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By Daniel Fischer Every page present in Europe & the U.S.!
| Ahead | Awards 
The latest issue!
| A German companion! (SuW version) Current mission news: MGS (latest pictures!) + Cassini + Galileo + NEAR |
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Compton is historyThe Compton Gamma Ray Observatory re-entered the Earth's atmosphere at approximately 6:10 UTC on June 4, according to calculations made by controllers at NASA's GSFC, in coordination with the U.S. Space Command's Control Center. As planned, pieces of the observatory that survived the re-entry landed in the Pacific Ocean approximately 3900 km southeast of Hawaii. The fourth and final burn needed to re-enter CGRO had been initiated at 5:22 UTC: Compton's Attitude Control thrusters and Orbit Adjust thrusters were fired for 30 minutes. The times of the last 2 thruster burns had been changed after new orbit calculations following the 2nd burn, so that the debris field stayed targeted for the zone selected initially.
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NASA's March decision to destroy the working observatory satellite
at the earliest possible date has remained mysterious til the very
end, as the numbers don't seem to match up. According to calculations
by NASA's engineers
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Over 500 fragments from rare Yukon meteoritehave been collected by researchers in recent months: The debris from the famous January 18 fireball (see Update # 182 story 3 sidebar 1) constitues the first carbonaceous chondrite found just after landfall since the Murchison meteorite in 1969! This is the first time ever that modern techniques can be used to study one of these. Carbonaceous chondrites, which comprise only about 2 percent of meteorites known to have fallen to Earth, are typically difficult to recover because they easily break down during entry into Earth's atmosphere and during weathering on the ground. The Canadian Nomenclature Committee of the Meteoritical Society has officially designated the name Tagish Lake Meteorite for the new specimens.The fireball had exploded with an estimated yield of 5-10 thousand tons of TNT, and the original object was about 7 meters across and had a mass of 200 to 250 metric tons - it was basically a C-class asteroid detonating in the atmosphere over the Arctic. The first fragments of the object had been discovered in January by a local resident near the spot where the meteorite hit: He had placed them in clean plastic bags and kept them continuously frozen - and they were never touched by human hands. He found several dozen pieces after looking for 90 minutes, but when a group of researchers returning to the site in April spent days harvesting, they came out with over 400 fragments. The biggest single piece was 200-300 grams, and the total mass collected was 5 - 10 kilograms. Using eyewitness and photographic data gathered during the field investigations, and observations from two US Department of Defense satellite systems, the trajectory and velocity of the fireball were determined. The ability to calculate this is a relatively new development in meteorite science - essentially allowing researchers to determine a meteorite's pre-fall size, orbit and origin in space. There have only been five previous meteorites for which accurate orbits are known (see Update # 190 story 4 for the latest such success), and no orbits for a carbonaceous chondrite have ever been secured. |
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Canadian astronomy plan echoes U.S. goalsJust weeks after a master plan for U.S. investments in space and groundbased astronomy was published (see Update # 190), a similar Long Range Planning Panel for Canada has released its conclusions - and they all but mirror the priorities set by the U.S. panel by urging Canada to join many of the leading international big projects (most of whcih already have a European component, too). The report is said to be the consensus of Canada's entire astronomical community for its priorities in astronomy in the coming 10-15 years.The LRPP strongly recommends that Canada should quickly join the Atacama Large Millimeter Array (ALMA) project: This should be its highest priority for participation in a major ground-based observatory. And Canada, through its space agency CSA, should also quickly join the Next Generation Space Telescope (NGST) project, as its highest priority for participation in a major space-based observatory. ALMA and NGST are seen as the two new, first generation world observatories that will appear in 2000-2010: They will be among the key observatories of the next century and have the highest priority in the USA, and European astronomical plans. But the LRPP looks even further: The panel strongly recommends that the Canadian Large Adaptive Reflector (LAR) concept be carried forward into prototypes for key component studies, as one of the highest priorities among moderate size projects. Canada is poised to play a leading role in the second generation of world observatories that will likely be constructed in 2010 - 2020, particularly in the unique and highly innovative LAR design concept for the world Square Kilometre Array (SKA) for centimetre wave radio astronomy. And the LRPP strongly recommends that a team be established to develop designs for an international Very Large Optical Telescope (VLOT) with about 25 meters diameter. |
