for distant, powerful bursts of gamma rays detected by satellites about once a day.

The two glowing clouds in M101 aren’t new discoveries, but up to now have been classified as remnants of ordinary supernovas. Measurements from the German ROSAT satellite, however, showed that the two nebulae emit 10 times more X-ray energy than the brightest supernova remnants seen in our Milky Way galaxy. Similar to calculating the power of a bomb explosion by the size of the crater it leaves behind, Wang, along with collaborators at the University of Illinois and Dartmouth College, calculated the energy needed required to produce the M101 remnants.

The results were astronomical; according to the calculations, the explosions had to have been hypernovas. Wang presented his findings today at the meeting of the High Energy Astrophysics Division of the American Astrophysical Society in Hilton Head, S.C. The findings will also appear in the May 20 issue of Astrophysical Journal Letters. “It’s very important,” comments Princeton University astrophysicist Bohdan Paczynski, who coined the hypernova term last year. “It is the best case yet [of a hypernova remnant].”


Space Index


"Mother Ship" will take on a whole new meaning...04/07/99

(NASA) Presenting a paper at the International Conference on Advanced Propulsion held in Huntsville, Ala., Drs. David Noever and Subbiah Baskaran, both of the NASA Marshall Space Sciences Laboratory, discussed the potential of spacecraft reproduction and evolution.

"The next generation of spacecraft will more than likely evolve traits that their parent-ships could not have equaled," says Noever.

Computers can create infinite lists of combinations to try to solve a particular problem, a process called "soft-computing." But you don't want a computer to endlessly spew out random lists of possibilities. Instead, by breeding the most successful operations, the following generations can learn from past mistakes and successively improve. This process shares some features with the biological concept of natural selection, in which the most able organisms survive in the face of environmental pressure and multiply. Survival of the fittest, when applied to computer design, is one of the ingredients for artificial intelligence.

NASA has been developing spacecraft with artificial intelligence capabilities. The Mars Pathfinder, the Earth Observer, and the Deep Space 1 Interplanetary Probe are just some of the most recent applications of this technology.

Deep Space 1 is especially interesting to Noever and Baskaran, because it is the first major spacecraft that is expected to learn during its long, lonely trip through the solar system.


Space Index


Surveyor scouts prime sites for Mars landings...03/30/99

(CNN) Mars Global Surveyor is paving the way for an armada of spacecraft NASA wants to either put in orbit or land on Mars over the next decade. From its 240-mile-high orbit, Surveyor is scouting out interesting -- and safe -- landing sites for the series of landers and rovers that will explore Mars' enigmatic, windswept surface. And there's lots of territory to cover. Even though Mars is only about half the size of Earth, it has roughly the same land surface area because it doesn't have oceans.


Space Index


Hubble surveys 6 spiral galaxies...03/23/99

(CNN) -- The Hubble Space Telescope has provided scientists with a "photo essay" of six spiral galaxies, offering fresh views of star birth. To capture the images, part of a survey of about 100 spiral galaxies, scientists used the telescope's infrared vision to penetrate the dust clouds swirling around the centers of the galaxies.

The pictures showcase different views of spiral galaxies, including a face-on image of an entire galaxy and a close-up of a core. In the images, red corresponds to glowing hydrogen, the raw material for star birth. The red knots outlining the curving spiral arms in NGC 5653 and NGC 3593, for example, pinpoint rich star-forming regions where the surrounding hydrogen gas is heated by intense ultraviolet radiation from young, massive stars.

In visible light, many of these regions can be hidden from view by the clouds of gas and dust in which they were born, the Space Telescope Science Institute said in a statement.

The glowing hydrogen found inside the cores of these galaxies, as in NGC 6946, may be due to star birth; radiation from active galactic nuclei, which are powered by massive black holes; or a combination of both, astronomers said. Clusters of stars appear as white dots, as in NGC 2903.

The galaxy cores are mostly white because of their dense concentration of stars. The dark material seen in the images is dust.

The galaxies range in distance from Earth from 19 million light-years to 161 million light-years.


Space Index


Moonlight and Earthshine...03/18/99

( NASA) This week, on Friday, March 19, 1999, the crescent Moon, Venus and Saturn will present a beautiful display when they appear together in the western sky just after sunset. To see the show simply go outside at twilight and look west. The Moon and Venus will be nearly impossible to miss approximately 15 degrees above the horizon. Venus is so bright that it is often mistaken for an airplane, but it does not blink or move so it should be easy to identify.

Approximately midway between Venus and the Moon lies a fainter object, the ringed planet Saturn. Saturn and Venus will be separated by a scant 2 1/2 degrees.

The celestial trio of Venus, Saturn, and the Moon clustered so in the evening sky should be a memorable sight. But there's more: Cradled in the arms of the slim crescent Moon will appear the ghostly outline of the full Moon, a dim glow that astronomers call "Earthshine."

