Space and astronomy news
Astrophotographer Bert Verstraete took this picture of the Sagittarius region in October 1997, with 10 minute exp , F3.5 28mm from near Upham, New Mexico.
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Karen Breytenbach took this picture of the moon and Jupiter on the 13th of July from Johannesburg, South Africa. Karen used digital Nikon Coolpix8700, mounted on a tripod, set on night landscape mode with maximum zoom.
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Astrophotographer Tom Diana took this picture of M100 – Spiral Galaxy in Coma Berenices from his backyard observatory in southeast Minnesota. Tom used C11 @f/6.5 telescope with Losmandy G-11 Gemini mount and ST-9 camera.
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Artist’s conception of the Earth’s inner layers. Image credit: S. Jacobsen, M. Wysession, and G. Caras. Click to enlarge
Recently, seismologists have observed that the speed and direction of seismic waves in Earth?s lower mantle, between 400 and 1,800 miles below the surface, vary tremendously. ?I think we may have discovered why the seismic waves travel so inconsistently there,? stated Jung-Fu Lin.* Lin was with the Carnegie Institution?s Geophysical Laboratory at the time of the study and lead author of the paper published in the July 21, issue of Nature. ?Until this research, scientists have simplified the effects of iron on mantle materials. It is the most abundant transition metal in the planet and our results are not what scientists have predicted,? he continued. ?We may have to reconsider what we think is going in that hidden zone. It?s much more complex than we imagined.?
The crushing pressures in the lower mantle squeeze atoms and electrons so closely together that they interact differently from under normal conditions, even forcing spinning electrons to pair up in orbits. In theory, seismic-wave behavior at those depths may result from the vice-gripping pressure effect on the electron spin-state of iron in lower-mantle materials. Lin?s team performed ultra high-pressure experiments on the most abundant oxide material there, magnesiow?stite (Mg,Fe)O, and found that the changing electron spin states of iron in that mineral drastically affect the elastic properties of magnesiow?stite. The research may explain the complex seismic wave anomalies observed in the lowermost mantle.
As co-author of the study Viktor Struzhkin elaborated: ?This is the first study to demonstrate experimentally that the elasticity of magnesiow?stite significantly changes under lower-mantle pressures ranging from over 500,000 to 1 million times the pressure at sea level (1 atmosphere). Magnesiow?stite, containing 20% iron oxide and 80% magnesium oxide, is believed to constitute roughly 20% of the lower mantle by volume. We found that when subjected to pressures between 530,000 and 660,000 atmospheres the iron?s electron spins went from a high-spin state (unpaired) to a low-spin state (spin-paired). While monitoring the spin-state of iron, we also measured the rate-of-change in the volume (density) of magnesiow?stite through the electronic transition. That information enabled us to determine how seismic velocities will vary across the transition.?
?Surprisingly, bulk seismic waves travel about 15% faster once the electrons of iron are spin-paired in the magnesium-iron oxide,? commented co-author Steven Jacobsen. ?The measured velocity jump across the transition might, therefore, be detectable seismically in the deep mantle.? The experiments were conducted inside a diamond-anvil pressure cell using the intense X-ray light source at the nation’s third-generation synchrotron source, Argonne National Laboratory near Chicago.
?The mysterious lower mantle region can?t be sampled directly. So we have to rely on experimentation and theory. Since what happens in Earth?s interior affects the dynamics of the entire planet, it?s important for us to find out what is causing the unusual behavior of seismic waves in that region,? stated Lin. ?Up to now, earth scientists have understood Earth?s interior by only considering pure oxides and silicates. Our results simply point out that iron, the most abundant transition metal throughout the entire Earth, gives rise to very complex properties in that deep region. We look forward to our next experiments to see if we can refine our understanding of what is happening there,? he concluded.
Original Source: Carnegie Institution News Release
The Return to Flight mission STS-114 crew. Image credit: NASA/KSC. Click to enlarge
With some work still to go, NASA is moving toward a new launch attempt for the Space Shuttle Discovery Tuesday, July 26, at 10:39 a.m. EDT. Engineers are wrapping up a troubleshooting plan to address a fuel sensor system issue that caused Space Shuttle managers to scrub the first launch attempt for the Return to Flight mission, STS-114.
