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By Daniel Fischer Every page present in Europe & the U.S.!
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| A German companion! (the latest updates) Current mission news: MGS (latest pictures!) + Cassini + Galileo + NEAR |
was provided by Florida Today, Spaceflight Now and Space.com Specials! More from NASA MSFC, JSC, NSSDC, Fla. Today, Space.com, CNN and SpaceViews.
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New claims for the most distant objects in the Universehave been voiced in mid-April: While the Sloan Digital Sky Survey has bagged yet another high-redshift quasar with a spectroscopically measured record value of 5.8, another close look at the Hubble Deep Field has turned up more probable galaxies with extreme red colors - that may have redshifts way beyond 6 and in one case near 12.5. There are no spectra available for any of these galaxies however, so the SDSS quasar can claim to have the highest measured redshift. The 'photometric redshift' technique used to guess the redshift values of the red HDF galaxies has been shown to be quite reliable in the past, often to within 10 to 20 percent, so the decision on the most distant known sky objects is out and might have to wait for the Next Generation Space Telescope.The quasar - tracked down by a grad student - has the number SDSS 1044-0125 and with its z=5.8 beats out a recently discovered galaxy with z=5.7. More important is the sheer number of hi-z quasars found by this large sky survey, however, which has already bagged 8 of the 10 highest-z objects and two thirds of all quasars with z>4.5: Such a large sample will be useful for studies of the evolution of the Universe. The SDSS data support the view that the number of quasars rose dramatically from a billion years after the big bang to a peak 2.5 Gyr later, followed by a sharp fall-off. The SDSS is currently trying to measure the redshifts of several candidate quasars with estimated values larger than 6. The possible galaxies with even much higher redshifts were found with the help of NICMOS images of the Norther Hubble Deep Field: Various galaxies were spotted that, based on their extremely red colors, should have redshifts between 4.5 and 9 - and one object may have a redshift oft about 12.5! Galaxies with redshifts that high, which would trace the very beginning of stellar evolution in the Universe, can only be studied in detail with the Next Generation Space Telescope. There is a heated race going on to find the galaxies with the highest redshifts now - check the lead stories of Cosmic Mirrors # 172 and 104 for recent claims of success. |
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Bewildering torrent of data collected during 1999 Leonid stormUnique records of rare celestial event on parade at first major conference / Value of amateur observations hailed / USAF drops out of Leonid businessIt was one of those Woodstock-style events that punktuate the steady flow of scientific progress now and then: The first scientific conference after a rare space event can sometimes turn into a fast-paced presentation of one mysterious and/or spectacular observation after the other, with often little theoretical understanding - but everyone present feels that something special has happened and that years of scientific work will be initiated by the encounter with the unknown. The sessions on the Great Comet Crash of 1994 at the IAU General Assembly in The Hague were such a special event - and the Leonid MAC 2000 Workshop in mid-April in Tel Aviv was no less exciting."MAC" stands for the Multi Instrument Aircraft Campaign that the U.S. Air Force, NASA and other agencies had run during the 1999 Leonid storm, and the meeting at Tel Aviv University was the first occasion for a joint presentation of the observations made from the two aircraft that had flown "through" the storm near Italy. But many groundbased teams, associated with MAC'99 or independent, were represented, too, as were amateur astronomers from Israel (who had observed the storm in the Negev desert) and Germany (who had been in Tenerife and Jordan). The theme running through most of the conference could be described as: "The meteors are coming - let's try something new!" A number of speakers had used instruments during the meteor storm that had rarely or never been used for meteor work before: big radar dishes, networks of radio antennae, HDTV cameras etc. Almost every other speaker had a video cassette to show with sometimes strange but more often breathtaking views of the celestial spectacle. The "best picture" award would clearly go to the wide-angle HDTV tape shot by Japanese researchers from one of the airplanes which really showed the rain of several meteors per second during the peak of the storm (H. Yano). Almost as captivating was a Czech video of meteor spectra in realtime (J. Borovicka), also shot from the air. Here are a few of the highlights of the meeting and some early discoveries - a collection of refereed papers should be published as a special issue of Earth, Moon, and Planets as well as a book this November:
