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METEORS FROM HALLEY'S
COMET: The Orionid meteor shower, caused
by debris from Halley's comet, peaks this week. Forecasters
expect dozens of meteors per hour during the dark hours before
sunrise on Wednesday, Oct. 21st. Science@NASA has the full
story. Orionid meteor galleries: 2006,
2008
ROCKET FUEL DUMP:
A Centaur rocket caused a minor sensation
on Sunday night, Oct. 18th, when it flew over Europe and dumped
a load of excess propellant. "We saw it at 9:15 pm local
time (1915 UT)," report Federico and Chiara Bellini of
Bodio Lomnago, Italy. "It looked like a comet with a
fan-shaped tail." They took this 30-second exposure using
a Nikon
D70s:
"About 20 seconds later, a
second object appeared." That was a US military weather
satellite (DMSP F-18), which the Centaur booster had helped
launch earlier in the evening from Vandenberg, Air Force
Base in California. "And then," the Bellinis continue,
"a big circular halo followed the two across the sky."
The halo, shown here
in a movie recorded by Jonas Förste of Jakobstad, Finland,
was probably an expanding puff of gas emitted during an earlier
firing of the Centaur.
more images: from
Marko Posavec of Koprivnica, Croatia; from
Davide Trezzi of Varenna, Italy; from
Vince Tuboly of Hegyhátsál, Hungary; from
Quentin D. of le Havre, Normandy, France; from
Feys Filip of the Sasteria public observatory, Crete
LUNAR IMPACT PLUME:
There was a plume after all. Observers
on Earth had their doubts after LCROSS and its Centaur booster
rocket hit the Moon on Friday, Oct. 9th. The twin lunar impacts
failed to produce visible plumes of debris, prompting speculation
that something had gone wrong. On the contrary, members of
the LCROSS science team are now calling the experiment "a
smashing success."
Fifteen seconds after the Centaur hit the shadowy floor of
crater Cabeus, the LCROSS spacecraft flying 600 km overhead
took the following picture of a plume measuring 6 to 8 km
wide:
"There is a clear indication of a plume
of vapor and fine debris," says LCROSS principal investigator
Tony Colaprete of NASA/Ames. "The ejecta brightness appears
to be at the low end of our predictions and this may be a
clue to the properties of the material the Centaur hit."
Nine cameras and spectrometers on LCROSS captured
every phase of the Centaur's impact: the
intial flash, the debris plume, and the creation of the
Centaur's crater. "We are blown away by the data
returned," says Colaprete. "The team is working
hard on the analysis and the data appear to be of very high
quality."
But did the impact reveal any water at the bottom
of Cabeus? The LCROSS team isn't ready to say yet. Combining
their data with those of other observatories and analyzing
the full dataset could take weeks. According to NASA, "any
new information will undergo the normal scientific review
process and will be released as soon as it is available."
For more information, read NASA's Oct. 16th
press
release and browse the gallery
of images.
Sept.
2009 Aurora Gallery
[previous Septembers: 2008, 2007, 2006, 2005, 2004, 2002, 2001]
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