At a meeting today of the Mission Management Team, Shuttle managers decided on a plan to complete outstanding work on the External Tank’s liquid hydrogen low-level fuel sensor system circuit that runs from the External Tank into the Orbiter. The plan outlines a series of steps that could culminate in a launch next Tuesday. First, engineers will complete tests to look at electromagnetic interference as a factor in the sensor system circuit malfunction. Then, workers will swap circuits for two of the sensors to provide a means to isolate the problem to the wiring or the point sensor box, should the problem recur during the countdown. Next, engineers will shore up the electrical grounding to reduce further the chance of electromagnetic interference with the sensor system.
For a Tuesday launch, the official launch countdown for Discovery will begin Saturday. During the countdown, engineers will closely watch the behavior of the sensor system circuit as the tank is filled with super-cooled propellants.
Including the first launch attempt on Tuesday, there are at least four opportunities for Discovery to launch during the current launch window, which extends until July 31. NASA managers are also looking at the possibility of additional launch opportunities in the first week of August.
For the latest information on the Space Shuttle’s Return to Flight, visit:
http://www.nasa.gov/returntoflight
Original Source: NASA News Release
UV image of supernova in spiral galaxy M100. Image credit: ESA/NASA/Immer et al. Click to enlarge
Scientists have found that a star that exploded in 1979 is as bright today in X-ray light as it was when it was discovered years ago, a surprise finding because such objects usually fade significantly after only a few months.
Using ESA?s XMM-Newton space observatory, a team of astronomers has discovered that this supernova, called SN 1979C, shows no sign of fading. The scientists can document a unique history of the star, both before and after the explosion, by studying rings of light left over from the blast, similar to counting rings in a tree trunk.
?This 25-year-old candle in the night has allowed us to study aspects of a star explosion never before seen in such detail,? said Dr Stefan Immler, leader of the team, from NASA?s Goddard Space Flight Center, USA. ?All the important information that usually fades away in a couple of months is still there.?
Among the many unique finds is the history of the star?s stellar wind dating back 16 000 years before the explosion. Such a history is not even known about our Sun. Also, the scientists could measure the density of the material around the star, another first. The lingering mystery, though, is how this star could fade away in visible light yet remain so radiant in X-rays.
Without fuel and thus energy to support their gravity, such stars first implode. The core reaches a critical density, and much of the collapsing matter gets bounced back out violently into space by powerful shockwaves.
Supernovae can outshine an entire galaxy and are often easily seen in neighbouring galaxies with simple amateur telescopes. Supernovae are typically half as bright after about ten days and fade steadily after that, regardless of the wavelength.
SN 1979C has in fact faded in optical light by a factor of 250 becoming barely visible with a good amateur telescope. In X-rays, however, this supernova is still the brightest object in its host galaxy, M100, in the constellation ?Coma Berenices?.
In identifying the history of the star that created SN 1979C, the team found that this star, about 18 times more massive than our Sun, produced fierce stellar winds. That material was flung into space for millions of years, creating concentric rings around the star.
The X-rays – produced after the explosion when the supernova shock caught up with the stellar wind and heated it to a temperature of several million degrees – illuminated 16 000 years? worth of stellar activity.
?We can use the X-ray light from SN 1979C as a ?time machine? to study the life of a dead star long before it exploded,? said Immler.
The detailed analysis was only possible because SN 1979C has not yet faded away. Scientists have 25 years? worth of data in a variety of wavelengths, from radio waves through to optical/ultraviolet and X-rays. They speculate that the abundance of stellar wind has provided ample material to keep SN 1979C glowing so brightly.
The team also captured a rare glimpse of the ultraviolet radiation from the supernova using XMM-Newton. The ultraviolet image independently confirms what the X-ray analysis found: that the circumstellar material ? covering a region 25 times larger than our Solar System – has a relatively high density of 10 000 atoms per cubic centimetre, or about 1000 times denser than the wind from our Sun. The ultraviolet image also shows galaxy M100 in detail never seen before.
?XMM-Newton is known among scientists as a superior X-ray observatory, but the study of SN 1979 demonstrates the importance of the satellite’s simultaneously observing ultraviolet and optical telescope,? said Dr Norbert Schartel, XMM-Newton Project Scientist at ESA’s European Space Astronomy Centre (ESAC) in Spain.
Original Source: ESA Portal
Artist’s conception of a possible collision around BD +20 307. Image credit: Gemini Observatory/Jon Lomberg. Click to enlarge
A relatively young star located about 300 light-years away is greatly improving our understanding of the formation of Earth-like planets.
The star, going by the unassuming name of BD +20 307, is shrouded by the dustiest environment ever seen so close to a Sun-like star well after its formation. The warm dust is believed to be from recent collisions of rocky bodies at distances from the star comparable to that of the Earth from the Sun. The results were based on observations done at the Gemini and W.M. Keck Observatories, and were published in the July 21 issue of the British science journal Nature.
