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By Daniel Fischer Every page present in Europe & the U.S.!
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The latest issue!
| A German companion! (SuW version) Current mission news: MGS (latest pictures!) + Cassini + Galileo + NEAR |
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First light for the 4th VLT telescope!It was a historical moment in the VLT Control Room at the Paranal Observatory, after nearly 15 years of hard work: During the night of Sept. 3-4, four teams of astronomers and engineers were sitting at their terminals - and each team with access to a different 8.2-m telescope, including YEPUN, the last Unit Telescope to come online. From now on, the powerful "Paranal Quartet" will be observing night after night, with a combined mirror surface of more than 210 m^2, though no combination of the light from all 4 telescopes into one detector is possible or planned. In mid-2001, however, two of the Unit Telescopes will be linked interferometrically to form part of the VLT Interferometer for high angular resolution experiments.The ESO Director General, Catherine Cesarsky, who was present on Paranal during YEPUN's First Light, congratulated the ESO staff to the great achievement, herewith bringing a major phase of the VLT project to a successful end. She was particularly impressed by the excellent optical quality that was achieved at this early moment of the telecope's commissioning tests. A measurement showed that already now, 80% of the light is concentrated within 0.22 arcsec. The manager of the VLT project, Massimo Tarenghi, was very happy to reach this crucial project milestone, after nearly fifteen years of hard work. He also remarked that with YEPUN's M2 mirror already now "in the active optics loop", the telescope was correctly compensating for the somewhat mediocre atmospheric conditions on this night. |
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2000 QW7 captured by Arecibo radarA group of astronomers of the Arecibo Observatory has already made the first radar detection of asteroid 2000 QW7 that came close to Earth earlier this month, using NASA's Goldstone antenna in the Mojave desert. Radar measurements, in combination with optical data, can immediately shrink trajectory uncertainties by a factor of 1000 or more for a recently discovered object like 2000 QW7. An improved orbit from the radar data will help us run the orbit backwards and search for pre-discovery images of the asteroid - it's a bit of a mystery why this one hadn't been spotted before.Amor asteroid approaches Earth, 12 mag possible!2000 QW7 was at 13.6 magnitudes when the asteroid was found by the NEAT telescope on August 26, and it should brighten to around 12.7 mag at the end of the month when the object approaches Earth to within 0.032 Astronomical Units or 4.7 million km or 12 Earth-Moon distances. 2000 QW7 can be found in the constellation Aquarius right now; see the links in the sidebar for an ephemeris. Because the object comes so close to Earth, being in different locations can shift the asteroid's position markedly through the parallax effect, by the way.The orbital elements show that 2000 QW7 belongs to the Amor family and follows an orbit inclined 4.2 degrees to the ecliptic. It ranges as far out as the main belt of asteroids, but every 2.7 years it comes in to a point fairly close to the Earth's orbit. As far as is currently known, the object has not been detected by astronomers before. Its brightness suggests it may be roughly 800 meters across. Several occultations of stars have already been predicted, but only when radar data should become available will the ground tracks be known with any precision. |
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"Yukon" chondrite as primitive as it getsA chemical analysis of the famous uncontaminated 4.5 billion-year-old meteorite that fell to Earth earlier this year in Canada (see Update # 192 story 2) shows that its composition sets it apart from other meteorites found on Earth, giving scientists a glimpse of the solar system that has not been seen before. The meteorite, called the Tagish Lake meteorite, is a carbonaceous chondrite: These rare meteorites contain carbon as organic compounds, some of which are the basic building blocks for life, and interstellar material, which comes from exploded stars outside of our solar system. But the Tagish Lake sample differs from other carbonaceous chondrites and sits in a gap between two subtypes of meteorites in that class, CI and the metamorphosed CM.Thermally metamorphosed meteorites came from parts of their parent bodies that went through some type of major heating experience that caused some volatile elements to vaporize. The fact that it's not thermally metamorphosed means that this meteorite is much more closely related to the CI meteorites than to any other kind of meteorite. CI meteorites are considered a "measuring stick" of sorts in cosmochemistry because they contain a chemical composition similar to the outside surface of the Sun. The Tagish Lake meteorite is, in fact, a sample of the pre-solar nebula, out of which the planets formed - scientists have never before had a sample of this material. |
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Why so many SOHO comets come in pairsThere have now been over 200 comet discoveries by the coronagraphs of the SOHO solar observer (see sidebar and Update # 152 story 8), but at least 15 times two comets appeared in their fields of view within half a day. This cannot be a coincidence: Statistically one would have expected just one such pair. The explanation, says JPL comet theorist Zdenek Sekanina, is that we are witnessing a cascading decay of comet fragments: The original comet from which all these "sungrazers" come broke up long ago, but the fragments continue to split spontaneously at random times, often near aphelion. Rotational forces or uneven illumination may play a role in these break-ups which were also seen in the evolving chain of comet fragments that was Shoemaker-Levy 9. The result, according to Sekanina, is "a complex hierarchy of fragments (secondary, tertiary, etc.) whose number is ever increasing - while their sizes decreasing" all the time. (Cometary Science Team Preprint # 185 of August 2000) |
