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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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Surprisingly bright radio emission from a Brown Dwarfhas been discovered with the VLA: LP944-20 had shown a "shocking" X-ray flare (see Update # 196 story 4), and now quiescent and flaring radio emission has been discovered from this source. This is the first detection of persistent radio emission from a brown dwarf - but with luminosities that are several orders of magnitude larger than predicted from an empirical relation between the X-ray and radio luminosities of many stellar types. LP944-20 apparently possesses an unusually weak magnetic field in comparison to active dwarf M stars, which might explain both the null results from previous optical and X-ray observations of this source, and the deviation from the empirical relations. |
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The end is coming later - and much quickerMir's mission control is now planning to bring down the space station with three de-orbit burns over just 4 or 5 orbits (or 6 to 7.5 hours), on the day its average orbital altitude has fallen to 215 to 220 km: This new plan, markedly different from the earlier scenario with 4 burns spread out over several days, has been confirmed to the Cosmic Mirror by leading experts of the German space agency DLR and the European Space Operations Center. The main reason for both the delay and the speeding up of operations is, as reported before, the need to keep Mir in a steady attitude during the de-orbit procedure, and that could had become too fuel-intensive under the old plan, with Mir struggling against the ever-increasing air drag for days.The disadvantage of the faster scenario is that there remains less time between the burns to check Mir's new orbit for their accuracy: The first two burns will come during two subsequent orbits, the last one either during orbit 4 or 5, depending on the selection of the actual impacting trajectory (every window for dumping Mir offers about 3 suitable subsequent orbits). On March 13th, Mir's orbit was shrinking by 2.2 km per day, and when it will have reached 220 km, it'll decay by 4 km per day. This crucial mark will be reached on March 21 (+2,-1 days), according to the Trajectory Report #55 of March 14 - and flight controllers now believe that they'll take Mir down on March 22 at 6:21 UTC. Even if left alone, Mir would be gone by March 28th +/- 3 days: The station is history by month's end even in the (unlikely) case all control would be lost.
On reaching the altitude of 250 km, three de-orbit (breaking) impulses will be performed by the special Progress ship docked to Mir since Jan. 27, over a period of 2 to 3 days to lower the station's orbit to approximately 220 x 150/160 km with the perigee above the planned final impact point in the southern Pacific. The final de-orbit impulse (approx. 20 m/sec) will be carried out within the 3 days immediately following completion of the three initial impulses. The final impulse (lasting approximately 800 sec) will be initiated in the area of Africa and will be completed over Russia, with a predicted impact point (to be reached approximately 45 min later) to the southeast of Australia at approximately 47 degrees south 140 degrees west. |
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NASA Pluto mission alive again - kind ofThe apparent decision to kill the just-revived Pluto mission (or rather the competition for a possible mission; see last Update story 3) has been reversed again! "NASA has been requested to allow the AO proposals to be submitted" by some high-ranking member of the U.S. Congress, Colleen Hartman, NASA's Outer Planets Program director has told SPACE.com: "If the Congress appropriates funds for the Pluto-Kuiper Belt mission, we [at] NASA will proceed with funding of a winning proposal, if there are any. But all those proposing should be aware that the [Bush] administration does not support this course of action," Hartman added. According to Space.com, Senate Appropriations Committee staff notified NASA that both majority and minority appropriations members would object to a termination of the Announcement of Opportunity (see Update # 213). Meanwhile solar physicists are fighting to save the terminated Solar Probe mission as well. |
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NASA trashes X-33 and X-34 and starts from scratchAlmost a billion dollars of public money has been sunk into the X-33 project since 1996, and Lockheed Martin has burned another $360m of its own money - but a flight-tested model of a possible successor for the space shuttle the result was not. Already last year NASA threatened to abandon the program but allowed it to compete for Space Launch Initiative funds with other concepts - not anymore: "NASA determined that the benefits to be derived from flight testing these X-vehicles did not warrant the magnitude of government investment required and that SLI funds should be applied to higher priority needs." What those would be has not been announced yet, but one thing is clear: Any decision on an STS successor (and thus that vehicle itself) will now come at least 5 years later than hoped in 1996, and the space shuttle is likely to serve as NASA's only own manned access to orbit until 2015 the least. The X-34 is also gone, BTW. |