This finding supports the idea that comparable collisions of rocky bodies occurred early in our solar system’s formation about 4.5 billion years ago. Additionally, this work could lead to more discoveries of this sort which would indicate that the rocky planets and moons of our inner solar system are not as rare as some astronomers suspect.
?We were lucky. This set of observations is like finding the proverbial needle in the haystack,? said Inseok Song, the Gemini Observatory astronomer who led the U.S.-based research team. ?The dust we detected is exactly what we would expect from collisions of rocky asteroids or even planet-sized objects, and to find this dust so close to a star like our Sun bumps the significance way up. However, I can’t help but think that astronomers will now find more average stars where collisions like these have occurred.”
For years, astronomers have patiently studied hundreds of thousands of stars in the hopes of finding one with an infrared dust signature (the characteristics of the starlight absorbed, heated up and reemitted by the dust) as strong as this one at Earth-to-Sun distances from the star. “The amount of warm dust near BD+20 307 is so unprecedented I wouldn’t be surprised if it was the result of a massive collision between planet-size objects, for example, a collision like the one which many scientists believe formed Earth’s moon,” said Benjamin Zuckerman, UCLA professor of physics and astronomy, member of NASA’s Astrobiology Institute, and a co-author on the paper. The research team also included Eric Becklin of UCLA and Alycia Weinberger formerly at UCLA and now at the Carnegie Institution.
BD +20 307 is slightly more massive than our Sun and lies in the constellation Aries. The large dust disk that surrounds the star has been known since astronomers detected an excess of infrared radiation with the Infrared Astronomical Satellite (IRAS) in 1983. The Gemini and Keck observations provide a strong correlation between the observed emissions and dust particles of the size and temperatures expected by the collision of two or more rocky bodies close to a star.
Because the star is estimated to be about 300 million years old, any large planets that might orbit BD +20 307 must have already formed. However, the dynamics of rocky remnants from the planetary formantion process might be dictated by the planets in the system, as Jupiter did in our early solar system. The collisions responsible for the observed dust must have been between bodies at least as large as the largest asteroids present today in our solar system (about 300 kilometers across). “Whatever massive collision ocurred, it managed to totally pulverize a lot of rock,” said team member Alycia Weinberger.
Given the properties of this dust, the team estimates that the collisions could not have occurred more than about 1,000 years ago. A longer history would give the fine dust (about the size of cigarette smoke particles) enough time to be dragged into the central star.
The dusty environment around BD +20 307 is thought to be quite similar, but much more tenuous than what remains from the formation of our solar system. “What is so amazing is that the amount of dust around this star is approximately one million time greater than the dust around the Sun,” said UCLA team member Eric Becklin. In our solar system the remaining dust scatters sunlight to create an extremely faint glow called the zodiacal light (see image above). It can be seen under ideal conditions with the naked eye for a few hours after evening or before morning twilight.
The team?s observations were obtained using Michelle, a mid-infrared spectrograph/imager built by the UK Astronomy Technology Centre, on the Frederick C. Gillette Gemini North Telescope, and the Long Wavelength Spectrograph (LWS) at the W.M. Keck Observatory on Keck I.
Original Source: Gemini Observatory News Release
The impact crater, known as “Endurance”. Image credit: NASA/JPL/Cornell. Click to enlarge
Mars is the planet that refuses to say “die.” In 1996, after centuries of speculation about canals, icecaps and vegetation, NASA’s David McKay reported seeing traces of ancient bacteria in a meteorite from Mars. Scientists have debated this finding ever since, and many now believe that the intriguing traces are probably not of biological origin.
Within the last few years, however, two simple chemicals intimately associated with life on Earth have been discovered on Mars. Large amounts of frozen water were discovered at the surface, and traces of methane appeared in the atmosphere.
Water is necessary for life as we know it, and most of the methane on Earth is made by microbes. Although the twin discoveries redoubled interest in the possibility of life on Mars, nobody is suggesting that anything is living on the planet’s surface, where temperatures average minus 63 degrees Celsius and harmful ultraviolet radiation pierces the thin atmosphere.
On Mars, as on Earth, temperatures rise as you go deeper down into the planet. Somewhere between a dozen and a thousand meters below the surface, conditions may be warm enough for liquid water, which is necessary for even non-biological methane production on Earth. But could a living ecosystem be hidden deep under the martian surface? On Earth, subterranean microbes survive without sunlight, free oxygen, or contact with the surface.
