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By Daniel Fischer Every page present in Europe & the U.S.!
| Ahead | Awards 
The latest issue!
| A German companion - only available here! Current mission news: MGS (latest pictures!) + Cassini + Stardust |
ESA's Rosetta spacecraft flew past Earth on March 4, coming within 1955 km of the surface west of Mexico - it tried out a few instruments at the Earth and the Moon and was itself captured by amateur astronomers: ESA Releases of March 14, 9, 7 and 5 and Feb. 23, an MPS PM, an ESA Special Page (with a collection of images from the ground; also another site and what they 'saw' at ESTEC), more pictures by L�then, Wagner, Pikhard, Brinkmann and G�hrken and coverage of Mar. 9: Welt. Mar. 8: BBC, NZ. Mar. 7: S&T. Mar. 6: ST. Mar. 5: SN. Mar. 3: BBC. Feb. 28: Welt. Feb. 25: NZ.
| Posted in part from an internet café in Halle (Saale) |
Formation of "Meteor Crater" modelled: impactor was slowed down in atmosphereScientists have finally discovered why there isn't much impact-melted rock at Meteor Crater in northern Arizona: The iron meteorite that blasted out Meteor Crater almost 50,000 years ago was traveling much slower than has been assumed. Previous research had supposed that the meteorite hit the surface at a velocity between about 15 and 20 km/sec, but new sophisticated mathematical models have now been used in analyzing how the meteorite would have broken up and decelerated as it plummeted down through the atmosphere. About half of the original 300,000 ton, 40-m-diameter space rock would have fractured into pieces before it hit the ground, and the other half would have remained intact and hit at about 12 km/sec - too slow to have melted much of the white Coconino formation in northern Arizona, solving a mystery that's stumped researchers for years.Scientists had tried to explain why there's not more melted rock at the crater by theorizing that water in the target rocks vaporized on impact, dispersing the melted rock into tiny droplets in the process. Or they've theorized that carbonates in the target rock exploded, vaporizing into carbon dioxide. But if the consequences of atmospheric entry are properly taken into account, there is no melt discrepancy at all. When a meteorite hits the atmosphere, the pressure is like hitting a wall. Even strong iron meteorites, not just weaker stony meteorites, are affected. Even though iron is very strong, the meteorite had probably been cracked from collisions in space. The weakened pieces began to come apart and shower down from about 14 km high. And as they came apart, atmospheric drag slowed them down, increasing the forces that crushed them so that they crumbled and slowed more. |
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Upper mass limit for stars establishedAstronomers have taken an important step toward establishing an upper limit to the masses of stars. Using the HST, they made the first direct measurement within our Milky Way Galaxy, and concluded stars cannot get any larger than about 150 times the mass of our sun. The astronomers used Hubble to probe the Arches cluster, the densest in our galaxy: They used the Near Infrared Camera and Multi-Object Spectrometer to study hundreds of stars ranging from six to 130 solar masses. Although they did not find any stars larger than 130 solar masses, they conservatively set the upper limit at 150 solar masses. The Arches cluster is a youngster about 2 to 2.5 million years old. It resides 25,000 light-years away from Earth in our galaxy's hub, a hotbed of massive star formation. In this region huge clouds of gas collide to form behemoth stars.Astronomers have been uncertain about how large a star can get before it cannot hold itself together and blows apart: They don't know enough about the details of the star-formation process to estimate a star's upper mass. Consequently, theories have predicted stars can be anywhere between 100 to 1,000 times more massive than the sun. The NICMOS finding is consistent with statistical studies of smaller-mass star clusters in our galaxy and with observations of a massive star cluster known as R136 in our galactic neighbor, the Large Magellanic Cloud. Hubble's infrared camera was well suited to analyze the Arches cluster, because it penetrates the dusty core of our galaxy. And it produces sharp images, allowing the telescope to see individual stars in a tightly packed cluster. |
