And new: An experimental German companion to the CM.
Five planets in the sky / Venus, Moon & Regulus in triangle: NASA Science News, Houston Chronicle and ABC Raw News.
Update # 150 of October 6th, 1999, at 18:45 UTC
MCO controllers had doubts about trajectory, did nothingThe flight controllers of the Mars Climate Orbiter had detected a discrepancy between two types of tracking information during the spacecraft's voyage to Mars but decided not to act. Several days before the MCO rammed into the Martian atmosphere it had been noted that measurements based on the Doppler shift of the MCO's radio signal and others based on ranging data gave somewhat confusing results. A discussion was prompted on whether another late trajectory correction might be necessary just before orbit insertion. But as the discrepancies were small (and not uncommon in interplanetary navigation) it was decided not to do the manoeuver: Any targetting error was thought to be within safe limits. (Nature of Sept. 30, 1999, p. 415)Whether another course correction would have saved the MCO is unclear at this point. It is now believed that the spacecraft probably bounced off the Martian atmosphere and is now on a heliocentric orbit but that it was damaged so severely by its unintentional hard aerobraking that it doesn't respond commands anymore. The fatal deviations in the trajectory had been building up over time through slightly wrong settings of small thrusters - the effect of the units mix-up between LockMart in Denver and the JPL in Pasadena was on one hand just big enough to doom the mission but small enough to escape serious attention... (Washington Post of Oct. 1st etc.) |
Update on the investigation from Space.com. NASA's embarrassing mistake should prompt wide review: an editorial from Florida Today. Metric Mandate after Mars Mishap? ABC. Can't happen on the ISS? Space.com. Is cost-cutting to blame for MCO's loss? Or was it just a "breakdown of communications"? Space.com. In other Mars news: Martian meteorite carbonate 3.9 Gyr old - the carbonate minerals in ALH 84001 were formed about 3.9 billion years ago when the planet had flowing surface water and warmer temperatures: JSC Press Release; ABQ Journal, Astr. Now, Space.com and SpaceViews stories. Mars a target for space tourism? Only if you learn metric units... Space Daily. More on space tourism visions from Wired. Can Martian microbes endanger the Earth? A statement by a Mars Sample Return critic. Eric Idle, The Road to Mars - a book review from Space.com. |
Gamma Ray Bursts and Supernovae: a connection after all?There is yet another twist in one of the most dynamic research arenas in modern astrophysics: The last few months have brought several lines of evidence that two of the most energetic phenomena in the Universe could be linked. When it was established 2 1/2 years ago that Gamma Ray Bursts (GRBs) come from very distant galaxies (see Updates # 40, 47 and 58 for early articles from 1997), the search for the ultimate mechanism of these giant explosions soon concentrated on two scenarios: mergers between neutron stars or neutron stars and black holes - or collapses of very massive stars (sometimes called hypernovae).Since what we observe during and after an GRB is merely a relativistic fireball (i.e. an explosion expanding nearly with the speed of light) and its interaction with the interstellar medium, there is no way to spot the 'central engine' that blew up directly. So indirect evidence is needed to find the most plausible candidate(s), and the fact that many GRBs take place inside galaxies, often those with active star formation, has been interpreted widely (though not universally) as pointing towards exploding young stars: neutron star pairs would be old and should have drifted way out of their galaxies by the time they merge. Now new evidence has emerged linking GRBs to exploding massive stars. While the precise mechanism is still elusive and controversial, the observational evidence deserves attention:
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Observational papers linking supernovae and GRBs: Reichard and Galama & al. (evidence for a SN in the lightcurve and spectrum of GRB070228 - this was actually the GRB for which the first-ever optical afterglow was seen, revolutionizing the field). Bloom & al. (unusual afterglow of GRB980326; published in Nature of Sept. 30, 1999, 453-6). Germany & al. (SN 1997cy & GRB970514), Some theoretical attempts to link SNe and GRBs: Cheng & Dai (the highly complex 'two-step model' in which hypercritical accretion from the SN ejecta lets the neutron star implode to a black hole; the GRB is then created by a 2nd jet shooting out of that mess). Wang & al. (their neutron star turns into strange matter after a while, making the GRB). A press release regarding the Bloom & al. paper: Caltech Press Release. And an earlier release about the SN 1998bw case: NASA Science News. News coverage about Bloom & al.: SpaceViews, Astronomy Now, Space Daily, CNN, Space.com, ABC and the ABQ Journal. Other recent GRB developments: Fading embers hold clues to puzzle of gamma-ray