Like all the planets we see in the night sky, the Moon does not shine by its own light. It reflects sunlight. The side of the Moon facing the sun shines brightly, and the side facing away is nearly dark. The only significant illumination on the "dark side of the Moon" is due to Earthshine -- sunlight that bounces off the Earth and falls on the lunar surface. A slender crescent Moon with Earthshine is widely regarded as one of the most delicate and beautiful sights in the night sky.

As if a triple conjunction with Earthshine weren't enough, there will be one additional treat for sky watchers with access to a telescope or a good pair of binoculars. Sky & Telescope reports that a telescope will reveal a 6th-magnitude star just a fraction of a degree from Venus. It will look very much like a satellite of the planet. In fact, Venus is one of only two planets in the Solar System with no moons at all (the other is Mercury).


Space Index


NASA to fix Hubble Telescope...03/15/99

CAPE CANAVERAL, Fla. (AP) - NASA will launch an emergency repair mission this fall to the Hubble Space Telescope, which is in danger of shutting down. NASA decided Wednesday to move up the next regularly scheduled Hubble visit to October so that spacewalking astronauts can fix the telescope's deteriorating pointing system. The mission had been set for June 2000. Two of Hubble's six gyroscopes, needed for pointing and stability, have failed since astronauts' last service call, in 1997. And a third gyroscope is partly broken and is considered unreliable. Astronomers need at least three perfect gyroscopes to conduct observations throughout the universe.


Space Index


Saturn's Mysterious Moon...03/11/99

(NASA) Since mid-February the western sky has been a showcase of bright planets. On Feb. 23, Venus and Jupiter executed a dazzling conjunction seen by millions. Barely two weeks later Mercury appeared from behind the sun and four planets -- Mercury, Venus, Jupiter, and Saturn -- were visible at the same time in the western sky.

The show is continuing this week, and this time the star, or rather the planet, is Saturn. Saturn is visible to the naked eye soon after sunset. To find the ringed planet, it's easiest to "planet-hop" from Venus. Face west-southwest after the sun sets and look just above the horizon. Venus, at magnitude -4.0, will be impossible to miss. Venus is so bright that it is often mistaken for an airplane, but it does not blink or move so it should be easy to identify. Saturn is to the upper left of Venus, approximately 10 degrees away. At magnitude +0.5, it will be easily visible to the naked eye.

Saturn is widely regarded as the jewel of the night sky. It's not the brightest planet as seen from Earth, but it rarely fails to evoke a gasp of awe when seen through a telescope for the first time. The reason, of course, is Saturn's spectacular system of rings spanning over a half a million kilometers in diameter.


Space Index


NASA to fix Hubble trouble...03/11/99

CAPE CANAVERAL, Fla. (AP) - Astronauts will rush to the Hubble Space Telescope this fall - eight months early - to fix its deteriorating pointing system. NASA approved the emergency repair mission on Wednesday. "We are one failure away from losing all science on the Hubble Space Telescope," said Ed Weiler, head of NASA's space science program. By splitting the originally planned June 2000 mission into two parts - one in October and the other in late 2000 or early 2001 - Hubble's science program hopefully will be preserved and the astronauts' chores will be more manageable, Weiler said. "If we had waited until June 2000, there is a very reasonable chance that we could lose three, four or even more months of science," Weiler said. "This is a rather good insurance policy we're buying here." The extra mission will cost NASA $75 million more than what's been budgeted.


Space Index


Finding the 'smoking gun' before it fires...03/10/99

(NASA) Physicists discover a new tool for predicting solar eruptions. Solar scientist Ron Moore extended his right hand and clasped a visitor at mid-forearm. "These are the solar magnetic field lines snaking around each other, forming the letter 'S'," he explained. "Usually they go past each other. But if they connect at the wrists, it's like a coronal short circuit. The mid-section pops up and drives out a coronal mass ejection, a CME. Nobody understand exactly why this happens. But you don't explode very often unless you're twisted." And until recently, no one could predict when it would happen. But a new study, published today in Geophysical Research Letters, is putting scientists on the trail of predicting such eruptions. It's something that scientists have suspected for decades, and it will help give advance notice for the Solar Vector Magnetograph (SVMG) at NASA's Marshall Space Flight Center.


Space Index


NASA tries to save spinning craft...03/08/99

LOS ANGELES (AP) - Ground controllers worked Saturday to regain control of a science satellite spinning uselessly in orbit. The Wide-Field Infrared Explorer, or Wire, has been spinning at one revolution per second since its launch Thursday, apparently because of the thruster-like action of hydrogen gas venting from a system used to keep the satellite's telescope extremely cold. The $67 million mission was designed to help scientists understand how and when galaxies formed, and the history of star formation. Ground controllers were in contact with Wire and were trying to write a software program using the spacecraft's limited attitude control system to make it stop spinning.


Space Index


NASA announces completion of 'space plane' launch port...03/07/99

CNN) -- NASA and Lockheed Martin Corp. announced on Friday the completion of a space flight center that could usher in an age of cheaper, more frequent space travel.

A small "spaceport" prototype, the 30-acre center is dramatically different from other launch sites. "This center is designed to allow us to service and launch the X-33 from one spot, with a ground crew of fewer than 50 people," said NASA's Gene Austin.