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Proper motion of a nearby galaxy measured: 30 µas/year!Astronomers had struggled for 80+ years to measure the motion of galaxies relative to Earth not only along the line of sight (easy with spectroscopy) but also in the plane of the sky - and now they have succeeded, thanks to the Very Long Baseline Array and water masers in the galaxy Messier 33 at a distance of 2.4 million light years! It is creeping along the sky at 30 millionths of an arc second per year (± 5 µas/a) or one Moon diameter every 60 Myr. An international scientific team had analyzed VLBA observations made over two and a half years to detect minuscule shifts in the sky position of the spiral galaxy M33. Combined with previous measurements of the galaxy's motion toward Earth, the new data allowed the astronomers to calculate M33's movement in three dimensions for the first time. Not only did they have to detect an impressively tiny amount of motion across the sky, but they also had to separate the actual motion of M33 from the apparent motion caused by our Solar System's motion around the center of the Milky Way.In addition to measuring the motion of M33 as a whole, the astronomers also were able to make a direct measurement of the spiral galaxy's rotation. Both measurements were made by observing the changes in position of giant clouds of molecules inside the galaxy. The water vapor in these clouds acts as a natural maser, strengthening, or amplifying, radio emission the same way that lasers amplify light emission. The natural masers acted as bright radio beacons whose movement could be tracked by the ultra-sharp radio "vision" of the VLBA. The radio astronomers now plan to continue measuring M33's motion and also to make similar measurements of M31's motion. This will allow them to answer important questions about the composition, history and fates of the two galaxies as well as of the Milky Way. The goal is to determine the orbits of M31 and M33: That will help us learn about their history, specifically, how close have they come in the past. |
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A galaxy consisting almost entirely of Dark Matter?Astronomers have discovered an object that appears to be an invisible galaxy made almost entirely of dark matter - the first ever detected. A dark galaxy is an area in the universe containing a large amount of mass that rotates like a galaxy, but contains no stars. Without any stars to give light, it could only be found using radio telescopes. It was first seen with the University of Manchester's Lovell Telescope in the UK, and the sighting was confirmed with the Arecibo telescope in Puerto Rico. The unknown material that is thought to hold these galaxies together is known as `dark matter', but scientists still know very little about what that is. The international team from the UK, France, Italy and Australia has been searching for dark galaxies using not visible light, but radio waves. They have been studying the distribution of hydrogen atoms throughout the Universe.In the Virgo cluster of galaxies they hit upon a mass of hydrogen atoms a hundred million times the mass of the Sun. The Virgo cluster is a large group of galaxies about 50 million light years away. From the speed it is spinning this object, called VIRGOHI21, was a thousand times more massive than could be accounted for by the observed hydrogen atoms alone. If it were an ordinary galaxy, then it should be quite bright and would be visible with a good amateur telescope. Similar objects that have previously been discovered have since turned out to contain stars when studied with high-powered optical telescopes. Others have been found to be the remnants of two galaxies colliding. However, when the scientists studied the area in question using the Isaac Newton Telescope in La Palma, they found no visible trace of any stars, and no nearby galaxies that would suggest a collision. |
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Controversial detection of formaldehyde on Mars makes some believe in bacteriaThe story had been around for a few days - e.g. in the New Scientist of Feb. 19, p. 6.7 - but it was quite another thing to hear a leading researcher with the ESA Mars orbiter Mars Express say it at an official news conference: "Life is probably the only source than can produce so much methane." Not that his PFS instrument has seen vast amounts of this gas in the Martian atmosphere: The reading is still an average of 11 parts per billion by volume as measured earlier, varying between 0 and 35 ppb. But the PI of the PFS, Vittorio Formisano, is now also reporting formaldehyde, averaging 130 ppb (and varying between 0 and 250 ppb) - and laboratory experiments in Germany just a few days ago had convinced him that this gas is actually the product of catalyzed oxidation of methane. Under that assumption the annual methane outgassing of Mars jumps from the 150 metric tons calculated from the measured methane alone to a whopping 2.5 million. And for that a non-biological source is all but ruled