The question becomes more intriguing when you consider that most deep-Earth microbes are primitive, single-celled organisms that power their metabolism with chemical energy from their environment. These microbes are called “methanogens” because they make methane as a waste product.
Three NASA missions have discovered signs of water on Mars. In 2000, Mars Global Surveyor images of gullies suggested to many that water recently flowed on the martian surface. In May 2002, the gamma ray spectrometer on Mars Odyssey found a huge deposit of hydrogen in shallow polar soil — a sure sign of water ice. Then, in December 2004, researchers using the Mars Exploration Rover Opportunity announced that they had discovered rocks that had been formed by the periodic flooding of water on the surface. Such findings support the idea that Mars was warm and wet billions of years ago.
While water is a necessary condition for life, methane may be actual evidence of life. In the past two years, three separate research groups have seen spectral signs of methane on Mars:
* In 2003, Michael Mumma of Goddard Space Flight Center (GSFC) detected methane using spectrometers at two large earthbound telescopes. He has since told several scientific meetings that large variations exist in methane concentration on Mars. In a presentation at a NASA Astrobiology Institute meeting in April 2005, Mumma said the detection of martian methane varied with geography: there was an average of 200 parts per billion (ppb) detected at the equator, and 20 to 60 ppb near the poles.
* Vladimir Krasnopolsky, a research professor at Catholic University of America in Washington D.C., also detected methane on Mars. Like Mumma, Krasnopolsky used spectrometers on Earth-based telescopes. He calculated a global average of 11 ppb, with a range of 7 to 15 ppb. The data, as Krasnopolsky reported to a European Geosciences Union meeting in April 2004, came from 1999 observations of the whole planet’s disk.
“We didn’t try to make localized measurements because we did not expect any variation from place to place,” Krasnopolsky told Astrobiology Magazine.
* In December 2004, the European Space Agency’s Mars Express delivered the first methane data from a Mars orbiter. In the journal Science, Vittorio Formisano of the Institute of the Physics of Interplanetary Space in Rome and colleagues reported measurements made with the satellite’s Planetary Fourier Spectrometer. Their measurements were similar to Krasnopolsky’s numbers: A concentration of 10 ppb, plus or minus 5 ppb.
Although the Krasnopolsky and Formisano studies independently pointed to similar concentrations of methane, some planetary scientists express skepticism because the amount detected is very faint.
“The detections have been right at the detection limit of the instruments,” says William Boynton of the University of Arizona, principal investigator on the gamma ray spectrometer on Mars Odyssey. “I’m not completely convinced it’s a solid detection yet. It’s likely, but I wouldn’t put it in the bank.”
The matter of methane
The methane on Mars was detected with spectrometry — the analysis of light waves. Because each atom and molecule emits and absorbs characteristic wavelengths of light, spectrometers can determine the composition of distant objects by measuring these wavelengths. To study gases in the atmosphere of Mars, spectroscopists use instruments that can analyze the infrared light that is emitted when solar radiation warms the planet’s surface. As that infrared radiation speeds toward Earth, gases in the martian atmosphere can block, or absorb, certain frequencies. When the infrared light is concentrated in a telescope and separated by a spectroscope’s diffraction grating, the missing wavelengths show which particular atoms or molecules have absorbed light en route to Earth. Thus, a methane “line” on a spectroscope curve is a reflection of the light that methane has blocked.
There are complications, however. When faint light from a planet is collected in a terrestrial telescope, atoms and molecules in space or in Earth’s atmosphere will block some wavelengths. Spectroscopists must compensate for these non-martian signals. And because Mars is moving relative to Earth, the absorption lines appear in the “wrong” places until additional compensations are made.
Any methane on Mars today is not a legacy of ancient conditions, because solar radiation would destroy the molecules in the atmosphere within 600 years. Instead, the methane either was brought to Mars on comets or meteorites, or it was made on Mars. If we have glimpsed some made-on-Mars methane, was it made by geological or chemical processes — or by biology?
Original Source: NASA Astrobiology
Space Shuttle is largely hidden by the Rotating Service Structure. Image credit: NASA/KSC. Click to enlarge
NASA is targeting Tuesday, July 26 as the earliest possible date to launch the Space Shuttle Discovery on the Return to Flight mission (STS-114). The determination was made during Monday’s meeting of the Mission Management Team (MMT) at Kennedy.