The X-33 is a $1.2 billion joint program between NASA and Lockheed Martin to test the design of the VentureStar, a reusable, next-generation space shuttle. The X-33 is a scaled down version that was expected to fly early this year.

Lockheed Martin officials estimate the new system would decrease the cost of putting a payload in space from $10,000 to $1,000 per pound.

The launch center is 40 miles northeast of the Lockheed Martin Skunk Works facility, where the X-33 is being assembled. The $32 million flight operations center was designed and constructed in just under 12 months and under budget, according to Lockheed Martin.

But the experimental spacecraft project has suffered from a number of setbacks. In December the inner wall of one of the fuel tanks separated while being bonded at the company's Sunnyvale, California, facility. In January a Lockheed Martin spokesman said the problem would delay the first flight perhaps as long as seven months.

Before then the X-33 experienced another setback when the delivery of its engine was delayed five months. Lockheed Martin officials plan to have the VentureStar operational by 2004.

The craft will transport supplies to space stations and place satellites in orbit more cheaply than the space shuttle. Space 'lifeboat' performs well Earlier in the day Friday, NASA and Lockheed Martin officials a carried out a successful unmanned test flight of another experimental spacecraft, the X-38 crew return vehicle. The X-38, the prototype of a space lifeboat to return astronauts Earth from the International Space Station, had a "flawless" trial run at Dryden Flight Research Center, flight officials said.

Onboard computers controlled much of the descent until moments before it landed on a dry lakebed. Designed to bring crews back from the planned International Space Station during emergencies, the 7-ton craft dove from beneath the wing of a B-52 at 30,000 feet and coasted underneath a giant parafoil to a landing in the Mojave Desert. The vehicle, which has no wings or engine, experienced the softest landing yet compared to several earlier flights, an X-38 engineer said.

Flight officials plan more tests over the next couple of years at increasingly higher altitudes, including a flight from space in 2001.


Space Index


Satellite launched to study stars...03/05/99

VANDENBERG AIR FORCE BASE, Calif. (AP) - A NASA satellite carrying a telescope designed to shed light on the history of star formation was launched Thursday night over the Pacific Ocean. The Wide-Field Infrared Explorer, better known as Wire, was carried into space on a Pegasus-XL rocket. The Wire spacecraft will be inserted into an orbit 340 miles high, circling the Earth every 90 minutes. NASA designed the four-month mission to help scientists understand how and when galaxies formed and the subsequent history of star-formation in the universe. Wire principal investigator Perry Hacking said the mission's science team will measure how densely filled the universe has been with star-forming galaxies during its history and how quickly those galaxies have been forming stars.


Space Index


Bringing Mars into the Iron Age...03/03/99

(NASA) A metal-making process known to the ancient Romans could be pressed into service to bring Mars into the Iron Age - and start opening the solar system to human habitation. "If you look at the soil composition of Mars, the one thing that really strikes you is that it's 5 to 14 percent iron oxide," said Dr. Peter Curreri, a materials scientist at NASA's Marshall Space Flight Center. "It's almost ore-grade material."

Using Mars ore, Curreri says, early explorers could build receivers to generate electricity from radio waves beamed from a mother ship in Mars orbit. While NASA does not have a program to put humans on Mars, it is developing technologies and mission concepts for such a possibility.

A gleam in the eye "What really put the gleam in my eye," said Curreri, "when I got into space 20 years ago as a graduate student, was the concept that if you can process materials in space for use in space, you can really open up the frontier. Putting a manufacturing device on the Moon or Mars can provide products that weigh 20 times or more the weight of the propellants to deliver it. That becomes a very powerful lever."


Space Index


Future telescope could shatter solar high-resolution barrier...03/02/99

(NASA) Discovery is always just beyond the limit of resolution, scientists like to say. To reach beyond limits that are about to be stretched by the Solar-B satellite, scientists at NASA's Marshall Space Flight Center and the University of Alabama propose to design a telescope that would virtually put solar flares under a microscope.

"What we'd like to do is shatter the resolution barrier and routinely observe magnetic fields with near kilometer-scale resolution over active-region fields of view," said Dr. John Davis, deputy chief of the Physics and Astronomy Division in the Space Sciences Laboratory at NASA/Marshall.

Davis will present a proposal for a "Next Generation of Solar High-Resolution Imaging Instrumentation" at a meeting today of the Mechanisms of Solar Variability Science Working Group in Washington, D.C. NASA charters such working groups to look ahead to the kinds ofadvanced instruments that will be needed to answer questions that will be raised by new instruments that are still being built.

"The Transition Region and Coronal Explorer, launched in 1998, demonstrates that improvements in resolution reveal new and unexpected phenomena," Davis explained. This was true of each new solar telescope that preceded TRACE, all the way back to Galileo's discovery of sunspots in 1610. TRACE is studying the mysterious transition region where the solar atmosphere's temperature soars to millions of degrees even as it is thinning out.