out in Formisano's mind.None of the other Mars Express representatives on the panel on Feb. 25 contradicted Formisano's interpretation right away, but when polled about their confidence in current life on Mars, only 2 raised their hands - the same 25% ratio, incidentally, that had voiced that opinion in a similar poll of all particpants of the first scientific conference on Mars Express of which the press conference was part. Doubts have already been raised about the reliability of the formaldehyde detection by the PFS, though, even last year, and it will be a very long way until the radical conclusions will be accepted widely, if ever. Meanwhile other - somewhat less controversial - Mars Express discoveries made headlines, too, especially a probable frozen ocean imaged by the HRSC: While it has not been proven yet that the features seen in one equatorial region are actually ice floats stuck in a frozen flat icy matrix, this is the most tempting interpretation (which is under heavy fire in the U.S., though). Another HRSC surprise were apparently very young volcanoes near the north pole. |
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Dead pigs and the meaning of StonehengeThe discovery of pig teeth during the Stonehenge Riverside Project may force a radical rethinking of this ancient site: Perhaps its original and main use was not to observe - and celebrate - the summer solstice (as Stonehenge afficionados still do today) but instead to mark the winter solstice. And one was not to go inside and look out towards the heel stone and the Northeast but stand at that stone and look into and through the stone structure towards the Southwest, where the Sun would set in midwinter. The evidence is scant but intriguing: lots of teeth of pigs about 9 months old found all around the structure. Since in the harsh Northern climate pigs should be born in spring, this means that they were killed - and eaten in a big barbeque - around winter solstice. This is only one of many discoveries of ongoing field research around Stonehenge that will put the structure into a much larger context. (Talk by Mike Parker Pearson at the Nebra conference - see below - on Feb. 18, 2005) |
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Finally some craters on Titan ... and other Cassini storiesNews came thick and fast in the past four weeks, from the ongoing analysis of the Huygens data, a mid-February flyby by Cassini at Titan - with the radar on again - and Feb. & March flybys of Enceladus (where intriguing deformation features were found in the surface that resemble Ganymede's and Europa's), while some 70 pages of scientific papers appeared in the technical literature. A giant impact crater was spotted on Titan by Cassini's radar instrument during the Feb. 15 flyby: Cassini came within 1577 km of its surface during the third close Titan flyby of the mission and only the second time the radar instrument has examined the satellite. Scientists see some things that look familiar, along with scenes that are completely new. "It's reassuring to look at two parts of Titan and see similar things," says one: "At the same time, there are new and strange things."This flyby is the first time that Cassini's radar and the imaging camera overlapped: This overlap in coverage should be able to provide more information about the surface features than either technique alone. The 440-km-wide crater identified by the radar instrument was seen before with Cassini's imaging cameras, but not in this detail. Another radar image shows features nicknamed "cat scratches": These parallel linear features are intriguing, and may be formed by winds, like sand dunes, or by other geological processes. In other Titan news, both Cassini's Ion Neutral Mass Spectrometer and Huygen's Gas Chromatograph Mass Spectrometer have sampled Titan's atmosphere (last October and this January, resp.), covering the uppermost atmosphere down to the surface. Neither detected the non-radiogenic form of argon: That suggests that the planetesimals that formed Titan contained nitrogen mostly in the form of ammonia. |