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Ulysses returns to the Sun's polar regionsSix years after it first swooped over the Sun's poles, the European Space Agency's intrepid Ulysses spacecraft is about to start its second reconnaissance of these mysterious regions - just as our nearest star is reaching a peak in its 11-year cycle of activity. On 8 September, Ulysses will cross the solar latitude of 70 degrees south. After spending four months flying over the Sun's south polar region, the spacecraft will swing towards the equator before turning its attention to the solar northern hemisphere. The robotic explorer's passage over the Sun's northern polar expanses will commence on 3 September 2001.Although Ulysses will be returning along the same orbit that it followed six years ago, solar conditions will be quite different and new discoveries are eagerly awaited. Solar storms are already numerous and the high latitude solar wind (the stream of electrically charged particles that blows at supersonic speeds away from the Sun) is chaotic and blustery. In contrast, during its first south polar pass in 1994, when solar activity was very low, the solar wind at high latitudes was fast (blowing at a steady 750 km/s) and steady. |
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A close quasar pair at z=4.25has been found in the Sloan Digital Sky Survey, and it's not a gravitational lens - the two objects are likely to be physically associated, with a separation of less than 1 Mpc. The existence of this pair is strong circumstantial evidence that quasars at redshifts around 4 are clustered: paper by Schneider & al.A remote extremely dusty starburst galaxy that had been found by SCUBA in the sub-mm range has been revealed by the HST: paper by Smail & al. & HST Release ( alternate version). Omega Centauri - a former nucleus of a dwarf galaxy?The famous big Southern globular star cluster Omega Centauri could be the remnant of another galaxy - this hypothesis has been strengthened by photometry of its red giants which shows populations of different ages and metal enrichment even in the metal-poor population: paper by Hilker & Richtler.He2-90 - a misclassified object?He2-90 is probably neither a planetary nebula nor a young star but two old stars, HST images show - one member of the duo is a bloated red giant star shedding matter from its outer layers which is then gravitationally captured in a rotating, pancake-shaped accretion disk around a compact partner, which is most likely a young white dwarf: STScI Press Release, Space.com, Reuters.CRL 618, a proto-planetary nebula, is a "superb example" of the transition taking place in the later stages of the life of a Sun-like star after it has lost most of its mass and before it emerges as a Planetary Nebula: HST Photo Release, SpaceViews, CNN. The 'Spirograph Nebula', a comparably uneventful Planetary Nebula: STScI, Space.com. Hints of the "Higgs" at CERN?Researchers working at CERN say they have detected a handful of events that may indicate the fleeting appearance of the Higgs boson, the predicted elementary particle that gives matter its mass: BBC story, the Higgs hunters homepage and all the CERN experiments.NEAR lifts orbit againNEAR Shoemaker is taking a wider view of Eros, after an Aug. 26 maneuver sent it climbing toward an orbit reaching up to 100 km from the asteroid's center - it was to be circularized at 100 km on Sept. 5: News Flash, SpaceViews.Dozens of "Discovery" proposals for moderately cheap interplanetary missions have been submitted to NASA: Space.com. Cancellation of Pluto mission still a distinct possibility despite great efforts to save it: Fla. Today. |
3 out of 4 Russian satellites close to break-downOf the 44 Russian civilian satellites in orbit, 34 "could break down at any moment," a spokesman for the Russian Space Agency has warned - the satellites, which transmit telecommunication and television signals and support meteorological and earth-observation work "have outlived their guarantee": AFP.Mars balloon remote inflation technology demonstrated in Earth's atmosphere: Pioneer Astronautics Press Release, Space.com. The Mars Pathfinder landing site seen in an unusual way: PhotoJournal, Spacefl. Now. And another Pathfinder conspiracy... "Microscouts" could advance planetary exploration, such as a tiny rover vehicle studying an asteroid and a diminutive glider swooping through Martian skies: Space.com. Atlantis countdown proceeds smoothyThe countdown towards a Sept. 8 launch of the shuttle Atlantis to the ISS continues with few issues other than a concern over the weather: Spacefl. Now, Discovery, Fla. Today (more stories plus pictures), CNN, NYT, SpaceViews. Mission Guide: SpaceRef.The mission objectives: Space.com, Fla. Today, Spaceflight Now series (stories # 1, 2, 3, 4). Commercial Generic Bioprocessing Apparatus flies on the mission: Press Release. The launch window is very short, 2.5 minutes: Space.com, Fla. Today. Spacesuits cleared for EVA: Fla. Today, SpaceViews. The unusual EVA: Space.com. Worker shortage threatens shuttle safety, study says: GAO Letter, Bloomberg, CNN, AvNow, Houston Chron., SpaceViews, Fla. Today. Russia has not funded all of the 2001 Soyuz, Progress missions: Spacefl. Now, Houston Chr., AvNow. Station not finished before 2006: Reuters. The Personal Satellite Assistant for future ISS crews: Space.com. Change of guard at the Central Bureau for Astronomical TelegramsDan Green succeeds Brian Marsden as the director of this universal clearing house for astronomical discoveries - Marsden had held this post since 1968: IAUC # 7479.
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All other historical issues can be found in the Archive.
The U.S. site of this Cosmic Mirror has been visited
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Compiled and written by Daniel Fischer
(send me a mail to [email protected]!), Skyweek
