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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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So what did we learn from the Leonids 2000?Even though the rich display of the Leonid meteors last month has confirmed the predictions from the dust trail model in principle (see Updates # 209 and 210), there are still many open questions - and the forecast for 2001 is still uncertain by an order of magnitude with respect to the strength of the display. At the moment the detailled behavior of the 2000 Leonids isn't known yet as not all data are in: It seems likely (but not certain) that the two maxima of Nov. 18 were up to 1/2 hour "early", and there is some debate whether the 2nd maximum reached a ZHR of 420 or rather 700 to 800 (as several observers in North America say).Three different calculations based on the dust trail model had been published this year, for 2000 and later years (we won't deal with other ideas anymore as they failed completely in 2000): by Jenniskens & al. (Earth, Moon & Planets 82-83, 191-208 and 1-26), by Lyytinen & van Flandern (ibid., 149-166) and by Asher & McNaught (WGN 28, 138-143). The three studies take different observed or presumed effects into account and differ quite a bit in their predicted ZHRs - the times of the maxima predicted, however, agree to within a few minutes (UTC; rounded to the nearest 5 minutes below). Here is what the three groups had to say about 2000 (dashes mean: no prediction published):
Nov. 17 | 07:50 | 2-rev | Je: 207 | Ly: 215 | As: - So the first model has the 2nd night way too low and the first one too high, as has the 2nd which fares better in the 2nd night, while the third model has all maxima too low. Now here's what our modellers had to say about 2001 and 2002, respectively, before the 2000 data were in:
Nov. 18 | 10:00 | 7-rev | Je: - | Ly: 2000 | As: 2500 ?
Nov. 19 | 04:00 | 7-rev | Je: - | Ly: 4500 | As: 15000 While Jenniskens even in one of his papers says that his extremely low values for 2001 and 2002 come from "perhaps too simple geometric considerations", both Lyytinen and McNaught have claimed success after the 2000 experience. Lyytinen thinks that his rates for 2001 and 2002 may have to be reduced "somewhat", though he still expects "a good storm for the 4 rev. encounter in 2001." And McNaught believes that "the storm encounters we predict for 2001 and 2002 will occur within 5 minutes of our prediction and about a factor of two in the rates." (The EM&P volume represents the Proceedings of the Tel Aviv conference discussed in Update # 186 story 2 and is also available as a shockingly expensive 600-page book.) |
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Lunar "heavy bombardement" was a sharp eventLunar meteorite ages present new, strong evidence for the "lunar cataclysm," a 20-to-200 million-year episode of intense bombardment of the moon and the Earth at 3.9 billion years ago - just when the first evidence of life appeared on Earth. The rocks returned by the Apollo and Luna missions in the 1970s had already shown that the Moon was blasted in solar system debris back then, but all spacecraft were landed near the Moon's equator, on the side facing Earth, and no one could say if just this part or the entire Moon had been hammered. Now argon-argon dating has provided the impact melt ages of four lunar meteorites, rocks ejected at random from the Moon's surface: All of the Moon was bombarded 3.9 billion years ago, a true global lunar cataclysm. And there is no evidence for heavy impacts before 3.9 billion years ago, in contrast to theoretical models that assume a steady falloff in the lunar and inner solar system cratering rate through time. |
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New evidence for (water-deposited?) sediments on Marshas been presented at a NASA news conference - for a third time in the last 4 years such a media event, initially linked to the publication of a Mars paper in Science, has been moved forward after sketchy details had been leaked. On Dec. 4 the topic were layered geologic outcrops on the planet which may be composed of sedimentary rock that dates from the earliest span of martian history, between 4.3. and 3.5 billion years ago. Images of these sedimentary rock exposures, captured by the Mars Orbiter Camera (MOC), suggest that parts of ancient Mars may have resembled a land of lakes, and that the geology of early Mars was much more dynamic than previously suspected.If life existed on Mars during this time period (about which the data say nothing, of course), fossil remnants might be sandwiched within the sedimentary rock layers, just as they are on Earth. The martian outcrops, in some cases a few kilometers thick, appear to be made of fine-grained materials deposited in horizontal layers, the hallmark of sedimentary rock. They are found inside craters, between craters, and within chasms, and there are three main outcrop types: layered units, massive units, and thin mesa units. While sediments can be deposited in a variety of ways - including wind, water, volcanic