|
By Daniel Fischer Every page present in Europe & the U.S.!
| Ahead | Awards 
The latest issue!
| An experimental German companion. Current mission news: MGS (latest pictures!) + Cassini + Galileo + NEAR |
Mission Status, Homepage, NASA Sci. , LMMS, ASTRONET, Sp. Daily, Disc., Space.com.
| |
Compton Gamma Ray Observatory doomed: to be de-orbited around June 3rd!The reprieve for the aging big observatory satellite in February (see Update # 179 story 3 sidebar) was only temporary: On March 24th NASA announced that it intends to send the Compton Gamma Ray Observatory into the atmosphere after all. Despite intense efforts to find a safe mode of operation without the full complement of gyroscopes, the space agency wasn't going to risk the 17-ton spacecraft crashing out of control. "NASA plans to safely direct the satellite back into Earth's atmosphere no earlier than June 1 with the remaining two gyroscopes, which are used to steer the craft," the NASA announcement reads: "As an extra precaution, Compton engineers are also developing a method to control the satellite without any gyroscopes, for use as backup during the reentry maneuvers in case an anomaly is encountered with the gyroscopes.""Compton has been a workhorse for nine years, far exceeding our expectations for a two- to five-year mission," said Dr. Alan Bunner, director of NASA's Structure and Evolution of the Universe science theme: "New discoveries made by Compton changed our view of the Universe in fundamental ways." Compton's lasting legacy will be its impact on gamma ray astronomy: The telescope detected more than 400 gamma ray sources, 10 times more than were previously known (see sidebar for the ongoing analysis). Compton recorded more than 2500 gamma ray bursts; before Compton, only about 300 had been detected. "NASA must have a controlled reentry to direct Compton towards an uninhabited area in the Pacific ocean, " said Dr. Ed Weiler, Associate Administrator for the Office of Space Science: "NASA decided before Compton was launched that, due to its size, it would be returned to Earth by controlled reentry when the mission was over. This was always NASA's plan. "The propulsion system on Compton lacks sufficient fuel to boost the spacecraft to a higher, longer-lived orbit. But left alone, Compton will eventually fall from orbit due to a minute drag from the Earth's tenuous atmosphere, after 3 to 12 years. Unlike most other satellites, Compton is too large to burn up entirely in the atmosphere during reentry - and an uncontrolled reentry would expose some area under its orbital path (+/-28.5 degrees latitude) to the risk of falling debris. The decision to reenter Compton before a second gyroscope fails, even though the satellite is functioning normally, was made at NASA HQ on March 23, 2000, after extensive study to consider all options: Research showed it was significantly safer to perform a controlled reentry than any other method of dealing with the satellite. Debris from the reentry will be scattered over an area estimated to be 26 km wide and 1550 km long. The center of the reentry area is on the equator approximately 4000 km southeast of Hawaii (about 120 degrees west longitude). A large portion of the satellite will vaporize as it transits the atmosphere, and most of the pieces that survive will be tiny. However, Compton contains structures made of titanium, which are expected to fall as larger pieces: 30 to 40 fragments of more than 18 kg could reach the ground. |
| |||||||||
NASA vehemently denies allegations of MPL cover-upAccidental engine shutoff by ill-programmed switch remains leading theory for lossDid a veteran space journalist go overboard with dubious "sources" - or is NASA trying to cover up a major scandal that happened during the testing of the Mars Polar Lander, knowingly sending it onto a suicide mission? Since the independent investigation report about the loss of the MPL will only be released to the public on March 28th (19:00 UTC), it's hard to tell - but the fact that NASA has issued a detailled and unusually aggressive rebuttal to a simple wire service story is remarkable in itself and may reveal something about the waves the double loss of the Mars Surveyor 1988 spacecraft is making inside the agency as well as the U.S. government."James Oberg of UPI claims that NASA knew there was a problem with the Mars Polar Lander propulsion system prior to the Dec. 3 landing attempt and 'withheld this conclusion from the public,'" NASA says in a press release from March 22nd: "NASA categorically denies this charge." The basic issue had actually been widely reported last November - see e.g. the big sidebar of story 2 in Update # 157: The investigation of the loss of the Mars Climate Orbiter had turned up a potential problem with the descent engines of the MPL that might be too cold when the spacecraft reached Mars. "Had UPI researched the public documents released on Nov. 10, which have been available online at the NASA Home Page, the reporter would have been able to conclude that NASA did indeed publicly address propulsion issues, and specifically, the propulsion system's 'catalyst bed' temperature concern," the NASA statement reads: "Based on this review, NASA knew about the concerns with the propulsion system, NASA took corrective action, and NASA hid nothing from the public. We made our concerns known in early November." Oberg had claimed that some middle manager had manipulated tests of the engines and hidden the truth about the temperature concerns. The NASA release goes on to confirm that the possible design error in an MPL switch that could have led to an inadvertent shutting off of the descent engines (see Update # 176) is indeed one of several failure scenarios pondered by the investigators. But then the NASA statement ends in a most unusual fashion: Both investigation "teams have surfaced no evidence relating to thruster acceptance testing irregularities as alleged by UPI. In fact, members of the review teams are using words like 'bunk,' 'complete nonsense,' and 'wacko,' to describe their reactions to UPI's charge." |