Space Index


New rocket prototype unveiled...03/02/99

MOJAVE, Calif. (AP) - The prototype of a reusable, manned rocket that can land like a helicopter after carrying satellites into orbit was unveiled Monday. The Roton, built by Rotary Rocket Co. of Redwood City, is a launch vehicle powered by kerosene instead of costly hydrogen, which the firm hopes will cut launch costs by 90%. It has been designed to launch like a rocket, then deploy a propeller and land like a helicopter. Some 1,200 people gathered as the prototype was rolled out of a hangar at Mojave Airport. Among them were NASA chief engineer Daniel Mulville, who hopes his agency will become a customer of the commercial launch vehicles, and novelist Tom Clancy, a Rotary Rocket investor. The prototype, dubbed Roton ATV, does not have launch engines. It will be used to test the rocket's landing system, which uses rotor blades with tip rockets to slow the vehicle down so it can land like a helicopter.


Space Index


Once in a Blue Moon...02/27/99

(NASA) We've all heard the saying "it happens only once in a blue moon," generally used to describe an uncommon occurance. But for the first quarter of 1999, using the phrase "once in a blue moon" could also mean "two out of three times."

In astronomical terms, a 'blue moon' really doesn't have anything to do with color. Instead, it is the term used to denote the second full moon that occurs within a given calendar month. Because it takes the moon about 29 days to circle the Earth once in its orbit, it is possible that two full moons can occur within the same calendar month. Such was the case in January 1999, when the moon was full on the 2nd and the 31st, making the full moon on the 31st a 'blue moon.' On average, this takes place once every two and a half years. This time, however, we don't have to wait over 2 years for another blue moon. A second blue moon will appear this March, with the moon displaying its full-phase on the 2nd and the 31st of March.

Although a 'blue moon' doesn't really look blue, there have been times when the moon does seem to have a blue color. This can be caused by dust particles in the atmosphere, which scatter light. The effects of this dust on the light coming from the moon can cause it to appear bluish in color. Fine dust particles are ejected into the Earth's upper atmosphere after large volcanic eruptions, for example. The eruption of the Krakatoa volcano in 1883 gave us one such 'blue moon'. For about 24 months after this volcano exploded, the dust it spewed into the upper atmosphere caused the moon to appear green and blue when viewed from around the world.


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Chandra will target the age of the Universe...02/22/99

(NASA) In recent years astronomers have come to realize that the Universe is somewhere between 12 and 18 billion years old. They arrive at this estimate by measuring how fast the Universe is expanding due to the Big Bang and whether the expansion is accelerating or decelerating. By tracing the cosmos back in time to an era when the entire Universe was contained in a single point, they can estimate the time elapsed since the Big Bang.

Unfortunately for cosmologists, who would like to know exactly when the Big Bang happened, it's difficult to measure precisely how fast the Universe is expanding and how the rate of expansion has changed since the Big Bang. Traditional methods lead to rather large uncertainties in the final answer.

Now two astronomers, Dr. Marshall Joy (NASA/MSFC) and Dr. John Carlstrom (University of Chicago), may have a new way to tackle the problem. For the past 7 years Joy, Carlstrom, and their colleagues have used radio interferometers to probe tiny fluctuations in the Cosmic Microwave Background Radiation (or "CMBR"). By combining their radio-wavelength images with data from NASA's Chandra X-ray Observatory they hope to open a new window on the history of the Universe.

"We could be on the brink of answering some important cosmological questions," says Joy, "but we need more data that only Chandra can provide." Joy and Carlstrom's quest for the age of the Universe begins with a little-known phenomenon called the Sunyaev-Zeldovich Effect that causes small fluctuations in the cosmic microwave background. One of the astonishing things about the CMBR is its smoothness. When astronomers compare the intensity of the CMBR in different parts of the sky, the differences they find are all smaller than 1 part in 105. In 1980, the Russian physicists Sunyaev and Zeldovich suggested that tiny fluctuations in the CMBR might be found if astronomers looked in the direction of giant clusters of galaxies.


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Researchers find clues to life`s origin in interstellar clouds...02/19/99

David F. Salisbury, News Service (650) 725-1944; e-mail: david.salisbury@stanford.edu A team of scientists from NASA and Stanford University have created some of the chemicals essential for life in an environment similar to that found in deep space. This finding could shed light on the origin of life itself. The team reported its results in the Feb. 19 issue of the journal Science.

Astrobiologists at NASA`s Ames Research Center, Moffett Field, Calif., and chemists at Stanford University conducted lab experiments to simulate the conditions that exist in interstellar clouds of dust and gas. The dust in such clouds plays an important role in the life cycles of solar systems. It is the debris of previous generations of stars and the material from which new stars and solar systems will develop.

To conduct their experiments, NASA scientists simulated the dust clouds of the interstellar medium by freezing and then irradiating the most common carbon-bearing molecules found there. The Stanford researchers then analyzed the resulting chemical products. Their results confirmed the presence of organics that served as the building blocks for the development of life on Earth.