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Mountains on the Sun caused by cyclone wavesThe surface of the Sun is covered with long-lasting depressions and humps that are very similar to oceanographic features on the Earth: This new result from SOHO is the most sensitive measurement ever made of a star's shape and links the fields of oceanography and stellar astrophysics. The surface of the sun is covered with 100 meter high "hills" each separated from the next by about 90 000 km. These hills are the solar equivalent to a pattern of terrestrial oceanic "bumps" of only a few centimeters in height. The oceanic hillocks barely move, crossing the atlantic and pacific over periods of months to years. The sun's bumps are caused by a phenomenon called Rossby waves which produce a grid of weak cyclones that generate the hills and valleys on the sun's visible surface.The solar features were measured from space with an experiment called the Michelson Doppler Imager (MDI), a part of the Solar and Heliospheric Observatory (SOHO). This experiment allows, for the first time, tiny changes in the position of the edge ("limb") of the sun to be seen. To detect these hills the MDI experiment measured the changing shape of the solar limb over almost a 3 year period as the sun's rotation carried the Rossby wave hills around the limb. Unlike previous techniques, which have looked for waves by measuring the brightness or velocity of the gas in the solar atmosphere, this experiment demonstrates the feasibility of measuring tiny changes in the position of the sun's atmosphere. |
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Sgr A* pulses every 106 daysAnother mystery in the center of our galaxy: Why is the radio emission from the accretion disk around the central massive object Sagittarius A* (pronounced "Sag A star") pulsing every 106 days? This unexpected periodicity has now been discovered during a computer analysis of 20 years of data from the Very Large Array radio telescope: The reason could be hot "bubbles" in the dense, rapidly- spinning disk of material being sucked into the central object, but what causes the periodicity of the effect is completely unclear. It is the first time any regular, quasi-periodic variation has been found in the radiation from Sgr A*. |
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Comet Hale-Bopp may have formed near Neptune, noble gas revealsThis conclusion is based on the first-ever measurement of a noble gas in a comet, which revealed it has an abundance of argon - the data come from UV observations performed during a sounding rocket flight in 1997, and the presence of abundant argon means that the comet has formed in a region of space that is no hotter than 20 degrees Kelvin: SWRI Press Release, SpaceViews, Space.com stories, ESA Science News.Are stellar collisions not that rare after all?Astronomers once thought stellar collisions never or rarely happened, but new research has convinced many that stellar mergers are commonplace and perhaps capable of producing the most violent and energetic events observable in the universe: CNN.Mir being prepared for hibernationThe cosmonauts working onboard the Mir space station have started preparing for their return home next month - the current plans are to mothball the station, as the next piloted launch to Mir is not expected until November: Space.com.The station is in good condition and can still be used for years: Interfax. Zvezda passes all tests and is ready for the July 8 to 12 launch (the precise date is fluctuating once more and will be announced later this month: Status): AP. The ISS could be lost if it loses pressure: SpaceViews. How to depose of the ISS in the end: NASA.
NASA enters a multimedia partnership with a private companywhich will result in everything from an online archive of existing NASA photos and videos to HDTV broadcasts from the shuttle and the ISS - but there will be a lot of competition: SpaceViews, Fla. Today ( earlier), RP, Welt. |
NASA's Mars programm open to all suggestionsNASA's Space Science Enterprise is openly considering all facets of its Mars Exploration Program starting with the 2005 opportunity and carrying through 15 years and beyond - in order to cast a wide net for capturing ideas and potential participants for missions, mission elements, and experiments, NASA is sponsoring a two-and-a-half-day workshop at the Lunar and Planetary Institute in Houston, Texas, on July 18-20, 2000: Space Daily. The options for 2003: Space Daily.Defrosting dunes on Mars look like bushes in new MGS pictures: Spacefl. Now. And another odd feature on Mars. Eleven new spectacular Io imageshave been released, continuing the series from Update # 190 story 5 sidebar: PIA025... 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60. What it all means: JPL Press Release (Spacefl. Now version), Discovery, Space.com, SpaceViews, Spacefl. Now.More sharp images of Mercury like those from Boston University (see last Update story 3) have been obtained by an amateur astronomer (also from Boston) with the same 1.5 meter telescope on Mt. Wilson at the same time - but with simpler equipment: a paper, MOS Press Release, pictures, SpaceViews, CNN. Mercury now in the sky: NASA Science News.
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Compiled and written by Daniel Fischer
(send me a mail to [email protected]!), Skyweek