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Nebra Sky Disk amazes and confuses more than ever after first big conferenceThe situation was beyond bizarre and probably a first in the history of science: a unique archaeological artefact, unearthed in an illegal dig, is eventually captured by authorities and hailed as one of the most important ever (as amply described in Updates # 236, 243 and 282) - and while the first major conference devoted to the meaning of the Nebra Sky Disk is taking place exactly three years later, in a lawsuit in the same city against the artefact's dealers its authenticity is called into question by a defense witness. This was the scene in Halle, Saxony-Anhalt, Germany, from Feb. 16 to 21, 2005: More than 400 archaeologists, astronomers and Sky Disk afficionados had assembled there at the university in order to put the surprise discovery into a broad cultural context - and on the final day, when many went to a field trip to the site where it was discovered in 1999, in the court house the experts for the prosecution (read: the archaeologists studying the Disk for three years) and for the defense (read: one external bronze age expert who had only seen photographs of the Disk) clashed ...There isn't a verdict yet, but according to numerous reports, things went very well for the disk faction: Not only could they present hard physical evidence for the disk being really 3600+ years old and having spent many centuries in the ground, they could even point to strong traces of copper at the discovery site, indicating that there really was a major ancient deposit of metal artefacts. One of the few witnesses for the defense even switched sides that day in court and is now regarding the Nebra Sky Disk as a genuine early bronze age phenomenon, too! But - and that's perhaps the quintessence of the conference - it is a most unique piece of art in its era, almost isolated from the rest of the world of 1600 BCE. Even the extreme hypothesis cannot be dismissed out of hand that it is just an astonishing aberration, a work by some prehistoric 'Leonardo' centuries ahead of his day. Many previously claimed direct links to established iconographic concepts of the same era are now in doubt, and we have actually fewer clues than before to what the artist may have been thinking:
There is also increasing uncertainty about where the copper for the disk's bronze and the gold for the imagery came from. Especially the origin of the latter is controversial, and while Transylvania is still the leading candidate, there are many more possible sources, under certain hydrological conditions even close to the discovery site. The copper most likely came from Austria, but again the case is far from clear-cut. Much more definitive statements can be made about the steps in which the Disk was made and re-made several times, though the sequence of events is not established as firmly, and how long intervals were between the modifications is not known at all. The Disk could well have been in use for centuries before its disposal as costly artefacts are often handed down several generations (»heirloom effect«). At least two artists were involved and both worked on such an artefact for the first time: One can follow their learning-by-doing directly. e.g. from one star to the next. The stars, including the 7 in the rosette arrangement, together with the golden disk - now widely seen as the full Moon - and the crescent clearly came first and were incrusted by the same artist #1. Then artist #2 moved several stars (damaging one in the process so it had to be replaced) in order to add the two horizon arcs - and before that he tried out his incrustation tool on the back of the disk. Differences in method and slight differences in the gold chemistry prove that this was a distinctly different time step. At at yet another time, probably last (but possibly between the other two) the third golden arc was added: Its gold is much purer than all in all other elements, giving it even a more 'golden' appearance. Whoever was involved in the numerous metallurgical operations: Those who could handle metals were special in the beginning metal ages, forming something of an elite in society, with political and presumably also spiritual power. Therefore the meaning of the motives on the disk could tell us a lot - if we read them correctly. Regarding the meaning of the gold elements, the lack of experienced archaeo- and ethnoastronomers in the audience, apart from Germany's W. Schlosser, prevented much progress: Not one of the great names in the field was present! This is not to say that Schlosser's »standard model«, developed soon after the Disk's recovery in 2002, doesn't still stand strong, being both selfconsistent and simple. See the rosette as the Pleiades, with the Moon nearby as a crescent in the west in spring and in full in autum, framing the agricultural year, and you have two of the most important dates in the year symbolized in one striking image. But the extremely sober, almost sterile, representation of the - apparent - celestial phenomena and the limited number of elements might also give way to somewhat or radically different interpretations, perhaps even non-astronomical ones. If only someone with serious knowledge of astronomy and bronze age thinking would propose them! |
