|
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 |
Splendid skies in many parts of Europe, Africa and Asia have provided for fine views of May 7th's transit of Mercury: The best pictures came, of course, from a 1-meter telescope on La Palma, others can be seen at AIP, Merkurtransit, Gudensberg, VdS, SpaceWeather, WAA, GONG, Dierick, Astronomie.de, Salzgeber (animated), TRACE, AstroSurf (!), SOHO [APOD], ESO, Mira, Hannover, AstroDe, Murner, Guido, CarlKop, Nelkenbrecher, Radebeul, Jena, Munich, Singer, Zollern-Alb, Ayiomamitis, Nehru Planetarium (India) and Zayed Univ. (UAE); more links in this collection. Plus coverage by S&T, BBC, CNN, SC, ZDF. The whole event actually lasted over two days, with Mercury also visible in SOHO's LASCO C2 images in front of the corona: hi-res real-time images eg. from May 6 at 14:46 and 20:30 UTC, from May 7 at 0:06, 22:30 and 23:06 UTC and from May 8 at 2:54 and 9:54 UTC. Advance press releases: ESO, NASA, ESA, GSFC, Uni Jena. More websites: Espenak, SOHO, NSO, ALPO, ISS, PopAstro, Vigyan Prasar, Merkurtransit.de, Astro Mainz, Hannover, Backhaus and WAA. Advance coverage: S&T, PlanetQuest, SC (earlier), CNN, Rtr, NZ and RP (fr�her). Plus a paper by Halley himself and a strange painting from 1914 ...
| |
The first asteroid sample return mission is under way!An M V rocket has launched Japan's MUSES-C spacecraft on May 9 to meet the 500-meter asteroid # 25,143 (formerly known as 1998 SF36) in 2005 - and in 2007 a container with samples will come back to Earth and will be picked up somewhere in Australia. Through this mission, the Institute of Space and Astronautical Science (ISAS) intends to establish the technology to bring back samples of an asteroid's surface to earth - however small the sample amount may be, as it will enable detailed analysis on Earth, its scientific significance is enormous. The main objective of the MUSES-C mission is to acquire and verify the leading-edge technology required for such a sample-return mission. MUSES stands for "Mu Space Engineering Spacecraft" (a space engineering spacecraft launched by a Mu rocket) and "C" means "the third".MUSES-A, the first of the MUSES series, was called HITEN and was launched in 1990, targeting technologies such as a swing-by using the moon's gravity. MUSES-B was called HALCA and was launched in 1997: It presently plays an active part in ISAS' missions as a VLBI (Very-Long Baseline Interferometry) satellite in radio wave region. MUSES-C will arrive at the asteroid in the summer of 2005. After staying in close proximity to the asteroid for about 5 months and performing scientific observations and sample collections, it will depart from the asteroid and return to Earth in the summer of 2007. The full flight will take about 4 and half years. The MUSES-C mission employs a high-performance electric propulsion engine, which is continuously activated for the flight to and from the asteroid. When returning to Earth, a reentry capsule will separate from the spacecraft and plunge into the atmosphere. There are 4 major space engineering tasks in the MUSES-C mission: Electric Propulsion, Autonomous Navigation Technique, Technique of Collecting Samples from an Asteroid and Returning to Earth. The electric propulsion engine to be used by MUSES-C first ionizes the propellant, Xenon, by microwave, then accelerates the ions in a strong electric field and expels them at high speed. For navigation close to the asteroid the spacecraft is equipped with highly autonomous functions that enable it to decide each move on its own by measuring the distance to and the shapes of the asteroid surface. In order to successfully descend on a candidate-landing point, MUSES-C not only uses an artificial target called Target Marker that is released from the spacecraft to the surface, but also adjusts its position by processing the images sent from the camera and keeping an eye on landmarks. After arriving in the vicinity of the asteroid, the spacecraft will hover at about 10 km altitude to collect the data of the asteroid. It will investigate the asteroid's physical dynamics including dimensions, shape, topographic data and rotation axis and period as well as surface composition and structure using ONC, LIDAR, X-ray spectrometer and infrared spectrometer. These data not only enrich the data obtained from samples, but also help select the sampling sites. A small jump robot, MINERVA, which was developed by ISAS, is also used to move around and explore the surface of the asteroid. The MUSES-C spacecraft will approach and stay near the asteroid for about five months, with autonomous navigation and guidance using ONC and LIDAR. After constructing a 3D model of the asteroid