The MMT reviewed efforts by teams of engineers. The engineers are working through a troubleshooting plan to address an issue with a liquid hydrogen low-level fuel sensor circuit. The sensor circuit failed a routine prelaunch check during the countdown July 13, delaying Discovery’s first launch attempt.
NASA is still working to launch Discovery by the end of the July window that extends to the 31st. A dozen teams, with hundreds of engineers across the country, are expected to complete their battery of tests by Wednesday. While they have not isolated a cause of the sensor circuit failure, they have eliminated a number of possibilities. If the remaining tests are inconclusive, NASA could reload the External Tank with super-cooled propellants to see how the sensor circuit behaves. The tanking could be done as a test or as part of an actual launch countdown.
Commander Eileen Collins and her six Discovery crewmates come out of quarantine today for one day off. They resume quarantine and training later this week.
For the latest information about STS-114 on the Web, visit: http://www.nasa.gov/returntoflight
Original Source: NASA News Release
An artist’s conception of Pluto and its moon Charon. Image credit: NASA. Click to enlarge
On a clear summer night, the stars aligned for MIT researchers watching and waiting for one small light in the heavens to be extinguished, just briefly.
Thanks to a feat of both astronomical and terrestrial alignment, a group of scientists from MIT and Williams College succeeded in observing distant Pluto’s tiny moon, Charon, hide a star. Such an event had been seen only once before, by a single telescope 25 years ago, and then not nearly as well.
The MIT-Williams consortium spotted it with four telescopes in Chile on the night of July 10-11.
The team expects to use data from this observation to assess whether Charon has an atmosphere, to measure its radius and to determine how round it is.
The data and results from the observation will be presented at the 2005 meeting of the American Astronomical Society’s Division of Planetary Sciences meeting to be held in Cambridge, England, in September.
MIT team leader James L. Elliot headed the group at the Clay Telescope at Las Campanas Observatory in Chile.
“We have been waiting many years for this opportunity. Watching Charon approach the star and then snuff it out was spectacular,” said Elliot, a professor in the Department of Earth, Atmospheric and Planetary Science and the Department of Physics at MIT in Cambridge, Mass.
Jay M. Pasachoff, team leader from Williams College in Williamstown, Mass., and a professor in that school’s Department of Astronomy, said, “It’s amazing that people in our group could get in the right place at the right time to line up a tiny body 4 billion miles away. It’s quite a reward for so many people who worked so hard to arrange and integrate the equipment and to get the observations.”
With the Clay Telescope’s 6.5-meter mirror (more than 21 feet across, the size of a large room) the researchers were able to observe changes throughout the event, which lasted less than a minute. While their electronic cameras sensitively recorded data, the light of the faint star was seen to dim and then, some seconds later, brighten. This kind of disappearance of a celestial body behind a closer, apparently larger one is known as an occultation.
Studying how the light dimmed and brightened will let the MIT-Williams consortium look for signs that Charon has an atmosphere. It has very little mass and thus little gravity to hold in an atmosphere, but it is so cold (being some 40 times farther from the sun than the Earth) that some gases could be held in place by the small amount of Charon’s gravity.
Other telescopes around Chile used by the MIT-Williams consortium included the 8-meter (more than 26 feet across) Gemini South on Cerro Pachon, the 2.5-meter (more than 8 feet across) DuPont Telescope at Las Campanas Observatory and the 0.8-meter (almost 3 feet across) telescope at the Cerro Armazones Observatory of Chile’s Catholic University of the North near Cerro Paranal.
The team had searched for a distribution of telescopes along a north-south line in Chile since the predictions of the starlight shadow of Charon were uncertain by several hundred kilometers. Since the star that was hidden is so far away, it casts a shadow of Charon that is the same size as Charon itself, about 1,200 kilometers in diameter. To see the event, the distant star, Charon and the telescopes in Chile had to be perfectly aligned. All of these telescopes had clear views of the event.
Other MIT affiliates involved in the observation were MIT graduate students Elisabeth Adams, Michael Person and Susan Kern and postdoctoral associate Amanda Gulbis.
The images from three telescopes in Chile, including the Clay Telescope, and one in Brazil, were taken with new electronic cameras and computer control obtained by MIT and Williams with an equipment grant from NASA. The expeditions were sponsored by NASA’s Planetary Astronomy Program.
A video showing the star dimming as Charon passes in front of it and then brightening again is posted on the Web at http://occult.mit.edu/research/occultations/Charon/C313.2/C313OccMovie.html.
Teams from the Observatory of Paris at Meudon and from the Southwest Research Institute in Boulder, Colo., also observed the occultation.
Original Source: MIT News Release
