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By Daniel Fischer Every page present in Europe & the U.S.!
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The galaxies formed even earlierthan recent investigations have indicated: So many bright galaxies are now being detected at very high redshift (z>4) that galaxies must be even older and have formed even earlier than previously thought. Tens of hours of exposure time went into a picture taken in red light at the William Herschel Telescope and another similarly long exposure made in infrared light at Calar Alto. These pictures have been compared to new pictures in infrared light taken with the Hubble Space Telescope in its Hubble Deep Field North and to new optical and infrared pictures in the Hubble Deep Field South.The Space Telescope exposure was a total of 120 hours in a single tiny patch of sky and reaches deeper than the ground-based pictures, but covers a smaller area of sky. However, the basic result is that the counts of high redshift galaxies from both the ground- and space-based experiments agree well, in the range where they can be compared and so both these experiments appear to be giving consistent results. In 1996, the Herschel and Hubble Deep Fields had revealed so many faint blue galaxies at a redshift of 2 that they already challenged the claims of the most popular cosmological theory, which suggested that galaxies formed around a redshift of 1, when the universe was about half as big as it is now. Since then, observations at the 10-m Keck telescope confirmed those results by finding many galaxies at redshifts of 3 and 4. And now, applying similar techniques as before but to the new red and infra-red pictures, large numbers of galaxies at the even higher redshifts of 5 to 6 have turned up - there are as many galaxies at these high redshifts as are found locally. This makes the epoch of galaxy formation earlier in the history of the universe than astronomers previously thought - the detection of bright galaxies at z=4-6 opens up the question as to whether galaxies at even higher redshift may exist. Though it would make even more problems for theorists, the timespan between z=10 or z=20 and z=5 is incredibly short relative to the timespan between z=5 and z=0. To observe galaxies at these redshifts we need even deeper pictures over a relatively wide field, particularly at infra-red wavebands. The new Wide Field Camera at the UK Infrared Telescope on Hawaii and the UK VISTA telescope in Chile which will be available in a few years will open up these new redshift regimes for observation. A few years later the giant NASA-ESA 6.5-m Next Generation Space Telescope (NGST) will be launched to observe even deeper and further into the infrared with the prime aim of detecting at the highest redshifts the dawn of the age of the galaxies. Current submillimeter radio telescopes like the JCMT in Hawaii and the Plateau de Bure interferometer in France are already providing further clues about the history of star formation in the Universe. For the first billion years of the life of the universe, the star formation rate in galaxies built up steadily to a level over ten times higher than it is today. It continued at that rate for several billion years. During that period most of the chemical elements were created inside stars and subsequently blasted out into space. By the time the Sun and Earth formed 4.5 billion years ago, the rate of star formation had dropped to only about 3 times what it is today. |
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Wet mysteries in interstellar spaceNASA's Submillimeter Wave Astronomy Satellite (SWAS) has detected water vapor throughout interstellar space - but in the very coldest reaches, where temperatures are found just 30 degrees above absolute zero, astronomers measured water vapor concentrations of only a few parts per billion, far less than predicted by most theories and a real puzzle to the understanding of the chemistry of interstellar clouds. In warmer regions of space, however, water vapor is more plentiful: Within gas clouds where new stars are being born, the gas can be heated to high temperatures, and there the water concentration seems to be as much as 10 thousand times larger.The new results are the product of 18 months of observations with SWAS, a compact radio observatory launched in 1998 to study the composition of interstellar gas clouds and their collapse to form new stars (see Update # 113 story 2). SWAS allows scientists to detect radiation from water and oxygen molecules that is ordinarily hidden from view by Earth's atmosphere and is also capable of detecting oxygen molecules in interstellar space, although little has been found. The absence of molecular oxygen is another mystery: There must be no more than one oxygen molecule for every 10 million hydrogen molecules, otherwise SWAS would have detected a signal from molecular oxygen. Most of the oxygen atoms in interstellar space thus remain hidden in some form that has yet to be detected. In addition to observing distant clouds of interstellar gas, SWAS has detected water vapor closer to home in the atmospheres of Mars and the gas giants Jupiter and Saturn. The water vapor seen in the gas giants is almost certainly the result of bombardment by small icy particles that come from interplanetary space and are rapidly vaporized once they hit the planetary atmosphere. SWAS also measured the amount and distribution of water vapor in the atmosphere of Mars, confirming the long-held belief that the relative humidity of the atmosphere is near 100 percent. However, since Mars is so cold, the total amount of atmospheric water is a several thousand times less than in the Earth's atmosphere. |
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Mars microphone to fly on the 2003 rovers?The Cosmic Mirror has learned that the Planetary Society is in negotiations with Cornell University which supplies the Athena payload for the two 2003 NASA Mars rovers (see Updates # 198 story 1 & 199 story 2) to have copies of the tiny Mars Microphone included which - after much anticipation - had vanished with the Mars Polar Lander. "We are working now with the project and the Principal Investigator for the payload to define a possible role for the microphone," Lou Friedman, the Executive Director of the Planetary Society, has told the CM: "We have every hope that it will be included in the mission.We are also working with the French for possible inclusion of a microphone on their Netlander mission in 2005 or 2007. The British scientists on Beagle 2 have shown no interest in our participation." And Gregory T. Delory from the UC Berkeley Space Sciences Laboratory confirms the negotatiations about the 2003 rovers, adding that the Mars Microphone has "more or less a sure shot on the French NetLander mission in '05. That is as specific as we can be for the moment. However we're confident and hopeful that something will work out given the enormous public support for this instrument." |
