The Cosmic Mirror

of News events across the Universe

Compiled and written by Daniel Fischer, Skyweek - older "Mirrors" in the Archive - and find out what the future might bring!


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Update # 158 of November 26th, 1999, at 16:30 UTC

5000+ meteors per hour: Leonids yield formidable storm!

It was a night that made history: On the morning of November 18th, the Earth experienced the first meteor storm since 1966, one of only four this century - and the peak struck exactly on time, just as predicted by the new dust trail model by David Asher and Rob McNaught (see Updates # 153 [story 2] and 157). Both astronomers (and yours truly as well) were among the guests of the Jordanian Astronomical Society for a unique meteor conference and an observing camp deep in the desert (see my special report) and could experience the triumph of their work with their own eyes: Meteor stream prognosis has matured into an exact science!

Asher/McNaught model gets timing right, strength wrong

But while the time of the maximum was hit spot-on by the model and the expectation that most meteors would be faint became true also, the surprising strength of the outburst was not foreseen - the zenithal hourly rate (ZHR) grew to roughly 10 times the anticipated value, peaking at more than 5000 in 5-minute intervals around 2:04 UTC. Also the time profile of the storm and the shower in general from Nov. 17 til 19 was more complex than expected, with a secondary storm peak of about ZHR 3500 ten minutes before the main peak and a broad shallow maximum with a ZHR in the low 100's 15 hours later (the latter best seen from China).

While the secondary maxima might be attributed to specific dust trails other than the 1899 specimen that produced the main peak, the strength of that outburst is a real challenge for the dust model. Its fathers had always stressed that calculating the times was the easy part (involving mainly rigid celestial mechanics), while the forecasts of the ZHRs relied on reports from past storms. Now it seems likely that many of those had been underestimating the number of meteors in the sky by a factor of several - but whether the already high predictions for Leonid storms in 2001 and 2002 now need to be raised even higher, remains to be figured out.

Meteors were raining from the sky...

Even though the 1999 storm was modest compared to the three big ones of 1799, 1833 and 1966, it still strained the capabilities of even many experienced meteor watchers to count the meteors and to record their brightness (which is important, too) - quite a few at Al Azraq actually stopped scientific recordings altogether in the 20 minutes or so around the peak, 45 minutes before dawn. The heavenly vista was just too overwhelming: Up to 100 meteors could be seen with the naked eye in one minute, often half a dozen simultaneously, and it actually felt as if they were streaming from the head of Leo (thus the name radiant for the point where they seem to originate). No technical system available today, be it photographic or video, could capture in full what we saw in these precious minutes.

Other successful observing sites with similiarly high meteor rates and fine skies were in Israel and Egypt, while all around the Mediterranean and in Europe often bad weather prevailed (and the lower radiant also meant fewer meteors visible to the eye). The best locations here were in Southern France and Spain, while unexpected cloud holes could open anywhere anytime (such as in Darmstadt, Germany, and in some places on the North Sea coast), but mostly didn't. When the radiant rose in North America, the storm was already over, and most observers there felt that the early 1998 shower with its preponderance of fireballs (see Update # 111) has been a better display.

Ample science, strange numbers from international campaign

For the 2nd year in a row a major international observing campaign had been put together to a) provide "situational awareness" for satellite operators (who would have taken action to safeguard their spacecraft in the case of a major storm) and to b) get the most science out of the rare Leonids activity. While in 1998 NASA and a joint Canadian astronomers/USAF group had gone different ways (see the special report on the Mongolian activities of the latter), this time they had joined their forces. Observers with video and radar equipment on more than half a dozen ground sites around the globe and an two aircraft reported their observations to a "Leonids Environmental Operations Center" at NASA's MSFC in Huntsville.

The scientific part of the operation, esp. the observations from the aircraft, seems to have gone very well, and lead scientist Peter Jenniskens was elated. But something went seriously wrong with the situational awareness part: The number for the maximum meteor rate the LEOC provided, 1688, was too low by at least a factor of 3, and the value of 2200 provided by the European Space Agency was too small as well. The Cosmic Mirror has learned from several sources involved in the campaign that the meteor counting had gone smoothly, be it visually or via intensified video feeds (as on the planes) - but that the conversion of these data into a precise ZHR value has apparently failed. It's thus still a long way to a fully automated worldwide network of meteor watching machines (that the USAF already dreamt about last year).