while the two months of the global mapping phase, MUSES-C project team will decide a landing point considering some constraints. To land upon and gather fragments from the surface of the asteroid, the spacecraft has optical autonomous navigation, guidance and control system, which employs ONC and LIDAR above 100 m altitude. For the measurement of the relative position and attitude to the surface in the final landing phase under 100 m altitude, ONC, LRF and a Target Marker (TM), which is an artificial target and released at about 100 m altitude, are used. FBSs are also used for obstacle detection. Touch down is detected by another LRF which measures the distance between LRF and the sampler horn and a bullet is fired. Just after sampling, the spacecraft will lift off immediately and autonomously re-establish three-axis attitude and safe position. Contrary to many news stories, by the way, this is not the first sample return mission flown since the finally Apollo Moon landing in 1972: In 1976 the Soviet Union's Luna 24i brought back yet another sample from the Moon! |
| |||||||||
"Neuschwanstein" proof of heterogeneous meteorite streams ?When a bright bolide shocked Germans on April 6, 2002, the calculated orbit had turned out to be shockingly close to the one of another bolide seen and photographed on April 7, 1959 (see Update # 236 story 3) - but when a meteorite from the 2002 event was discovered it turned out to have a completely different composition. To some meteoriticists that meant that the extreme similarity of the orbital elements was a coincidence after all - but to those researchers who run the current European Fireball Network which led to the discovery of the "Neuschwanstein" meteorite, the case is rather evidence for "a heterogeneous stream" of meteorites which the Earth has been exposed to at least twice. "Taking 200 sets of orbital elements of established 'meteorite candidates' as a basis," Spurny & al. write, "we estimate that the chance of finding two meteorites among these 200 with orbits matching as well as those of Pribram and Neuschwanstein is one in 100,000."Therefore, they conclude, "this paired meteorite fall is probably not a coincidence, and implies that the two recovered samples are members of a 'stream' of similar objects. The existence of such meteorite streams was previously postulated on the basis of observed grouping of fireballs, Earth-crossing asteroids, and historical meteorite falls. From the known fireball detection efficiency of the European Fireball Network (the cameras have monitored an area of 106 km2, 3 hours per day over the past 40 years, on average), and the separation of the two meteorite orbits in space, we estimate that the stream should contain about 109 meteoroids of comparable size. [...] In the light of the different classifications of the two meteorites (Pribram is an H5 ordinary chondrite, Neuschwanstein an EL6 enstatite chondrite), a common primordial parent body for the two objects is most unlikely," however. Furthermore, "the cosmic-ray exposure ages of Pribram and Neuschwanstein differ significantly - 12 Myr and 48 Myr, respectively. Both these ages, which are believed to represent the time span from the release of the meteoroid from the interior of a parent body to its encounter with Earth, are significantly longer than the typical survival times of meteoric streams. [...] Though none of the orbits of previous fireballs matches the orbits of Pribram and Neuschwanstein exactly, we find several fireballs that could be tentatively associated with the pair" - including the famous "Glanerbrug L-LL chondrite [...] which fell on 7 April 1990 in the Netherlands, and whose orbit was recovered from visual observations. Judging from the atmospheric behaviour of these fireballs and from the chemistry of Glanerbrug, we see large structural variety, suggesting that objects in the 'Pribram stream' vary greatly in their chemical composition, structure and ages." |
| |||||||||
The crucial foam firing tests have begun!On May 8th the crucial experiments at the Southwest Research Institute in Texas have finally begun in which pieces of foam are fired at actual space shuttle orbiter wings, in order to recreate the events of January 16 during Columbia's launch. The initial experiments are admittedly unrealistic, though: The test stand was built before the actual impact location on Columbia's left wing had been nailed down. Experiments to recreate the Jan. 16 event as closely as possible will not begin until June. So far small pieces of foam have been fired at the wing underside of the orbiter prototype Enterprise, causing only minor damage. In other STS news, NASA has chosen a new shuttle program