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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 |
Magnetic measurements give strongest evidence yet for Europa's oceanThe direction that a magnetic compass on Europa would point to flips around in a way that's best explained by the presence of a layer of electrically conducting liquid, such as saltwater, beneath the ice: These conclusions from measurements by the Galileo spacecraft this January (which had been evident just days after the encounter - see Update # 166 story 4) have now been published and are being hailed as the strongest evidence yet for a liquid ocean below the frozen icy crust today. The surface layers of Europa are made up of water that is either frozen or liquid: Earlier gravity measurements show a low density, such as water's, for the moon's outer portions. But ice is not a good conductor, and therefore the conductor may be a liquid ocean.Galileo has flown near Europa frequently since the spacecraft began orbiting Jupiter and its moons in December 1995. Pictures from those flybys show patterns that scientists see as evidence of a hidden ocean. In some, rafts of ice appear to have shifted position by floating on fluid below. In others, fluid appears to have risen to the surface and frozen. However, those features could be explained by a past ocean that has subsequently frozen solid - the magnetometer data is the only indication we have that there's an ocean there now, rather than in the geological past. The evidence is still indirect, though, and requires several steps of inference to get to the conclusion there is really a salty ocean. |
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50 Brown Dwarfs in the Trapezium - and a census clarifies their roleProbing deep within a neighborhood stellar nursery, the Hubble Space Telescope's IR vision has uncovered a swarm of about 50 newborn Brown Dwarfs throughout the Orion Nebula's Trapezium cluster - further evidence that Brown Dwarfs, once considered exotic objects, are nearly as abundant as stars. The most complete inventory to date of Brown Dwarfs by the HST, meanwhile, has determined that like stars, there are more low mass brown dwarfs than high mass ones, and this trend continues down to low, nearly planetary masses: This conclusion is based on NICMOS observation of the young cluster IC 348 where 30 Brown Dwarfs were found. Those isolated ("free-floating") Brown Dwarfs appear to represent the low mass counterparts of the more massive stars - suggesting that stars and free-floating brown dwarfs form in the same way.However, the Hubble finding also offers the strongest evidence to date that free-floating brown dwarfs are a completely different population from the recently discovered planets that orbit nearby stars: They are far more common in isolation than in orbit around other stars. This suggests that the extra-solar planets and, by extension, the planets in our own solar system, formed very differently from how the Sun and other stars formed - stars through the gravitational collapse of molecular clouds and planets through the sticking of micron-sized particles of stardust. The study also found that Brown Dwarfs are unlikely to contribute significantly to the "dark matter" that dominates the mass of our galaxy and the universe - they contribute less than 0.1 percent of the mass of the Milky Way's halo. |
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Soyuz trouble during 2nd Cluster launch - but Fregat saved the dayOnly the power of the new Fregat upper stage made it possible that the 2nd pair of Cluster satellites reached its planned orbit because the Soyuz rocket underperformed, it has now been revealed. The incident is now being investigated and it is possible that the third stage may not have been completely filled with propellant and thus shut down earlier than planned. Fortunately the Fregat upper stage has a large propellant supply and an engine that can be restarted multiple times, so its burn could be prolonged until the planned parking orbit for the Cluster spacecraft was reached. By now all four satellites are in their final orbits and undergoing checkout, and by December all 44 instruments should be operational. |
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Delta 3 finally makes it in the 3rd attemptAfter two failed launches in each of which a real payload was destroyed, Boeing's new Delta 3 rocket has finally made it into orbit on August 23 - but this time only a data-gathering, simulated payload was aboard. While the orbit's apogee fell a bit short of expectations, it was still within specifications, and Boeing is hailing the flight as a complete success. Instruments aboard the 4-ton test satellite will provide information to further validate Boeing baseline data on launch vehicle performance.Designated DM-F3 for Delta Mission-Flight 3, the payload was designed to match the mass and frequency characteristics of common commercial communication satellites sized for Delta III. Thus, the interaction during flight between an actual payload and the Delta III was accurately duplicated. Delta III was designed to address the growing size of commercial satellites and move Boeing out of its role as a niche player in the launch industry: The Delta III can carry 3.8 tons to geosynchronous transfer orbit, or twice the payload of the Delta II. |