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The 'small comets' raise their head again - do they?Ever since the idea that a rain of 10-meter-sized comets is pummeling the Earth's atmosphere 20 times a minute had been discussed and widely rejected during the famous "snowball fight" more than three years ago (see Update # 66 story 3), few people had still cared about that bizarre hypothesis, staunchly defended by one respected geophysicist and rejected by about everyone else. But both this scientist and his critics had carried on with yet another test of the hypothesis: The small comets, if they existed, should be detectable as faint point sources in space, before dispersing above the atmosphere. The Iowa Robotic Observatory (IRO) was put to the task of searching for exactly those objects.In December of 1999 the verdict was in, or so it seemed: "University of Iowa astronomy professor Robert Mutel announced today that an eight-month search using an Arizona-based telescope has failed to detect evidence supporting a 13-year-old theory that small comets composed of snow are continually bombarding the Earth," a press release said - but on March 1, 2001, the very same service has now reported that "University of Iowa Physics Professor Louis A. Frank says that he has found new evidence to support his theory that the water in Earth's oceans arrived by way of small snow comets," by spotting nine samples of 'his' objects on 1500 IRO images. Experts on the matter contacted by the Cosmic Mirror have already expressed their doubts and think that - once more - the data presented are just noise: The debate will go on for some time ... |
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Mysterious Cosmic Infrared Background component emergesThe cosmic background at 1.25 microns and 2.2 microns is significantly higher than integrated galaxy counts, suggesting either an increase of the galaxy luminosity function for magnitudes fainter than 30 or the existence of another contribution to the cosmic background from primeval stars, black holes, or relic particle decay: paper by Cambresy & al.Chandra Deep Fields continue resolving the X-ray background into distant active galactic nuclei (as already reported in Updates # 212, 209 and 167) - millions of seconds of exposure time have been devoted to specific sky fields: Chandra, ESO and JHU Press Releases, SC, Reuters, CNN, RP, SPIEGEL (früher). 2dF low-density Universe results now published in Nature: paper by Peacock & al., AAO Release, BBC, Astronomy, SC - the result that the density of the Universe is only 0.3 of critical was already mentioned in Update # 213 small items. Metal abundance variations in globular clustershave been discovered with the VLT, especially for the common elements Oxygen, Sodium, Magnesium and Aluminium - this phenomenon has never been seen in Sun-like dwarf stars before and might be evidence of "ashes" of earlier stars embedded in the younger ones: paper by Gratton & al., ESO Press Release.Adaptive Optics find close companions to 2 planet-bearing starsAn adaptive optics (AO) imaging survey of extrasolar planetary systems has detected stellar companions to the planet bearing stars HD 114762 and Tau Boo: paper by Lloyd & al.The age distribution of earth-like planets can be calculated from the evolution of the star formation rate of the Universe, the metallicity evolution of the star-forming regions of the Universe and the most recent observations of extrasolar planets: paper by Lineweaver. Mars' Volcanoes May Have Melted IceTwo of the oldest volcanoes on Mars, which have been active for 3.5 billion years, are surrounded by the largest and greatest numbers of channels associated with any Martinan volcano, indicating that there was a lot of water around when they were forming, though there doesn't appear to be any around now: Univ. at Buffalo Press Release, BBC, SPIEGEL.Observations of Mars from mid-Jan. to mid-Feb.: CMO, Parker, Hernandez. New pictures of Ganymede by Galileo: PIA 0321... 4, 5, 6, 7, 8. And a new HST view of Jupiter's aurorae. British Lords demand asteroid actionThe science minister was urged to do more about Near Earth Objects than just promise further studies: full transcript of the speeches, BBC coverage and comments.Flora, fauna rebounded quickly after the K/T impactLife was irtually wiped out for a period of time after the big impact 65 Myr ago, but then reappeared just as abruptly only 10,000 years after the collision, most likely a single catastrophic impact: CalTech Press Release, coverage by SC, SPIEGEL. |
How special will the "Space Jump" be?A parachutist is causing some excitement with the announcement to jump from 40 km altitude (about half way to space) in March 2002 - but already in 1960 (!) Joseph Kittinger has jumped from a comparable altitude of 31 km, and already this October Cheryl Stearns ("the most decorared skydiver in the world") is planning to jump from 40 km as well: Kittinger's bio, another one, jump details and a 1998 FT story, Stearns' homepage and her Stratoquest, the new announcement [SD] and coverage by BBC, SPIEGEL, AP.
ULDB flight ends early againThis time the Ultra Long Duration Balloon failed to regain its proper daytime pressure and was brought down over the coast of Australia rather than allow it to float out over the ocean: Hot News, Wallops Release (earlier), AFP, CNN (earlier), BBC, AP (earlier ).First, direct observational evidence of a change in the Earth's greenhouse effectThere has been a significant change in the Earth's greenhouse effect over the last 30 years, a finding which is consistent with concerns over so-called 'radiative forcing' of the climate - previous studies have depended on theoretical simulations, but now data sets collected by two different earth-orbiting spacecraft in 1970 and 1997 unequivocally establish that significant changes in greenhouse gas emissions from the Earth have caused the change to the planet's greenhouse effect over this time period: Imperial College Press Release, Reuters.Microbes flying across the Galaxy aboard meteorites? There is a slim chance that microbes could be carried from one solar system to another on rocks blasted from terrestrial planets by asteroid impacts, spreading life across the Galaxy: New Scientist.
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Compiled and written by Daniel Fischer
(send me a mail to dfischer@astro.uni-bonn.de!), Skyweek