``We wanted to see what chemistry could occur under conditions like those in molecular clouds - the places where solar systems are made,`` said Max Bernstein, principal author and chemist at Ames and the SETI Institute in Mountain View, Calif. ``The chemical compounds that resulted are similar to those ubiquitous in living systems today, and play important roles in essential biological processes,`` he said.

``The importance of this work is that it increases the odds that carbon-based life may have evolved elsewhere,`` said Richard Zare, chemistry professor and team leader of the Stanford collaborators.

``The molecules that we isolated in our lab experiments may have been exploited by the Earth`s earliest organisms. That may be how these kinds of compounds become incorporated into our biochemistry,`` said Lou Allamandola, team senior researcher at Ames. ``This is the dead center of the astrobiology bull`s-eye,`` he said, referring to Ames` core space initiative for the 21st century.

The researchers think that the molecules they created in the lab were biologically important for pre-biotic cells in two ways: quinones (oxidized hydrocarbons that are present in St. John`s wort, aloe and henna) play a crucial part in electron transport in cells, and other by-products of the experiment enable cells to harness light energy for photosynthesis. The chemical products produced included quinones, aromatic ketones, alcohols and ethers.

``The same kinds of compounds that we detected in our experiments have been found in carbon-rich meteorites,`` said Scott Sandford of Ames. ``We are now seeing how these molecules in meteorites may have formed.``

In space, oxidized hydrocarbons (similar to those the researchers created in the lab) are made in the interstellar medium and brought to Earth in interplanetary dust particles (microscopic bits of comets and asteroids) that drift down by the ton every day.

Previously, Allamandola showed that a family of carbon-containing compounds, which are common on Earth in coal, soot and automobile exhaust, are the most abundant class of organic molecules in the universe.

Bernstein, Sandford and Allamandola conducted the experiments at the Astrochemistry Lab at Ames. The mass spectral analysis was carried out at the Chemistry Department at Stanford University by graduate student J. Seb Gillette, Simon Clemett, now at MVA Inc. in Norcross, Georgia, and Zare.


Space Index


Much ado about Pluto...02/17/99

Recent discoveries of Pluto-like objects in the outer solar system have sparked debate about the nature of the tiniest "planet" In 1979 the Solar System became a bit mixed up.

That's when Pluto, which travels in a highly elliptical orbit, temporarily moved closer to the sun than Neptune. Every 248 years the two planets swap places and for about 20 years Pluto becomes the eighth planet and Neptune the ninth. This topsy-turvy situation was rectified last Thursday, Feb. 11, when Pluto crossed Neptune's orbit and became the ninth planet once again.

Pluto is the only planet that has not been visited by a spacecraft. Even the Hubble Space Telescope can resolve only the largest features on its surface, shown in this image of one hemisphere. The brightness variations could be due to craters and basins, methane and nitrogen frosts, or even areas of primordial organic matter. No one knows, and the mystery may remain until some future spacecraft pays a visit to this distant planet. More information One of these things is not like the others But is Pluto really a planet? That's what astronomers have been discussing since late last year when some members of the International Astronomical Union suggested that Pluto be given a minor planet designation. Why? For one thing Pluto is very small. It's 6 times smaller than Earth, and even smaller than seven of the solar system's moons (the Moon, Io, Europa, Ganymede, Callisto, Titan and Triton). Pluto's own moon, Charon, is larger in proportion to its planet than any other satellite in the solar system. Some astronomers consider the pair to be a double planet.


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Evidence for great volcanism on Mars...02/17/99

New photos from the Mars Global Surveyor show that horizontal layers extend deep into the canyons of Mars. The structure and composition of the layers suggest that volcanism played a far greater role in the early geology of the Red Planet than previously believed, scientists report in this week's issue (Feb. 18) of Nature.

Further, volcanism that lasted for at least the first billion years of Mars' geologic history might have continually resupplied the martian atmosphere with carbon dioxide that sustained its warm and wet early climate, according to Alfred S. McEwen of The University of Arizona in Tucson and co-authors of the article.

McEwen is director of the Planetary Image Research Lab at the UA Lunar and Planetary Laboratory. Co-authors are Michael C. Malin of Malin Space Science Systems in San Diego, Michael H. Carr of the U.S. Geological Survey and William S. Hartmann of the Planetary Science Institute in Tucson. Theirs is one of four articles in the Feb. 18 Nature analyzing close-up images of Mars taken during the aerobraking phase of the Mars Global Surveyor mission.

The new images from the Mars Orbital Camera show horizontal layers at least as keep as 8 kilometers (5 miles) in the canyons spanning the enire 4,000-kilometer (2,480-mile) Valles Marineris canyon system, McEwen and colleagues report. Earlier studies predicted the photographs would show large chunks of breccia and bedrock fractured by impacts during the heavy bombardment phase of solar system formation, between 3.5 billion and 4.3 billion years ago, and that these coarse layers would be laced with thin lava layers at the planet's uppermost crust.