| |||||||||
Amateur astronomers excited by close asteroidSeveral amateur astronomers have spotted the newly discovered asteroid 2000 EW70 (see Updates # 181 story 3 and 182 story 3 sidebar 5) in the vicinity of the Earth by now, both with CCD cameras (it trails fast) and visually. C. Harder caught it - despite hazy skies - on March 22nd with a 10" Newton and could see it move within minutes. And both he and another observer noted that the 13.9 mag. object was fuzzy and not a point source like near-by stars: It looked more like a Planetary Nebula. Since the diameter of 2000 EW70 should be between 200 and 300 meters, given its absolute magnitude of +21, it doesn't seem possible that the observers were visually resolving its disk. Other observers on March 21 describe the asteroid's image as clearly stellar. (Harder in astro@naa.net March 22 + Marsden, personal message March 23 + Hasubick, pm March 24) |
|
Ariane 5's 5th mission a full successThe flight was delayed 31 minutes because of last-moment troubles with weather, one of the satellite payloads and a suspect reading from a sensor in the liquid oxygen fuel line at the launch pad, but eventually the rocket made it off the pad and delivered two communications satellites into orbit - the first 'real' commercial customers. It was also the first launch of Ariane 5 that totally demonstrated the configurations which will be used in the future: Arianespace Press Release, Spaceflight Now, SpaceViews, Space.com, WELT, RP, AP, AFP, BBC.Sea Launch assembles Review Board to investigate launch failure - so far the company isn't commenting on the Ukrainian theory of a ground system software error: News Release. A giant seaplane could launch vehicles into space - the plan is to mount a spaceplane on the back of a 1500-tonne, rocket-propelled seaplane, known in Russia as an "ekranoplan": New Scientist. Another amateur space launch attemptA group of spaceflight enthusiasts hope to break the government and industry stranglehold on the "final frontier" this weekend by becoming the first amateur organization to ever launch a rocket into space: Space.com.Amateur rocket altitude record in the UK - Sheffield Rocketry Association reaches 4.4 km: BBC. Ultra Low Frequency waves within Jupiter's middle magnetospherethat had already been detected by the Voyagers and Ulysses are also evident in data from Galileo - 88% of crossings through the equatorial current sheet have some wave signatures in at least some component of the magnetic field in the 10 - 20 minute period regime: Geophys. Res. Lett.Space anniversaries galoreThe following events have moderately 'round' anniversaries these days, in addition to the EVA anniversary mentioned at the end of the last Update:
|
JPL damages HESSI satellite during shake test!NASA engineers running ground tests on the $40m science satellite mistakenly shook it with 10 times as much force as planned, cracking its wing-like solar arrays and damaging the spacecraft's frame - the launch will slip from July to next January the earliest: Space.com, AvNow, AP, SpaceViews, JPL, NASA Press Releases. JPL innocent? AP.13 free-floating planets in the Orion Nebula discoveredThe most sensitive survey ever undertaken of the region in the Orion Nebula where new stars are forming has revealed 13 "free-floating planets" (i.e. objects with less than 13 Jupiter masses) as well as more than one hundred very young brown dwarfs: RAS Press Release (SpaceRef version), BBC, Space.com = EZ, SPIEGEL, SpaceViews.Anarchy in the heart of the SunThe ghostly particles called neutrinos, which come in three different flavours, can inter-convert between the three in a thoroughly irregular way that the researchers call 'neutrino anarchy' - the existing results on neutrino oscillations evince no requirement for symmetry, and the flipping could just as well happen at random: Nature Science Update.Solar cycle update - maximum still not here: SpaceScience. Coronal Mass Ejections and their consequences: Gannett. EU approves "Astrium" space industry mergerA satellite joint venture between Matra Marconi Space and DaimlerChyrsler's aerospace unit DASA has now been approved - Astrium is expected to be Europe's leading space group and one of the biggest on Earth, with sales of 2.25 billion euros (2.4 billion dollars) and a workforce for more than 8000: Space.com, AFP.
|
All other historical issues can be found in the Archive.
The U.S. site of this Cosmic Mirror has been visited
since it was issued (the German site has no counter).
Compiled and written by Daniel Fischer
(send me a mail to dfischer@astro.uni-bonn.de!), Skyweek