| None of the ideas presented by the 'alternative' Disk-ology faction at the conference came even close: Inviting ethnographers or even (art) psychologists might have helped move the debate on, though the breadth of approaches presented at the conference - and the severe 'clash of civilizations' between the dominant archaeologists and e.g. the astronomers - was already quite amazing. And so we stand, some 3600+ years later, marvelling at a message from the past, preserved in an exceptional piece of art without much context. Its sheer simplicity of design is both a source of beauty - the Disk has largely replaced the ice man Ötzi as the face of archaeology here - and a puzzle that will perhaps never be solved to everyone's standards. The proceedings of the conference will be published - still this year, it's hoped, awfully fast in archaeology - in two volumes that will also constitute the formal full description of the discovery. Then the rest of the world will have a chance to ponder its meaning and importance for decades to come ... |
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Progress for IceCube neutrino telescope at the South PoleWorking under harsh Antarctic conditions, an international team of scientists, engineers and technicians has set in place the first critical elements of a massive neutrino telescope at the South Pole. The successful deployment - in a 2.5-km-deep hole drilled into the Antarctic ice - of a string of 60 optical detectors designed to sample phantom-like high-energy particles from deep space represents a key first step in the construction of the $272m telescope known as IceCube. Building the telescope requires drilling at least 70 such holes in the Antarctic ice using a novel hot-water drill, and then lowering long strings of volleyball-sized optical detectors - 4200 in all - into the holes, where they will be frozen in place.The first string, with 60 detectors, was successfully lowered into the ice in late January, and communication with the detectors, each of which is like a small computer, has been successfully established. When completed, the telescope will utilize a cubic kilometer of Antarctic ice as a detector, and will be capable of capturing information-laden, high-energy particles from some of the most distant and violent events in the universe. It promises a new window to the heavens, and it may be astronomy's best bet to resolve the century-old quest to identify the sources of cosmic rays. |
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ISS etc. UpdateMichael D. Griffin, a physicist and aerospace engineer "with a passion for exploration" has been nominated as the next NASA boss, while the Return to Flight for the shuttle has been set for May 15. WhiteHouse announcement, Plan. Soc. and House Science Comm. reaction, NASA (other, earlier, still earlier, even earlier), ESA (earlier) and EU Press Releases and coverage of Mar. 15: Nat. Mar. 14: SpRev, HC, AD, BBC, S&T, NZ. Mar. 13: FT (other and another story). Mar. 12: FT (sidebar, OpEd), HC (other and another story). |
Mar. 11:
HC,
NwS,
AFP,
ST
(earlier).
Mar. 9:
UPI,
ST.
Mar. 8:
FT,
ARRL,
BBC.
Mar. 7:
FT.
Mar. 4:
WN,
SN.
Mar. 3:
FT.
Mar. 2:
SN,
ST,
NZ.
Mar. 1:
SR,
FT.
Feb. 28:
SpRev,
SN,
BBC,
AFP,
ST.
Feb. 27:
FT.
Feb. 25:
FT,
HC.
Feb. 24:
AP,
HC.
Feb. 21:
KR.
Feb. 20:
USAT.
Feb. 19:
HC,
BBC,
FT,
ST,
NZ.
Feb. 18:
SN,
HC,
FT
(other story),
CNN,
NwS.
Feb. 17:
AP,
HC.
Feb. 16:
FT
(earlier),
ST.
The HST crisis - could it be illegal not to service the satellite one last time? The Final Report from the Nat'l Acad. of Sci., another AAS Statement, Hubbles current Status and coverage of Mar. 11: FT. Mar. 10: The Daily, FT, SC. Mar. 9: HC. Mar. 7: Sp.N., WildCat, SpRev. Mar. 5: NwS. Mar. 2: Discover. Feb. 24: New Sci., Sentinel. Feb. 18: JHU Newsletter. Feb. 15: USAT. |
Hans Bethe dead at 98He won the Nobel Prize (the first one ever for astrophysical work) in 1967 for understanding how the Sun shines - and was the lead theoretician during the construction of the A bomb: Cornell Press Release, S&T, BBC, Welt, NetZeitung.Did giant space clouds ice Earth?Eons ago, giant clouds in space may have led to global extinctions: NASA Release, SC. Planet formation model improved again: Indiana Univ. PR, BdW. Sticky ice as the glue: PNL PR [SD], BdW. And where the chondrules come from: Carnegie PR.Solar flares magnified atmospheric ozone loss over the Northern hemisphere - the effect was active even months after the large solar activity of Oct./Nov. 2003: U. Colorado PR, Dsc., Nat., NwS. Atmospheric studies with the German CRISTA payload: Univ. Wuppertal PM. How lightning clears a safe zone in Earth's Radiation Belt has now been modelled: NASA Release, AFP, FT. Magnetospheric deformation: ESA Release. 