manager. And in ISS/Soyuz news the reason for the incident during Soyuz TMA-1's return on May 4 is still being investigated, with a software bug more likely than astronaut error. NASA, by the way, has not been invited to join the investigation ...The CAIB now has a working hypothesisbut the Investigation Board "has not reached any final conclusions and has not determined the cause of the loss of the shuttle and crew," according an announcement on May 6. While it would make sense that the foam impact during launch played a key role, this crucial link in the chain of events has not been established yet! And so no fewer than ten "analyses and testing [are] underway to refine the details of the scenario: 1) Completion of RCC and tile impact testing at Southwest Research Institute. 2) Aerothermal analyses to correlate off nominal heating trends in left fuselage sidewall and left Orbiter Maneuvering System (OMS) pod heating that were observed in the MADS data. 3) Instrumentation wire burn-through arc jet tests and thermal analyses to support the timing of observed instrumentation failures. 4) Instrumentation circuit analyses or testing to confirm the failure signatures observed in the data.5) Hypersonic wind tunnel testing and aerodynamic analyses to explain aerodynamic roll and yaw moments observed in flight data. 6) Thermal analysis of RCC panel 9 clevis and spar temperature sensor responses to support or refute flight data. 7) Gas flow and heat transfer calculations internal to the wing to support the MADS sensor readings in and around the wheel well. 8) Arc jet testing and/or analysis of previous arc jet testing to determine feasibility of RCC erosion observed in several key pieces of RCC panel 8/9 debris. 9) Continued forensic testing and analysis of significant recovered debris. 10) ET dissection and cryopumping tests." So the detective work is anything but over, and the "board's final report will be issued [only] later this summer," perhaps in late July: That would be just in time for congressional summer recess.
An investigation into this rather unusual landing mishap has now been launched: This was the first of a new generation of Soyuz vehicles, the TMA series, which was expected to be more comfortable etc. While the shuttles are grounded (and the Shenzhous aren't in manned operations yet) they are mankind's only means for travelling to and from space - and the only way for the two-person Expedition 7 to come home in October. By then the Soyuz TMA problems should be solved and the shuttle program already in the middle of its recovery. In other shuttle news it has now been determined that there was no way the Columbia crew could have been saved, even if the fatal damage to the orbiter's wing had been known before Feb. 1. And ... some worms have survived the crash and continued to reproduce in their enclosure which was retrieved later in the debris. |
|
HST mosaic of Helix nebula releasedfor Astronomy Day - both ACS images and groundbased material were used: HST and ESA HST Releases, APOD, Ast.Young stars in the halo of M 31 have been discovered - surprisingly - thanks to a deep HST image that also shows countless background galaxies: HST Release, S&T, Ast., BBC, NZ. Merging galaxies make for striking HST image - a dusty spiral galaxy and a bright elliptical galaxy in deep interaction: HST Release, Ast. Cosmology with distant supernovae alonecan yield results practically as good as analysis of the WMAP data, say Tonry & al. in a very long paper. Omega-m = 0.3±0.1 - without priors: a paper by Feldman & al. How population III stars reionized the Universe and thus can explain more of the WMAP data: MPA note.New subatomic particle found - mysterious quark blend hints at what holds atoms together: NSU. Particle physics and cosmology: a long lecture by Ellis - and an Introductory overview of modern cosmology by Gumjudpai. High Velocity Clouds are shredded galaxies, not primordial stuff, Parkes observations show: CSIRO Press Release. New Look at Satellite Data Supports Global Warming TrendA new analysis of satellite data collected since the late 1970s from the lowest few km of the atmosphere indicates a global temperature rise of about 1/5 Kelvin between 1979 and 1999 - this is at odds with previous analyses that show virtually no warming in the satellite record over the 20-year period: UCAR Release.An x-ray image of Stephen's Quintet shows what an intruding galaxy has done: Chandra picture. |
All other historical issues can be found in the Archive.
The U.S. site of this Cosmic Mirror has been visited
since it was issued (the German site has no counter).
Compiled and written by Daniel Fischer
(send me a mail to [email protected]!), Skyweek