bursts - afterglow points to long-sought shock-wave features: NASA Science News and many useful links therein as well as in these earlier science news items from Jan. 1998 and March and April 1999. A major GRB that took place right during a recent conference devoted to the phenomenon: UNH Press Release. Could GRBs be messages from aliens...? New Scientist. And lots of GRB links from CalTech plus a big list of all bursts with afterglows in various wavelengths and the GRB Coordinates Network. Recent reviews of the GRB field: Lamb (stresses both the open questions - and the fun of trying to answer them), Piran (very systematic review) and Paczynski (stresses the possible supernova connection). Coming attraction for the observers: HETE, the next GRB satellite: Homepage (launch currently set for Jan. 23, 2000). |
First light for new VLT instrumentA major new astronomical instrument for the ESO Very Large Telescope, the UVES high-resolution spectrograph, has just made its first observations of astronomical objects. The second VLT 8.2-m Unit Telescope, KUEYEN, is in the process of being tuned to perfection before it will be "handed" over to the astronomers on April 1, 2000; UVES is the first of three instruments to be installed there. It is a complex two-channel spectrograph built around two giant optical diffraction gratings, each ruled on a 84 cm x 21 cm x 12 cm block of the ceramic material Zerodur (the same that is used for the VLT 8.2-m main mirrors) and weighing more than 60 kg. UVES' resolving power may reach 110,000, a very high value for an astronomical instrument of such a large size. |
ESO Press Release. Other new picture releases: Hubble views structure of NGC 1365 in various wavelengths, revealing how the barred spiral galaxy is feeding material into its central region, igniting massive star birth and probably causing its bulge of stars to grow: STScI Press Release, ESA Science News, ABC, Space.com, CNN, SpaceViews, MSNBC. Pictures of the moon of asteroid Eugenia (reported in Update # 124, story 2) have been published in Nature - and are available here. Plus BBC, ExploreZone and SpaceViews stories. |
New comet visible naked-eye in 2000?Comet C/1999 S4 (LINEAR), currently at 17th mag., will reach a perihelion of 0.7 AU in July 2000 and could become visible to the naked eye with perhaps 3rd mag. (IAUC # 7267. See also VdS Fachgruppe Kometen Latest News and Morris' news page)How the Leonids "work"is explained graphically by D. Asher on a special website: The show depends on which particle clouds in space the Earth encounters and how old that cloud is. Finally a way to make reliable predictions? Here's Asher's try at 1999 ...Did Giotto discover a companion of comet Grigg-Skjellerup?Particle data from 1992 might indicate a fragment of the nucleus: IAUC # 7243, ESA Science News, Space Daily.Another potentially hazardous asteroidhas been discovered by the LINEAR system: 1999 RM45 has a chance of 1:250-330 million to collide with the Earth in 2042 and 2050. The NEODys risk page, details about the asteroid, CCNet, SpaceViews and MSNBC stories.The earliest observation of a Trojan asteroid was not in 1906 but 1904, it has been realized only now: CfA Press Release. How Venus' surface got its 'wrinkles'A period of high volcanic activity on Venus once affected the climate so severely that the energy was folded back into the surface, putting wrinkles on the face of our nearest planetary neighbor: ExploreZone, Space Daily.ESA considers insurance for XMMUsually scientific spacecraft are not insured, but for the hugely expensive XMM X-ray satellite ESA might make an exception as it has accidentally become customer #4 for the Ariane 5 - a rocket that has worked perfectly only once and has never flown operationally. That scares many astronomers... (Nature of Sept. 30, 1999, p. 415)No insurance for NASA's space assets despite the Floyd scare: Space.com. |
Astronomy in the 21st centurywill be based on 'mining' enormous multi-wavelength data bases open to everyone, predicts S. van den Bergh.Two more extrasolar planetshave been announced recently by the Swiss planet hunters: a 0.76 Jupiter mass planet around the nearby star HD 192263 (details) and a Jupiter mass planet around HD 130322 (details). The Exoplanets Catalog has now 20 entries of stars with planets that are most likely not brown dwarfs.NASA budget conference starts this weekA House-Senate conference committee is expected to take up differences between versions of an appropriations bill that includes NASA's budget this week, as efforts may be under way behind the scene's to restore the space agency's space science budget: SpaceViews. Will all cuts go away? Space.com. Triana probably doomed: Space.com.China plans launch pad in South China SeaChina is planning to build a satellite launching centre on Hainan island in the South China Sea - Hainan's low latitude could help increase the capability of rockets by up to seven percent: Space Daily, BBC.
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Compiled and written by Daniel Fischer
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