Several Leonid hits seen on the dark side of the Moon!

The Leonid storm of 1999 brought yet another first: At least five times video cameras (from amateurs!) captured brief flashes on the dark side of the Moon that are most likely related to impacts from Leonid meteoroids. At the moment it is rather unclear how big those particles were, but their effect - impacting with over 70 km/s - was remarkable. The first indication came from a visual (!) report: Brian Cudnik in Houston, Texas, was watching the Moon with a 14-inch telescope, when he saw a brief bright flash near the center of the dark side. At the same time David Dunham was videorecording the dark side of the Moon using a 5-inch telescope at Mount Airy, Maryland. Sure enough, when he played back the tape, the event was there in the location described!

And that was only the beginning: Soon Pedro Valdes Sada reported two lunar flashes that he videorecorded near Monterrey, Mexico, about half an hour after the event seen by Brian Cudnik - and those flashes are on Dunham's tape as well. And finally David Palmer reported two more lunar impacts that he videotaped at his home in Greenbelt, Marylandi - again also visible in the video recording Dunham made at Mount Airy, about 60 km to the northwest. That brought the total to five confirmed lunar impacts: four on Dunham's tape and also on videotapes made by others, and the other, the first one reported, confirmed with Brian Cudnik's timed visual observation.

"Brian Cudnik reports that the flash he saw was yellowish-orange in color," writes Dunham, "redder than nearby psi1 Aquarii. All of the videorecordings are black-and-white. A third probable untimed visual confirmation of that event has been provided by Steve Hendrix, who watched the dark side of the Moon with a 4.5-inch Meade telescope from Cameron, Missouri. [...] Before hearing about Cudnik's and my description of the flash, Hendrix was hesitant to share his observation since he had 'never seen anything like this before and didn't want to appear over zealous'."


A complete link list is at the end of the Jordan report - some selected highlights:
Still the best photograph of the storm and some image processing experiments on it are on another special page.
Pages with observations & early analysis:
IMO, AKM, DMS, Astronomy Online, ESO, JAS, AMS, BAA, L. Comolli, MAC'99, NASA, LeonidStorm.com.
Press Releases: Collections from NASA and ASTRONET. Individual early releases by NASA Ames, NASA MSFC, ESA, RAS and IMO.
News coverage:
Collections by SpaceRef, Space.com, SpaceViews, Yahoo U.S. and Yahoo D. Selected articles from CNN, BBC, ABC, Discovery, CCNet, ExploreZone, SpaceViews, Astron. Now, MSNBC and CSM.
Some insights before it stormed:
The final model predictions, why others failed (story 3), articles from McNaught and Fischer; stories from Discovery, ExploreZone, SpaceViews, RP and ESA.
Leonid hits on the Moon:
All data as collected by IOTA. News coverage of the first discovery by NASA Science News (which had also called for observations before the storm), BBC, Space.com and SpaceViews.

Related news:
No "Linearids" were seen, as expected, on Nov. 11: SpaceViews. Vague radar echoes were reported, though: Ondrejov.

Galileo survives 2nd Io flyby - after emerging from safemode at the last moment

The radiation-battered Galileo spacecraft has completed the closest-ever encounter with Jupiter's volcanic moon Io early on Nov. 26th UTC, but not before giving ground controllers a Thanksgiving day white-knuckler. Galileo dipped to the planned 300 kilometers above Io at 4:40 UTC. But only four hours before the flyby, while Galileo was being bombarded by strong radiation near Io, its onboard computers had reset and placed the spacecraft into standby mode. Onboard fault protection software told the spacecraft cameras and science instruments to stop taking data and enter a safe state until further instructions were received from the ground.

Galileo engineers at NASA's Jet Propulsion Laboratory sprang into action, scrambling to send new commands to the spacecraft and bring it out of safe mode in order to save the flyby. "With so little time to spare, it would have been easy to think 'no way' can we do this," said Galileo project manager Jim Erickson. "But our team members jumped to the challenge, in some cases leaving behind half-eaten Thanksgiving dinners." The team finished sending new computer commands to Galileo, which were received and executed by the spacecraft at 4:45 UTC, four minutes after the closest approach. This enabled the spacecraft to complete more than half of its planned observations of Io and its plasma torus and all the planned observations of Europa!