activity, and even cosmic impact - the prevalence of the martian sedimentary outcrops within basin-like features suggests that they were deposited by water, perhaps in lakes that formed within the craters and chasms. Under this scenario, sediments may have been transported into the lakes in regular, swift pulses, building up thin layer units. Massive units may have been deposited when the lake became stagnant or deep enough to cause sediments to sift down through the water over longer intervals. The sedimentary units show no telltale signs of wind deposition, and the researchers concluded that explosive volcanic eruptions and impact cratering probably could not have produced enough sediment to create the large-scale and geographically widespread outcrops seen on the martian surface. Although water is the favored sedimentary suspect, there is also an alternative model that involves changes in atmospheric pressure on early Mars. Periods of relatively high atmospheric pressure - caused by fluctuations in the amount of solid carbon dioxide on the planet's surface - could have increased the atmosphere's ability to carry dust produced by heavy cratering. To confuse matters, there are no clues to where the original sediments came from, or how they were transported to their final resting places, since there are no traces of gullies or streams or other channels associated with the outcrops. Erosion may have wiped out both the source of the sediments and their travel routes. |
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Record-redshift galaxy claim withdrawnIt had been controversial from the start: the determination of a redshift of 6.68 for an extremely faint galaxy (see Updates # 104 lead and 126 small items). And now new studies of the object - known as STIS 123627+621755 or "Sharon" in some circles - have shown that its redshift must be below 5: The galaxy was seen in optical B and V images where it should have been completely invisible when at a higher redshift. Interestingly, though, the spectral energy distribution of the object cannot be fit by either any known galaxy template nor stellar spectra - the redshift thus remains undetermined.With the "loss" of the z=6.68 galaxy, the current record-holder for the extragalactic object with the highest measured redshift is the quasar SDSS 1044-0125 with z=5.80, discovered this year by the Sloan Digital Sky Survey (see Update # 186) - and it is also the most distant object detected in X-rays! The XMM-Newton X-ray satellite with its large collecting area was able to see the quasar, though only 30 photons were caught in an 8-hour exposure. Ten times fewer than expected: Either the quasar is well-shielded at the source, or it's actually a proto-quasar. |
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Hubble's spare mirror going to the NASMThe almost mythical "2nd mirror" for the Hubble Space Telescope, manufactured by Kodak as a back-up for the HST's main mirror, is finally coming out of storage and will go on display at the National Air and Space Museum in Washington. "I'm delighted to report that we now have a 100% green light for the transfer and shipping of the Kodak HST back-up mirror from Raytheon Systems in Danbury, Connecticut to the Museum for the Explore the Universe gallery," David Devorkin, NASM's curator for the history of astronomy, reported on Nov. 27, and the mirror safely reached the NASM soon thereafter."We hope to make the mirror visible to the public starting sometime after December 16th," says Devorkin: "It has been in storage in Danbury for over a decade, and was recently inspected by Kodak opticians, who found it in excellent shape. The HST mirror will be juxtaposed with the [Mt. Wilson] 100-inch cage, making the visceral statement that the largest optical telescope industry could produce at the beginning of the century now has been put into orbit. Even so, the master narrative created by Hubble with the 100-inch has not yet been overthrown by the Hubble Space Telescope." |
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ISS/STS-97 UpdateDuring their 3rd EVA on Dec. 7 the STS-97 astronauts made fast work of a solar wing fix-it job at the ISS, finishing up a billion-dollar bid to quintuple electrical supplies at the power-hungry complex. NASA's latest, the Mission Status and Journal and a detailled multi-part Preview.STS-97 MCC Status # 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 and ISS Status # 60. Plus an EVA picture gallery. Coverage of Dec. 8: Spacefl. Now, AvNow, Discovery, BBC, CNN, AP ( earlier), FT, RP, SPIEGEL, SpaceViews. Dec. 7: Spacefl. Now, AvNow, CNN (other story), AP ( earlier). Dec. 6: Spacefl. Now, CNN, AP, SpaceViews, AP, SPIEGEL, FT. Dec. 5: Spacefl. Now, FT, AP, SPIEGEL, SpaceViews (earlier). Dec. 4: Spacefl. Now (earlier), NYT, HC, BBC, CNN, AvNow, SPIEGEL, AP, SpaceViews. Dec. 3: CSA Press Release, AFP, SPIEGEL, RP, FT. Dec. 2: CNN, FT, Spacefl. Now, Discovery, AFP, HC, SpaceViews (earlier). Dec. 1: Science@NASA, VA Tech Press Rel., CNN, BBC, FT, HC, CNN, RP, SpaceViews, SPIEGEL, Spacefl. Now (earlier). |
Nov. 30:
CNN.