3D magnetic reconnection studied by the Clusters: ESA Release. Gamma-ray bursts from the upper atmosphere of Earth are much more frequentthan first calculated from CGRO data - extrapolating from RHESSI measurements there are at least 50 'TGF's per day: UCSC [SR, SN] and NASA Releases, NwS (other story), TP.Mysterious flash above Earth's atmosphere seen by Israeli camera during fatal Columbia flight: AGU Press Release [SN], NwS, FT. Visible aurorae can be triggered by intense radio transmissions - it's not clear, though, whether faint natural polar lights have already to be present for this effect: Nat., NwS, BdW. Magnetic fields detected in central stars of Planetary NebulaeBut it is still not clear whether they are the main forming agent in the strange shapes of many PNe: A&A and Univ. HD Press Releases, ScAm, NZ, BdW. Meet the 'Water Fountain Nebula': Keck Release.How interstellar dust absorbs and scatters ultraviolet starlight, has been studied by FUSE in the Orion nebula: JHU Press Release. 2175 Angstrom bump in interstellar spectra explained: Livermore PR, Dsc. How stars form in the Trifid Nebula: S&T. A young Sun-like star and what we can learn from it on events in the early solar system: Villanova PR. Why Red Dwarfs have fewer disks: UCLA PR. Clumps in Beta Pic's disk and what could have happened here: U. FLA PR. A young star with a 40 Jupiter mass companion, DH Tauri: NAOJ Press Release. Sgr A* much more active just 350 years agoThis could be determined thanks to a kind of gamma echo at a nearby molecular cloud: ESA Release [SN, SR], BdW.SN 2004dj was not spherical - non-spherical supernovae are of interest in the context of GRB models: Caltech PR (PDF). Quark stars behind classical GRBs? Nat. SN role in solar system formation strengthened: ASU PR, BBC, BdW. 100th Gemini paper reveals White Dwarf progenitors are prolific mass expellers - stars with initial masses between 2.8 and 3.4 that of the Sun will lose 70-75% of their masses through stellar evolution: Gemini Release. Helium-richest stars found in Omega Centauri: ESO Release. |
Jupiter reflects solar X-raysand the faint echo could even be used for flare monitoring on the far side of the Sun: ESA, PPARC and related Chandra Press Releases, NwS.Cluster galaxy's location proves "just right" for star formation in the case of UGC 6697: Chandra Release. How matter disappears into a Black Holeand sends out a final burst of radiation has been modelled in new detail: JHU Press Release. How LISA will observe BH mergers: PSU PR. Black holes bend light the 'wrong' way - refraction effect may be distorting astronomers' results: Nat.Smallest B.H. candidate in a galactic center found, with less than 1 million solar masses: Ohio State Univ. PR, BdW, NZ. Mass limits for B.H. growth: Chandra Release. Theory predicts self-limiting growth: MPG PM, BdW. Relativistically affected iron X-ray line found in background radiation which is the sum of the emmission of countless distant galaxies and their nuclei: MPG Release (German version). Spitzer's optics not perfectThe slight deficiencies were known before launch and deemed not severe: S&T.Optical interferometer resolves Regulus and finds a weird, oblate shape: GSU PR. MINOS experiment planned with neutrinos being sent through the Earth in a controlled fashion: NwS. Research ballon made record-breaking flight over Antarctica - CREAM stayed aloft for nearly 42 days: GSFC and NASA Releases. Voyagers run out of money!Nasa's twin Voyager probes may have to close down in October to save money, the US space agency has said: BBC, FT, SD.Cluster mission extended - the ESA Science Programme Committee has approved the extension, pushing back the end date from December 2005 to December 2009: ESA Release, Status. SMART-1 in final lunar orbit - as planned - on Feb. 27: ESA Release. How it got there: AB. What it'll learn at the Moon: ESA Release. Genesis science retrieval seems successful: S&T, BBC, Deseret News, NwS. H2-A launches flawlesslyon Feb. 26 and brings Japan back into the launcher game after a lengthy hiatus: JAXA Release, BBC, AFP (earlier, still earlier), ST (earlier).Atlas 5 launches Inmarsat satellite which will bring global broadband access to small terminals: FT, SN, ST. Are rocket launches in Baikonur a health risk? A controversial study says so: BBC, AFP, NZ. VLTI sees first fringes with Auxiliary TelescopesSoon the big optical interferometer will be open to the general community, all the time: ESO Press Release."Einstein@Home" counts 55'000 particpants in distributed hunt for gravitational waves: APS Press Release (earlier), NZ. Satellite watchers worried about Air Force restrictions w.r.t. access to orbital element databases: SN.
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All other historical issues can be found in the Archive.
Compiled and written by Daniel Fischer