Galileo Mission Status and ABC and SpaceViews coverage.
Related:
More pictures from the October Io flyby were released on Nov. 19th - the latest flyby has shown us gigantic lava flows and lava lakes, and towering, collapsing mountains. The new data focus on three of Io's most active volcanoes, Pele, Loki and Prometheus: NASA Science News plus JPL Press Release; coverage by Space Daily, CNN, ABC, SpaceViews.
Galileo probe revealed strange composition of Jupiter's atmosphere - did the planet not form where it is now? The gas giant was found to contain two to three times more of the heavy noble gases Argon, Krypton and Xenon than one would expect had it formed solely from solar nebulae. It also had about three times more nitrogen than would be expected under the prevailing models of how our solar system formed. Press Releases from U. Michigan, JPL and ARC; coverage by Nature, ExploreZone, ABC, Space Daily, New Scientist, SpaceViews.

Two direct detections of extrasolar planets

have been reported in mid-November: One planet has made itself known both by tugging on its sun and by passing in front of its disk, while the other is reflecting light from its star - that has now been extracted from the overall spectrum. While the data on the first case are freely available, the details about the 2nd discovery are still embargoed, pending publication in the scientific literature.

The planet of HD 209458, yet another 'hot Jupiter', was first detected with the classical radial velocity method by Geoffrey Marcy and colleagues on Nov. 5. As with all new planets they detect, the team immediately brought it to the attention of collaborator Greg Henry, an astronomer who conducts research with several automatic telescopes. Henry turned one of them on the star at the time Marcy had predicted the planet would cross the face of the star if the planet's orbital plane were lucky enough to carry it between Earth and the star. And for the first time it worked: On Nov. 7 Henry observed a 1.7 percent dip in the star's brightness! Now we know precisely that the planet's mass is 0.63 Jupiters, and from the transit light curve we also know that it has 1.6 times Jupiter's diameter. It probably didn't form in its present location, just 7 mio. km from the star, but has migrated there.


All about the discovery.
Stories from NASA Science News, ExploreZone, Space Daily, SpaceViews and Fla. Today.
Articles from Science News and BBC (both with an independent confirmation of the transits).

Related articles:
"When Stars Cause Indigestion" - it is becoming clear that when old stars grow huge enough to swallow their planets, they can become quite ill: New Scientist.
"New Object in Solar System Defies Categories" - 1999 TD 10 is the first observational evidence that there's no difference between scattered disc objects and centaurs: Space.com.

The possible detection of starlight off a planet comes from the Tau Bootis system whose planet was already discovered in 1996. But only now has high-resolution optical spectroscopy been able to - probably - detect the Doppler-shifted signature of starlight reflected from the giant exoplanet. The data give the planet's orbital inclination as 29 degrees, indicating that its mass is some 8 times that of Jupiter. And they suggest strongly that the planet has the size and reflectivity expected for a gas-giant planet.

A 'secret' preprint you may read but not talk about in public until Dec. 22nd - it's the law...
Coverage nonetheless by BBC and MSNBC.
Tau Boo entry in the Extrasolar Planets Encyclopaedia.

China tests manned spacecraft, hardware has Russian heritage

Officially it's "another milestone in China's astronautical history" and "the country's new major breakthrough in manned space flight technology," but Western analysts are not very impressed by the Shenzhou space vehicle that performed a brief unmanned test flight on November 21st - it looks like a hardly modified copy of the Russian Soyuz capsule. After months of speculations about China's timetable, it now seems likely that the first manned mission will follow sometime in 2000.

While China calls the Shenzhou "completely indigenous", American experts in particular are convinced that China simply paid Russia (a lot) for sharing its 40 years of experience. And even Chinese media are now reporting about a "secret accord signed with Russia following President Boris Yeltsin's 1996 visit." During the test flight the capsule carried a dummy 'taikonaut' and many instruments - the analysis of the flight data should be taking several months now. Other 'payloads' included various flags, seeds and stamps...


Official coverage of the Shenzhou flight from Xinhua, mirrored by SpaceRef. Plus Shenzhou pictures.
Ample news coverage from SpaceViews, BBC, Fla. Today, MSNBC, ABC, Space Daily, CNN, Space Daily and CNN (on what it meant for China), SPIEGEL, Space Daily (on the U.S. reaction), BBC and Space Daily (on the Russian roots), Space Daily (with further thoughts) and Space Daily (on the payload).