This year's Leonid activity will be a decisive test whether there will really be more storms in 2001 and 2002 and should thus be monitored well, many speakers emphasized. The leading theoretician of the Leonid dust trails, D. Asher, stated once more that all reasonable cometary dust ejection models make Leonid storms in 2001 and 2002 all but inevitable, and P. Jenniskens is already qualifying his doubts (mentioned in the just-released June issue of Sky & Telescope) and is now hoping for ZHRs of 6000 and more in those two years. Again, new and ususal observing methods are likely to be brought into action, followed by years of data analysis... |
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3rd Shuttle flight to ISS scrubbed twice - next attempt on WednesdayWeather should be much better then / STS-101 necessary mainly because improper use has damaged Zarya's batteriesThere isn't even a permanent crew aboard the International Space Station yet, and most of its main modules have still to be added - but NASA is already forced to send repairmen up: Atlantis' mission STS-101 has become necessary because ground controllers in Moscow have damaged several of the embryonic station's batteries by using wrong procedures. The same batteries had been used on Mir for years without incident, but the electric procedures on the Zarya module are different - and when the controllers at the TsUP center near Moscow had realized that, they had already damaged several of the cells beyond repair.Two attempts to launch Atlantis had to be scrubbed on April 24th and 25th: Crosswinds were just too strong at the emergency landing strip at Kennedy Space Center. Officials are now planning for another try on the 26th when the weather should be greatly improved: There is a 90 percent chance of acceptable conditions at Kennedy Space. The launch window will extend from 19:27 to 19:32 UTC. This launch attempt will be unprecedented in the 19-year space shuttle program - it will mark the third consecutive day that NASA tries to launch a shuttle. Never before have attempts been made on three straight days. This will be the 98th shuttle mission of all and the 21st for Atlantis. The first task of the 7-member crew after docking to the ISS will be a single EVA, to be performed by Jim Voss and Jeff Williams. The astronauts will resecure a U.S.-made crane that had been mounted outside the ISS during the last visit but has become loose, they have to complete the Russian Strela crane and they will replace Unity's faulty "early comm" antenna system. After the EVA is complete, the remaining days will be spent inside the ISS. There the crew will first have to check whether the air is o.k. (the last visitors had encountered some physiological symptoms because of CO2 buildup, which they didn't report in time to be fixed). Then they will unload about 1 ton of supplies from a Spacehab module carried by Atlantis and concentrate on replacing 3 or 4 of Zarya's 6 batteries and installing new electrical systems. Another important task will be to raise the orbit of the space station which is decaying about 2 km every weak due to friction with the atmosphere by 30 km. Undocking is planned for either flight day 9 or 10, with landing at KSC a day later. To be ready for the original April 24 launch window, NASA engineers had to replace a faulty rudder power drive hydraulics unit on the launch pad, a tricky task finished in time. Atlantis last flew in 1997: The orbiter had spend the last three years undergoing major upgrades in more than 2 dozen areas. The most visible change: the installation of a "Multifunction Electronic Display Subsystem" (MEDS) with 9 flashy LCD display screens in the cockpit that give the astronauts much more situational awareness, specially during launch emergencies. Until now the crew had to cope with 3 older screens and 32 gauges and electromechanical readouts. (With AW&ST of April 17, p. 94-98) In other ISS news, on April 14 the European Space Agency took delivery of the primary structure of the Columbus Attached Pressurized Module (APM), its most visible contribution to the space station - and the (so far, hollow) cylinder was ready on time and on budget. Once outfitted and tested, the APM will be handed over in June 2001 to DASA for the final integration and testing - but because of delays in the ISS program it won't be launched before the end of 2004, two years later than planned. (AW&ST of April 24, p. 60-61) |
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Yet another method to "look behind the Sun"has been established to complement the helioseismoholographic approach which made headlines last month (see Update # 180): Major activity centers emit so much Lyman alpha radiation that its reflection off the interplanetary dust can be used to track their strength and position, even when they are on the 'back' side of the Sun. This possibility was first mentioned last year (see Update # 136 small items), but now its predictive power is being stressed. Although the Sun constantly emits Lyman alpha radiation, its active regions can be thought of as projectors, beaming this radiation in stronger and more concentrated streams.Hydrogen atoms in space then function as screens illuminated in their ultraviolet spectrum by the Lyman alpha radiation. Lyman alpha is detected by the SWAN (Solar Wind ANisotropies) instrument aboard the SOHO (SOlar Heliospheric Observatory) satellite: SWAN scans the whole sky and is thus able to detect strongly illuminated regions of hydrogen atoms in space beyond the far side of the Sun. By tracking the movement of these strongly illuminated regions, scientists can in effect see around the corner and predict when the sunspots producing strong radiation streams will rotate around and face toward the Earth. This will provide more time to take corrective action in advance of heavy solar weather they may produce. |