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Group: NASA headed for crisis...02/06/99

CAPE CANAVERAL, Fla. (AP) - NASA is headed for a crisis because of cutbacks that could jeopardize space shuttle safety, an oversight group warns. While shuttle safety is satisfactory for now, it could suffer in the future as a result of inadequate job skills and other shortfalls in the work force, the Aerospace Safety Advisory Panel said Thursday in its annual report to NASA. The panel described the situation as a looming crisis. As of last year, the shuttle work force totaled about 21,000 nationwide, mostly contractors. That's down about one-third from six years earlier, according to NASA statistics.


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NASA rearranges flights because of telescope, Russian trouble...02/06/99

(CNN) NASA was forced to rearrange its entire shuttle flight schedule Friday because of trouble with an X-ray telescope and Russia's inability to get a crucial piece of the international space station into orbit. That will mean five shuttle flights in 1999 instead of six. That also will mean a gap of nearly six months between shuttle launches, the longest gap since the 2 1/2-year hiatus following the 1986 Challenger disaster.


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A star just visible to the naked eye in the southern constellation of Centaurus is today's "Astronomy Picture of the Day" at a popular NASA website and topic for a University of Arizona astronomer in NASA-televised space science update to be broadcast Tuesday, Feb. 9.

UA astronomer Glenn Schneider is on a team of Hubble Space Telescope scientists who recently used the space telescope's NICMOS camera and a coronagraph to photograph a narrow, reddish-grey dust ring around the star, HR 4796A. The images are posted at http://antwrp.gsfc.nasa.gov/apod, the "Astronomy Picture of the Day" site.

The star, about 70 percent larger than our sun, is about 10 million years old, the NICMOS scientists say. They collaborate in a project called "EONS," or Environments of Nearby Stars. What is remarkable is that a star so young should have a narrow dust ring.

Astronomers focus on young star, dust ring...02/06/99

That narrowness implies that planets or protoplanets are present to confine the dust into a ring whose width is equal to the distance between Mars and Uranus. The ring's width is only a tenth of its diameter. Few thought that planets might form in less than 10 million years.

Schneider and two other astronomers will talk more about mechanisms believed to form planets in disks around stars for a NASA-televised Space Science Update to be broadcast from the agency's headquarters in Washington, D.C., at 11 a.m. MST (1 p.m. EST) Tuesday, Feb. 9. The live broadcast can be viewed on a television monitor in the lobby of the UA Steward Observatory.

Schneider's UA phone number is 520-621-6458,
e-mail gschneider@stsci.edu or gschneid@as.arizona.edu


Space Index


SOHO satellite brought back to life...02/05/99

(Reuters) The SOHO sun-observing satellite has returned to service more than a month after the gyroscope that kept it stable malfunctioned. The $1 billion satellite's controllers returned it to service Tuesday using a new computer program to help it keep its orientation without the failed gyroscope, Bernard Fleck, European Space Agency project scientist for SOHO, said Wednesday in a telephone interview.


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It's official: no 'demotion' for planet Pluto...02/04/99

WASHINGTON (Reuters) -- Finally, after weeks of controversy, it's official. There will be no "demotion" for Pluto. Pluto has always been something of a misfit among the other major planets, but a move by the International Astronomical Union last month that some felt would have reclassified it as a minor planet drew howls of protest.


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NASA planning plane bound for Mars02/02/99

WASHINGTON (AP) - To mark the 100th anniversary of the Wright Brothers first airplane flight NASA wants to duplicate the event - sort of - on Mars. The NASA budget for 2000 contains $50 million to begin development of a Mars airplane. An animated video played at the budget briefing showed a small, pilotless plane parachuting toward the sandy surface, unfolding its wings and propeller, and puttering off. In actuality, a lot about the plane remains to be determined, including actual design and means of propulsion and delivery to Mars, NASA Administrator Daniel S. Goldin said. Flying in Mars' atmosphere is like flying at 100,000 to 130,000 feet altitude above Earth, he said, so much research needs to be done. A long-range jetliner flies at about 30,000 feet altitude. There is also an eight-minute time lag for radio messages between Earth and Mars, complicating the control of the plane, which would be unmanned. The goal, is all goes well, is to make the flight in 2003, the 100th a! nniversary of the Wright Brothers flight, though NASA's briefing papers admitted it could slip to 2005.


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NASA Space Science News...02/02/99

(NASA) Galileo buzzes Europa: This weekend the Galileo spacecraft passed a scant 894 miles above the surface of Jupiter's moon Europa. Scientists are intrigued by Europa because of mounting evidence that liquid water exists beneath its frozen surface. Recent images reveal a complex terrain in 3D featuring cryo-volcanoes, gigantic faults and new evidence for possible oceans


Space Index


NASA Reports on recent Gamma Ray Blast...01/29/99

(NASA)Gamma Ray Bursts have puzzled scientists for over 30 years, since their discovery in 1967. This week's news of the identification of an optical counterpart to a burst as it was occurring is only the latest in a three-decade search for understanding of these enigmatic objects. Three decades of research have allowed scientists to finally answer the question "Where are the Gamma-Ray Bursts?", and can now move on to answer the question "What causes them?"