HC,
AP,
Space.com,
Reuters,
FT,
AP,
SPIEGEL,
SpaceViews,
WELT.
Nov. 29:
Science@NASA,
AW&ST,
HC,
AFP,
SPIEGEL,
Space.com
(
other story).
Nov. 28:
NASA Release,
Space.com,
FT,
Spacefl. Now.
Nov. 27:
LockMart
Press Release,
Spacef.
Now,
HC,
SpaceViews.
Nov. 26:
FT,
Science@NASA.
Nov. 25:
FT.
And a remarkable picture taken
during launch ...
:-)
SRB problem during Endeavour's launch - one of two explosive cartridges used to separate a strut holding the base of the orbiter's left-side solid-fuel booster to the ship's external fuel tank failed to fire: Spaceflight Now, FT, SpaceViews. Trips to the ISS to be won in European TV show - Astrium confirms the bizarre announcement by a German production company and the launch contract for 7 passengers in the 2002 to 2008 timeframe: Brainpool Press Release, SPIEGEL, WELT. Duma moves to save Mir - a resolution was approved that calls on the Russian government to find both budgeted and extra-budgetary means to support the continuous manned operation of the station: AvNow, Reuters, SpaceViews. Koptev confirms deorbiting: AFP. Tito's options: AP ( FT version), BBC, SpaceViews. |
Ulysses again over the solar south poleOn Nov. 27 Ulysses became the first space probe to fly over the south pole of the Sun twice, when it reached a maximum latitude of 80.1 degrees south: ESA Science News.Solar flares caused radio blackouts on the side of Earth facing the Sun: SpaceRef, Discovery, Space.com, ESA Science News. How IMAGE sees the Earth's aurora change in the far UV: BBC, SPIEGEL. NASA will try to contact its oldest space probe35 years after Pioneer 6 was launched: Space.com.The Deep Space Network struggles with high demand that could lead to a crisis in 2003: Space.com. First Iridium satellite reentersThe first Iridium telecommunications satellite to reenter the atmosphere broke up over the Arctic Ocean early on Nov. 29 - it was long dead, however, and the constellation of operational Iridium satellites, recently bought by another company, is safe: Space.com. Earlier = SpaceViews. And satellite re-entry notices.DoD will pay for unlimited Iridium use - the Pentagon decided to make only a two-year commitment to the service, however, to preserve its option to look at comparable services that may materialize in the near future: DoD Press Release, AvNow, AP, Heise, Space.com = SpaceViews. A clever stellar trick to align Giza's pyramidsin the N/S direction with arc minute precision may have been uncovered 4500 years later - the data look great, but it would shift the chronology: Nature Feature of the Week and Science Update, BBC, Space.com, Discovery.Nazca lines linked to water sources? They may be more than works of art: U Mass Press Rel., details. Sagittarius' 'teapot' on an Easter Island stone? It would be the first depiction of an asterism on Rapa Nui: paper by Hockey. The Center for Archaeoastronomy: Homepage. |
A search for a "Sirius C"with coronagraphs has come up empty and set new hard constraints on any unknown additional companions of Sirius A: Obs. de Paris Press Release and details.Stars "run away" for two reasons, SN explosions that destroy a binary partner and close encounters with other stars - runaway stars blaze through the heavens at up to 200 km/s: NSU. Israeli Earth satellite launched on Russian rocketA Start 1 rocket on Dec. 5 successfully launched an Israeli observation satellite into orbit from Russia's Far East - Eros A1 is Israel's first civilian photography satellite, with 1.8 m resolution: Press Release, Space Daily, AP, SpaceViews.Quickbird's loss still mysterious - was it a malfunction of the Cosmos rocket's 2nd stage, or did the satellite itself cause the disaster? SpaceViews. Earlier: Interfax. First space launch from Alaska next AugustKodiak Star, the first planned orbital launch from the new Kodiak Launch Complex in Alaska will be a NASA collaborative mission with the DoD - the payload consists of four small satellites to be launched aboard a Lockheed Martin Athena I launch vehicle on Aug. 31, 2001: KSC Press Release.U.S. Galaxy 7 television satellite lost in space - for the third time in two years an American-made telecommunications satellite has spun out of control in geostationary orbit after its computer brain malfunctioned due to a design flaw: Spacefl. Now. Japan postpones H2-A maiden launch to August 2001: AP, Reuters, AFP.
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Compiled and written by Daniel Fischer
(send me a mail to [email protected]!), Skyweek