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Polar lights dazzle Europe, U.S. during major geomagnetic stormObservers all over Central and even Southern Europe have been treated to a marvellous aurora display during the night from April 6th to 7th, with at least two strong outbursts of activity several hours apart - in regions from where polar lights are usually seen only once in a decade, many different features could be witnessed, from a strong red glow (that triggered the unavoidable phone calls at fire and police stations) to fast-moving rays to actual curtains. And while the ubiquitous light pollution present in Central Europe softened the display somewhat in many places, countless observers could - many, like yours truly, for the first time in their lives - see a grand spectacle of Nature with their own eyes that they had known only from second hand reports.This was all thanks to one of the most vigorous interplanetary disturbances to impact the Earth so far this solar cycle, which had collided with the Earth's magnetosphere near 16:40 UTC on April 6th - and thanks to the satellite ACE positioned between the Earth and the Sun, there was even some last-minute warning available. The disturbance had been preceded by one of the strongest shock fronts yet observed this solar cycle: Solar wind velocities had almost instantaneously increased by almost 200 km/s within a minute or two from a background quiet-time value of 380 km/sec to a value exceeding 570 km/sec. The strength of the magnetic fields in space (which originate from the Sun and are dragged outward by the solar wind) had also increased dramatically in magnitude by a factor of almost 4 times the normal quiet-time background value. The sudden increase in solar wind pressure against the Earth's magnetosphere, combined with the favorable southward orientation of the solar wind magnetic fields, resulted in increased erosion and compression of the sunward side of the Earth's magnetic field - with all kinds of both interesting and sometimes hazardous (for certain satellites, that is) effects. The impact of the disturbance was strongly felt in the Earth's ionosphere, for example, where it causes heavy degradation in the quality of radio signals that rely on the ionosphere to propagate to distant locations around the world. And another adverse effect of the storm was to increase the atmospheric drag on satellites, which can change the orbital elements of lower orbiting spacecraft, particularly those with perigees below about 500 kilometers. A significant increase in geomagnetic activity was observed at about 16:45 UTC on April 6th, as a consequence of the interplanetary shock wave that had been detected by the ACE satellite at around 16:30 UTC that day. Magnetic activity increased at all U.S. Geological Survey magnetic observatories about 15 minutes later. Geomagnetic storms occur when plasma from a solar eruption impacts the Earth's magnetic field causing it to fluctuate wildly - the actual eruption plus coronal mass ejection that caused the activity on April 6 and 7 had taken place around 15:00 UTC on April 4. The SOHO coronagraphs had clearly recorded the so-called halo event following the CME. Solar eruptions can produce billions of tons of plasma traveling at speeds in excess of 1.5 million km/h. In the morning (UTC) of April 7th, the largest auroral storm of the current solar cycle had, for all intents and purposes, ended: The magnetic fields which were driving this auroral storm had returned to background levels. The auroral oval had quieted significantly, and no new outburst of activity was likely (nor reported). So far the solar cycle that is now approaching its maximum has not produced an abundance of major geomagnetic storms. The rate of activity is expected to continue to increase though the next few months, however: The solar maximum as determined by sunspot numbers is expected later this year, but the full volley of geomagnetic storms may not occur for another two years or so. (Based on various 'space weather' information services; see sidebar) |
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Martian South polar mosaics from the MGSshow some of the most exotic planetary landscapes in our Solar System in new clarity - the layers exposed in the south polar residual cap are thought to contain detailed records of Mars' climate history over the last 100 million years or so: MSSS Release, AP, Discovery, BBC, Space.com, SPIEGEL, Spaceflight Now.Also released: all Cydonia images the MGS has taken so far (discussed by CNN), and a cut across Olympus Mons - MSSS, Spaceflight Now. NASA selects new Mars manager - spurred by criticism over failed missions, NASA's JPL has chosen scientist Firouz Naderi to head a newly formed Mars program aimed at improving future robotic explorations: JPL Release, SpaceViews, AP. NASA leaders take more heat in congress: SpaceViews, Fla. Today.