Recent discoveries in this field by a collection of international astronomers have demonstrated that these bursts are from the most remote parts of the universe, releasing perhaps as much energy in 10 seconds as the Sun emits in its entire 10-billion-year lifetime. Yet scientists are still baffled in many respects when it comes to answering the question "What could cause something like this?"

Until this week, astronomers had no idea how bright the optical emission might be during the actual time the burst was occurring. However, capturing that emission - if there actually was any - remained a high priority in the scientific community. In order to determine the gamma-ray burst location more quickly, a team of scientists, led by Dr. Scott Barthelmy at NASA's Goddard Space Flight Center, implemented the Gamma-ray burst Coordinates Network (GCN). This system automatically intercepts BATSE data at Goddard, calculates a rough gamma-ray burst position, and within seconds distributes the location over the Internet to eager observers around the world.

Due to the challenges of determining the burst position in the sky, previous observations of visible light from gamma-ray bursts have all been made hours after the burst had ended. The light by that time was so dim it could only be detected by the world's largest telescopes. But thanks to GCN's rapid response time, the ROTSE-I telephoto camera array in Los Alamos, N.M. was able to watch a gamma-ray burst as it occurred. Dr. Carl Akerlof of the University of Michigan in Ann Arbor, along with several colleagues, designed ROTSE to point quickly to a gamma-ray burst location after receiving GCN data. ROTSE uses four telephoto lenses and charge-coupled devices (CCDs) on an automated pointing system, to image a piece of sky 16.5 degrees across as fast as every 8 seconds

ROTSE received a GCN location 4 seconds after the burst was identified by BATSE, and was able to observe the gamma-ray burst a mere 22 seconds after it had begun. At its brightest, the burst reached an apparent magnitude of 8.9, approximately 15 times dimmer than the faintest stars visible to the naked eye.


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Pluto may be stripped of planetary status...01/21/99

(CNN) Pluto, smaller than Earth's moon, was first classified as a planet nearly 40 years ago. Now the International Astronomical Union is considering revoking that honor, leaving our solar system with just eight major planets. The head of the Planetary Systems Sciences Division says it's "obvious" Pluto doesn't fit because of its small size and irregular orbit.


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Saturn-bound Cassini develops problem...01/15/99

NASA's biggest and most complex interplanetary probe went into so-called safe mode this week when it detected a potential problem on its way to Saturn. The probe sensed the possible problem Monday, triggering a program designed to halt non-critical activity, NASA's Jet Propulsion Laboratory said Wednesday. The spacecraft began using minimum power and pointing its 12-foot antenna toward the sun to shade the rest of the spacecraft.


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Astronomers expand estimate of galaxies in the universe...1/8/99

Looking back in time at a tiny section of sky, the Hubble Space Telescope found there may be 125 billion galaxies in the universe, about 45 billion more than the last best estimate, astronomers reported on Thursday. The new number was based on observations by the orbiting telescope's Deep Field camera last October, when it looked at the southern sky, taking what amounts to a visual core sample. The Hubble looked at the northern sky in 1995; 80 billion galaxies were estimated then.

 


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Solar storm blew away part of the Earth's upper atmosphere...1/7/99

NASA - Plasma scientists plan polar CAPER to study auroral ion fountain.

"Can You say H.A.A.R.P. project. I knew you could."

Mitch

http://science.nasa.gov/newhome/headlines/ast07jan99_1.htm

 


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Exciting New Hubble Space Telescope Images...1/6/99

Astronomers predict that remarkable new images from the Hubble Space Telescope to be released Friday morning, Jan. 8, will be one of the major news stories at the 193rd national meeting of the American Astronomical Society (AAS) in Austin, Texas. More than 1,700 astronomers are attending this meeting, which features 1,100 scientific papers and a full schedule of media events, according to AAS press officer Stephen P. Maran.

Glenn Schneider of The University of Arizona in Tucson is a panelist at the 9:30 a.m. CST Friday briefing on “Circumstellar Systems.” The news conference, open to credentialed media, will be held at the Austin Convention Center. Contact Maran, or Lynn Cominsky, deputy press officer, at the AAS Press Room, phone 512-404-4650.

Schneider, University of Hawaii astronomer Brad Smith (formerly on the UA faculty) and their colleagues will present high- resolution (sharp) images made with a coronagraph on NICMOS, the Near Infrared Camera and Multi-Object Spectrometer. The images “may bear on the formation and evolution of planetary systems,” according to the AAS.

NICMOS is a Hubble Space Telescope instrument designed, developed and operated by a team led by UA astronomers. Schneider, Smith, UA astronomer Donald McCarthy, UA astronomer Rodger Thompson – who is principal investigator for NICMOS -- and others collaborate in a major NICMOS science program called “EONS,” or Environments of Nearby Stars.