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Debris from explosion of Chinese rocket detected by satelliteThe space dust instrument (SPADUS) on the ARGOS satellite has detected a cloud of tiny debris particles that was scattered into space when the upper stage of a Chinese Long March 4 rocket unexpectedly exploded March 11 after five months in orbit: This is the first time that scientists have been able to link ultra-small particles to the break-up of a particular satellite. During its first year in orbit after ARGOS' Feb. 1999 launch SPADUS has recorded 195 impacts: Some impacts were produced by natural cosmic dust or cometary debris flying in from interstellar space, but most were the result of man-made orbital debris.SPADUS normally detects one orbital debris impact every two days, but there were three spikes earlier this year, the most pronounced of which has now been linked to the exploding Chinese rocket: That cloud produced approximately 40 impacts from March 25 to April 1. SPADUS generally recorded more impacts when ARGOS crossed or neared the orbital plane of the Chinese rocket. The cause of the explosion was probably residual propellant left on board the upper stage, a common problem in spaceflight that all spacefaring nations have promised to take care of. |
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Colliding galaxies full of superbubblesThe Antennae Galaxies, two colliding galaxies named NGC 4038 and NGC 4039, contain numerous "superbubbles" formed from supernova remnants - new Chandra observations provide a nearby example of the what it was like fifteen billion years ago when our Universe was young and galaxies were just forming: Chandra & IAU Press Releases, CNN, Discovery, SpaceViews.The role of the dark centers of galaxies, usually interpreted as supermassive Black Holes, is getting clearer now that Hubble's STIS spectrograph is finding these compact masses in most galaxies - 34 cases have already been logged: semi-popular review by Kormendy. The youngest massive star cluster in the Milky Wayis W49 - it appears to contain about 100 type O stars but it is so dusty that even IR telescopes cannot see them: IAU Press Release, Space.com.Pictures of the current Supernova 2000db by B. Brinkmann. X-ray pulses from neutron stars show frame-draggingX-rays from rapidly spinning neutron stars suggest that the fabric of space-time is being dragged around them as they rotate - data from the RXTE satellite seem to show the predicted Lense-Thirring precession: Abstract, Space Daily, Nature Science Update, NYT.Shifting arctic ice monitored by RADARSATUsing RADARSAT's special sensors to take images at night and to peer through clouds, NASA researchers can now see the complete ice cover of the Arctic - this allows tracking of any shifts and changes, in unprecedented detail, over the course of an entire winter: JPL Press Release & pictures, Science@NASA, Space.com.What does the current lack of ice at the North Pole mean? The discovery has been interpreted both as a sign of global warming and as a natural fluctuation: NYT, BBC, WELT, SPIEGEL ( earlier), SZ, AP. Cryosat promises more answers: WELT. Terra monitors forest fires, Hurricane Hector at the same time: JPL Press Release, fires, fires & hurricane. Hurricane Carlotta in 3D: Terra picture. Super typhoon Bilis images from various NASA satellites: JPL Press Release & pictures (individually: 1047 and 1048). ERS interferometry leads to reduced quake risk in N. California: JPL Press Release, picture, Space.com. Many moons and craters were namedduring the recent IAU GA - even the small moon of asteroid Eugenia: IAU Press Release. And there were also the usual dire warnings about radio & light pollution and celebrations of pro-am astronomy programs.Australian elected new IAU president - Professor Ron Ekers is a radio astronomer who heads CSIRO's Australia Telescope National Facility: Space Daily. Plus lots of stories from the IAU GA from Sky & Tel. |
Green Bank Telescope dedicatedIn an isolated mountain valley in W. Virginia, a giant radio telescope nearly as tall as the Washington Monument is about to start searching the sky for clues to the creation of the universe - the GBT has a 100 by 110 meters dish and is fully movable: Homepage, dedication info, First Light, AP ( Houston Chr. version), Space.com.Explosion of discoveries beyond NeptuneThe count of Centaurs, Kuiper Belt Objects and Scattered KBOs is going up all the time - and there are also weird objects now that cross into the main planets' orbits like the Centaurs but also wander way beyond Pluto, like the Scattered KBOs: IAU Press Release. Ice worlds beyond Neptune yield clues to history of the Solar System: IAU Press Release, SpaceViews.Comet dust can be amorphous as well as crystalline, and these properties seem to code the time when the matter was 'processed' in the early solar system: GSFC Press Release, Spacefl. Now, SpaceViews. Lots of large dust particles near the nucleus of comet Encke: paper by Reach & al.
The October ISS mission could be delayedbecause of a possible problem with stabilizing gyroscopes on the Z1 truss that Discovery will carry to the station: Fla. Today, Spaceflight Now. The truss: Fla. Today. NASA to fund studies of alternate Space Station access: SpaceViews. Launch windows for ISS missions will be shortened: Spaceflight Now.Will the ISS deliver science? Space.com. Key space station tech still weak: IDG. The people behind the ISS: Space.com. Russia's ISS funding problems remain unresolved: Interfax. And Status # 39. "Citizen explorer" enters training for flight to Mir - Dennis Tito has passed the rigorous physical and psychological screening to qualify as a cosmonaut: MirCorp Press Release, SpaceViews, AP. How life on Mir was for A. Thomas: Univ. Today. Columbia has 3,500 defects in wiring - recent inspections have revealed about 600 to 700 wiring defects in Atlantis, Discovery and Endeavour, but Columbia showed up in California with about 3,500: Fla. Today.
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Compiled and written by Daniel Fischer
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