Somewhat related:
Japan's H2 rocket fails again, destroying MTSAT: NASDA infos, Space Daily, Fla. Today, SpaceViews coverage.
Russia's Proton remains grounded until at least March 2000, but other rockets have resumed their launches from Baikonur: SpaceViews, Space Daily, Space.com.
Report on the Delta 3 disaster says Boeing underestimated the design challenge: Press Release.

Hubble in safe mode - servicing mission delayed

After yet another gyro has died on Nov. 13, the Hubble Space Telescope is in a stable - but scientifically useless - safe mode, waiting for the emergency servicing mission that NASA is preparing since spring. But the launch preparations themselves have run into further trouble, with Discovery's takeoff now set for no earlier than December 9th - new repairs to wiring between the shuttle and its external tank had become necessary. The new push back of the launch date leaves NASA little room for additional delays.

The gyro failure: ESA Release and coverage from SpaceRef, SpaceViews, CNN, Space Daily, Space.com, BBC.
New STS-103 delay: ESA News, stories by MSNBC, Space.com, Fla. Today, SpaceViews.
The 2001 servicing mission: Space.com.

Related: Multiple Galaxy Collisions Surprise Hubble Astronomers - STScI Press Release, coverage from CNN, ExploreZone, Space.com, SpaceViews.

AO resolves Kleopatra: a contact binary asteroid?

New Adaptive Optics images of the main-belt asteroid (216) Kleopatra have shown it to be not only a very elongated object - but it could actually be two asteroids next to each other, forming a so-called contact binary. Kleopatra has been known for long to be an interesting body: Its light-curve shows amplitudes so large that it had been modeled as a very elongated tri-axial ellipsoid (a/b=2.6; b/c=1.3). The asteroid was observed on 25 Oct 1999 at ESO's 3.6 meter telescope on La Silla with the ADONIS Adaptive Optics system.

Deconvolved images display a nearly-contact binary system: The two distinct lobes are of similar size and magnitude (flux ratio is around 0.8) with a separation estimated to 0.125 arcsec, close to the diffraction limit of the 3.6 m telescope. Kleopatra is thus comprised of two similarly sized lobes, neither of which is small enough to be called a moon. Such asteroid binaries raise questions about their origin: Some are thought to have been knocked from other larger bodies, others might be congealed piles of space rubble left over from the initial formation of the solar system.


Kleopatra AO special page and a Space.com article.
Related news:
Now 200 Potentially Hazardous Asteroids known - this milestone was reached with 1999 VP11, found on Nov. 7 by LINEAR. In less than 3 years this project has yielded more than one-third of all the PHAs, which are asteroids that can pass within 0.05 AU of the Earth and are more than about 200 m across: CfA Press Release, Space.com, SpaceViews, ExploreZone coverage.
How craters on porous asteroids may form: by compression instead of excavation. This process my have been at work on asteroid Mathilde: Space.com, InSCIght, SpaceViews.
Were the last of the dinosaurs roasted alive? The impact of a giant asteroid or comet in the Gulf of Mexico may have unleashed vast quantities of methane that set the air ablaze: New Scientist, BBC, Space.com.

TRACE, SOHO watch transit of Mercury

There was not much science in this event, but it made for many pretty pictures: When the planet Mercury moved in front of the Sun on Nov. 15th, it were not only amateur astronomers who were watching (from Australia and the U.S.) - the two solar science satellites in the Lagrange Point 1 between Earth and Sun were also having a look. For TRACE the view was similar to Earth's, and time-lapse sequences in different wavelengths show the planet entering and exiting the disk. But from SOHO's slightly different vantage point the planet never touched the disk and travelled across the corona instead. That could be used for measuring the stray light inside the optics of many SOHO instruments, though: Theoretically the disk should have been pitch-black; any residual brightening must be internal.

TRACE pictures & animations from Montana and Harvard.
SOHO pictures from ESA Science News and NASCOM.
What it was good for and other previews: ESA Science News, NASA Science News, Space.com, Space Daily.

A coming attraction - the Venus transit of 2004!


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Compiled and written by Daniel Fischer
(send me a mail to dfischer@astro.uni-bonn.de!), Skyweek