INTERVIEWS: Phone interviews with Schneider can be arranged through Lori Stiles, UA News Services, 520-626-4402, e-mail: lstiles@u.arizona.edu. Contact Stiles before noon CST (10 a.m. MST) Friday. Schneider will be available for phone interviews after the news conference and available for in-person interviews when he returns to Steward Observatory Monday afternoon, Jan. 11.


Space Index


A Gas Bar "Feeding" An Active Galactic Nucleus...1/6/99

From Mark W. Sincell, for UA News Services)

Astronomers announced today the discovery of a gaseous bar that appears to be "feeding" a supermassive black hole located in the nucleus of the active galaxy, Circinus. Located in the Southern Hemisphere constellation of the same name, Circinus is approximately 10 million light years from Earth.

This report was presented at the 193rd Meeting of the American Astronomical Society in Austin, Texas, by Almudena Alonso-Herrero, an astronomer at The University of Arizona's Steward Observatory in Tucson, Ariz. She led an international team of astronomers including Roberto Maiolino of the Osservatorio di Arcetri in Italy; Marcia Rieke, Alice Quillen, and George Rieke, all from the Steward Observatory; and Lowell Tacconi-Garman at the Max-Planck-Institut fur Extraterrestrische Physik in Garching, Germany.

"We believe that this is the first direct evidence of molecular gas flowing into the center of an active galaxy," says Alonso-Herrero.

Active galaxies are among the brightest objects in the sky. Astronomers have long believed that they are powered by material falling into supermassive black holes -- each weighing millions of times the mass of our sun -- which lie at the center of these galaxies. However, theorists do not clearly understand how this material is dislodged from its orbit far from the black hole so that it can be funneled down into the hole. One popular theory holds that gas from the host galaxy is transported into the center of the galaxy where it forms a bar. The gas in the bar then "feeds" the black hole.

A nuclear gas bar is an extended column of material centered on the nucleus of the galaxy. The bar rotates rigidly about the galactic nucleus, much like a propeller rotating on its axle. Bars are relatively common features in optical images of galaxies, but these bars are typically thousands of light years across. To power an active galaxy, material must approach within a hundred light years of the central black hole.

Motivated by these theoretical arguments and by the presence of large-scale bars, many astronomers have looked long and hard for evidence of small-scale bars in the cores of active galaxies. Unfortunately, previous searches failed to uncover evidence for any small-scale bars.

Now, using images from the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope and the Max-Planck Institute's 3D Spectrometer on the 3.9-meter Anglo-Australian Telescope (AAT) in Australia, Alonso-Herrero and team members have mapped a bar of molecular gas in the center of the galaxy Circinus.

They chose Circinus because it is one of the nearest active galaxies. The gas bar is only a few hundred light years across and even the largest telescopes have difficulty resolving objects that small at such great distances.

Alonso-Herrero imaged the gas bar using a method called two-color mapping. First, the team gathered NICMOS observations of Circinus in two infrared wavebands at different frequencies. Dust, which is mixed in with the molecular gas, preferentially absorbs the high frequency radiation so the lower frequency radiation from the underlying galaxy can pass freely through the dust in the bar. The high frequency radiation from the galaxy is absorbed in the bar, in the same way that a bone absorbs X-rays. By taking the ratio of the high and low frequency images, Alonso-Herrero created a very accurate map of the nuclear bar.

The NICMOS images also clearly show a cone of ionized material emanating from the nucleus. The intense radiation emitted by the central black hole is absorbed by clouds of gas in the galaxy, ionizing them and causing them to radiate in the infrared. The light detected by Alonso-Herrero and her coworkers comes from highly ionized silicon emission lines. Ionization cones are often seen in HST images of nearby active galaxies.

Additional observations of radiation from molecular hydrogen, taken with the AAT, indicated that the gas along the leading edge of the bar, the edge that lies in the direction of the motion of the rotating bar, is flowing into the center of Circinus. A shock wave on the leading edge appears to be energizing the molecular hydrogen, causing it to radiate emission lines. The emission lines from molecular hydrogen in the bar are Doppler shifted in precisely the amount expected from theoretical models of gas bars. (Doppler shifting is the change in the observed frequency of radiation due to motion of the radiating gas.)

"We are very excited by how much our results are indicative of gas motions toward the center of the galaxy, as predicted by the models," says Alonso-Herrero.

Although the gas inflow in Circinus appears to confirm the theory that material in bars can flow towards the center of active galaxies, eventually feeding the central black hole in active galaxies, Alonso-Herrero cautions that this is only one object. "We still don't know if it is a special case or not," she says.

Extensive surveys of other active galaxies are necessary to make a general confirmation of the theory.

Contact:: Almudena Alonso-Herrero,
520-621-2054,
aalonso@as.arizona.edu

 


Space Index


NASA rockets to Mars with Polar Lander...1/4/99

CNN) NASA's Mars Polar Lander spacecraft lifted off on schedule Sunday, beginning an 11-month journey that is to culminate with a landing on the red planet's northernmost icy surface. Mission controllers were able to take advantage of Sunday's 10-second launch window to send the spacecraft skyward aboard a Boeing Delta 2 rocket.


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