July 4, 2004
Cassini Peeks at Titan
By J. Kelly Beatty
http://skyandtelescope.com/news/article_1293_1.asp
Two days ago, as the Cassini spacecraft was settling into routine operations
while orbiting Saturn, it passed Titan, the planet's largest moon, at a
distant 339,000 kilometers (211,000 miles). That was too far away for the
mission team to consider the event an official flyby - but close enough for
the spacecraft's telephoto camera and an imaging spectrometer to take a peek
anyway.
The two instruments' snapshots show the surface in surprising detail,
despite the interference from Titan's opaque, haze-choked atmosphere.
Cassini's views reveal a tantalizing variety of straight, curved, and round
surface features, suggesting that the Mercury-size moon has been (or is)
geologically active. "We're seeing a totally alien surface," reports
Elizabeth Turtle, an imaging-team member from the University of Arizona.
Even this "raw" near-infrared image shows enigmatic geologic features. Is
this 700-km-long chain of dark markings a frozen river system? A fault
complex? An eruption of organic goo? Mission scientists are hoping to see
Titan's surface much more clearly in the months ahead. Courtesy
NASA/JPL/Space Science Institute.
Lots of subtle features are obvious even in raw, unenhanced images of Titan,
raising scientists' hopes that far more detail will become evident during
the first close brush (1,200 km away) on October 26th. After that there'll
be 44 additional flybys over the next four years, some as close as 950 km.
Titan's nitrogen-dominated atmosphere proved completely opaque in 1981 when
Voyager 1 swept by at a distance of just 4,000 km. The secret to Cassini's
success has been to view the enshrouded moon through specific slices of
near-infrared light, sometimes in combination with a polarizing filter, and
at these wavelengths the atmosphere is mostly transparent. The onboard
camera has been using a near-infrared filter at 938 nanometers (9380
angstroms), while the Visual and Infrared Mapping Spectrometer, or VIMS, has
found success farther in the infrared at 2.0 and 5.0 microns.
A large cluster of clouds, roughly 500 kilometers across and probably
consisting of liquid methane, floats high above the surface of Titan.
Cassini's telephoto camera recorded this near-infrared image on July 2,
2004, when the spacecraft was about 340,000 km away. Courtesy NASA/JPL/
Space Science Institute.
Thanks to earlier efforts by ground-based observers and the Hubble Space
Telescope, Cassini scientists suspected that brighter, higher regions on
Titan were "continents" of water ice, and that organic solids and liquids
probably covered the low, dark areas. But already this mysterious moon has
challenged those expectations. "At some wavelengths," comments VIMS
investigator Kevin Baines (Jet Propulsion Laboratory), "we see dark regions
of relatively pure water ice and brighter regions with a much higher amount
of non-ice materials, such as simple hydrocarbons."
Once it gets closer to Titan, Cassini will be able to use its onboard radar
system to probe and map the surface directly, without atmospheric
interference. And a much closer look at the surface should come early on
January 14, 2005, when the European-built Huygens probe plops or splashes
down after a 2-hour descent through Titan's atmosphere.
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| User: "Werewolfy" |
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| Title: Re: Cassini Peeks at Titan |
06 Jul 2004 12:46:30 PM |
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"mondo" <mondo@mondo.com> wrote in message news:<lBpGc.8898$_L5.47525@newscontent-01.sprint.ca>...
Cassini Peeks at Titan
================================================================================
Oh, I see now. A space probe.
When I read the headline Iggy Wiggy, I thought it was a post about
your latest toilet exploit.
Werewolfy
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| User: "mondo" |
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| Title: Re: Cassini Peeks at Titan |
06 Jul 2004 02:13:08 PM |
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But you do have a wicked sense of humor. You make me laugh!
"Werewolfy" <RickyColeclough@aol.com> wrote in message
news:85ebfda0.0407060946.7988d070@posting.google.com...
"mondo" <mondo@mondo.com> wrote in message
news:<lBpGc.8898$_L5.47525@newscontent-01.sprint.ca>...
Cassini Peeks at Titan
============================================================================
====
Oh, I see now. A space probe.
When I read the headline Iggy Wiggy, I thought it was a post about
your latest toilet exploit.
Werewolfy
.
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| User: "mondo" |
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| Title: Re: Cassini Peeks at Titan |
06 Jul 2004 02:05:32 PM |
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I think you have me mixed with someone else Werewolf. I thought "Iggy Wiggy"
gave you the farewell a while back. Why are you still looking for that
******* anyhow?
"Werewolfy" <RickyColeclough@aol.com> wrote in message
news:85ebfda0.0407060946.7988d070@posting.google.com...
"mondo" <mondo@mondo.com> wrote in message
news:<lBpGc.8898$_L5.47525@newscontent-01.sprint.ca>...
Cassini Peeks at Titan
============================================================================
====
Oh, I see now. A space probe.
When I read the headline Iggy Wiggy, I thought it was a post about
your latest toilet exploit.
Werewolfy
.
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| User: "Jean Guernon" |
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| Title: Re: Cassini Peeks at Titan |
06 Jul 2004 02:13:48 PM |
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Werewolfy a écrit:
"mondo" <mondo@mondo.com> wrote in message news:<lBpGc.8898$_L5.47525@newscontent-01.sprint.ca>...
Cassini Peeks at Titan
================================================================================
Oh, I see now. A space probe.
When I read the headline Iggy Wiggy, I thought it was a post about
your latest toilet exploit.
Werewolfy
Lots of methane clouds there nonehteless! ;-)
J.
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