Launch date set for 2001 orbiterIt's April 7, 2001: Space.com. The future of Mars exploration - more thoughts on the options in SpaceViews.A Mars Sample Return Mission would jeopardize all other science on Mars for a decade and cost at least $1.5 billion, a top Mars scientist says: Space.com. Search for life ain't cheap: Space Daily. Mars Express, Nozomi coordinate action for 2003: ESA Science News. "White Rock" on Mars not the work of bacteria but just a wind-blown deposit like a huge sand dune, new MGS TES data indicate - the prime site to search for Martian fossils is no more: Nature Science Update. More Martian insights from the 31st Annual Lunar and Planetary Science Conference are presented by Space Daily, plus further thoughts on water, life on Europa (again and again and again), Io and anything else in the solar system. And "What the hell is astrobiology?" "ASTROVIRTEL" - a virtual telescopethat consists of huge astronomical data bases with 7 Terabytes in total that can be accessed like a real telescope - is now having "First Light": Homepage, ESO, ESA Press Releases.A gigantic archive of the 2MASS sky survey at 2 micrometers wavelength (with an anticipated 2 Terabytes of data when finished) has become available online in steps - "2MASS represents part of astronomy's future, as scientists learn interesting new things by analyzing terabyte-sized sets of data": Homepage. Mauna Kea telescopes accessible by "Internet 2" - with a capacity of 45 million bits per second, the new link will dramatically expand the capacity of astronomers around the world to remotely use telescopes located on the Hawaii mountaintop: UHI Press Release More speculations about worm hole travelcan be found - as usual - in the New Scientist, based on this Preprint. Coverage by BBC, SPIEGEL and Heise. NASA's "Advanced Space Transportation Program" - what can really be done? Earth Science News = NASA Science feature. Or do you prefer black hole atoms? Once more the New Scientist ...Terra "open for business"NASA's premier Earth Observing System Satellite, Terra, has completed on-orbit checkout and verification and is now "open for business" - the Terra team estimates that the scientific community will complete the first Earth-system models making full use of Terra data by 2005: JPL Press Release, Terra gallery, picture archive, NASA Release, pictures # 2600, 2601, 2602, 2603; SpaceViews, CNN, Space.com, Discovery, BBC.Envisat takes shape - the largest environmental satellite is currently undergoing integration and tests at ESTEC in the Netherlands: ESA Press Release. SRTM data show San Andreas fault in unprecedented detail: JPL Press Release, images # 2745, 2746 and 2747, image collection, Space.com. "Blue Marble 2000" - a new space image of the Earth: GSFC Special Page, BBC, Space.com. 30 years of Earth Day - various articles from Space.com. |
NASA sticks to Pluto launch in 2003As reported here first (see Update # 180 story 2), NASA planners for the Outer Planets Program continue pushing for an early launch of the Pluto-Kuiper Express mission in late 2003 (with the Pluto fly-by in the summer of 2011), even though that will delay the launch of the popular Europa Orbiter and prevent it from entering orbit until 2010: Space Daily.Cluster launches delayed to July, AugustThe Cluster II quartet are now scheduled to fly out in pairs from Basel-Mulhouse airport on 27 April and 3 May, with their launches set for 12 July and 9 August, pending the results of the current tests of their thrusters - doubts about the quality of a specific lot of these German-made thrusters had led to the delay of many satellite launches besides the Cluster quartet: ESA Science News, SpaceViews. The thruster problem: SpaceViews.Inhabitable galaxiesMost galaxies might have only limited regions where Earth-like planets could both form at all and be able to support life, not too far out, not too central - and because many galaxies have less heavy elements than the Milky Way, their habitable zones might shrink out of existence, leaving no room for life: Nature Science Update.Milky Way's collision with M 31 simulatedThe 2.2-million-light-year gap between the Milky Way and Andromeda is closing at about 500 000 kilometres an hour, and that pace will quicken as the two galaxies near each other - a detailled simulation of this Milky Way-Andromeda interaction has now followed the motion of more than 100 million stars and dark matter particles as the gravitational forces of the two galaxies force them to collide: U. Toronto Press Release, the simulations, Discovery, ABC, SpaceViews stories.SETI array prototype unveiledA prototype of the "One Hectare Telescope", a joint project of the SETI Institute and the University of California, Berkeley, is now in place in California, with the first seven 3.6-meter dishes up and running. By 2005 the project could include as many as 1000 6-meter dishes on 2 1/2 acres near Mount Lassen in the rugged hills of Northern California: 1HT, RPA Homepages, SETI Institute, Berkeley Press Releases, coverage by SpaceViews, AP, Spacefl. Now, CNN, Space.com ( earlier), BBC.
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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