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Planet light detection retractedThe vague detection of starlight reflected off the planet of the star Tau Bootis (see Updates # 158 story 2 and 163 small items) was a measurement error and it could not be repeated. If light from the Tau Boo planet had been detected, it would have indicated an exceptional body - that it has not means the planet must have more usual dimensions and reflective properties: BBC.Perseids came packaged with bright aurora - for Canada and the U.S.A geomagnetic storm triggered a dazzling aurora for Northern America during the peak of the 2000 Perseid meteor shower - some call it the best auroral display in these longitudes since 1991: Science@NASA, CNN, Space.com, Columbus Dispatch. And USA Today and the Why Files on how aurorae work.The Perseids, meanwhile, did o.k., with a peak Zenithal Hourly Rate of 110-120 around 11:00 UTC on Aug. 12 - while for the first time after the return of comet Swift-Tuttle no pre-maximum peak (which would have been at 5:00 UTC) was seen: IMO Shower Circular. The "300 seen in a hour" from Germany in this RP story are erroneous (a group count?). A picture of a 2000 Perseid: Analemma. Bolide sightings: CENAP News. And some of the (more or less acurate) Perseid previews: Meteor Outlook, Science@NASA, Space.com, Houston Chron., Arizona Republic, RP, SPIEGEL. Deep Space One keeps going ... and goingThe ion propulsion engine on Deep Space 1 has now accumulated more operating time in space than any other propulsion system in the history of the space program - the spacecraft, designed to test new technologies, has run its unique propulsion system for more than 200 days (4,800 hours): JPL News, AP, Science@NASA, Space.com, CNN, BBC. How ion engines work: Geek. Earlier: a new Mission Log and JPL News and SpaceViews on the recovery.New NEAR pictures: over the hill, Zebra stripes, craters, grooves & more, confusing slope, obliterated craters. Asteroid orbiter marks halfway point in historic flight: CNN, Weekly Status. Stardust's CCD is being heated to remove contaminants: Status. Sometimes impacts help life flourishNot everyone loses out when the sky falls in - two almost simultaneous giant meteorite impacts 35 million years ago boosted the abundance of some marine microorganisms, despite triggering a cold spell that lasted about 100,000 years: Nature Science Update.China builds new observatory to detect Near-Earth Asteroids in the Tieshanshi State Forest Park in the eastern Jiangsu Province - the observatory will house a telescope with a mirror diameter of 1.2 m: Space Daily. MightySat 2.1 "nearly perfect" in early operations, checkoutAfter more than 350 revolutions of Earth in its 565-km sun-synchronous orbit, the second of AFRL's small technology demonstration spacecraft (see Update # 197 story 3) is performing flawlessly: MightySat 2.1's primary payload, the Fourier Transform Hyperspectral Imager (FTHSI), is believed to be the first ever such imager to use a monolithic glass interferometer instead of dispersive elements to discern colors in its image.MightySat 2.1 also hosts a pair of "picosats" similar to those placed into orbit on Feb. 7, 2000 (see Update # 174 story 6), but possessing improved features. The new picosats are to be released into orbit from MightySat 2.1 in about a year: Aero.org Press Release. |
A gravity anomaly during a solar eclipse?Physicists taking precise gravimetric measurements during the total solar eclipse of 1997 saw a decrease in g, just at the time of the eclipse - they claim that that change in g, even when corrected for all the effects (like tides) predicted by existing theory, was still too big to be explained by errors in their instruments: Nature Science Update.Can the electron split? A bizarre quantum mechanical effect has been described that may be supported by experiments: Brown Univ. Press Release. 10 physics questions to ponder for a millennium or two, brought to you by the NYT. Cluster satellite quartet congregate in polar orbitAfter five major orbital manoeuvres per spacecraft executed in five days, the second pair of Cluster spacecraft have been successfully inserted into their operational polar orbits: ESA Science News ( earlier), ESOC Status, Space.com. What the mission is about: ZEIT.The CHAMP satellite - resolved by radar from the FGAN: a movie! Atlantis prepped for launch to ISSThe shuttle Atlantis was hauled to a coastal launching pad at its Florida base on Aug. 14 in preparation for its September mission STS-106: Houston Chron., SpaceViews. Mission status: Spaceflight Now. The Aria GAS payload of STS-106: Homepage, GSFC story. ISS emergency training: BBC, AP. ISS underwater training: Houston Chron. Shuttle flight rate called reasonable: Space.com.Shuttle Safe Haven opens at KSC: Space.com. ISS crew eager to go: Fla. Today. Russia to build two more modules: Interfax. Russia's ISS mission control: Space.com. NASA creates a place to learn mission control: Houston Chron. Could a space laser clean the way for the ISS? Orion proposal, New Scientist, AFP, BBC, RP, SpaceViews, SPIEGEL. Plus ISS Status # 38. Hurricane Alberto as seen by SeaWiFS(the Sea-viewing Wide Field-of-view Sensor) on the afternoon of Aug 11. - the storm is almost directly east of Bermuda, which is the small green area in the lower right of the image: Fla. Today.Next test for the IRDT will launch from a submarineA Russian military submarine could be the launch pad for an upcoming attempt to test an inflatable spacecraft - Lavochkin is preparing a Russian Naval sub for the $700,000 experiment known as Inflatable Reentry and Descend Technology: Space.com.New space experiments with inflatable structures will come - and the ARISE radio astronomy mission could be the first application: JPL Press Release.
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Compiled and written by Daniel Fischer
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